PHOTOCHEMICAL AIR POLLUTANT
EFFECTS ON MIXED CONIFER ECOSYSTEM!
A Progress Report
CERL-026
orvains
nvironmental
=1 esearch
¦laboratory
200 S.W. 35th STREET
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PHOTOCHEMICAL AIR POLLUTANT
EFFECTS ON MIXED CONIFER ECOSYSTEMS
A Progress Report
CERL-026
by
R. N. Kickert, P. R. Miller, 0. C. Taylor,
J. R. McBrlde, J. Barbieri, R. Arkley,
F. Cobb, Jr., D. Dahlsten, W. W. Wilcox,
J. Wenz, J. R. Parmeter, Jr., R. F. Luck,
M. White
Statewide A1r Pollution Research Center
University of California
Riverside, California 92502
Contract No. 68-03-0273
Project Officer
R. G. Wilhour
Terrestrial Ecology Branch
Ecological Effects Research Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
CORVALLIS, OREGON 97330
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DISCLAIMER
This report has been reviewed by the Corvallis Environmental
Research Laboratory, U.S. Environmental Protection Agency, and approved
for publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection
Agency, nor does mention of trade names or commercial products consti-
tute endorsement or recommendation for use.
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ABSTRACT
In 1972, a multi-disciplinary team of ecologists assembled to
monitor and analyze some of the ecological consequences of photochemical
oxidant air pollutants in California Mixed Conifer Forest ecosystems of
the San Bernardino Mountains east of Los Angeles. The purposes included
gathering documentary evidence on the impact on these forests, design-
ing a computerized data management system to process the data, and con-
structing computer simulation models to project possible future conse-
quences. Seven meteorological and air quality monitoring stations have
been maintained, nineteen mountain study plots have been examined for
air pollution injury to vegetation, and a variety of additional plots
have been identified for studying soil conditions, tree growth and
death, tree diseases, bark beetle interactions, needle litter build-up
beneath trees, decay of dead wood in the forest, microarthropods in
the litter, and microbial breakdown of pine needles. Additional work
examines conifer tree seed production in relation to small mammal popu-
lations and oxidant levels, as well as long-term changes occurring
in the kinds of trees present.
From the late 1960's, through the present 1974, documentary evi-
dence shows that both concentration and dose of oxidant air pollutants
are continuing to increase at locations in the San Bernardino Mountains
and extremely exceed Federal Air Quality Standards. This condition
can influence infection and colonization by Fomes annosus, one of a set
of processes contributing to tree mortality. The rate of bark beetle
attack was lower on individual oxidant-injured ponderosa pines, but
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fewer beetles were required to kill oxidant-injured trees. These for-
ests have no noticeable shortage of necessary plant nutrients in the
soils, but a drought stress to vegetation, beginning in July and August,
is preceded by an active growth period beginning in May. Air pollution
injury to vegetation can be expected to increase during this acceler-
ated growth period. Between 1973 and 1974, visible air pollution
injury to pine trees increased in 37 percent of the study plots, while
the annual death rate per plot was ten times greater in areas showing
at least slight visible injury, compared to plots having very slight
or no visible injury.
Merchantable volume growth of ponderosa pine trees, 30 years of
age, is reduced by 83 percent in zones of highest ozone concentration.
Pine needles fall from the trees and accumulate on the ground at a
faster rate as visible oxidant injury increases to a moderate level.
With increasingly severe injury, needle litter production falls off,
since fewer and smaller needles are produced under these conditions.
A decrease in the abundance and diversity of small mammal populations
is found on sites subjected to greater oxidant concentrations.
This report was submitted to describe the progress of Contract
Number 68-03-0273, by the Statewide Air Pollution Research Center,
University of California, Riverside, sponsored by the Environmental
Protection Agency. Work has not yet reached completion.
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CONTENTS
Page
List of Figures ix
List of Tables xv
Acknowledgements xvii
SECTIONS
I Introduction 1
II Conclusions 7
Regarding the Process of Deriving Recommendations 7
Regarding the Forest Ecosystems 7
Regarding Ramifications for Society 16
Regarding Appropriateness of New Research Methods 17
III Recommendations 19
IV Climate and Present Structure of the Mixed Conifer Forest
Ecosystems 27
Climate 27
Temporal and Spatial Trends of Temperature and
Precipitation 27
Topography, Meteorology and Pollutant Transport 30
Soils 36
Soil Classification for the San Bernardino Mountain
Study Plots 37
Chemical and Physical Soil Morphology 39
Particle Size Distribution 40
Bu:lk Density of Soils 43
Exchangeable and Soluble Cations 45
Soil Organic Matter 46
Soil Water Available for Vegetation Growth 46
Amounts of Organic Litter on the Forest Floor 47
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CONTENTS (Continued)
Sections Page
Vegetation 51
Importance 51
Vegetation Zones 52
Vegetation Types 52
Study Plots Within Vegetation Types 54
V Toward Forecasting Alternative Future Ecosystem Responses 63
Ecosystem Modeling 53
Background and Project Objectives 63
Purposes for Building Computer Simulation Models
of Ecosystem Level Response to Photochemical Air
Pollutants 66
Brief Review of Past Research in Support of
Assumptions 69
Subsystems of the Forest Ecosystems and their
Investigators 75
Methods of the Modeling Design and Development
Process 78
The Data Management System 85
Data Capture 86
The Data Bank 87
Data Manipulation 91
Trends of Photochemical Air Pollutant Concentrations
During Growing Seasons 92
Oxidant Trends in Downtown San Bernardino and at
a Nearby Mountain, Forest Station 92
Comparative Daily Maximum Hourly Averages for
Ozone, Total Oxidant, Peroxyacetyl Nitrate (PAN),
and Nitrogen Dioxide (NO2) at Sky Forest,
August 1974 97
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CONTENTS (Continued)
Sections
Comparative Hourly Concentrations of Total
Oxidant, Nitrogen Dioxide (NO2) and
Peroxyacetyl Nitrate (PAN)
Page
98
Definition of the West to East Gradient of
Surface Total Oxidant Concentrations in the
San Bernardino Mountains, 1974 100
Mountainous Surface Windflow and Pollutant
Dispersion 104
Processes in Ecosystems — Impacts on Vegetation
Injury, Mortality, and Litter Accumulation 108
Oxidant Dose/Vegetation Injury Response 108
Oxidant Effects on Tree Growth 124
The Climate in the Soil and the Drought Stress 138
Effects on Epidemiology of Forest Tree
Pathogens 147
Oxidant Effects on Bark Beetle Infestations 1^9
Oxidant Effects on Pine Needle Litter Production
on the Forest Floor -173
Processes in Ecosystems — Impacts on Litter
Decomposition 177
Effects on Major Decay Fungi of Woody
Litter 177
Effects on Microarthropods in Forest Litter and Soil
181
Effects on Microbial Activity in Needle
Litter Decomposition and Nutrient Cycling 19Q
Consequences for Renewal of Biological Resources for
Human Welfare 199
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CONTENTS (Continued)
Sections Page
Cone and Seed Production for Dominant
Conifer Tree Reproduction 199
Distribution and Role of Wildlife Populations
under Oxidant Pollutant Stress 210
Long-Term Change in Forest Composition:
Succession of the Vegetation 221
VI References 226
VII Glossary 236
VIII Appendices 246
viii
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1
2
3
4
5
6
7
8
9
10
11
12
13
LIST OF FIGURES
Page
Location of study plots in the San Bernardino National
Forest 4
Long-term Weather Bureau records for monthly means of
temperature and precipitation at Lake Arrowhead and
Big Bear Lake Dam 28
Major topographic features of the Los Angeles Basin
showing the aircraft flight routes and ground stations
used by Edinger et al. (1972) to describe the
daily inland and upslope flow of polluted air. 32
Daily increase of upslope advection at 1200, 1400, and
1600 hr from the basin across the Lake Arrowhead area 33
The annual cycle of monthly photochemical oxidant
concentrations at Sky Forest, California, 1973-1975 35
Three representative soil profiles of particle size
distribution 41
Average particle size distribution of soils of study
plots 42
Representative soil bulk density profiles on study plots 44
Comparison of thicker forest floor litter at Sky Forest
with Snow Valley, and an example of excessive litter
and heavy fuel accumulation at Sky Forest 50
Vegetation zones of the San Bernardino Mountains 53
Overstory vegetation type map of the San Bernardino
Mountains 55
East-West distribution of vegetation types in the San
Bernardino Mountains 56
Tree species composition of five permanent plots 60
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15
16
17
18
19
20
21
22
23
24
25
26
Page
Aerial views of study plots which represent five conifer
forest types in the San Bernardino Mountains; from top
to bottom:
a) Ponderosa type, Camp Paivika
b) Ponderosa-White Fir type, Sky Forest
c) Ponderosa-Jeffrey pine, Barton Flats
d) Jeffrey pine-White Fir type, Bluff Lake
e) Jeffrey pine type, Holcomb Valley 61
Objectives for the study of effects of ambient oxidant
pollutants on mixed conifer forest ecosystems 65
Subsystems being investigated by various project
investigators within the forest ecosystem 76
The system simulation modeling process 79
Needle litter and woody litter production subsystem 84
The arthropod data capture system 88
Basic design philosophy of 'Master Control' 89
The San Bernardino Data Management System 90
Number of hours of total oxidant, July through September,
greater than or equal to 392 jig/m3 (0.20 ppm) at the
downtown San Bernardino County Air Pollution Control
District Station, 1963-1974, and Rim Forest/Sky Forest,
1968-1974 94
Monthly summation, June through September, 1968-1974,
of total oxidant dose, and total number of hours at a
dose greater than, or equal to, 157 yg/tn3 (0.08 ppm),
at Rim Forest/Sky Forest 96
Comparative daily maximum hourly averages for ozone,
total oxidant, PAN, and N02 at Sky Forest, August 1974 98
Comparative hourly concentrations of total oxidant, PAN,
and NO2 at Sky Forest, November 18, 19, 1973, and total
oxidants at Big Bear Ranger Station and Barton Flats 99
Topographic projection of the San Bernardino Mountains
showing monthly summation, June through October 1974,
of total oxidant dose at seven monitoring stations 101
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Figure
Page
27 Topographic projection of the San Bernardino Mountains
with a comparison of total daylight and night hours
during August, September, and October 1974, when total
oxidant concentrations were greater than, or equal to,
157 ug/m3 (0.08 ppm) at seven air monitoring stations 103
28 Surface wind fields generated from a computer model for
1300 hr PST, August 31, 1974, for a limited portion of
the study area (see caption in next figure) 105
29 Wind direction and speed at selected surface stations
at 1300 hr PST, August 31, 1974, compared with the
concentration of total oxidants at 1200, 1300, and 1400
hours PST 106
30 Oxidant dose/vegetation injury subsystem 109
31 Chlorotic mottle, necrosis caused by an experimental
ozone fumigation, and superficial necrotic flecks not
associated with oxidant injury but rather winter weather 110
32 Development of oxidant injury symptoms on current, and
current plus one year old, needles of ponderosa pine
saplings, in relation to stage of current year needle
growth and time during the summer season and in relation
to total dose of oxidant 112
33 Topographic projection of the San Bernardino Mountains,
showing a comparison of oxidant injury to black oaks at
major study sites, August 31, 1974 with accumulated
total oxidant dose, June-August, measured at nearby
monitoring stations 115
34 Examples of oxidant injury, chlorotic mottle followed
by interveinal necrosis, to leaves of black oak,
Quercus kelloggii 116
35 A fish eye lens view of the crowns of severely oxidant
injured ponderosa pines with another stand having slight
injury. Each tree is scored for needls retention,
needle condition, needle length, and branch mortality
by binocular inspection. 117
36 Topographic projection, San Bernardino Mountains, show-
ing how ponderosa and Jeffrey pines, in major study
sites, are distributed in six injury classes in rela-
tion to seasonal dose of total oxidant 118
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Figure
Page
37 Vegetation growth subsystem 124
38 Aluminum framed greenhouse covered with transparent
plastic film and provided with a carbon filter-blower.
Carbon filters were removed to obtain the ambient air
treatment in a second house 125
39 The appearance of a typical upper crown branch from a
ponderosa pine exposed to ambient oxidant air pollutants
in a greenhouse for 5 years shows fewer and shorter
needles. A similar branch exposed to carbon filtered
air retains more needles which are longer; at the outset
of the experiment, this branch resembled the one on the
left 126
40 Injury score of current plus one-year needles, 1968-
1973, from ponderosa pine saplings maintained in fil-
tered (FAH), or unfiltered air greenhouse (AAH), and an
outside ambient air treatment (AAO) 127
41 Average dry weight of all needle fascicles per inter-
node in filtered (FAH), or unfiltered air greenhouse
(AAH), and an outside ambient air treatment (AAO) 128
42 Annual growth of the terminal shoot and first order
branches in upper half of sapling from ponderosa pine
maintained in filtered (FAH), or unfiltered air green-
house (AAH), and an outside ambient air treatment (AAO) 130
43 Calculated average cross-sections of two 30-year-old
ponderosa pines at breast height grown in polluted air
and in non-polluted air based on radial growth samples
from 1941-1971 and 1910-1940 132
44 Calculated average growth of 30-year-old ponderosa
pines in polluted and non-polluted air based on radial
growth samples from 1941-1971 and 1910-1940 134
45 The place of the soil subsystem in the ecosystem 139
46 Portable soil moisture meter temporarily attached to
fiberglass moisture blocks installed permanently at
depths from 15 to 174 cm. At the same site are cans
for collecting crown drip and screens for collecting
litter fall. 140
47 Soil moisture and temperature regime 1973-74 at
Dogwood plot 141
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Figure Page
48 Time intervals during which the soil at various depths
contained moisture available for plants during spring
and summer 1974 1^3
49 Crown drip cation concentration in relation to distance
from ponderosa pine tree trunk 147
50 Crown drip cation concentration in relation to oxidant
injury score of ponderosa pine 148
51 The disease subsystem in the ecosystem 150
52 Conceptual model of oxidant effects on the Fomes
annosus root disease 151
53 Bark beetle subsystem in the ecosystem 163
54 Graphic summary of the population sampling procedures
used for the western pine beetle, showing data sets
and the type of information included for the San
Bernardino study 165
55 Mass of ponderosa pine needle litter-fall compared to
oxidant injury score, 1974; for Camp Paivika plot to
Camp 0-0ngo plot 175
56 Ponderosa and Jeffrey pine needle-fall compared to
oxidant injury score, September-December, 1973 and 1974 176
57 Woody litter decay subsystem 178
58 Agar-block screening test for establishing ability of
fungi to decay wood, showing a range in fungal ability
to invade wood blocks 180
59 Litter microarthropod decomposer subsystem 182
60 Needle litter decomposition subsystem 191
61 Source and location of decomposition study envelopes 193
62 Conifer seed production subsystem 200
63 Examples of Keen's tree age and growth vigor classes
for east side Sierra Nevada and southern California
ponderosa pine (Keen, 1936) 204
64 Wildlife subsystem 211
xiii
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Figure Page
65 Number of small mammals caught per year per plot 214
66 Number of small mammals caught on plots with light,
moderate, and heavy oxidant air pollutant levels 215
67 Immature cones stripped of seed by the gray squirrel
compared to a single mature cone of ponderosa pine 217
68 Comparison of cone utilization by gray squirrels in
1973 and 1974 by plot 218
69 Extremes of weekly cone utilization by gray squirrels
in 1974 220
70 Age distribution for various tree species at Dogwood
plot 224
71 Age distribution for various tree species at Sand
Canyon plot 225
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LIST OF TABLES
Table Page
1 COMPARISON OF MEASURED AND PROJECTED MEAN ANNUAL
PRECIPITATION FROM SAN BERNARDINO COUNTY FLOOD
CONTROL DISTRICT STATIONS NEARBY THE PERMANENT
VEGETATION STUDY PLOTS 29
2 WINTER PRECIPITATION, 1973-1974, AND 1974-1975
AT EACH MAJOR VEGETATION STUDY PLOT, DETERMINED
BY SNOW STORAGE GAUGES, SEPTEMBER 15 TO MAY 1 31
3 MASS AND THICKNESS OF THE FOREST FLOOR ON MAJOR
STUDY PLOTS 49
4 TREE LAYER DATA FROM PLOTS REPRESENTATIVE OF EACH
VEGETATION TYPE DOMINATED BY PONDEROSA OR JEFFREY
PINE IN THE SAN BERNARDINO MOUNTAINS 58
5 POTENTIAL COUPLINGS BETWEEN STRESSED ECOSYSTEM
RESPONSES AND SOCIO-POLITOCO-ECONOMIC SYSTEMS
UNDER VARIOUS FOREST LAND-USE POLICIES 81
6 OXIDANT INJURY SCORES AND MORTALITY RATES OF PONDEROSA
AND JEFFREY PINES AT 18 MAJOR STUDY PLOTS, 1973-1974 120
7 OXIDANT INJURY SCORES OF WHITE FIRS, INCENSE CEDARS,
AND SUGAR PINES AT 18 MAJOR STUDY PLOTS, 1973-1974 122
8 AVERAGE ANNUAL RADIAL GROWTH OF 19 PONDEROSA PINE
TREES IN TWO LEVELS OF OXIDANT AIR POLLUTANTS 131
9 CORRELATIONS BETWEEN PONDEROSA PINE RADIAL GROWTH (Y)
IN CENTIMETERS AND OXIDANT INJURY SCORE (X) 135
10 CHANGES OF TIMBER VOLUME AND PERCENT OF TOTAL
JEFFREY PINES IN FOUR BARK BEETLE RISK CLASSES AT
TWO CONTROL PLOTS EXCLUDED FROM SANITATION SALVAGE
LOGGING BETWEEN 1952 AND 1972 AT BARTON FLATS IN THE
SAN BERNARDINO NATIONAL FOREST 136
11 INFECTION AND COLONIZATION BY Pomes annosus OF OXIDANT
INJURED JEFFREY AND PONDEROSA PINE TREES IN NATURAL 152
STANDS
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Table
Page
12 INFECTION OF OZONE FUMIGATED AND UNFUMIGATED JEFFREY
AND PONDEROSA PINE SEEDLINGS BY Fomes annosus 153
13 RELATIONSHIP OF CHRONIC OZONE INJURY OF PONDEROSA AND
JEFFREY PINE SEEDLINGS TO COLONIZATION OF ROOT CROWN
TISSUE BY Fomes anno8us 155
14 WESTERN PINE BEETLE EGG DISSECTION DATA GROUPED BY
GENERATION AND OXIDANT INJURY CLASS, 1973-1974 170
15 CONTENT OF NUTRIENT ELEMENTS IN NEEDLE FALL COLLECTED
IN AUTUMN, 1973 177
16 MEAN NUMBER OF MICROARTHROPODS IN SELECTED TAXONOMIC
GROUPINGS IN LITTER SAMPLES FROM BENEATH TWO TREES
AT THREE MAJOR PLOTS, NORTHEAST GREEN VALLEY (NEGV),
SNOW VALLEY (SV), AND BREEZY POINT (BP) 188
17 MEAN NUMBERS OF TOTAL MICROARTHROPODS UNDER INDIVIDUAL
TREES OF DIFFERENT OXIDANT INJURY AT NORTHEAST GREEN
VALLEY (NEGV), SNOW VALLEY (SV), AND BREEZY POINT
(BP), 1973 189
18 DESCRIPTION OF CROWN CLASS CHARACTERISTICS 203
19 INFLUENCE OF CROWN CLASS ON THE NUMBER OF TREES
WHICH PRODUCED CONES AND THE NUMBER OF CONES PRO-
DUCED BY PONDEROSA AND JEFFREY PINE IN 1973 AND
1974 IN 18 PLOTS 206
20 CONIFER SEED PRODUCTION FROM SELECTED STUDY SITES 208
21 SMALL MAMMAL SPECIES CAPTURED PER PLOT, 1972-1974 213
xvi
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ACKNOWLEDGEMENTS
Administrative services for the project are coordinated by O.C.
Taylor, Associate Director, Statewide Air Pollution Research Center,
University of California, Riverside.
Portions of this report were contributed by the following
investigators:
Pag
es
Authors
Section
21-26
0. C. Taylor
Introduction
Section IV
Climate and Present
Structure of the
Mixed Conifer Forest
Ecosystems
27-35
Paul R. Miller
USDA, Forest Service
Pacific Southwest Forest &
Range Experiment Station
Stationed at the Statewide
Air Pollution Research Center
University of California
Riverside, California
and
R. J. Arkley
Dept. of Soils & Plant Nutrition
University of California
Berkeley, California
Climate
36-51
R,. J. Arkley
Soils
51-62
Joe R. McBride
Dept. Forestry & Conserv.
University of California
Berkeley, California
Vegetation
xvii
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Pages
Authors
Sec t ion
63-85
85-92
92-103
104-108
108-123
124-138
138-147
147-159
R. N. Kickert Section V
Dept. of Forestry & Conserv. Toward Forecasting
University of California Alternative Future
Berkeley, California Ecosystem Responses
Ecosystem Modeling
J. Barbieri
Lawrence Livermore Laborato
Liverraore, California
The Data Management
y System
Paul R, Miller Trends of Photochemical
Air Pollutant Concen-
trations During Grow-
ing Seasons
Bill C. Ryan
USDA, Forest Service
Forest Fire Laboratory
Riverside, California
Paul R. Miller
Joe R. McBride
and Paul R. Miller
R. J. Ark ley
and R. L. Gersper
R . L . James,
F. W. Cobb , Jr. ,
J . R . Parmeter, Jr.,
N, L. Bruhn
Dept. of Plant Pathology
University of California
Berkeley, California
and
Paul R. Miller
Mountainous Surface
Windflow and Pollu-
tant Dispersion
Oxidant Dose-Vegetation
Injury Response
Oxidant Effects on
Tree Growth
The Climate in the Soil
and the Drought Stress
Effects on Epidemiology
of Forest Tree
Pathogens
xviii
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Pages
Authors
Section
159-173
173-177
177-181
181-190
190-198
199-210
210-221
D, L. Dahlsten, Oxidant Effects on
R. J. Swift Bark Beetle Infesta-
Dept. of Entomological Sciences tions
University of California
Berkeley, California
and
J. Barbieri
R. J. Ark ley, and
R. L. Gersper
Oxidant Effects on Pine
Needle Litter Produc-
tion on the Forest
Floor
W. W. Wilcox
University of California
Forest Products Laboratory
1301 S. 46th Street
Richmond, California
Effects on Major Decay
Fungi of Woody Litter
J. M. Wenz, Effects on Micro-
D. L. Dahlsten arthropods in
Dept. of Entomological Sciences Forest Litter and
University of California Soil
Berkeley, California
and
J. Barbieri
J. N. Bruhn,
J. R. Parmeter, Jr.,
F. W. Cobb, Jr.
Effects on Microbial
Activity in Needle
Litter Decomposition
and Nutrient Cycling
Robert F. Luck
Dept. of Entomology
University of California
Riverside, California
Cone and Seed Produc-
tion for Dominant
Conifer Tree
Reproduction
Marshall White,
and K. McDonald
Dept. of Forestry & Conserv.
University of California
Berkeley, California
Distribution and Role
of Wildlife Popula-
tions Under Oxidant
Pollutant Stress
xix
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Pages Authors
Section
221-225 Joe R. McBride Long-term Change in
Forest Composition:
Succession of the
Vegetat ion
The efforts of Henry P. Milligan, Joanne Leung, John Zorich and
James O'Connor at Riverside, California, are greatly appreciated in
relation to oxidant air pollutant monitoring and oxidant dose-plant
injury studies. Appreciation is expressed to Dave Nichols, Geography
Department, U. C. Riverside, for use of the figure described as a
topographic projection of the San Bernardino Mountains and to the San
Bernardino County Air Pollution Control District for oxidant concentra-
tion data at Lake Gregory and Big Bear Lake.
The study concerned with epidemiology of forest tree pathogens has
received necessary assistance from A. R. Weinhold, N. McKibbin, B.
Uhrenholdt, R. Ratto, J. N. Bruhn, D. J. Goheen and I. F. Alvarez.
With regard to the study of oxidant effects on bark beetle infesta-
tion, grateful appreciation is given to the personnel of the U.S. Forest
Service and the State Division of Forestry for their continued assist-
ance. We would further like to acknowledge Messrs. Ken Swain and Max
Ollieu of U.S. Forest Service Regional Office, Branch of Pest Control,
in San Francisco, for their cooperation. We also express our gratitude
to Ms. J. D. Wall, Messrs. W. A. Copper, D. E. Walter and D. J.
Voegtlin, and Drs. F. M. Stephen and R. F. Luck from the University of
California, for the many hours of laboratory and field assistance with-
out which this study could have never been undertaken.
xx
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The study concerning effects on microbial activity in litter
decomposition and nutrient cycling received the helpful attention of
D. Goheen and B. Uhrenholdt. Field assistance was given by John Harper
and Glen Scriven in that part of the program concerned with cone
productivity on the study plots.
Sincere appreciation is expressed for the participation and coop-
eration of the following individuals whose work was essential to the
vegetation subcommittee: Richard and Nikki Laven, Vaiva and John
Semion, Chal Landgren, William Perkins, Mike Schnitzer, Art and Dee
Stackhouse, Tana Hill, and Dr. Paul Miller.
A special expression of gratitude is extended to Frances Powell,
and the Office of Admissions and Records at the Berkeley campus, for
executing some automated editing procedures on the manuscript.
Editorial functions and final preparation of graphics for the
manuscript were done by Ronald N. Kickert and Paul R. Miller.
xxi
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SECTION I
INTRODUCTION
Since 1972, a multidisciplinary study has been underway to deter-
mine the impact of oxidant air pollutants on the mixed conifer forest
ecosystem in general, and on two dominant tree species (ponderosa, Pinus
ponderosa Laws, and Jeffrey pine, £. jeffreyi Grev. and Balf.), in par-
ticular. The ecosystem studied was in the San Bernardino National
Forest (SBNF) in southern California. The study is supported through
a contract with the Environmental Protection Agency. This effort
involves researchers on the Riverside and Berkeley campuses of the
University of California and from the U.S. Forest Service, Pacific
Southwest Forest and Range Experiment Station. The San Bernardino
National Forest is administered through the local U.S. Forest Service,
Supervisor's Office in San Bernardino, California. A large measure
of progress in the study has resulted from the helpful cooperation
of District level Forest Service personnel.
The SBNF includes approximately 64,750 ha (160,000 acres) of
mixed conifer and hardwood forest extending from Cajon pass northwest
of San Bernardino, and eastward to the San Gorgonio pass near Palm
Springs. The SBNF consistently has been the most frequently visited
National Forest in the United States with 6.0 million visitors in
1973. The areas included in the study range from 1368 to 2279 m
(4,500 to 7,500 feet) elevation.
The SBNF lies at the north and east boundaries of the South Coast
Air Basin (SCAB). Extensive urban and industrial development in the
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SCAB since 1940 has caused a rapid increase in oxidant air pollutants.
Combustion of petroleum base fuels for transportation, generation of
power and industrial operations release massive amounts of nitrogen
oxides and reactive hydrocarbons to the atmosphere.
Photochemical reactions involving these compounds generate ozone
(03) and peroxyacetyl nitrates (PANs) and intermediate compounds. Ozone
and PANs are both strong phytotoxicants and the PANs are strong lachry-
mators. Ozone concentrations frequently exceed 600 pg/m3 (30 parts
per hundred million (pphm)) in the SCAB and occasionally reach levels
of 1200 pg/ra^ (60 pphm); it accounts for approximately 85"i of the total
oxidant measured in polluted atmospheres. PANs seldom exceed 30 parts
per billion (ppb), but they are many times more phytotoxic than ozone.
The strong thermal inversions which characteristically form over
the basin, and the daytime, eastward drift of marine air under the
inversion provides an ideal delivery system to transport pollutants
from the basin to the SBNF. Typically the overall dosage of oxidant
pollutants in exposed parts of the forest exceeds that received by
areas in the SCAB.
Unusual injury symptoms, principally to ponderosa pine, i.e., a
characteristic type of needle mottle, defoliation, short needles and
reduced twig growth, were first recognized in the SBNF in the early
1950's. These symptoms were subsequently determined to be caused
by exposure to oxidant air pollutants. While the injury was severe
on many ponderosa pines in the area, early researchers observed that
some companion species were much more tolerant and that individuals
in the ponderosa species were more tolerant than others. Pollutant
2
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injured trees were observed to be more susceptible to bark beetle attack.
Consequently pollutant injury and the increased activity of bark beetles
have led to a forest management practice called sanitation salvage log-
ging, which requres an increasing amount of harvest of oxidant-injured
ponderosa and Jeffrey pines considered to have a high risk of being
attacked by bark beetles.
Loss of timber volume can be considered significant but the
greatest economic and esthetic impact is presently on the recreational
and watershed values. Direct effects on major tree species can be
observed, and short-term economic loss may be estimated; but, the long-
term effects of oxidant injury and present management practices on the
total ecosystem, which will irreversibly alter the total character of
the forest, are only dimly perceived.
The present study is intended to identify and, where possible,
measure the direct and indirect effect of the oxidant pollutants on
interdependent populations in the forest. Results from investigations
into oxidant pollutant interaction with vegetation successional trends
and with dependent populations of consumers, decomposers, and with the
management practices imposed on these populations will be used to
construct models useful in predicting future events.
In Figure 1, the detailed locations of various study sites (large
rectangles) in the SBNF are shown on a background of the overstory
vegetation types defined by U.S. Forest Service timber inventory stand-
ards. The most important sites are the 19 major vegetation plots which
are located along a decreasing gradient of total oxidant dose in a west
to east direction. One of the most important kinds of data gathered is
3
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the oxidant injury score of trees, herbs and shrubs.
Air monitoring stations, all measuring total oxidants, are similar-
ly distributed. The stations located at Camp Paivika (CP), Sky Forest
(SF), and Barton Flats (BF) telemeter ozone concentrations, wind, tem-
perature, relative humidity, and net radiation to a master station at
the U.S. Forest Service Fire Laboratory in Riverside. The stations are
normally polled once hourly throughout the May-October period. The
station at Sky Forest also measures peroxyacetyl nitrate (PAN), nitrogen
dioxide, sulfur dioxide, and particulates including lead. Wind speed
and direction are available at several Forest Service stations once
daily. These are indicated by an elbow-shaped symbol.
Other special experimental plots have been established to describe
the characteristics of surviving or new vegetation in areas which
represent a variety of elapsed times after wildfires. These succession-
al stages are usually comprised of fewer species than the mature or
climax conifer forest and may have less resiliency to oxidant stress.
The population dynamics of pine bark beetles are studied by locat-
ing infested ponderosa or Jeffrey pines as soon as possible after ini-
tial attack. This kind of sample plot may consist of only one tree at
a given site. These plot locations for 1973 and 1974 are indicated
by open circles enclosing numerals. The numeral describes the genera-
tion of the insect for each year. The dark squares represent three
plots ranging up to 90 X 120 m in size which are cooperatively studied
by the vegetation and bark beetle subprojects. An attempt is being
made to relate the degree of oxidant injury to ponderosa pine with the
probability of bark beetle attack.
5
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Plots to study rate of natural spread of F. armosus root disease
from dead stump(s) representing the point of initial infection at a
site to nearby trees are represented by a dark circle. The locations
of semipermanent F. annosus root inoculation studies, e.g. near Snow
Valley are not shown.
Other research projects are located nearby or within each of a
selected number of the major vegetation plots. Some examples include:
1. Collection and measurement of winter precipitation.
2. All year measurements of soil temperature and soil moisture
depletion and recharge cycles.
3. Collection and measurement of litter fall; studies of litter
decomposition including decomposers (fungi and microarthro-
pods).
4. Measurement of cone and seed production.
5. Trapping of small mammals.
6. Annual inspection to detect the incidence of other insect and
disease pests.
7. Analysis of stand age and structure.
Project personnel work out of a common lodging place located at
Running Springs which can be identified in Figure 1 as a triangular
symbol for an air monitoring station just east of the Camp O-ongo (COO)
vegetation plot.
6
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SECTION II
CONCLUSIONS
REGARDING THE PROCESS OF DERIVING RECOMMENDATIONS
Since this is a systems project, and since a systems ecologist was
only recently added to the project in early 1975, it is inappropriate,
and would be misleading, to give air quality management and forest re-
source management recommendations unless and until they can be based
upon systems analysis and computer simulation of the systems. To do
otherwise, would lead to fragmented recommendations which would not
evaluate the various ecological impacts caused throughout the system
from the possible implementation of such recommendations.
REGARDING THE FOREST ECOSYSTEMS
Trends in the Oxidant Air Pollution Climate
An inescapable consequence of the particular topography and meteor-
ology of the South Coast Air Basin, including the San Gabriel and San
Bernardino mountains, is the deep and frequent penetration of oxidant
polluted air into the montane conifer forests east and northeast of
Los Angeles. Year to year changes in the frequency of high air pollu-
tion episodes in this air basin are closely correlated with one partic-
ular synoptic pattern, namely, a persistent upper level (500 mb) high
pressure system over the southwest.
Comparisons of total oxidant dose, during the June through
7
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September period in the Rim Forest/Sky Forest area of the San Bernar-
dino mountains since 1968, suggest that the annual doses in this
period have remained high and did definitely increase in 1974.
Another comparison of episodes when total oxidant concentrations
have exceeded 329 yg/m3 (0.20 ppm), during July through September from
1963 to 1974 in downtown San Bernardino, and at Rim Forest/Sky Forest
in the mountains from 1968 to 1974, shows an alarming increase at both
stations even when 3-year moving averages are used to help remove some
of the variability due to meteorology. The worst year on record at
both stations was 1974.
A network of seven air monitoring stations, located along a 25-
mile long west to east transect (between the elevations of 1617 m in
the west and 2067 m in the east) in the San Bernardino mountains in
1974, have shown that total oxidant dose is 2/3 lower on the eastern
end. The western portion generally receives more nighttime hours of
high total oxidant concentrations.
Impacts on Vegetation Injury, Mortality, and Litter Accumulation
Oxidant Effects on Forest Tree Pathogens
Preliminary observations show that oxidant air pollutants may
reduce the resistance of conifer tree roots to infection by the dis-
ease fungus Fomes annosus. If this conclusion is substantiated by
data from work not yet completed, increased destruction by F. annosus
in the future is quite possible. Another important consideration is
that the fungus often causes greater damage in forests which are cut
periodically. This situation occurs throughout the San Bernardino
8
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Mountains due to necessary removal of air pollution and disease/insect
killed trees. Therefore, F. annosus, currently an important and wide-
spread pathogen in the area, may become even more damaging in the future.
Oxidant Effects on Bark Beetle Infestations
The western pine beetle attacks and kills trees over a consider-
able period of time during the course of a year, but for purposes of
sampling, two peak periods of attack during a year are considered, and
these are treated as generations. There is an early summer generation
and a late summer generation which is the overwintering generation.
The only information summarized and analyzed in a cursory manner
is the egg data. From a look at this information, it appears that the
populations of western pine beetle in the San Bernardino Mountains of
southern California are unique when compared with populations at
Blodgett Forest in northern California, an area not attacked to any
large extent by photochemical air pollutants.
Attack rates of beetles in the San Bernardino area varied by gen-
eration and by oxidant air pollutant-tree injury class. Attack rates
in the first generation were higher than those in the second generation
in both 1973 and 1974. Attack rates were generally higher on those
trees with the least amount of oxidant air pollutant injury. Attack
rates in the first generation of 1973 were much higher in the SBNF
than those recorded at any time at Blodgett Forest.
The number of eggs deposited per centimeter of gallery length was
usually lower in the first generation than in the second generation.
This is similar to the pattern of egg deposition at Blodgett Forest.
9
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However, the mean number of eggs per centimeter of gallery in pollutant
injured trees in the SBNF was much lower than the rates recorded at
Blodgett Forest.
The mean percentage of hatched eggs, which can be used as an indi-
cator of egg mortality, was similar in the first generation in the SBNF
and unpolluted Blodgett. In the SBNF, survivorship was much greater
in the first generation than in the second generation, a pattern which
did not occur at Blodgett. Also, survivorship was generally higher in
oxidant-injured trees.
These data have not been analyzed statistically but the trends
indicate that further summarization and analysis of all data sets will
yield information to show that the interaction between oxidant-injured
stands of trees and western pine beetle populations is indeed unique.
From a cursory look at one data type, it can be concluded that
photochemical air pollutants affecting ponderosa pine can indirectly
depress attack rates of the western pine beetle, have a variable effect
on, but possibly depress, the mean number of eggs per centimeter of
gallery length, and increase egg survivorship rates.
The California flatheaded borer was found to be an important
competitor with the Jeffrey pine beetle.
Soil Climate and Drought Stress on Vegetation
The soil moisture regime has been documented for 23 sites begin-
ning in the summer of 1973 to the present and measurements are contin-
uing, Soil moisture depletion is most rapid during June, and the upper
1.5 m of soil is depleted of soil moisture available for plants by
10
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about mid-July. However, some moisture at depths up to 2.7 m (9 ft)
is used by plants into August. The period of dynamic growth appears to
f
be from May to August, and it appears that air pollutant injury to
plants coincides with this period. The total storage capacity of soil
moisture available to pine trees in this system is generally consider
ably higher than the 15 cm often assumed in water balance studies.
Soil temperature regimes at 23 sites have been recorded since mid-
summer 1973. Preliminary analysis of the data suggest that mean annual
soil temperatures range from about 4.5 C to 11.5 C in the general study
area, with even higher soil temperatures on south facing aspects. Warm
and cold sites, dependent upon aspect and slope, can be found throughout
the range of air pollutant concentration.
Precipitation was collected both outside and under the crown of
a number of trees at Camp O-Ongo plot affected by air pollutants. It
was found that significantly more precipitation reached the ground
surface under the trees, than outside; this effect is assumed to be due
to the wind which causes the rain to fall at an angle rather than
vertically.
Soil Nutrients for Vegetation Growth
The concentration of cations in the precipitation is only 1/5 of
the concentration in the crown-drip near the trunk. The relationship
of the chemical composition of the cron-drip to air pollutant impact on
the trees is obscured by the variability due to differences in path of
water moving from needles to twigs to large limbs before falling to the
ground surface.
11
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Chemical analyses show that the soils generally contain adequate
mineral soil nutrients, especially calcium, which is often very low in
more humid forested soils. Also, the soils contain reasonably high
amounts of organic matter, and, with few exceptions, contain adequate
nitrogen for forest growth.
Vegetation Injury and Death
The relative doses of total oxidant received by ponderosa or
Jeffrey pines in 19 major vegetation plots along the oxidant monitoring
transect can be estimated from 1974 data. Going generally from west to
east, three plots were described as having severe injury, ten were
moderate, one slight, two very slight, and three had no visible
symptoms. The average amount of injury, based on scores of individual
trees, increased in seven of the 19 plots from 1973 to 1974.
During this period, the mortality of ponderosa and Jeffrey pines
ranged from 0.0 to 8.0 percent and averaged 2.9 percent in plots
categorized as slight, moderate and severe injury. Mortality was less
than 0.3 of one percent in the remaining plots described as very slight
and no visible injury.
At the end of August, 1974, observations of injury to black oaks,
where present in the 19 major vegetation plots, indicated a distinct
gradient of decreasing leaf injury in the first 2/3 of the west to east
transect.
So far, oxidant mediated mortality has not been observed in tree
species other than ponderosa and Jeffrey pines.
It is very important to understand that the present level of
12
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injury to woody vegetation is the result of annual doses of oxidant much
lower than those recorded in 1974. Since the 1974 oxidant dose was the
highest on record it should not be used alone to estimate vegetation
dose responses.
Oxidant Effect on Conifer Tree Growth
Quantification of the diminished needle leaf production and small
stem tissue production due to chronic oxidant exposure in sapling size
ponderosa pines suggests: (1) only a few trees may survive and grow
into larger size classes to replace dying overstory trees; (2) the
rate of growth of surviving trees will be slower, thus altering their
competitive ability with respect to competitors in both the understory
and overstory; (3) less materials and energy will be transferred to
the consumer and decomposer levels in the ecosystem; and (4) sapling
data from this study will enable estimates of biomass decreases in
larger trees which cannot be enclosed in greenhouse structures.
Oxidant air pollution in the forests of the San Bernardino Moun-
tains reduce the average annual diameter growth of ponderosa pine by
approximately 40% in trees under 30 years of age. Merchantable
volume growth of trees 30 years of age is reduced by 83% in the zones
of highest ozone dose. This reduction in growth, along with air pollu-
tant caused tree mortality, is of significance to the continued
production of timber in the San Bernardino Mountains.
Pine Needle Fall and the Forest Floor
»
Pine needle fall, collected on screens under trees in the fall of
1974, especially in the Lake Arrowhead regions, shows little accumula-
13
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tion under trees only slightly injured by oxidant air pollutants, a
marked increase under trees which were moderately affected, and a sharp
decline where trees were strongly injured. The latter case reflects
the scarcity and small size of needles which remain on the severely
injured trees.
The mass and length of the individual needle fascicles decreases
linearly with increasing air pollutant injury to the tree.
The thickness and mass of the forest floor (pine needle litter)
is shown to be greater at lower elevations, i.e. the Lake Arrowhead
Region and at Camp Angelus in the lower Santa Ana Canyon, than at higher
elevations. However, it was found that the thickness of the litter
layer was much more markedly reduced where disturbed by heavy recreation
activity or even by selective logging.
After selective felling of beetle infested trees or repeated sani-
tation salvage logging, particularly in the ponderosa pine and ponderosa
pine-white fir forest types, the accumulation of heavy fuels, e.g. slash,
represents a serious wildfire risk which would result in hotter fires.
Impacts on Litter Decomposition
As oxidant injury to conifer trees increases, the population sizes
of microarthropods acting as litter decomposers in the forest soil also
decrease .
Renewal of Mixed Conifer Forest Ecosystems as Biological Resources
In 1974, a larger than average cone crop was produced. Trees of
14
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dominant crown class were the greatest contributers: 73% of the trees
which bore cones in 1973 were dominant, and 63% of the trees in 1974
were dominant. When compared to the 197 3 crop, a greater percentage
of the 1974 crop was born by trees belonging to crown classes other
than dominant. Furthermore, those trees which bore cones in 1974
produced a larger number of cones per tree. A large number of factors
are known to affect cone crop size; hence, data from a period of
years are essential before the influence of some of these factors
can be sorted out.
The diversity and abundance of small mammals varies among the major
study plots. The data suggest relationships between oxidant dose,
oxidant injury rating of vegetation, and the number of small mammals
encountered.
The western gray squirrel, abundant throughout the forest eco-
system, feeds heavily on conifer seed by cutting green cones from the
trees. An alteration of the balance between pine and oak trees or a
change in the squirrel population due to oxidants, will affect the
balance of the seed-squirrel relationship and have a significant
influence on the forest, especially pine and oak regeneration. Most
cones are cut prior to seed maturity. Such destruction of the poten-
tial reproduction of conifer trees may be acting together with oxidant
injury to seriously reduce pine regeneration and thus hasten vegetation
change.
15
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REGARDING RAMIFICATIONS FOR SOCIETY
Decreased Timber Production
Some of the socio-economic consequences of the biological events
observed must be suggested. First, the potential productivity of the
forest for wood products must certainly decline. The merchantable
overstory has already been removed in some areas, and the rate of
growth of small timber into merchantable size classes is severely
restrained in the moderate and severely oxidant-injured areas. At this
point, there are no operational management practices known which can
ameliorate the continued losses.
Degraded Recreational Experience
Second, the quality of the recreational experiences of residents
and visitors will continue to decline. Published methods exist which
permit conversion of recreational pursuits into monetary values. The
San Bernardino National Forest continues to top the country's National
Forests in visitor-days of use at 6,053.5 M in 1973. The monetary
value of recreation enjoyed by visitors can range from $4,237.5 M
($0.70/person) to $45,401.3 M ($7.50/person) in 1971 dollars, based on
1973 visitor data. The difference is related to the type of recreation-
al pursuit. Visitors will enjoy much less for their investment. The
added stress to health by exposure to oxidant doses greater than in
the basin has not been included. Many recreational pursuits require in-
creased physical activity which only adds to the total stress.
16
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Conflict with Wilderness Ethic
Third, one of the most important characteristics of wilderness:
"where man has passed, let no sign of man remain", has been rendered
meaningless in portions of the San Gorgonio Wilderness Area. Oxidant
air pollution has brought this about in a unique manner.
REGARDING APPROPRIATENESS OF RESEARCH METHODS
The soils on the major study plyts have been classified according
to "Soil Taxonomy" (USDA - SCS 1973 preliminary text) and assigned soil
series names where applicable. The soil classification is adequate for
comparisons of the impact of a range of oxidant air pollutant on vege-
tation growing on essentially similar sets of soils.
Physical analyses of the soil show that most of the soils are
relatively uniform and low in clay content throughout the soil above
the contact with decomposed granite substrata. This simplifies the
possible comparison of the effect of soils on the relative air pollu-
tant injury to the vegetation. Two soil areas which have more clay in
the subsoil have similar soil temperatures but widely differing
intensity of air pollutant, so these two are suitable for comparison.
Studies were initiated on the mountain pine beetle and the Jeffrey
pine beetle in 1974. In an effort to develop sampling methods for both
these bark beetles, various sized samples were taken. These data have
not been thoroughly analyzed, but it appears that paired 500 cm 2
samples will be suitable for each species.
17
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The oxidant air monitoring network employed in 1974 provided a
good measure of the decrease of oxidant dose with distance from the
basin (SCAB); however, the complex effect of mountain terrain on sur-
face air flow and pollutant disperson will require that additional
temporary pollutant and wind monitoring stations be maintained in
selected configurations for short (1-2 weeks) periods.
The mathematical model of surface wind flow in mountainous
terrain, where no monitoring stations were available, promises to be a
feasible method for determining and describing, with sufficient
resolution, terrain influence on channeling and blocking of pollution
advection through forested areas.
18
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SECTION III
RECOMMENDATIONS
RESEARCH PLANNING
Objectives of this research program fall in two general categories.
The first objective is to gain a more clear understanding of the direct
and indirect impact of photochemical oxidants on the interrelated
biological components of a mixed conifer forest ecosystem. The second
objective is to utilize these results in models designed to predict
probable adjustments in the ecosystem to compensate for or encourage
recovery from the pollutant impact. Ultimately it is anticipated that
the models will be useful in relating the oxidant air pollutant impact
on a forest ecosystem to some aspects of human welfare.
Information produced from this project will be largely in the form
of scientific conclusions which will serve as a basis for future recom-
mendations. Portions of the project in which the impact of oxidant
pollutants can be identified and measured will be emphasized and
enlarged but areas where little or no impact can be demonstrated should
be deemphasized.
Design and development of a "Data Management System" by the
Lawrence Livermore Laboratory is scheduled for completion by January
1977. Routine maintenance of the system after this data is essential;
therefore, provisions must be made for a smooth transition.
It is suggested that groups of investigators meet on a regular,
systematic basis for the purpose of designing and developing sub-
systems models, based on their field and laboratory research, and
19
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oriented toward the overall problem of this program. Until such acti-
vity proceeds at least to the stage of quantifying the detailed rela-
tions expressed in the graphic flow chart versions of the models, but
ideally to the stage of sensitivity analysis of the computer implemen-
tations of the systems models, an evaluation of the merit of some of
the process studies recommended below cannot be given.
RESEARCH DEVELOPMENT
The following recommendations for critical research needs pertain
directly to the systems study underway to describe the effects of oxi-
dant air pollutants on a western mixed conifer forest ecosystem in the
San Bernardino Mountains of southern California. The report of signifi-
cant damage to similar forests in the southern Sierra Nevada of
California emphasizes the need to understand the biological consequences
of these tragic events.
Different ecosystem components change in magnitude on different
time scales. Some change faster than others over a given time incre-
ment. Those components which change daily and are non-biological in-
puts to the ecological system are monitored for the purpose of driving
the computer simulation models of the ecosystems. Data on these
components are considered as validation data for the modeling effort.
Those components which change relatively slowly so that annual
changes are virtually imperceptible are considered as site parameters.
They are considered to be relatively constant and are used for making
a model more applicable to a given site in the landscape and for deter-
mining the degree of spatial resolution needed in the model to gain
20
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better realistic representation to the ecosystem in the landscape.
Those components which change relatively rapidly and together
represent internal processes within the ecosystem are studied in order
to quantify the functional relationships cmprising the body of the
model. These are process studies which should be accomplished in
finite periods of time.
It is recommended that the evaluation of possible changes in
process studies, either expansion, contraction, or continuation in
contrast to the first two options, within this research program be
classified according to the following levels of present understanding.
Exploratory: (1) We don't know if a potential component
actually exists on the study plots;
(2) We don't know if a direct relationship exists
between two existing components;
Confirmatory: (3) We know potential components actually do exist
on the study plots, as does a direct relation-
ship between them, but we don't know how much
of a change in one component is transferred to
the others.
Environmental Monitoring for Driving System Models
A need is evident for models to diagnose and predict wind, air
temperature, and humidity for remote regions where monitoring stations
cannot be maintained. This information is necessary for driving dose-
injury response models for forest vegetation.
Soil moisture and soil temperature readings need to be continued
21
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in order to provide sufficient data to predict the long term soil mois-
ture regimes from weather records and evaluate the timing of soil
water availability with respect to oxidant air pollutant stress.
Site Parameter Determination
The topics of soil morphology and classification have been studied
in sufficient detail.
Only a few more soils will need to be analysed for chemical and
physical properties for plot parameterization. However, further anal-
yses will be needed of surface soils directly related to individual
trees variously affected by air pollutants.
Process Studies Determining Rates of Change of Ecosystem Components
Primary Productivity
One of the most important research goals is to understand the
relationships of meteorological variables and related variables like
soil moisture availability as they influence the oxidant dose -
vegetation (injury) interaction. Additional data needed are programmed
for collection during the next two calendar years but the definition of
a dose-injury submodel should begin immediately. Additional emphasis
must be placed on correlating other objective measurements of tree
health with the present classifications derived from visible symptoms.
As a specific portion of dose-injury determinations, studies are
needed relating soil moisture tension, xylem water potential and
stomatal behavior to oxidant susceptibility of pines.
22
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Consumer Control of Primary Productivity in the Ecosystem
Studies on the effects of air pollutants on the epidemiology of
Fomes annosus need to be continued. Such work includes completed
analyses of tree and stump susceptibility, continued establishment and
monitoring of infection centers, and effects of pollutants on decay
rates, growth, production and germination of reproductive spores, and
genetic adaptibility of the pathogen. Related studies including pollu-
tion effects on the pathogen's competitive abilities, and changes in
pathogenicity and virulence should be conducted to give an adequate
overall view of F. annosus - air pollution interactions.
Air pollution effects on the epidemiology of other important
forest diseases, such as dwarf mistletoe and Elytroderma deformans
needle cast, should be investigated. Further work on disease surveys
should help to set priorities on these future studies.
Additional studies of damping-off fungi are needed to help clarify
the effects of photochemical air pollutants on the composition, occur-
rence and density of these disease-causing organisms and their effect
on regeneration and successional trends in the forest. These studies
should include field and laboratory experiments concerning the types of
damping-off fungi present, their population levels (endemic and those
necessary for disease) and fluctuations, their relative position in the
forest floor, their impact on seed germination and seedling establish-
ment, and the effects of photochemical air pollutants on the fungi.
The initial phases of the study of the role of tree-killing
beetles on Jeffrey and particularly ponderosa pines have shown some
23
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interesting trends as to the influence of oxidant air pollutants on
forest communities in southern California. There is no question that
these beetles play a key role in causing mortality in the stands being
studied. A preliminary look at portions of the data summarized to date
indicates that the interaction between beetles and trees under these
circumstances is unique, and the rate of tree killing will, in turn,
influence the other biotic and physical processes under study in the
overall investigation.
It is recommended that sampling of the western pine beetle on
ponderosa pine be continued with greater emphasis on obtaining equal
numbers of infested trees of each oxidant injury category in each gen-
eration. Further efforts must be made on those data already captured
in terms of summarization and analysis. Because of the functional
sampling methods available, the western pine beetle is the best insect
indicator available for the influence of photochemical air pollutants.
Studies of the mountain pine beetle and the Jeffrey pine beetle
will of necessity be of lower priority, but some small scale rearing
studies should be continued.
Studies on the influence of the California flathead borer must be
initiated, as this insect appears to be far more important in the system
than previously thought:, particularly on Jeffrey pine. Complementary
surveys by the Forest Service should be encouraged; they will supply
additional information and permit increased understanding of the
influence of photochemical air pollutants on beetle-tree interactions.
Litter Accumulation
Thickness measurements of the forest floor (needle litter layer)
-------
need to be extended to include all major plots, and to a study of
individual trees.
Crown drip studies need to be extended to other plots for several
years, as the problem of vandalism of the collector cans requires a
large number of trials to obtain meaningful results.
Analysis of the nutrient status of needles falling from the trees
is continuing and should be continued for at least one more year in
order to determine the effect of air pollutants on the needles and
consequently on the forest floor.
Consumer Control of Decomposition
Further detailed studies on the roles of, and the interactions
between soil and microarthropods and soil microbes are needed to eval-
uate the effects of oxidants on needle quality and quantity and gross
decomposition rates.
Fumigation experiments should be carried out to determine the
effects of ozone on commonly occurring mite/fungus associations in the
detrital decomposer food chains.
Evaluation of the effects of air pollutants on activity of litter
decay fungi and on the resistance of woody litter to decay should be
continued in order to determine whether oxidant air pollutants will
change the rate of decomposition of fallen branches and tree trunks.
Such a change could affect the availability of mineral nutrients
necessary for stand regeneration.
Analysis of integrated needle litter decomposition will be com-
pleted in 2 years for sample materials now in the field. Further
25
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similar experiments involving the same, and perhaps additional trees
will be necessary in order to substantiate the results of this first
experiment. Additional studies are planned to begin in the fall of
1975 .
Fumigation experiments must be carried out in which sterilized
needles from trees involved in the integrated field needle decomposi-
tion study are innoculated with individual isolates of predominate
organisms and subjected to fumigated or filtered air and incubated at
room temperature of 12 C.
At least two more years of data will be required to form an
accurate picture of the succession of microorganisms involved in foli-
age decomposition. This will involve sampling of needles on trees
prior to litter fall as well as sampling needles separated annually by
nylon mesh squares on the forest floor.
In order to evaluate trends of fungal populations, fumigation
experiments to determine growth rate, spore production, spore viability
percentage, must be carried out with isolates of common decomposer
fungi from selected sites.
Long-Term Vegetational Succession Under Oxidant Stress
It is absolutely essential that the previously described studies
be synthesized in order to develop a plant succession model; the purpose
of the model is to predict the species composition and structure of
forest stands subjected to different doses of oxidant pollutants.
26
-------
SECTION IV
CLIMATE AND PRESENT STRUCTURE OF THE
MIXED CONIFER FOREST ECOSYSTEMS
CLIMATE
Temporal and Spatial Trends of Temperature and Precipitation
The climate of the San Bernardino Mountains is distinguished by
its Mediterranean character with maximum precipitation during the
cold months of November to April and minimum during the months of
June, July and August. The relationship between mean monthly precipi-
tation and temperature is illustrated in Figure 2 using long-term
Weather Bureau records for Lake Arrowhead and Big Bear Lake Dam.
Although Big Bear Lake is higher (Elev. 2078 m) and colder (mean annual
air temperature = 6.43 C) than Lake Arrowhead (Elev. 1587 m and mean
annual air temperature * 11.05 C) , it receives less average annual
precipitation (934 mm) than Lake Arrowhead (1063 mm).
The mean annual precipitation measured or projected for a number
of stations maintained by the San Bernardino Flood Control District is
shown in Table 1 in relation to nearby study plots and their eleva-
tions. The mean annual precipitation does not increase uniformly with
elevation in the area because of the configuration of the mountains and
its effect upon the movement of air masses and subsequent occurrence of
rain shadows. The long-term precipitation estimates indicate that
the plots near Lake Arrowhead (DUA, UCC, and SF) receive the greatest
precipitation, while those at the eastern end of the study area receive
27
-------
LAKE ARROWHEAD, LONG-TERM MEANS.
TEMP.
--PRECIP
150 S
MONTH
BIG BEAR LAKE DAM, LONG-TERM MEANS.
200
o 15
as
3
-FRECIP.
--TEMP.
100 £
Figure 2. Long-term Weather Bureau records for monthly means of
temperature and precipitation at Lake Arrowhead and
Big Bear Lake Dam.
28
-------
TABLE 1. COMPARISON OF MEASURED AND PROJECTED MEAN ANNUAL PRECIPITATION
FROM SAN BERNARDINO COUNTY FLOOD CONTROL DISTRICT STATIONS
NEARBY THE PERMANENT VEGETATION STUDY PLOTS
Direction
and
Distance
Nearest
(km)
Major
of station
Mean
Vege-
from major
Annual
Years
Elev.
tation
Vegetation
Precip.
of
Station
(meters)
Plots
Plot
(mm)
Record
Cedar Pines Park
1448
CP
1.6 N
579 a/
6
Job's Peak
1573
BP
1-5 W
707 a/
7
Blue Jay Co,
1073 a/
Yard
1646
DWA
1.0 NNW
4
Lake Arrowhead
1587
UCC
1.6 S
1063
35
Arrowhead RS
1705
SF
0
1112 a/
13
Running Springs
1854
COO
3.2 SE
960
21
Green Valley Lake
2098
NEGV
1.6 WSW
829 b/
6
GVC
2.4 ENE
Big Bear Lake Dam
2078
BL
2.4 N
934
33
Big Bear Lake
Fire Station
2056
HV
5.2 S
570
24
Big Bear City
2073
SC
6.4 N
301 c/
13
Green Canyon
Springs
2134
SC
2.4 E
331 c/
10
Heart Bar
2039
HB
0
389 c/
7
Camp Angelus
1762
CA
0
750 c/
5
a/ Long term mean projected from Lake Arrowhead by linear regression
T>/ Long term mean projected from Running Springs by linear regression
~c/ Long term mean projected from Big Bear Lake Fire Station by linear
"" regression
Correlation coefficients for linear regression are highly significant
with values at least 0.92, where 1.0 represents a perfect correlation.
29
-------
the least (HB and SC). However, two years of data collected with snow
storage gauges at each plot (Table 2), indicate that Holcomb Valley
north of Big Bear Lake receives low precipitation, while Bluff Lake
plot south of Big Bear Lake on a high plateau area receives more
precipitation than any other plot. The long-term means shown in
Table 1 may be compared with 1973-1974, and 1974-1975 precipitation
measured at each vegetation plot, Table 2. An improved precipitation
map for the SBNF can now be constructed from these data.
Precipitation variability across the transect of study plots might
have implications for the degree of oxidant injury to vegetation.
Analysis of this possible interaction is in progress at present and
further discussion can be found in that section of this report under:
The Climate in the Soil and the Drought Stress.
Topography, Meteorology, and Pollutant Transport
The San Gabriel and San Bernardino Mountains surround the northern
and eastern limits of the Los Angeles Basin and connected inland valleys
now designated the South Coast Air Basin. Studies by Edinger et al.
(1972) described the daily inland flow of polluted air on typical summer
days along a sample path from the coast at Santa Monica to Redlands and
north (upslope) to the mountain crest (Figure 3). The marine temperature-
inversion air layer, extending inland across the heavily urbanized Los
Angeles metropolitan area, frequently remains intact as far as 144 km
(90 miles) inland, depending on time of day and season. The intact
inversion air layer usually contacts the mountain slopes below 1216 m
(4,000 ft.) elevation. Surface heating of air under the inversion
30
-------
TABLE 2. WINTER PRECIPITATION, 1973-1974, AND 1974-1975, AT EACH MAJOR
VEGETATION PLOT, SAN BERNARDINO NATIONAL FOREST, DETERMINED
BY SNOW STORAGE GAUGES, SEPTEMBER 15 TO MAY 1.
Precipitation^ Precipitation**
(cm) (inches)
1973- 1974- 1973 1974-
1974 1975 1974 1975
cp 45.6 48.5 18.0 19.1
Bp 99.0 76.9 39.0 30.3
TUN 2 85.6 64.1 33.7 25.2
UCC 80.8 49.4 31.8 19.4
°WA -- 83.6 — 32.9
SF 106.9 79.5 42.1 31.3
COO 81.1 68.5 31.9 27.0
GVC 71.8 59.3 28.3 23.3
NEGV 73.3 54.8 28.9 21.5
SV 77.0 — 30.3
DL — 78.2 — 30.8
HV 39.7 30.8 15.6 12.1
BL L34.8& 68.9 53.lb 27.1
SC 35.1 31.1 13.8 12.2
CA 38.6 61.6 15.2 24.2
SCR 39.5 47.2 15.6 18.6
BF 40.1 40.9 15.8 16.1
CAO 43.1 35.1 17.0 13.8
HB 37.8 32.9 14.9 12.6
f All data calculated by formula using individual snow gauge dimensions.
Apparently much too large, snow probably drifted over the snow gauge.
31
-------
•.Coio>Vv£
.¦Po»» "T:
/ •.PgVodeno
Coble
Son OoIki«I Voll«y
Monte
Redlbnd*
onto
Monica
Riverside
^Svy/vV'v'-.-'tv Polmdolt ¦
.1'*: v>>; •; Sol triad
/ • rVV. .7/\r°" :
run'.
Victor*
.hesperio
'.nr.
Fernando
::::: >!"* i^X.:
••••/
¦ • • y* > • • • ^v.v.
>\ Feel obove seo level
::::::: 7..
:V^22-SA-':> -eit.no,'.
1
ABOVE 9,000
5,000-9,000
1,000-5,000
1,000-5,000
BELOW 1,000
20 -30 KM
I t
Figure 3. Major topographic features of the Los Angeles Basin show-
ing aircraft flight routes (solid lines) and ground sta-
tions (A,B,C,D) used by Edinger et al. (1972) to describe
the daily inland and upslope flow of polluted air.
tends to disrupt the inversion layer particularly along its inland
extent. The heated mountain slopes act as a chimney to vent oxidant
air pollutants over the forested crest toward the desert beyond,
(Figure 4). Both an instrumented aircraft and ground monitoring
stations (A, B, C, and D, Figure 3), documented the diurnal changes
in oxidant concentrations on the mountain slope and crest, (Edinger
et al. 1972). Edinger (1973) also described how part of the upslope
flow of pollutants may be injected horizontally away from the slope
32
-------
Figure 4. Daily increase of upslope advectiori at 1200 (top), 1400
(middle), and 1600 hr (lower), from the basin (left)
across the Lake Arrowhead area (right mid-ground).
33
-------
and back southward into the stable inversion layer. As a result, on
many days the inversion itself serves as a reservoir for oxidants
which may arrive later at downwind locations along the mountain slopes
and crests. Oxidants remain relatively undiluted owing to lack of
vertical mixing within the inversion layer and lack of contact with
fresh infusions of nitric oxide (NO):
sunlight
N02 + 02 * NO + 03
This phenomenon results in prolonged high concentrations of oxidants at
night in the mountains. Ground station "D", Figure 3, is located near
Rim Forest and Sky Forest at 1657 m (5450 ft) and will be referenced
frequently in a following section describing variations of oxidant
concentrations during the growing season.
The annual cycle of photochemical oxidant concentrations as illus-
trated by data collected at Sky Forest in 1973 and 1974 (Figure 5), bears
a remarkable resemblance to the mean monthly changes of air temperature
(Figure 2). The average of the maximum hourly averages for total oxi-
dant remains near the world-wide background concentration of 0.03-0.04
ppm only in December and January. By the middle of May, when new leaves
emerge on black oak, and pines begin new needle growth at Sky Forest,
the daily pollutant episodes far exceed Federal Air Quality Standards
(Appendix A). According to Figure 48, the soil moisture available for
plant roots is generally depleted at depths down to 2.7 m by the
middle of August.
The difference in the time of occurrence of high oxidant concen-
34
-------
SKY FOREST,CA.
• — ¦ MONTHLY PEAK
• MAXIMUM HOURLY AVERAGE
• AVERAGE, MAXIMUM HOURLY AVERAGES
-I 76
-I07B
- 980
- 196
%
A M J JASONOJFMAMJJASON D J F M
Figure 5. The annual cycle of monthly photochemical oxidant concen-
trations at Sky Forest, California, 1973-1975.
trations (Figure 5) suggests a lower dose during the period of maximum
water availability in 1973 and higher doses during this period in
1974. The meaning of this difference to the occurrence and amount
of vegetation injury is a central question which must be thoroughly
explored. Early results comparing injury in 1973 and 1974 (Tables 6
and 7) at all vegetation plots suggest more injury in 1974. These rela-
tionships will be discussed further in the following sections.
35
-------
SOILS
Soils of the various vegetation plots under investigation were
characterized with respect to their chemical and physical properties
in order to find relationships between soil properties and the suscep-
tibility of the vegetation to air pollutant damage, and to begin the
search for possible soil changes resulting from the effects of air
pollutants.
The soils were classified according to "Soil Taxonomy" (Soil
Survey Staff, USDA) in order that the results from this entire project
can be suitably projected to similar soils of other areas, primarily
by other soil scientists. The particle size distribution (soil tex-
ture) was measured because of its importance as an indicator of the
ability of the soils to store water and nutrients for plant use.
The bulk density was measured because of its affect upon root pene-
tration and distribution, and its relationship to soil porosity and
permeability to water and air. Exchangeable and soluble cations
and the pH of the soils were measured as they relate to the mineral
nutrient status of the soils; soil organic matter likewise affects
the structure, water retention, and porosity of the surface soil, and
is a source of nitrogen for plants and energy for microorganisms,
including pathogens. The water storage capacity of the soil is par-
ticularly important in this area because of the long, dry, warm summer
during which the plants are almost entirely dependent upon stored
soil moisture for their survival. Finally, the amount of organic
litter (needles and woody material) on the forest floor is related to
36
-------
the vigor of the forest and the production of the litter in relation
to its decomposition rate. It also directly affects seed germination,
seedling survival, and soil temperature, moisture, and humus content.
Soil Classification for the San Bernardino Mountain Study Plots
Soil3 were examined at a number of sites in each of 18 plots. The
parent material of the soils is partially weathered or decomposed
granitic rock on all of these plots except for three which also include
alluvial or colluvial material. Sand Canyon plot is on granitic rock
at its eastern end, but the bulk of the plot is colluvium including
some marble fragments derived from metamorphic rocks. It is located
southeast of Big Bear Lake. Heart Bar plot is dominantly mixed alluvium
derived from granitic and metamorphic rocks, and is located in the
upper end of Santa Ana Canyon. Camp Angelus plot is mainly stony
granitic colluvium, although the southern end of the plot is formed
directly on granitic rock.
The granitic rock weathers first to decomposed granite gruss, then
to coarse sand, loamy coarse sand, coarse sandy loam and eventually to
sandy clay loam or clay textured soils if the weathering is sufficiently
intense and of long duration. Above about 1800 m (6000 ft) in altitude,
the mean annual soil temperature is low (mairvly less than 8 C) with
reduced weathering intensity, so that the soils are mainly coarse sandy
loams, or loamy coarse sands, and without marked accumulation of clay
in the subsoil. At lower elevations, soils in moist sites show some
degree of clay accumulation in the subsoil, but only on the warmest
sites on the desert (north) side of the crest are continuous areas of
37
-------
soils with a sandy clay loam subsoil texture encountered. These plots
are Tunnel Two, U.C. Conference Center, and Holcomb Valley.
Using observed properties of soil color, texture, structure and
reaction (pH), the soils on the various plots were classified according
to "Soil Taxonomy" (Soil Survey Staff, USDA) preliminary text and
according to soil series names established by the National Cooperative
Soil Survey for California: see Appendix B. The soils in the Lake
Arrowhead region are dominantly of the Shaver series which is dark in
color to a depth of greater than 50 cm (Pachic), slightly acid in the
surface (Mollic), increasingly acid with depth (Ultic) and with no sig-
nificant clay accumulation in the subsoil (Haplic). The texture of the
subsoil is coarse sandy loam, classified as coarse loamy, the clay min-
eralogy for granitic soils is a mixture of kaolinite, mica, illite, and
vermiculite. The mean annual soil temperature is between 8 and 15 C
(Mesic), and the soils are continuously dry in the upper part for 90
days in summer (Xeric).
Thus the complete classification of the Shaver soil series is:
Order: Mollisol
Suborder: Xeroll
Great group: Haploxeroll
Subgroup: Pachic Ultic Haploxeroll
Family: Coarse, loamy, mixed, mesic
Soil series: Shaver,
The soils with distinct subsoil accumulation of clay, due to more
intense and prolonged weathering on the Tunnel Two and U.C. Conference
Center plots, differ in that on Tunnel Two, the surface is dark to a
38
-------
depth of less than 25 cm, while on the other plot it is between 25 and
50 cm in depth. Consequently, the Stump Springs soil on Tunnel Two is
an Ultic Haploxeralf, while U.C. Conference Center is an unnamed soil
classified as an Ultic Argixeroll. At Holcomb Valley north of Big Bear
Lake, are Typic Argixeroll soils of the Domingo Series, similar to those
of the U.C. Conference Center, but not increasingly acid with depth.
The remaining soils are either of coarse sandy loam (coarse loamy),
or loamy coarse sand (sandy) throughout the entire depth of soil, ex-
cept for the Cahto variant soil at Camp Angelus which is stony, coarse
sandy loam. Some are shallow (lithic), some are sandy (Psamments).
Some have dark, acid surface soils and slightly bleached layers below
(Umbrepts) or are not dark (Orthents and Ochrepts), Although Appendix
Table B shows that there are some 23 soils represented on these plots,
many are quite similar which makes it possible to compare the effects
of air pollutants of varying concentration on vegetation growing on
nearly identical soils in a number of cases.
Chemical and Physical Soil Morphology
In addition to the soil samples collected at 23 sites, morpho-
logical descriptions of soils at 62 sites were obtained on 18 plots.
Information included horizon designation, texture, color, pH, and sur-
face structure. Physical and chemical measurements also were made of
23 soils at the soil moisture sensor sites. These included particle
size distribution, bulk density, gravel and stone content, pH, exchange-
able and soluble cations, nitrogen and organic matter content. Only
partially complete information could be obtained from the plots at
39
-------
Camp Angelus, Barton Flat, and Gamp Oseola because the stony nature of
the soils there essentially precludes volumetric sampling. A total of
246 samples was analysed in this way. These data provide the basic
information for relating the nature of the soil to the kind and amount
of vegetation and its susceptibility to air pollution injury.
Particle Size Distribution
The content of sand, silt, clay, fine gravel and coarse gravel of
selected soil samples from 17 study plots is shown in Appendix C. All
values are given in percent of fine soil material, i.e. grams per 100
grams of soil material finer than 2.0 mm in effective diameter. The
samples reported include the surface soil, a subsoil sample showing the
maximum clay content and a deeper sample of minimum clay content at or
near the base of the soil where it grades into decomposed granite.
The variation of particle size distribution with depth for 3 rep-
resentative soils is shown in Figure 6. The soil labeled Unnamed-2
has a distinct maximum in clay content at a depth of 70 to 100 cm.
Similar soils are found at Tunnel Two and at Holcomb Valley. The
Shaver soil found on a number of plots in the Lake Arrowhead area
between Camp Paivika and Sky Forest contains less clay and shows only
a small and gradual decrease in clay content from the surface downward.
The Crouch variant soil at Schneider Creek is representative of the
sandier soils at Green Valley Creek, N.E. Green Valley, Heart Bar and
Sand Canyon which contain little clay and considerable fine gravel.
The soil at Bluff Lake is also sandy but contains little fine gravel.
As in most soils formed from granitic rock, these soils generally
40
-------
Umomed-2 Arglxeroll- u.C. Conference Center
Cioy-% of <2mm
Shaver Soil- Sky Forest R.S.
Cloy- % of < 2mm
Crouch Variant Soil-Schneider Creek
Cloy-% of <2mm
o H> 80 WO 0 20 60 no 0 20 60 100
Clay I 9»
100
»
E
tf
& W>
300
W 80 40
Sand-% of <2mm
so
a a
» 20
Fine Gravel
% of <12 mm
40
SS1
Sand
Clay
80
SO 40 20
Sand- % of <2mm
C 0
SSH
Fh*
400
[Clay
-I
200
300
SO
60 40 20
Sand-% of «2mm
20
Fine Gravel
% of <12mm
40
0 0
Figure 6. Three representative soil profiles of particle size distribution.
-------
contain considerable fine gravel (2 to 12 mm in diameter) and as a con-
sequence would technically be classified as gravelly. However, most of
the fine gravel is about 2 to 4 mm in diameter and behaves much like very
coarse sand in the soil, so the gravelly designation is omitted from the
coarse sandy loam and loamy coarse sand textural classifications.
The average particle size distribution and the textural classifi-
cation of the various soils is shown in Figure 7. This figure is only
a portion of the textural triangle chart used by the U.S.D.A. Soil
Conservation Service. As can be seen, the average texture of these
50,
45
40
Sandy Cloy
35,
30,
Sandy Clay Loam
20,
HV
>W-3
JWfcj
sy
SC-1
Sondy Loam
GVL /TSv,
Loamy Sand
NEG'
Sand
Sand %
Figure 7. Average particle size distribution of soils of study plots.
h2
-------
soils are either loamy sands or sandy loams. The soils with loamy
sand textures are all in plots located east of the Lake Arrowhead area
near Green Valley and Big Bear Lakes and in the Santa Ana Canyon.
Bulk Density of Soils
The bulk density or volume weight of soils (D^) was determined in
connection with the moisture sampling. The variation of bulk density
with depth is shown for eight representative soils in Figure 8. A
complete set of data is given in Appendix D.
Of the surface soils, the one at Breezy Point (BP) is the least
dense (0.74 gm/cm3) and very rich in organic matter. The soils with
the most dense surface soils are at Holcomb Valley (HV) and at the U.C.
Conference Center (UCC) with bulk densities of more than 1.4 gm/cra? ,
which are soils also having clayey subsoils and are in the warmer
north side of the general transects. Most of the soils have surface
a
bulk densities of 1.1 to 1.3 gm/cm , and are thus very porous and of
good granular or crumb structure.
Subsoil densities are generally from 1.5 to 1.7 gm/cm3 which is
very common for soils of sandy textures. The higher bulk densities are
associated with loose sandy soils which tend to crumble into the
sampling hole, so that those greater than 1.8 gm/cm3 may well be due to
sampling error. Notice that again the Breezy Point soil (BP) has a low
density to considerable depth; this soil also has the highest available
water storage capacity as indicated in Appendix H.
43
-------
0 1
100
200
E
0
1
£ 300
o.
« 0
o
CO
T~TT
c
Soil Bulk Density-gm/cc
Z 0 1 2 0 1 2 0
Dogwood - 2
J I I I
i n i i
sv
J L
100
200
300
TZ
Holcomb
Valley
J I I
Bluff
Loke
\
1 2
U.C. Conf.
Center
j~r—r
Breezy Pt.
I
T 1
Green Volley
Creek
II
Schneider
Creek
Figure 6. Representative soil bulk density profiles on study plots.
uu
-------
Exchangeable and Soluble Cations
Exchangeable and soluble cations were determined on 22 soils
throughout their total depths on the vegetation plots (omitting Camp
Angelus, and including two other sites at S22 and NE13) making a
total of 251 samples. Soluble cations were determined on a 1:1
water extract of the soil, and exchangeable cations on a neutral
1.0 normal ammonium acetate extract.
The results for surface soils are shown in Appendix E. The domi-
nant exchangeable cation is calcium (Ca) with magnesium (Mg), potassium
(K) and sodium (Na) decreasing in that order. The values obtained
are quite typical of surface soils formed on granitic rocks elsewhere
in California (Soil Survey Staff USDA, unpublished document). For
example the common range for exchangeable calcium is from 5.0 to
10.0 meq/100 g. Thus the soil at site 3 on the Dogwood plot (DW-3)
and that at Bluff Lake (BL) are low in calcium, the latter due to its
cold, humid climate. At Sand Canyon, the (SC) surface soil is rich in
calcium probably due to its proximity to the ridge above which contains
some marble, but exchangeable potassium content is quite low.
Soluble cations in the surface soil likewise are dominated by
calcium followed by potassium, magnesium and sodium in that order.
These again are in concentrations often found in granitic soils. All
except Sand Canyon site 1 (SC-1) appear to contain adequate supplies
of these elements for plant growth.
Exchangeable and soluble cations for representative subsoil layers
from the same soils are shown in Appendix F. Again the soils at DW-3
45
-------
and BL are low in cations, especially at BL. High values of exchange-
able calcium are shown for Holcomb Valley (HV) and U.C. Conference
Center (UCC) both of which have pronounced clay accumulations in the
subsoil. A number of the values for exchangeable and soluble potassium
are low (less than 0.1 and less than 0.005 meq/100 gm) respectively.
However, the complete data indicate that soluble potassium is low
throughout the entire depth of soil only in Bluff Lake (BL), Sand
Canyon site 1 (SC-1), and Green Valley Creek (GVC).
Soil Organic Matter
Organic carbon and nitrogen were determined on samples from major
plots to a depth of 50 or 60 cm. The results for the upper 25 cm of
soil only are shown in Appendix G. The soils with the most organic
matter are shown to be at Dogwood-3, Bluff Lake and Barton Flat with
organic carbon values of 2.99 g/100 g or more. Soils with the least
organic matter are Sand Canyon-1, Green Valley Creek and Heart Bar, all
of which have relatively thin needle-litter layers on the soil. The
highest value for nitrogen was found at Camp O-Ongo, but the unusually
low ratio of carbon to nitrogen (C/N) suggests possible contamination,
perhaps by riding horses from the nearby summer camp. Other sites
with high nitrogen levels are at Bluff Lake, Barton Flat, Dogwood-3
and Breezy Point. C/N ratios generally range from 20 to 30 which are
common under mixed conifer forests.
Soil Water Available for Vegetation Growth
In order to quantify the soil moisture regimes in terms of total
46
-------
quantities of water, the soils at the 23 sites were sampled volumetric-
ally for gravimetric measurement of total water content both in April
when full wet, and in October, when at minimum moisture content. The
difference is assumed to be the amount of water available to the
plants, assuming that the organic litter layer on the surface limits
air movement and thus limits direct evaporation from the soil to
very low levels. The values obtained by this procedure are shown in
Appendix H. Included are only those plots in which the soils were
sufficiently low in stone and gravel content to permit volumetric sam-
pling. The first 3 columns of data show the volumetric percent and
the total calculated depth of available water in April to a uniform
depth of 152 cm (5 ft). The last two columns show the total soil depth
and the total available water storage. The most significant fact shown
by these data is that the available soil moisture storage values within
the root zone of the pine forest is very high, about 30 cm (12 inches)
or more, compared to the values commonly used in water balance studies
of this kind (10 or 15 cm). The low values found for the last five
plots listed, may underestimate the water available to the trees, which
may be obtaining water from the firm weathered granite below the depth
of sampling; perhaps from cracks and joints in the rock.
Amounts of Organic Litter on the Forest Floor
In order to document the status of accumulated organic matter
(pine needles, twigs etc.) on the forest floor of the various study
plots in relation to the impact of air pollutants on the pine forest,
the thickness of the litter layer was measured at 2 m intervals along
47
-------
a line transect for the length of the plots. In addition, core samples
of the litter layer were collected at 135 representative sites, in
order to establish the relationship between mass and thickness of the
layer (T) in cm.
Regression analysis of the latter showed that:
Mass (Kg/m2) = 1.249 T + 1.329
The correlation coefficient was 0.902, and the regression line was not
significantly different from one passing through the origin (T = 0,
Mass = 0) which gave the relationship:
Mass = 1.41 T
Using the latter, the average amount of the litter on the forest floor
was calculated from the average thickness measured. However, it was
found that the litter layer on the forest floor on some plots had
been stripped away by recreation and logging activities, and in order
to obtain meaningful averages, these areas were treated separately.
The results are shown in Table 3. It can be seen that the thick-
est forest floor was found on undisturbed areas of Dogwood, Sky Forest
(Figure 9), U.C. Conference Center, Camp Paivika, Breezy Point and Camp
Angelus. Relatively thin layers were found on undisturbed plots at
Snow Valley (Figure 9), N.E. Green Valley and Holcomb Valley, but none
of these were as thin as the disturbed areas of Dogwood, Green Valley
Creek, Holcomb Valley and Camp Osceola. The very marked reduction in
thickness of the forest floor by recreation activities (mainly by
motorcycles) and by logging (even scattered sanitation logging removing
oxidant-injured or insect-infested trees) may have important conse-
48
-------
TABLE 3.
MASS AND THICKNESS OF THE FOREST FLOOR ON MAJOR STUDY PLOTS.
Mean Standard
Plot
Sample
Thickness,
Deviation
Massa
Standard
Size
T
of T
Deviation
Number
(cm)
(Kg/m2)
of mass
DWA
20
12.5
+ 1.23
17.61
+ 1.73
(disturbed)
(66)
(2.8)
(+0.42)
(3.92)
(+0.59)
SF
102
10.7
+0.43
15.11
+0.61
ucc
32
11.1
+1.03
15.73
+1.45
CP
76
10.3
+0.48
14.52
+0.68
BP
49
9.4
+0.50
13.23
+0.71
TUN 2
81
8.4
+0.54
11.8
+0.76
COO
84
7.5
+0.43
10.56
I0-61
GVC
20
8.4
+0.54
11.81
+0.76
(disturbed)
(60)
(3.3)
(+0.34)
(4.71)
(+0.48)
NEGV
127
5.3
+0.3
7.47
+0.47
sv
138
4.2
+0.39
5.91
+0.55
HV
77
5.2
+0.42
7.32
+0.59
(disturbed)
(52)
(1.3)
(+0.19)
(1.84)
(+0.27)
BL
110
6.6
+0.39
9.35
+0.55
CA
74
9.8
+0.55
13.75
+0.78
CAO
62
6.6
+0.40
9.27
+0.56
(disturbed)
(24)
(2.6)
(+0.29)
(3.65)
(+0.41)
Range
(undisturbed)
4.2/12.5
5.91/17
.61
Calculated mass ¦ 1.41 T
49
-------
Figure 9. Comparison of thicker forest floor litter at Sky Forest
(upper left) with Snow Valley (upper right), and an
example of excessive litter and heavy fuel accumulation
at Sky Forest (lower).
50
-------
quences with respect to seed germination, seedling survival, soil
temperature and moisture, animal habitats and fire behavior.
On the other hand, the accumulated needle litter, fallen (unhar-
vested) trees killed by the oxidant injury-bark beetle complex, and the
accumulated slash from repeated sanitation salvage logging have result-
ed in serious fuel overloads at places like Sky Forest (Figure 9).
The implication is that wildfires could cause the death of even large
trees because of sustained high temperatures.
VEGETATION
Importance
The vegetation of the San Bernardino Mountains is a valuable
resource for the people of the United States. It provides a setting
for recreation, commodity products such as lumber and forage, and
essential watershed protection. The vegetation is also an integral
component of the natural ecosystems that occur in the San Bernardino
Mountains. Oxidant air pollutants, arising from the urban areas to
the south and east of the San Bernardino Mountains, are injurious to
the vegetation. The impact of this injury has important consequences
to both man'8 use of the vegetation and to the functioning of the
natural ecosystem. An understanding of the impact on vegetation can
come about through an evaluation of vegetation and its successional
potential along gradients of oxidant air pollution. The impact of
pollution on the natural ecosystem can be understood if knowledge of
the interactions of vegetation, other ecosystem components, and air
51
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pollutants is available.
Vegetation Zones
The vegetation of the San Bernardino Mountains is composed about
equally of chaparral and forest types with important minor elements of
woodland, sagebrush, and grassland. Horton (1960) and Minnich et al.
(1969) have undertaken major treatments of this vegetation. Horton
(1960) recognized six vegetation zones on the basis of plant physiognomy
and environmental conditions (Figure 10): Chamise-chaparral, woodland-
chaparral, desert chaparral, pinyon-juniper woodland, timberland
chaparral, and coniferous forest. One or more vegetation types occur
within each zone. Twenty of these types were defined by Horton
(1960) on the basis of field reconnaissance. Minnich et al. (1969),
using infrared color imagery on aerial photographs, mapped 28 vegeta-
tion types in the San Bernardino Mountains. The relationship between
the vegetation types recognized by the two authors is indicated in
Appendix I.
Vegetation Types
Our study has focused on the Coniferous Forest Zone. This zone
ranges in elevation from 1524 m to 1981 m on the north facing slopes
and 1524 m to 2286 m on south facing slopes upwards to the highest
peaks (San Gorgonio, 3,505 m). Four coniferous forest vegetation types
were recognized by Horton (1960) in this zone. Two of these types,
Pine Forest and Ponderosa Pine-White Fir Forest, have been the central
concern of this study. An improved map has been prepared based on a
52
-------
\J1
U)
TIMBERLAND CHAPARRAL
CONIFEROUS FOREST
III Mill PINYON —JUNIPER WOODLAND
ROWHEAD-S&
I.G..J&AR.L
CHAMISE CHAPARRAL
3 WOODLAND CHAPARRAL
DESERT CHAPARRAL
Figure 10. Vegetation zones of the San Bernardino mountains.
-------
U.S. Forest Service (1973) type map to show the distribution of these
types (Figure 11). Our work has indicated that these two general
types may be further subdivided into five vegetation types on the basis
of species dominance. These types are as follows: Ponderosa Pine
Forest, Ponderosa Pine-White Fir Forest, Ponderosa Pine-Jeffrey Pine
Forest, Jeffrey Pine Forest, and Jeffrey Pine-White Fir Forest. Forest
vegetation types dominated by ponderosa pine are distributed mainly in
the western half of the San Bernardino Mountains, while Jeffrey pine
dominated types occur more frequently in the eastern half (Figure 12).
Study Plots Within Vegetation Types
The vegetation subcommittee participated in the establishment of
18 permanent study plots in the San Bernardino Mountains (Figure 1).
A nineteenth study plot, Deer Lick, was recently added, but results
presented in this report refer only to the first eighteen plots. The
first criterion for the selection of the location of these plots was
species composition. Stands were selected in which either ponderosa or
Jeffrey pine was dominant. Additional selection criteria included
tree size, topographic position, parent material, and position along
the oxidant gradient (Taylor, 1974). The descriptive characteristics
of the vegetation on these plots have been analyzed by the vegetation
subcommittee (McBride, 1974). The quadrat method (Clements, 1905) was
used to determine density and cover in the tree and herb layers, while
the line intercept method (Canfield, 1941) was employed in measuring
characteristics of the shrub layer.
54
-------
PAGE NOT
AVAILABLE
DIGITALLY
-------
Q\
ELEVATION
(METERS)
LAKE
ARROWHEAD
DF i PFm
W
PFm
BUTLER PEAK
BIG BEAR
1
; PF
l
i
PF j PJ
|
•
10
LEGEND
20 km
E
CS-COASTAL SAGE SCRUB
CH- HARD CHAPARRAL
DF-COULTER PINE-BLACK OAK
PFm - PONDEROSA PINE DOMINATED
TYPES
PF -JEFFREY PINE DOMINATED
TYPES
PJ - PINYON-JUNIPER
Figure 12. East-West distribution of vegetation types in the San Bernardino
Mountains.
-------
Tree Layer Data
Five plots, each representative of one vegetation type, are
summarized in Table 4. Similar data from the remaining plots is avail-
able in the Task D Report (McBride, 1974). Species composition in the
tree layer of each plot is illustrated in Figure 13. The Camp Paivika
plot is typical of the Ponderosa Pine Forest type, Figure 14. Ponderosa
pine makes up 57.9% of the composition of the plot. Black oak is a com-
mon species in the Ponderosa Pine Forest type and makes up 41.6% of the
tree composition on this plot. The Ponderosa Pine-White Fir Forest type
occurs on the Sky Forest plot, Figure 14. Here, ponderosa pine makes
up 46.9X of the tree composition with white fir contributing 30.2%.
Other tree species on the Sky Forest plot include sugar pine, incense
cedar, black oak, and dogwood. The Barton Flats plot is representative
of the Ponderosa Pine-Jeffrey Pine Forest type, Figure 13, Ponderosa
pine contributes 55.9% of the tree composition of the plot while Jeffrey
pine contributes 34.5%. The remaining 9.6% is contributed by black oak
and interior live oak. The Jeffrey Pine-White Fir Forest type occurs
on the Green Valley Creek plot, Figure 13. Here 19% of the composition
is due to Jeffrey pine and 30.3% to white fir. Other species occurring
on the Green Valley Creek plot are sugar pine, incense cedar, black oak,
and interior live oak. The Jeffrey Pine Forest type is well developed
on the Snow Valley plot, Figure 13. Jeffrey pine makes up 96.2% of the
tree composition on this plot.
Shrub and Herb Layers
The vegetation of each of 19 permanent plots can also be further
57
-------
TABLE 4. TREE LAYER DATA FROM PLOTS REPRESENTATIVE OF EACH VEGETATION
TYPE DOMINATED BY PONDEROSA OR JEFFREY PINE IN THE SAN
BERNARDINO MOUNTAINS.
Characteristics
Mixed conifer
#
forest types&
# treesb
Spp.
Dens i ty
Basal
Comp.
Area ^
Ponderosa Pine
(N.W. Paivika)
PP
98
57.9
217.8
24.11
SP
1
0.5
2.2
0.03
IC
—
—
—
—
WF
—
—
--
—
JP
—
—
—
—
BO
70
41.6
155.6
6.32
QW
—
—
—
—
DW
—
—
--
—
Total
169
100
375 .6
30.46
Ponderosa Pine -
White Fir
(sky Forest)
PP
104
46.9
144.4
28.38
SP
15
6.8
20.8
0.60
IC
25
11.2
34.7
4.10
WF
67
30.2
93.1
3.85
JP
—
—
—
—
BO
7
3.1
9.7
2.21
QW
—
—
—
—
DW
4
1.8
5.6
—
Total
222
100
308.3
39.14
Ponderosa Pine -
Jeffrey Pine
(Barton Flats)
PP
139
55.9
200.1
16.87
SP
—
—
--
—
IC
—
—
—
—
WF
—
—
—
—
JP
86
34.5
123 .8
10.21
BO
16
6.4
23.0
5.99
QW
8
3.2
11.6
0.56
DW
—
—
--
—
249
100
358.5
33.63
58
-------
TABLE 4. TREE LAYER DATA FROM PLOTS REPRESENTATIVE OF EACH VEGETATION
TYPE DOMINATED BY PONDEROSA OR JEFFREY PINE IN THE SAN
BERNARDINO MOUNTAINS. (Continued)
Mixed conifer
forest types** # trees^ Spp. Density^ Basal
Comp Area ^
Jeffrey Pine -
White Fir
(.Green Valley Cr .)
pp
—
—
—
—
SP
11
5.4
12.2
2.93
IC
10
4.9
11.1
1.63
WF
62
30.3
68.9
4.94
JP
39
19.0
43.3
12.20
BO
82
40.0
91.1
4.70
QW
1
0.4
1.1
0.02
DW
—
—
—
—
205
100
227.7
26.42
Jeffrey Pine
(Snow Valley)
PP
—
—
—
—
SP
—
—
—
—
IC
—
—
—
—
WF
3
2.9
3.9
1.30
JP
99
96.2
129.4
21.56
BO
1
0.9
1.3
0.16
QW
—
—
—
—
DW
—
—
—
—
103
100
134.6
23.02
TABLE LEGEND:
Symbol
Common Name
PP
ponderosa pine
SP
sugar pine
IC
incense cedar
WF
white fir
JP
Jeffrey pine
BO
black oak
QW
interior live oak
DW
dogwood
k Number of trees on the plot
c Percent species composition on the basis
^ Number of trees/hectare
^ Basal area in square meters/hectare
Scientific Name
Pinus ponderosa
Pinus lambertiaiia
Libocedrus decurrens
Abies concolor
Pinus jeffreyii
Quercus kelloggii
Quercus wislizenii
Cornus nuttallii
of number of trees
59
-------
CT\
O
A PONDEROSA PINE
B SUGAR PINE
C BLACK OAK
D WHITE FIR
IOO-
80-
55 6
-------
I
Figure 14.
Aerial views of study plot^s which represent five conifer
forest types in the San Bernardino Mountains; from top
to bottom:
a) Ponderosa type, Camp Paivika (left)
b) Ponderosa-White Fir type, Sky Forest (right)
c) Ponderosa-Jeffrey pine, Barton Flats (left)
d) Jeffrey pine-White Fir type, Bluff Lake (right)
e) Jeffrey pine type, Hoi comb Valley
•6l
-------
described in terms of the characteristics of the shrub and herb
layers (McBride, 1974). The plots occurring in forest types dominated
by ponderosa pine have an average shrub cover of 3.8% while those
plots occurring in forest types dominated by Jeffrey pine average 26%
shrub cover. Arctostaphylos pringlei and Ribes roezlu are typical
of the shrub layer in ponderosa pine dominated types. Ceanothus
cordulatus, Arctostaphylos patula and Artemisia tridentata are common
shrubs in the forest types dominated by Jeffrey pine. The occurrence
of herbaceous species in relation to forest type has not been analyzed
thus far in our study. The importance value (Curtis, 1951) of each
herbaceous species on each of the permanent plots will be calculated.
This value will be used as a measure of the relationship between
forest type and the occurrence of herbaceous species.
Use of Vegetation Survey Data
The descriptive information developed by the vegetation sub-
committee has been used by other investigators for the selection of
sampling locations, general habitat descriptions, and as a basis for
comparison with auxiliary plots. When auxiliary plots were established
by the Entomology subcommittee, these plots were surveyed by the
vegetation subcommittee using the same procedures used on the permanent
plots. This type of survey allows certain comparisons with other
data collected on the permanent plots.
62
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SECTION V
TOWARD FORECASTING ALTERNATIVE FUTURE ECOSYSTEM RESPONSES
ECOSYSTEM MODELING
Background and Project Objectives
Ecosystems are defined as units which are dependent upon (1) energy
and moisture flowing through them, (2) minerals cycling within them, and
as a result (3) vegetation reproduces, grows and dies, and supports (4)
a diversity of animal life, some of which feeds on the vegetation, and
some of which feeds on other animals. In ecosystems, (5) dead organic
matter accumulates and (6) decomposer organisms work to break it down
so that minerals and space are available for the next generation (Odum
1971). At any given time, some types of organisms are more dominant
than other types in the ecosystem processes listed as 3, 4, 5, and 6.
Over time, these patterns of dominance go through a gradual change.
After a disturbance occurs in an ecosystem, time is set back, and the
sequential patterns of dominance begin to take place again. In some
cases, the nature of the disturbance may lead to a different sequential
pattern of dominant plants and animals than the sequence that prevailed
before the disturbance. The subject of ecological succession has
received considerable study (Knapp 1974). An alteration of the natural
rates of dead organic matter accumulation, and/or its decomposition,
could be expected to change the patterns of dominance of vegetation
and wildlife communities.
Several investigators are studying this variety of processes in
63
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the laboratory and in the field as the first step in the hierarchy of
project objectives (Figure 15, bottom). Such process studies of the
components of ecosystems are necessary to determine and quantify direct
effects of oxidants as well as the biological effects resulting from
simultaneous occurrence of oxidants, drought, insect and plant disease
activity. These analyses are necessary in order to assemble our under-
standing of various processes into a set of quantitative models on an
electronic computer. With such models we plan to forecast the various
possible alternative futures for the ecosystems in the San Bernardino
National Forest (Figure 15, middle). Scientists do not expect to be
able to make predictions in an absolute sense, since too many qualify-
ing conditions, such as the future rate of use of the internal combus-
tion engine, and its possible technological modifications, as well as
future weather conditions, cannot be predicted with certainty. We can,
instead, plan to make forecasts of various possible alternative futures
for the forest ecosystems, by postulating sets of alternative, hypo-
thetical qualifying conditions, and seeing how the set of computer
simulation models responds to each set of qualifying conditions. For
example, one set of possible future conditions might assume twice the
annual oxidant dose of 1974 with a three or four year wet-weather
pattern of 1 1/2 times the normal rainfall, or alternatively, 1/2
the normal rainfall. We would then determine how the simulated forest
system behaves on the computer. There is, of course, no guarantee
that real forests will respond as the computer models do, but the other
option is merely to use informal, intuitive guesswork on the part of
individual specialists, rather than a synthesis of current scientific
64
-------
Ecosystem component
process studies
Assess interactive
effects
Develop systems models for
prediction of future conditions
Evaluate adaptability of
systems models to other
pollutant types and other
forest types
Evaluate direct impacts
of photochemical oxidants
on major components of a
forest ecosystem
Evaluate predicted consequences
of photochemical oxidants on
the forest ecosystems in terms
of human welfare effects a
Evaluate the effect of ambient photochemical
oxidant air pollution on a complex mixed
conifer forest ecosystem
a . .includes, but is not limited to, effects on soils, water, crops,
vegetation, man-made vaterials, animals, wildlife, weather, visibility,
and climate, damage to and deterioration of property, and hazards to
transportation, as well as effects on economic values and on personal
comfort and well-being."
Source: Clean Air Act 1970, Section 302 (h).
Figure 15. Objectives for the study of effects of ambient oxidant
pollutants on mixed conifer forest ecosystems.
65
-------
understanding of the processes which control whatever future forest
conditions actually will occur.
Purposes for Building Computer Simulation Models of Ecosystem
Level Response to Photochemical Air Pollutants
The types of ecosystem forecasts to be sought from using the com-
puter models must evaluate likely consequences in terms of "human
welfare effects" (Figure 15, top), an expression which can be rather
vague from a systems analysis viewpoint, but is defined in section
302(h) of The Clean Air Act, Environmental Protection Agency, 1970:
"All language referring to effects on welfare includes, but is not
limited to, effects on soils, water, crops, vegetation, man-made
materials, animals, wildlife, weather, visibility, and climate, damage
to and deterioration of property, and hazards to transportation, as
well as effects on economic values and on personal comfort and
wel1-being."
While we expect to find losses in the form of vegetal production
decreases and shifts in the balance of species abundance in forest
ecosystems under oxidant air pollution stress, probably one of the
ultimate questions to put to forest ecosystem simulation models for
evaluating consequences in terms of human welfare effects is the
question of ecosystem irreversibility. Is there some level of oxidant
air pollution, in some time and space definition, at which irreversi-
bility in forest stand succession patterns occurs? Can oxidant air
pollutants effect the limits of resilience for terrestrial ecosystems?
Particularly, is the detection of such irreversibility possible within
66
-------
one human lifetime, say 50 years, from 1950, when photochemical air
pollution is believed to have begun its chronic trend upward, above
natural background levels in the South Coast Air Basin, to the year
2000? In terms of the possible range of air quality conditions from
now to the year 2000, one possibility could be a worsening of this air
quality in the SBNF by some factor 2,3,4 times that at present. Under
such an extreme we might expect changes in the life form of dominant
vegetation to occur, as suggested by Woodwell (1970) in his studies on
the effects of gamma radiation. The other theoretical extreme, how-
ever, is that the present air pollution trend could be reduced by
virtually 100 percent at some time in the next 25 years. The irrevers-
ibility question asks, if the latter event is induced through political
and technological procedures, and the air pollution stress on the
forest ecosystems is removed (expectedly at high costs), might the
forest ecosystems resume their pre-stress species composition again
after a period of readjustment? Can oxidant air pollutants affect the
renewability of mixed conifer forest ecosystems?
There are two assumptions whose exploration and evaluation serve
as the goal for this work. The first is concerned with constructing an
ecosystem-level interpretation for stress induced from oxidant air
pollution; the second is an application of analysis and forecasting
method.
We think that combinations of non-biological stresses (i.e., in-
creases in ground-level concentration of photochemical oxidants,
changes in natural fire frequency distribution, various intensities of
meteorological drought) lead to changes in the natural frequency of
67
-------
periodic biological stresses (insect epidemics, disease epidemics). As
a result, sequences of ecologically dominant vegetation will undergo
changes which are not likely to reverse naturally, even after the
removal of any single non-biological stress.
In order to conduct this study of California mixed conifer forest
ecosystems, we feel that a systems analysis and simulation modeling
approach will provide participating scientists with a means of:
a) clarifying their concept definitions and explicitly exposing their
assumptions which ordinarily would tend to remain hidden; b) clarifica-
tion of relationships between system components; c) considering a larger
set of interrelated ecological variables than any single investigator is
able to observe in the field; d) collating a number of different scien-
tists' data sets; e) comparing similarly structured systems, e.g. from
different field plots, having different rates of change; and can provide
to government agencies responsible for air quality management and
forest resources management, a means of: a) forecasting ahead of time
the likely responses of ecosystem properties (species composition,
yield, stability, resilience) to possible trends in air quality,
forest resource harvesting methods, and other environmental stresses;
b) extension of the range of relevance of a set of field investigations
to other sites and other years (see middle of Figure 15); c) in-service
education of resource management personnel, through simulation-gaming,
of the possible consequences of alternative air quality management and
forest management strategies.
68
-------
Brief Review of Past Research in Support of Assumptions
Evidence Supporting the Ecosystem Stress Interpretation
Koenig and Tummala (1972) conceptualize three ecosystem states with
regard to pollution. Nonpollution levels exist when pollutants do not
cause the ecosystem state to move out of an environmental quality region
defined in ecological state space with regard to a set of resource uses.
Woodwell (1975) refutes the reality of assimilative capacity of ecosys-
tems, although the nonpollution level concept is also advanced by Smith
(1974). A second condition in Koenig and Tummala's (1972) concept is
Reversible Pollution. The input rate of pollutants may cause the
ecosystem to change beyond the configuration prescribed by the envi-
ronmental quality region; however, when the stress is removed or
"neutralized," by another stress, the system state returns within the
initial environmental quality region. A third possible condition is
Nonreversible Pollution. Under this condition, pollutant inputs cause
ecological states of the ecosystem to move outside of the pre-defined
environmental quality regions and remain there even after subsequent
reduction of the pollutant stimuli,
Woodwell (1970) presented a general principle of the gross sequence
of vegetal life-form elimination from an eastern oak-pine forest with a
spatial gradient of increasing exposure to gamma radiation, first trees,
then shrubs, followed by herbs, and lastly, low-growing cushion plants.
He concluded that this was a chronic effect to be expected from chronic
exposures to other chronic environmental stresses. This generalization,
when viewed in the context of the aims of this project and the nature of
69
-------
California mixed conifer forests under oxidant air pollution conditions,
causes certain discrepancies to become apparent regarding the perturba-
tion inputs to the system and the stress response of the system.
(1) The conclusion as to what is a chronic exposure and a chronic
effect, versus an acute exposure and an acute affect, might be relative
to the stress source. Woodwell claims that the pattern of vegetal
response was evident after only six month's exposure to gamma radiation.
Compared to other environmental perturbations, this immediacy of system
response could be categorized as an acute one. (2) If we assume that
the input used in the study reported by Woodwell, gamma radiation
absorption by vegetation, is not dependent upon the physiologic response
of the organisms within the population, then the concept of "exposure,"
or source "concentration," is sufficient. In contrast, the degree of
vegetal absorption of many material air pollutants, such as ozone in
the air near the ground, may be dependent upon the time-varying physio-
logic response of the organism (Makammal, 1965). In these cases, the
concept of "exposure" is insufficient for describing the input to the
vegetal components of the system. This feedback control in the SBNF
under oxidant air pollution would lead one to expect a longer time lag
between initiation of pollutant absorption by vegetation and the
detectability of effects, compared to the gamma radiation study (Wood-
well, 1970). in addition, the latter study used a constant pollutant
source compared to the time-varying input of photochemical oxidant air
pollutants in this study. One needs to ask how much of a pollutant,
with what time periodicity, will cause various degrees of growth
70
-------
reduction by age class, and between, as well as within, species of a
life form group. (3) A longer time lag may allow other additional
perturbation inputs to arise in the system. During the study period
reported by Woodwell in the gamma radiated forest, no other physical
nor biological stresses were reported to have been imposed on the
forest ecosystem. This may be because gamma radiation is a more direct
mortality agent in the forest, than oxidant air pollutants which, among
larger tree size classes, reduce rate of growth and overall vigor en-
abling other mortality agents to become active. Woodwell makes no
reference that the causes of mortality zones observed might have been
due to another mortality agent triggered in the course of increased
weakening of the various life forms by gamma radiation, so we must
assume that his mortality sequence was a straight-forward one of gamma
radiation killing vegetation. The claim that results from the gamma
radiation study are similar to the responses that can be expected from
other forest ecosystems under other types of stresses becomes question-
able under these circumstances. In this study of the SBNF, we are
looking at possible effects from meteorological drought, plant disease,
insect outbreaks, fire, and timber harvesting practices concurrent
with the stress induced from oxidant air pollution. Levin (1975) states
"... if stability is measured relative to the set of perturbations to
which the system is normally exposed (a variable criterion by which
different systems are compared with respect to different perturbation
sets), then such systems show up as more stable." Underscore and
parentheses are Levin's. (4) Woodwell (1970) does not deal with the
71
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evidence that the ranking of inter-species sensitivities to one stress-
inducing agent, for example oxidant air pollutants (Miller, 1973a)* are
often different from the order of sensitivity of the same species to
other, different stress agents, such as plant diseases, herbivorous
insects, or fire (Wellner, 1970; Kilgore, 1973). (5) In terms of
system response to changes in stress imposed, Woodwell's claim for
the generality of his conclusions, the nature of the SBNF ecosystems
under oxidant air pollution, and the concepts of Koenig and Tummala
(1972), one sees that Woodwell's reports (1970, 1975) say nothing about
the degree of reversibility of the effect after the stress agent has
been removed.
Due to the fact that the professional ecology literature is filled
with many natural history, descriptive accounts on the one hand, and
with theoretical analyses having questionable application for real
world ecosystems on the other, not a great deal of documentary evidence
is available on the irreversibility hypothesis although one finds the
question raised frequently in the research literature (Koenig and Tum-
mala, 1972; Holling, 1974; Edmonds and Sollins, 1974). Bryson and
Wendland (1970) claim that the arid lands of India are a result of
defoliation and elimination of vegetation which induces local climatic
changes inconducive to the re-establishment of the original vegetation.
Charney et a1. (1975) provide evidence for a similar positive feedback
for the Sahara. Glendening (1952) has shown that a defoliation stress
due to grazing intensity which then enables tree establishment will not
allow the ecosystem to revert back to its prior condition even after
72
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removal of the stress. Holling (1974) discusses evidence of aquatic
ecosystems failing to rejuvenate when stresses are removed. Habeck and
Mutch (1973) discuss the likelihood of forest fuel accumulations being
so great now, after a lowering of the natural fire frequency through
fire protection programs, that should those ecosystems now be subjected
to an uncontrolled fire, the heat intensity would probably be far
greater than that to which the systems are evolutionarily adapted.
La Chapelle (1967) reported on management attempts to reverse the other-
wise irreversible changes in Austrian sub-alpine timberline forest
equilibrium which resulted from previous logging and grazing activity
which activated a high frequency of snow avalanche perturbations in the
forest ecosystems.
Evidence Supporting the Usefulness and Necessity of Computer
18*"^ I'M H.l II! I1« I I. I —Mil I Mllllll ¦ —I
Modeling of Ecological Systems
Three stages of usefulness in applying systems modeling methods to
environmental research are identified by Innis (1973). "Conceptual
utility" is derived from the integrated frame of reference which an
explicit model, or set of interconnected submodels, provides. "Develop-
mental utility" is the usefulness of the ideas which the modeler and
presumably his field biologists acquire when assembling the various
functional hypotheses that comprise a simulation model. A large amount
of the published literature on~ecological systems simulation is
descriptive methodology in the sense that the article describes details
of how parts of the system model were constructed, but not what was done
with the model after it was constructed. Experimental reports explain-
73
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ing what discoveries were made at the ecosystem level as a result of
using the simulator, and accompanied by displays of the results of
the simulation experiments as evidence, are rare. The National Academy
of Science (1974) and the National Science Foundation (1972) have pro-
vided some evidence of the conceptual and developmental usefulness of
computer simulation modeling in ecosystem research. For an interesting
discussion of the value for non-scientists, as well as scientists, of
explicitly exposing assumptions used to construct a simulator , one can
refer to the discussion by Yorke following the paper by Boling and
Van Sickle (1975). Wiegert (1975) presents examples of the clarifica-
tion of relationships between system components which occurs when one
is working with a simulator. The ability to consider a larger set of
ecological variables than a single investigator is able to observe,
and the collation of various specialists' data sets, is true almost by
definition without the need for evidence, although a critical study of,
for example, the article by Van Dyne (1972), a team interdisciplinary
approach, compared to the papers in Fries (1974), a set of very disci-
plinary approaches, reveals the difference clearly.
The third stage of usefulness identified by Innis (1973) is "Out-
put Utility." This is the set of information from the computer model
performance which is in some sense useful by other people who were not
directly involved in the model development. Innis attributes the rela-
tive sparsity of published evidence at present for output usefulness of
ecological simulators as resulting from their dependence on more
uncertainties than comparable quantitative relations in the physical
sciences, Biswas (1975) also presents some reasons and remedies for
74
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system simulators not being used more frequently for environmental
management decision-making. An example of one type of output utility,
forecasting of ecosystem responses to trends in environmental stresses,
is found in Giese et al. (1975). This purpose is central to the
objectives of the Environmental Protection Agency in the present study
(Figure 15).
Another output utility, extending the range of relevance of inves-
tigations to other different locations and/or for other years aside
from those during which the study is performed, is discussed by Goodall
(1972). This purpose is also shown in the hierarchy of project objec-
tives in Figure 15. It may be a crucial one. To the extent that our
system simulators developed for the SBNF can be applied to coniferous
forests elsewhere in the western states for making comparative projec-
tions on a geographic scale we may be able to avoid having this study
treated by others as simply an isolated case study for one particular
location.
The usefulness of simulation-gaming for resource management person-
nel is treated by Holling and Chambers, 1973, and Biswas, 1975.
Subsystems of the Forest Ecosystem and Their Investigators
As a result of the complexity in ecosystems, a division of labor
among research ecologists is necessary. It is all too easy, however', to
lose sight of the whole system as an operating unit (Figure 16). In
the following sections of this report, each of the project's ten process
investigators discuss subsystems of the whole ecosystem. In Figure 16,
only the labels for these subsystems, and their coupling with other
75
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I
I
- + •
r_
i
CLIMATE
OXlTOFjT^L
1 Xj-dj
n
SPECIES
MATURE
COMPOSITION
VEGETATION
DEAD CANOPY
SNAGS
Si
SE UTTER I
FOREST FLOOR
4
FWTHOGENIC
MICROBES
MtCROARTHROPOOS
DECOMPOSER
MICROBES
CKJ - CONTROL VALVE, -
'MATERIAL TRANSFER, —
- -CONTROLLING INFLUENCE
— 'OXIDANT INFLUENCE
Figure 16. Subsystems being investigated by various project
investigators within the forest ecosystem.
subsystems, are represented, not the details within them. Any two or
three boxes, connected by arrows, represent one of the investigators'
subsystems. A solid-line arrow represents a transfer of material from
one sub-subsystem to another, with the exception of "species composi-
tion", where only a change in a characteristic property is implied.
The dashed-line arrows and "bow-tie" symbols indicate a control is
exerted on the rate of flow represented by the solid line. The dash-
dot-dash arrows represent the same information as the dashed-line
arrows except that the former refer to oxidant air pollutants' impact
directly. It bears emphasizing that the detailed interactions between
observable quantities in the ecosystem are hidden from view in this
76
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diagram. Some of these details will be revealed in each of the subse-
quent sections of this report.
To an extent, the sequence which is used in this report to discuss
the various subsystems under investigation is arbitrary; there is no
natural starting point when one begins to draw a circle. The logical
sequence we have chosen, however, is to present information about
initial states of the structure of these forest ecosystems, with regard
to climate, soils, and vegetation in Section IV. With regard to fore-
casting possible future states of these ecosystems, the third subsection
of Section V, presents information on the environmental variables of
major interest to this project in "driving" the ecosystems toward their
future conditions, photochemical air pollutant concentrations, and
their meteorological dispersion processes. The next set of information
deals with ecosystem processes, namely vegetational growth, accumula-
tion of dead organic matter in the forest, and processes controlling
the rate of decomposition of this material. The majority of the public
perceive only the wildlife and vegetation components of this complex
system when they visit the forest. As with any complex system, however,
there exist many other absolutely essential components and processes
which are equally important in the dynamic behavior of the system, but
are not readily visible to the casual observer. Apparent visibility
is no guide to importance within the system. The last portion of
Section V deals with system response and the degree to which kinds of
forest vegetation will be able to perpetuate their existence in the
presence of oxidant air pollutant stresses.
For the purpose of designing computer simulation models to mimic
77
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each of the subsystems, the project investigators are involved in a
sequence of stages for planning, development and application of
systems models, as shown in Figure 17.
Methods of the Modeling Design and Development Process
After the field monitoring design was established, the investi-
gators made initial explorations on conceptual models describing the
ecosystems (Taylor, 1974). In January 1975, a systems ecologist was
added to the project to organize and coordinate the systems modeling
effort.
Model construction is planned to evolve into a modified form of
"model-oriented, computer-assisted conferencing system" as described
by Kupperman, Wilcox, and Smith (1975). Two of the principal investi-
gators are located at the University of California at Riverside, and
nine are located at the University of California at Berkeley. A port-
able computer terminal is carried around for on-line access to a
computer center time-sharing system during modeling sessions.
With respect to the stages of modeling (Figure 17), the definition
of forecasting goals for the overriding project problem is a critical
starting point (Giles, 1972). Since two of the objectives (Figure 15)
are to "evaluate adaptability of system^ models to other pollutant
types and other forest types," and to forecast possible consequences
of photochemical oxidants on the forest ecosystems in terms of human
welfare effects, we must see that the simulators which we develop are
not too exclusively customized for giving forecasts on conditions of
unique interest in the San Bernardino National Forest, compared to other
78
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Model Planning
GOAL DEFINITIONS
Model
Development
EVALUATE
EXISTING
MODELS
-/ v.
ORIGINAL
DEVELOPMENT
GO
I
t -
Model Application
PUBLICATION-
DEMONSTRATION
MODIFY
VALIDATION
FLOW CHART
COMPONENTS
& CONTROLS
SYSTEM MODEL
EXPERIMENTATION
NTERACTION
TABLES
FLOW PARADIGM
TIME-SPACE
RESOLUTION
COMPUTER CODING
DEBUGGING
DERIVATION OF
PROJECTIONS ON
SUBSYSTEMS &
WHOLE SYSTEM
QUANTIFICATION
CONDITIONAL
LOGIC
Figure 17. The system simulation modeling process.
79
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more remote forests. Otherwise, the adaptability of such models is bound
to be very low by original design. Table 5 indicates how various
use-policies for different forests are likely to affect the forest
conditions for which we might want forecasts under possible future
air quality environments.
One of the major problems which this research group continually
needs to address is this: for what kinds of questions will the set of
system simulation models be expected to provide forecasts regarding
possible alternative future conditions of the forest so that the eco-
system irreversibility question discussed earlier can be examined? We
might then state an intermediate forecasting goal as follows: What
might be the effect of various changes in photochemical oxidant air
pollutant trends over the next 50 to 100 years, as seen in (1) number
of dead trees per hectare, (2) the rate of change in tree species
composition for ponderosa and Jeffrey pine, and (3) the vegetal life
form (trees, shrubs, grasses) and species which are likely to assume
an ecologically dominant role in various plant and animal communities
within the California mixed conifer forest type?
The work of Kickert et al. (1975) provides a useful inventory of
questions needing to be answered, by analysis of computer model behav-
ior, as evaluated by scientists and land managers for that aspect of
the problem that involves organic matter accumulation and its periodic
decomposition by fire events, a set of stresses which can occur con-
currently with oxidant stress.
The next step (Figure 17) is the construction of interaction tables
that show merely which variables are involved in various subsystems and
80
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TABLE 5. POTENTIAL COUPLINGS BETWEEN STRESSED ECOSYSTEM RESPONSES AND SOCIO-POLITICO-ECONOMIC
SYSTEMS UNDER VARIOUS FOREST LAND-USE POLICIES.
ECOSYSTEM
STRESSES
DISEASE
EPIDEMIC
OXIDANTS
DROUGHT
INSECT
EPIDEMIC
LAND-USE
WILDERNESS FORESTS
I i.e. WILDERNESS AREAS
* USFS
NATIONAL PARKS
NPS
RESIDENTIAL-
RECREATIONAL FORESTS
MULTIPLE-USE FORESTS
ECOSYSTEM RESPONSE
VEGETAL AND WILDLIFE
SPECIES COMPOSITION
CHANGES
DRY FUEL ACCUMULATION
TREE CANOPY DECREASE
GAME ANIMALS
TIMBER PRODUCTION AND
CUT
FORAGE PRODUCTION AND
QUALITY
SOCIO-POLITICO-ECONOMIC
IMPACT (POSSIBILITIES)
-CONTRADICTION OF
LEGISLATED POLICY FOR
LAND MANAGEMENT
-DEGRADATION OF
RECREATIONAL EXPERIENCE
-FUEL REDUCTION COSTS
(PRIVATE-OWNER)
-FIRE CONTROL
COSTS
-FLOOD CONTROL
COSTS
-HUNTING
-ALLOWABLE CUT
LUMBER COST
-GRAZING PERMITS
REAL ESTATE
TAX
REAL ESTATE
MARKET VALUE
-------
whether the interaction between any two variables is positive or
negative, an accelerating effect or decelerating effect. A previous
Task D Report (Taylor, 1974) showing various types of interaction
diagrams has been an aid.
The next stage (Figure 17) involves selecting the appropriate
paradigm for the substance which is conceived as flowing through the
various subsystems. A discussion of various types of paradigms is
found in Noy-Meir (1973). Possible flows may be energy, water, various
mineral nutrients, biomass, population densities, number of taxonomic
species, area occupied per biotic unit, or other possibilities.
Ecosystems can be defined at various spatial scales and for various
time scales. In this project, ecosystem simulators are planned for the
forest stand-community level. The stand-community ecosystem model may
simulate a time period of perhaps 50 years to 100 years at annual
intervals.
Review and evaluation of published simulation models (Figure 17)
for ecological systems is being done in order to build upon the work
of others wherever possible. For this purpose, continuous use is made
of the University of California Center for Information Services for
literature searches in the Cataloging and Indexing System (CAIN) for
agriculture, and also Biological Abstracts and Bio-Research Index.
Some existing models which we are modifying for subsystem simulation
are indicated below. Flow charts, as graphic representations of sub-
system model structures, have been defined, and will subsequently be
translated into computer code, for the following subsystems: (1) oxi-
dant flux-stand canopy response, drawing upon ideas of Mukammal (1965),
82
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and Reed and Waring (1974); (2) stand-level heat energy flow; (3) forest
stand moisture budget, with temporal modifications to the stand water
flow simulator described by Sollins et al. (1974); (4) forest stand
growth, using a simulator developed by Dr. Kenneth Reed (personal
communication, 1975); (5) stand level Fomes annosus root pathogen
infection, spread, mortality response; (6) western pine bark beetle
population dynamics-stand mortality response, using some of the work of
Stage (1973); (7) stand level needle litter and woody litter production;
(8) stand needle litter decomposition by micro-floral fungi with micro-
arthropod population dynamics; (9) woody litter decomposition; (10) cone
and seed production; (11) small mammal population dynamics and seed
predation in a forest stand, drawing on Patton (1975); (12) damping-off
fungi dynamics in conifer seedling establishment; (13) conifer tree
population dynamics.
An example of one of these subsystem flow charts is given in Fig-
ure 18. The same graphic symbolism of Figure 16 applies in Figure 18.
Functional interactions hypothesized to exist with other donating and
receiving subsystem models can be seen. We are now moving into that
stage of quantifying relations indicated in the flow chart models and
using these to construct the computer programs for the subsystem
simulators.
Documentation is being kept on the modeling stages as each of the
subsystem investigators proceeds through the sequence shown in
Figure 17. Such documentation is in line with Mar's suggestion (1974)
to include, for each simulation model: (1) identification of personnel
involved in construction, (2) documentation of model framework and
83
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FROM OZONE-INJURY SUBSYSTEM
ANNUAL
OZONE
DOSAGE
FROM TREE POPULATION
DYNAMICS SUBSYSTEM
NUMBER TREES
BY AGE CLASS
BY SPEC IES
SOURCE
AVAILABLE NUTRIENT
AMOUNTS IN
ROOT ZONE SOIL
STAND CANOPY
BRANCH BIOMASS
STAND CANOPY
FOLIAGE BIOMASS
BY SPECIES
SOURCE
FROM ROOT DISEASE SUBSYSTEM
NUMBER TREES WITH
ROOT CROWNS COLONIZED
BY FOMES ANNOSUS
BY CROWN-SIZE CLASS
FROM STAND MOISTURE DYNAMICS SUBSYSTEM
AVAILABLE
SOIL
MOISTURE
'ABOVE GROUND CONIFER'
FOLIAGE NUTRIENT
AMOUNTS BY ELEMENT .
TRANSPIRATION
RATIO
FROM BARK BEETLE SUBSYSTEM
CANOPY DRIP]
NUMBER TREES KILLED
BY WESTERN PINE BEETLE
BY CROWN-SIZE CLASS
[PERCENT CROWN COLONIZED
\BY MICROFLORA FUNGIJ
NEEDLE LITTERFALL
BY SPECIES
*><
WOODY UTTEAFALL
FOREST FLOOR
ORGANIC LAYER
NUTRIENT AMOUNTS
vooor LITTER
DECOMPOSITION
SUBSYSTEM
SEEDLING ESTABLISHMENT
SUBSYSTEM
NEEDLE UTTER
MASS ON
FOREST FLOOR
BY SPECIES
NEEDLE
LITTER £-
DEPTH
NSEDLS UTTER
MICROFLORAL FUNGI 6
MICROARTHROPOD
DECOMPOSITION
SUBSYSTEM
NEEDLE LITTER
SUBSTRATE WEIGHT LOSS
f LITTER
[infiltration RATE,
SURFACE MINERAL
SOIL AVAILABLE
NUTRIENT AMOUNTS
MINERAL SOIL
INFILTRATIOH RATE
Note; Nutrlcntt ar* N, P, Ca, Mg in Kg/he.
Figure 18, Needle litter and woody litter production subsystem.
8U
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theory, (3) flow charts, (4) description of methods to reduce data to
construct models, (5) listing of system variables and definitions,
(6) literal description of computer programs for models, (7) computer
program listing, (8) programmer manual, (9) operator's manual, (10) con-
struction, operation and maintenance cost data, (11) history of review
by peers, and (12) record of users and outcome.
As Figure 17 indicates, the ecological systems modeling process
will be partially dependent upon the Data Management System being
designed by Barbieri.
THE DATA MANAGEMENT SYSTEM
In any realistic attempt to study a particular environment it is
apparent that large amounts of diverse and highly structured data will
have to be collected and efficiently stored. The data are, in general,
dependent on the intrinsic properties of the process being measured and
on the sampling technique employed. In order to handle the large volume
of field data, a computer processing procedure seems advisable.
In this study, the types of field data being collected can be sub-
divided into six broad study classes: meteorological-pollutant dose
information, vegetation information, arthropod information, soils infor-
mation, pathogen information, and wildlife information. Each of these
broad classes of information can be further subdivided into the actual
type of data being collected. For example, vegetation information is
composed of six different data types. Thus, the hierarchical structure
of the data i« a mimic of the heirarchical biological structure of the
SBNF.
85
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To process the volume of extremely varied data for the SBNF
study, an efficient data management system has been designed at
Lawrence Livermore Laboratory. The purpose of the data management
system is to efficiently collect, store and process data which can then
be used in various types of ecosystem models. The data management
system designed for this study is divided into three general sections:
data capture, data banking, and data manipulation.
Data Capture
Data capture is defined to be the collection of techniques which
are used to convert field data into a format which is suitable for
storage into a computer. Because of the variability in the types of
field data being collected, no one data capture scheme will satisfy all
of the field researchers. The data capture system should, therefore,
be general enough to accept data with a quasi-arbitrary structure in
which the field collected data itself becomes the basis for entry into
the computer system. For the SBNF project, a fieldfree format input
was developed in which the field data are not required to appear in
specified columns on a data sheet. By allowing the field researcher
to design his own data sheets, it is hoped that the amount of error in
handling data will be minimized.
Computer systems have a tendency to fail catastrophically if the
field data are not recorded in a precise and consistent manner. To
counteract this tendency, the data capture system designed for the SBNF
study notes inconsistencies and then ignores the inconsistency — such
data are not processed. Therefore, instead of rejecting whole data
86
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sets because of an error in the data set, the data capture system
records the error and then processes the remaining acceptable data.
The data capture system is itself divided into three types of
computer routines: The executive and library routines, the operational
routines, and the decoding routines. The executive routines contain
all of the general logic for determining the type of data being entered
and also contains a library of all names and mnemonics used by any of
the operational routines. The decoding routines are responsible for
decoding and classifying the actual data into integers, floating point
numbers, alphabetic character(s) and/or special symbols. The opera-
tional routines determine whether the data is of an acceptable format
and stores the acceptable data into given locations for future use.
A schematic diagram for the arthropod data capture system is given in
Figure 19. Presently the data capture system is capable of accepting
twenty different field data types.
Each operational subroutine will have summarization and statis-
tical analysis capability which will analyze the incoming field data.
The summarization and statistical analysis performed by these pack-
ages are determined by the requirements of the user. At present there
are eight suinnation routines coded. Once the data are in an acceptable
form, they will be stored in a data bank.
The Data Bank
The data banking system which will be used is a system designed
for Lawrence Livermore Laboratory called Master Control (Hampel and
Ramus, 1975). Master Control is a computer program designed to unify
87
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1
£
E
"
REE
STIK
I
mrx aerru
•TlCKV-
TREE
C ACTON
DATA
DATA
1
'
'
BTREESUM
STIK SUM
EXECUTIVE ROUTINES
I.AACIICHC
ZLlBRARf
1CAPTURE
4RDCR03
DECODING ROUTINES
lFFCRDS
2.FFNI
J.FFNC
4FFSrN
X RAY
REAR
X NAY
EGGS UM XRAYSUMI REARSUM
OPERATIONAL ROUTINES
SUMMARY ROUTINES
(TO PATA BAttK)
Figure 19, The arthropod data capture system.
88
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storage, manipulate, reorganize, retrieve, and display data from dis-
similar data bases. It is open end and user oriented. Some of the
characteristics of Master Control are packed memory allocation,
hierarchical ordering using pointers for random access, a telegram-
like command language, and options to interrogate and manipulate data
bases in both batch modes or time-share modes. Master Control allows
progressive adaptation of data bases to contemporary needs (Figure 20).
Each of the six main classes of field data (vegetation, arthropods,
etc.) will initially have its own data bank created by Master Control.
In each of these data banks, the processed field data received from
the data capture routines will be stored. Using the general command
language of Master Control, new data banks can be constructed which
will reflect the needs of the user (Figure 21). The command language
consists of ten general operations. The operations are (1) define,
BASIC DESIGN PHILOSOPHY OF MASTER CONTROL
UNDEFINED
BASIC
PROGRAM
DEFINITION
OF ARRAYS
LISTER,ETC
¦USER
DEFINITION
OF ARRAYS
LISTER,ETC.
Figure 20. Basic design philosophy of 'Master Control*.
89
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METEOROLOGY
VEGETATION
ARTHROPODS
SOILS
PATHOGENS
WILDLIFE
USER
USER
USER
DATA
CAPTURE
MC
VEG
SOIL+MET
f VEG+ARTH
MC"
WILD
MC'
MC
WILD
MC
MET
DATA
CAPTURE
ARTH
MC"
MC
SOILS
MC
ARTH
DATA
CAPTURE
DATA
CAPTURE
PATH
MC'
DATA
CAPTURE
SOIL-VEG
DATA BANK
MC
PATH
DATA
CAPTURE
MASTER
CONTROL
MASTER
CONTROL
MASTER
CONTROL
MASTER
CONTROL
MATH-STAT
PACKAGE
MATH-STAT
PACKAGE
MATH- STAT
PACKAGE
U-
Figure 21. The Sari Bernardino Data Management System.
(2) initialization, (3) generation, (4) construction, (5) file transfer,
(6) alter, (7) edit, (8) search, (9) numerical operations, and (10)
macro-operations.
At present Master Control exists on the Lawrence Livermore
Laboratory CDC-7600 and CDC-6600 and is written in the CHAP language —
an internal version of FORTRAN-IV. Master Control, however, is
currently being modified so that it will be compatable with other
computer systems. Work on applying Master Control to the SBNF study
90
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began in April 1975.
In order to use the data banking system effectively it will be
necessary to provide the user (either the modeler(s) or subsystem
investigators) with a library of numerical, statistical, and graphical
techniques.
Data Manipulation
The data manipulation facility of this data management system will
contain a library of operational programs which can be used to analyze
parts of the data in any given data bank. This facility will reflect
the desires indicated by the modeling activity, and together with the
commands available in Master Control, will provide the modeling activ-
ity with a method of obtaining data for input into various model
development activities.
There exist a variety of approaches which have been used to design
ecological system models (Jeffers, 1973; Mar, 1974). Aa a consequence
of this diverse condition in the state-of-the-art, and also since field
data for this project are being collected on four different classes of
observations: nominal, ordinal, interval, and ratio Bcale, the speci-
fic data manipulation procedures have not been defined yet. In general,
they will comprise three separate categories of computer programs as
identified by Bridges (1974): (1) graphic display procedures to
visually examine graphic plots, spatial maps, response surfaces, and
tabularization of observations from field sites and computer model
behavior, (2) statistical procedures for use in model design and sub-
sequent model evaluation against the actual landscape ecosystems, and
91
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(3) ecological subject data procedures which transcend conventional
statistical methods and provide computer analysis capability for
climate analysis, population analysis, biological community analysis,
and calculation of ecosystem indices such as species diversity.
TRENDS OF PHOTOCHEMICAL AIR POLLUTANT CONCENTRATIONS DURING
GROWING SEASONS
Oxidant Trends in Downtown San Bernardino and at a Nearby Mountain,
Forest Station
The National Primary and Secondary Air Quality Standards for Photo-
chemical Oxidants (California Air Resources Board, 1974), Appendix
A, provide the basis for evaluating the trends of concentrations in the
area under study. Data are available back to 1963 from the downtown
San Bernardino station operated by the County Air Pollution Control
District (APCD)» The colorimetric potassium iodide method was used to
measure total oxidants. A recent revision (California Air Resources
Board, DeMore Committee, 1974) for calibration of ozone sensing instru-
ments suggests that an interim correction of ail ozone concentration
data could be made with a multiplication by 0.80. The former primary
standard calibration procedure, using buffered potassium iodide, was
found to be 20% higher than ultraviolet photometry which has now been
accepted as a valid primary (transfer) standard in California. Begin-
ning in 1968, continuous total oxidant measurements were obtained at
Rim Forest/Sky Forest by the Forest Service, Pacific Southwest Forest
and Range Experiment Station, from June through September annually.
The Mast ozone analyzer employed was calibrated according to the
92
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method of the California Air Resources Board. A positive correction
factor of 1.22 was employed to adjust for decreased pressure at the
mountain station compared to the calibration site at Riverside.
Another useful way of identifying the trends in air pollution
doses is to compare the number of days or total hours each year when
concentrations exceed some threshold higher than the Federal Standard,
160 yg/m3. At the selected threshold, human health and welfare is
imperiled especially because the daily peak oxidant concentration can
reach up to 1176 jjg/m3 (0.60 ppm) on these days. Local communities
and both State and Federal agencies have adopted different threshold
values to signify adverse effects. The State of California employs
several descriptive thresholds, one being 392 yg/m3 (0.20 ppm), to
identify the frequency of air pollution episodes or periods of
sustained high concentrations of atmospheric pollutants.
Data from the mountain station at Rim Forest/Sky Forest were
compared with published data from the San Bernardino County APCD
in terras of the number of hours during which total oxidant concentra-
tion exceeded 392jjg/m3(0.20 ppm) during July, August, and September
from 1968 to 1974, when both stations operated. From 1963 to 1967,
data are available only from the San Bernardino APCD station, Air
Resources Board (1973). A large part of the year-to-year differences
at the same station and between stations can be attributed to differ-
ences in synoptic and mesoscale meteorological patterns. For example,
the differences in 1972, 1973, and 1974, at Rim Forest/Sky Forest
(Figure 22) are associated with 6, 16, and 46 days respectively,
when a persistent 500 mb high pressure system occurred over the
93
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400..
300..
I
Q
X
o
< 1200
t~ a.
0 O
t- oj
f 2
1 too.
(fl *
QC CVi
8 8
X A
SAN BERNARDINO APCO (DOWNTOWN) PERCENT DATA AVAILABLE RF/SF
RIM FOREST/SKY FOREST ~ 99
93 9 8 78 9 3 91 96
JULY, AUGUST, SEPTEMBER
THREE VCAR MOVING AVERAGES;
APCD
RF/SF
,.400
..200
1963 1964 1965 1966
1967 1968
YEAR
1969 1970 1971 1972 1973 1974
Figure 22. Number of hours of total oxidant, July through September,
greater than or equal to 392 yg/ir* (0.20 ppm) at the down-
town San Bernardino County Air Pollution Control District
Station, 1963-1974, and Rim Forest/Sky Forest, 1968-1974.
(For absolute values, oxidant concentrations might be
multiplied by 0.8 to comply with a new, tentative cali-
bration procedure.)
southwest, particularly southern California. The difference between
stations in the same year is probably influenced most by inversion
height. Lower inversion heights would partially restrain transport
upslope to shorter periods daily. Higher inversions would have the
opposite effect and in addition allow a greater air volume below to
dilute oxidants. The index for comparison chosen in Figure 22, i.e.,
hours with total oxidant concentration 1392 jig/m3 should be largely
determined by inversion height. The three-year moving averages for
each station tend to remove some of the variation due to higher fre-
quency fluctuations. In terms of hours with total oxidant concentration
91+
-------
-392 ng/m3, the moving average between 1970 and 1973 at Sky Forest/Rim
Forest has increased from 175 to 290 hours. This trend is the reverse
of that in upwind, urban Los Angeles County where increased emissions
of NO (nitric oxide in fresh auto exhaust) tends to shift the chemical
equilibrium to the left towards the ozone precursors in the chemical
reaction which produces ozone.
The most recent data analyzed suggest that oxidant will either
increase annually or oscillate around the mean of present high levels
in the foreseeable future at these distant locations unless dramatic
improvements are made in control strategies (Corn et al., 1975;
Blumenthal et al., 1974).
A second method of documenting trends of oxidant levels during
the 1968 to 1974 period at Rim Forest/Sky Forest expresses the accumu-
lated dose (yg/m3-hr) and number of hours of dose -157 yg/m3 (0.08 ppm),
the Federal Standard, Appendix A, for June through September (Figure 23).
This period represents the main part of the growing season; however,
doses during the remaining months of the year are also being documented
in present and proposed work. These doses exclude the background con-
centration of less than 59 yg/m3 (0.03 ppm), as reported by Gloria et
al. (1974). The percent of valid data recovered is also indicated.
The absence of some data, up to as much as 17.8 percent in 1970, but
averaging 8.3 percent during the seven years, presents a margin of error
that cannot presently be adjusted with any certainty. Future analysis
of past meteorological data may permit some adjustments to be made. The
percent of the total possible hours for which data could be obtained
during the June through September period is also indicated. The
95
-------
vo
o*>
in
O
ro
E
N
o»
51
CT>
m
At
l
ro
E
s
o»
a.
UJ
in
O
Q
2
<
Q
X
o
<
H
O
DOSE OF TOTAL OXIDANT , JUNE - SE PTEMBER
RIM FOREST /SKY FOREST . CA.
PERCENT OF TOTAL HOURS , JUNE- SEPTEMBER.
94. 4
99.6
2000 S
1500
94.7
S«pt
3.0 -
1000 o
2.0 .
82.4
Jul
7 7.9 I:::::
June
"iitmn
1968
Figure 23.
1970 1971
YEARS
1974
Monthly summation, June through September, 1968-74, of total oxidant
dose and total number of hours at a dose greater than, or equal to,
157 ug/m3 (0.08 ppm), at Rim Forest/Sky Forest. (For absolute values,
oxidant concentrations and doses might be multiplied by 0.8 to comply
with a new, tentative calibration procedure.)
-------
number of hours with total oxidant concentration -157 vig/m^ (0.08 ppm)
was never less than 1300 hours per year during the seven year period.
The present level of compliance with Federal Air Quality Standards can
be described as a ludicrous situation.
The dose data have been used to estimate dose-injury relationships
for ponderosa pine needles (Figure 32) and are being stratified in
various ways to test for possible correlations with radial (ring) growth
of ponderosa pine (Figure 43).
Comparative Daily Maximum Hourly Averages for Ozone, Total .Oxidant, PAN,
and NO? at Sky Forest, August 1974
The daily concentrations of ozone and total oxidant for August 1974
closely mimic one another (Figure 24). The data from the DASIBI ultra-
violet spectrophotometer, which measures ozone specifically, were always
lower than the Mast KI instrument, which responds to other oxidants,
except for one day, August 8. It is important to observe that ozone is
a good surrogate for the total oxidant measurement, and in addition it
is the most important pollutant causing injury to conifers. Because
August is usually one of the more severe months for pollution, this
record probably displays one of the highest frequencies of air pollution
episodes to be expected in the mountain area. PAN concentrations were
sufficient to cause injury to common herbaceous plants frequently used
in laboratory studies, but PAN symptoms were not distinguished from
ozone symptoms on nearby herb layer plant species. Nitrogen dioxide
remained at low concentrations compared to the other oxidants.
97
-------
Comparative Hourly Concentrations of Total Oxidant, Nitrogen Dioxide
(NOq) and Peroxyacetyl Nitrate (PAN)
A comparison of total oxidant at Sky Forest, Big Bear Station, and
Barton Flats, with winds at Sky Forest and Big Bear Ranger Station dur-
ing two days in October 1973 (Figure 25), shows that total oxidants may
peak out later at more distant stations (October 18) or nearly simulta-
neously (October 19). The stronger winds on the 19th may have caused
45
~-TOTAL OXIDANT (pphm>,KI,MA3T
40-
35
30-
2 0-
OZONE(pphm) UV, DASIBI
TELEMETRY,ONCE HOURLY
I 0-
PAN (ppt>) G.C..ELECTRON
5-
SALTZMAN
N02 (pphm)TECHNICON IV
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
DAYS
Figure 24. Comparative daily maximum hourly averages for ozone,
total oxidant, PAN and W02 at Sky Forest, August 1974.
(For absolute values, oxidant concentrations might be
multiplied by 0.8 to comply with a new, tentative
calibration procedure.)
98
-------
ftt
LL
-ii
liriaat—IntM Flit)
¦
\\
Ittltat ft H71
Figure 25. Comparative hourly concentrations of total oxidant, PAN, and NO2 at
Sky Forest, November 18, 19, 1973, and total oxidants at Big Bear
Ranger Station and Barton Flats. (For absolute values, oxidant
concentrations and doses might be multiplied by 0.8 to comply with
a new, tentative calibration procedure.)
-------
the more uniform peaking time. At Sky Forest, PAN peaks a littler later
than total oxidant. Nitrogen dioxide has a very small peak around
0800 hr and a larger one at 2000 to 2100 hr PST.
The interaction of time of day when oxidants reach adverse levels
with the prevailing meteorological conditions at that time undoubtedly
influences plant susceptibility. Studies are in progress with coop-
erators at the USDA, Forest Service Fire Laboratory at Riverside,
California, to collect the meteorological data necessary to generate
air temperature, humidity, and wind fields with computer models. Three
telemetering stations located at Camp Paivika, Sky Forest, and Barton
Flats continuously measure winds, air temperature, humidity, net radia-
tion, and ozone at hourly intervals during the growing season. The
first objective is to understand the relationship of terrain to surface
flow in order to interpret pollutant dispersion.
Definition of the West to East Gradient of Surface Total Oxidant
Concentrations in the San Bernardino Mountains, 1974
Seven ground stations were maintained from June through October,
1974", along a west to east transect. These stations can be located by
intersection on the scales superimposed above the topographic projection
of the San Bernardino Mountains (Figure 26). The cumulative monthly
doses which are presented in Figure 26 do not include data from every
hour possible during each month because of intermittent instrument
failure. On the average, at least 90 percent of the data are available.
Since 1974 was one of the most severe air pollution years on record
(Figure 23), these data probably represent an overestimate of the
100
-------
s
V*
4
<7G *
S&Z
o-cvs
at'
t4°se
Stvo^
Ba"^
?ss""
3t°}
e^1
fife
o*©
2b
to?0^"
3Mtve
ta?'
t**
_ of the San Berna.
1974, of total oxidant do*,-
recovered is indicated by mo...
-st (SF) "-"ining Springs (Rj>, ,
1 lut ion strict (BBAPCD) ai.v
-¦»« might be
etvt
h OctODe. f tot
f total data overe-
(CP) Sky Fore
,tto'
,-ttic ^otet v., a * eC°VnteSt Y7„o '""V.io"8
The perceive
/ere: Camp Paivi.
Dam (BBD) Big
v<=olute values
a new
i>a
c°T^biat
centratioi.^ and
•"¦ion procedure.)
Be
a*
V*V> • -
V*
a to
-------
average doses along this gradient in pervious years.
The influence of terrain likely causes the rapid decline in dose
between Sky Forest (SF) and Snow Valley (SV) because the elevation
gradually increases from 1661 m (5,450 ft) to 2052 m (6,750 ft). The
slight dose increase at Big Bear Dam (BBD) occurs because the monitoring
station is in a notch which channels air flow at the top of a major
canyon leading up from the basin. The terrain along the interval between
BBD and the Big Bear Air Pollution Control District Station (BBA) is
mainly lake surface. Barton Flats (BF) monitoring station is located on
the forested north slope of the Santa Ana River drainage and is exposed
to the unimpeded afternoon up-canyon flow of polluted air. The informa-
tion in Figure 26 does not adequately represent the complete eastward
extent of pollutant transport in the mixed conifer forest which is nec-
essary to fully define the dose gradient. More important, the western
part of the transect generally overlooks the basin and additional data
must be obtained by placing stations in a south to north configuration.
In Figure 27, the total hours with oxidant concentration -157 yg/m3,
the Federal Standard, are separated into daylight and night-time hours
for August, September, and October, 1974. It is readily apparent that
the western, lower elevation monitoring stations receive more night-
time hours when oxidant concentrations exceeded 157 ug/m3 , especially
at Camp Paivika. The greater oxidant concentration at night may be
associated with the nocturnal position of the inversion layer which is
acting as a reservoir for oxidant as suggested by Edinger (1973). The
west to east gradient of decreasing oxidant dose is plainly evident in
this analysis, as well as in Figure 26.
102
-------
PERflFNT TOTAL
-------
MOUNTAINOUS SURFACE WINDFLOW AND POLLUTANT DISPERSION
Earlier studies by Edinger et al. (1972) have demonstrated a
natural bond between fire meteorology and air pollution research in
terms of kinds of data and data collection techniques required. In
the case of air pollution studies, it is important to understand the
relationship of terrain to surfaced wind flow and pollutant dis-
persion. To integrate the complexities of terrain effects on surface
flow, a mathematical wind model was formulated by the Fire Meteorology
Project (Ryan, 1974). The need for a model is magnified by the lack of
meteorological observations in mountainous areas. Because of the lack
of observational data, the model was designed to predict winds at
remote locations if only sky condition, 850-mb data, and terrain height
were available for input. If other data are available, the model is
designed to incorporate them.
The model design is based on the premise that mountain winds are
a result of the vectorial sum of component winds generated by several
different mechanisms and factors. Component factors included in the
model are valley-mountain wind, slope wind, sea breeze, larger scale
pressure-gradient induced winds, and the sheltering and diverting
effect of the terrain.
The detailed terrain effects on wind flow (Figure 28) were computed
by the model for 1300 PST on August 31, 1974 for a limited area (see
Box Figure 29). Detailed terrain effects on wind flow for the entire
area (Figure 29) are not modeled because of lack of data at the
present time.
104
-------
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57-
49-
41 -
33-
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17-
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SURFACE
WINDS AT
1300 HRS 8/3J
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/ / / / •
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DIRECTION OF FLOW
x 20
Figure 28. Surface wind fields generated from a computer model for
1300 hr PST, August 31, 1974, for a limited portion of the
study area (see caption in next figure).
105
-------
HOCK CAMP
CAMP
PAtVtKA
A
i2,12,13
235,231,235
o
S^AKe£RI,Y SKYFOfiEST
Ai2.l2.l8
y 235,235.353
A
o
&i<3 BEAR
^fiSGER STATION
BEAR APCO
O
CONVERSE
BOUNDARY OF INTENSIVE SURFACE
WIND AMM.TS1S
BARTON FLATS
A
9,«0,SZ
IT6.l9e.eS5
SURFACE AIR ANALYSIS
ktrry P
.__c
MB.L CREEK I
—LOCATION Of 0*lO**T 3ENS0*
(i iiMiii w *•» <«fti '• H*m.
m4 ttn M"®«" 3 to >¦•/¦*, #'
utw »1 1200.1300. »M
1400 h.«T,M h(Mt 3l.r97«i
*M ««•« gx*« »»' 1500 tn at*)
-"cwenMirnw sy u.s. poucst
SPMCE
•"I—1 '-fl
ay
I ! i I
Figure 29.
Wind direction and speed at selected surface stations at 1300 hr PST,
August 31, 1974, compared with the concentration of total oxidants at
1200, 1300, and 1400 hrs PST.
-------
The synoptic conditions on August 31 resemble a class 4 day of
relatively low air pollution potential (McCutchan and Schroeder, 1973).
A surface thermal trough was over the desert, and a weak 500 mb
trough was just off the coast of southern California. Flow aloft
was southwesterly, and the sea breeze was strong from the southwest.
The combined effect produced a prevailing surface wind from the
southwest with speeds near 6.7 m/sec (15 mph).
Sheltering of the fairly strong southwest flow resulting from the
effects of terrain can be seen in several areas such as around grid
point X = 31, T = 61 and around X - 46, Y ¦ 36. In these areas the
strong flow is blocked by higher terrain up-wind. In contrast to these
sheltered areas, channels through which strong winds are allowed to flow
are evident, such as near grid point X * 16, Y = 66. Examples of change
of direction caused by terrain effects are also displayed such as at
gridpoint X « 21, Y » 61. Changes in wind direction are the result of
three different terrain effects: mechanical diversion, wind component
produced by differential heating on slopes, and wind component produced
by differential heating in valleys.
Observed prevailing surface winds were south to southwest over
the entire area (Figure 29). Variation from the prevailing direction
owing to terrain influence is evident at Converse, The east-west
orientation of Santa Ana Canyon is responsible for the west wind at
Converse.
The hourly average of total oxidant concentrations at 1200, 1300,
and 1400 hr, the hours before, during, and after the wind observations,
are indicated in Figure 29 where monitoring stations were present. For
107
-------
example, the concentrations at Sky Forest were 235, 235, 353 yg/m^ for
the three consecutive hours. The expected increases of concentrations
to a daily maximum sometime after 1400 are evident at all six monitor-
ing stations. When detailed wind fields can be obtained from the model
for the whole mountain area it will be possible to evaluate the
relationships of flow patterns and pollutant dispersion in relation to
forest vegetation injury.
PROCESSES IN ECOSYSTEMS ~ IMPACTS ON FOREST VEGETATION INJURY,
MORTALITY, AND LITTER ACCUMULATION
Oxidant Dose/Vegetation Injury Response
Chronic injury to vegetation in the San Bernardino Mountains is
being inflicted upon a complex mosaic of forest types. These forest
types exist along gradients of increasing elevation and decreasing rain-
fall in a west to east direction. In a similar way, oxidant air pol-
lutants at adverse concentrations and durations decrease from west to
east. Differences in such common environmental variables as soil
moisture availability, air temperature, relative humidity, and wind
have an important influence on degree of plant sensitivity to oxidant
pollutants. Ozone is of particular interest because it is primarily
responsible for injury to conifers, as determined from controlled
fumigations (Miller and Milligan - in preparation). The role of
other oxidants, e.g., PAN and NO2, assumes more importance with
broadleaf trees, shrubs, and with herbaceous understory plants.
The purpose of this study is to define the relationship between
108
-------
oxidant (particularly ozone) dose and amount of chronic injury (Fig-
ure 30) to individual species comprising the mosaic of vegetation
types along the west-east gradient of decreasing levels of oxidant
pollutants. An integral part of this task is to gain an understanding
of the influences of other environmental variables which may condition
plant sensitivity; the role of other stresses acting in concert with
chronic oxidant injury to cause mortality is also of special interest.
SPECIES
COMPOSITION
VEGETATION!
40 4
i
p<*5
i
ICOAteE UTTEftl
PATHOGENIC
MICROBES
»«
¦H
FOREST FL66R
MICRQARTHftOPODSl
zt
4-
DECOMPOSER
MICROBES
CX « CONTROL VALVE, -
= MATERIAL TRANSFER,—
* CONTROLLING INFLUENCE
'OXIDANT INFLUENCE
Figure 30. Oxidant dose/vegetation injury subsystem.
109
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Interpretation of Dose-Injury Observations Following Chronic Exposure
of Ponderosa and Jeffrey Pines to Ambient Total Oxidants
Two injury rating systems have been employed to provide an index
of the amount of oxidant injury. The first system is employed with
container-grown seedlings and with saplings less than 10 cm dbh, where
the trees are usually small enough so that needle complements can be
reached and inspected from the ground. Needles are inspected closely
to determine the amount of chlorotic mottle, necrosis, and abscission
(Figure 31). Each of the three symptoms are rated as: none = 0, very
Figure 31. Chlorotic mottle (top), necrosis caused by an experimental
ozone fumigation (middle), and superficial necrotic flecks
not associated with oxidant injury but rather winter weather
(lower).
slight ¦ 1, slight = 2, moderate » 3, and severe = 4. The worst
possible score for a single needle complement is 12 and comparisons
of complements of the same age from tree to tree form the basis for
110
-------
evaluation of injury differences. Following chronic injury, the current
year and one-year-old needle complements are the only ones remaining.
With the seedling-sapling injury evaluation, the higher scores mean
greater injury.
The second system is employed only with trees 10 cm dbh and larger
in the field and was contrived as a "penalty score or index" system
which would be useful to forest managers. Most of the elements making
up this score must be determined by binocular inspection of each tree.
With this system, the higher scores mean less injury (Miller, 1973a).
Dose-injury observations of ponderosa saplings From 1968 to
1973, three nearby groups of 10 ponderosa pine saplings averaging 18
years of age were each subjected to a different treatment: activated
charcoal-filtered air in a greenhouse, unfiltered ambient air polluted
with oxidants in a second greenhouse, and polluted ambient air outside
of the greenhouses. The abbreviations FAH, AAH, and AAO represent
each treatment''in the order named above. The differences in growth,
needle biomass retained, and needle injury symptoms among these
three treatments are described in the following section: "Oxidant
Effects on Tree Growth."
The AAO treatment in this experiment offered the opportunity to
observe the rate of symptom development on current and one-year-old
needles in relation to total oxidant dose. In addition, the rate of
current year needle growth (cm) was measured (40 needles per tree
monthly) to determine (a) the relationships of season to inception
and completion of needle elongation, (b) the time of appearance and
111
-------
intensity of needle symptoms, and (c) the accumulated oxidant dose
associated with needle injury. In Figure 32, the data for three years
with complete records, 1969, 1970, and 1971, are combined. Trees grow-
ing outside greenhouses began to show slight injury to current year
needles before needle elongation was completed (between Julian days
200-225, July 19 to August 13). Injury continued to increase on
DEVELOPMENT OF NEEDLE
SYMPTOMS COMPARED TO PATE AND
STAQC OF NEW NEEDLE GROWTH;
JUNE THRU SEPTEMBER IMS, 1970, 1971
PONOEROSA PINK SAPLINSS
MM FOREST, CALIFORNIA
•'CURRENT YEAR
NEEDLE OROWTH
~•CURRENT >ONE-YEAR
010 NEEDLES
a iOO-
6-CURRENT YEAR
NCEOLEt ONLY
i oct m
T"
200
(Mil*
JULIAN DATE
INCREASE OP VISIBLE NEEDLE SYMPTOMS
COMPARED WITH TOTAL OXIDANT DOSE
PONDEROSA PINE SAPLINGS
RIM POREST, CA
iJUNE- SEPTCMSER
I9S9,1970,1971
CURRENT PLUS
ONE-TEAR-OLD
NEEDLES
CURRENT YEAR
NEEOLES ALONE
00 i-0 i.s to z'.n to
ACCUMULATED DOSE hrt ,10* - 99«g/m>
(BACKGROUND
Figure 32. Development of oxidant injury symptoms on current, and
current plus one year old, needles of ponderosa pine
saplings, in relation to stage of current year needle
growth and time during the summer season (left) and in
relation to total dose of oxidant (right). (For absolute
values, oxidant dose might be multiplied by 0.8 to comply
with a new, tentative calibration procedure.)
112
-------
current year needles for the duration of the summer observation period.
In Figure 32 (left), an average of the three years shows that by
Julian day 250 (September 7), the current year needles had a score of
2.2 indicating slight chlorotic mottle; there was usually no necrosis
and almost always no abscission of current year needles. On the same
date, the combined score of the current and one-year-old needles was
about 9, suggesting a combination of mottle, necrosis, and abscission
scores for one-year-old needles totaling about 7, with current year
needles having a score of about 2. The worst score a single needle
complement could have is 12. Two-year-old needle complements were
rarely present on this group of injured saplings because the abscis-
sion of older needles is the most characteristic result of chronic
injury. The trees in the filtered air house nearby usually retained
at least 4 needle complements.
The accumulated oxidant dose (yg/m3-hra) since June 1, which is
associated with the current year, or one-year-old needle injury
expressed in Figure 32 (left), can be estimated by transferring the
injury score to Figure 32 (right). For example, the current year
needle score of 2.2 on September 7 is associated with a dose of 2.75
X 105 yg/n^-hrs total oxidant. The 95 percent confidence limits
indicated in both parts of Figure 32 may not encompass all of the
variation because they assume that 100 percent of the air monitoring
data were available; on the average, about 90 percent was available.
Other precautions must be introduced when interpreting the dose
response in Figure 32. As indicated in Figure 24, the frequency of
pollution episodes is random so the accumulated dose is a composite of
113
-------
high, moderate, arid low dose days. The relative injury-inducing effect
of different dose sequences is unknown. The three years of data which
comprise Figure 32 are not sufficient to sample the variation involved.
It is also assumed that visible injury increases by equal intervals
or units from the first visible symptoms to the most severe. Further
investigations will hopefully determine the true form of the dose-
injury curve. These investigations must also evaluate the controlling
influences of soil moisture availability and other important micro-
climatic variables on the development of injury. Changes of needle
sensitivity to ozone have been observed to occur throughout the growing
season when container-grown plants were fumigated (Miller and
Hilligan, In Manuscript).
Observations of Injury in 1974 to Ponderosa and Jeffrey Pines and Black
Oak at 19 Study Sites Along a Gradient of Decreasing Oxidant Dose
In September, October, and early November, 1974 all tree species
at 19 major study sites or plots were scored individually by binocular
inspection. The data from conifers could be obtained this late in the
season, however the single most important deciduous species, black oak,
was also evaluated during 3 days, August 28-31, to distinguish between
oxidant injury symptoms and natural autumn senescence of leaves. The
visible injury on oaks observed in August, 1974, is reported here. The
details of the scoring method have been described (Miller, 1974). [The
higher the score, the smaller the injury.]
The injury to black oak as of August 31, 1974, at several repre~
sentative study sites, along with the June through August accumulated
dose at nearby monitoring stations, is shown in relation to the topo-
114
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PfRCFNT TOTAL
AIR MPNITQRINS
AVAILABLE
JUNE- AUGUST
1\, v' . to-c^
®otv ft .a *°
f ig,uT (
33.
rtovitvta^"tV kug,ust 0
^o 4;t'ec"^e
o« 0,^ea \°l* abs<^U..,i-
-------
graphic projection of the San Bernardino Mountains (Figure 33). The
darkened portion of the bar representing oak injury is for leaf
chlorotic mottle and interveinal necrosis (Figure 34). A score of 8
means no injury. The remaining portion of the score is the sum of
scores for leaf complement, leaf size, and twig mortality, not shown
separately. These data suggest that oak shows no injury symptoms when
the accumulated June through August dose does not exceed about 2.0 X
5
10 yg/nr-hr, or from around Snow Valley eastward. It is also interest-
ing to note that a frost in late May killed all the emerging foliage
east of a point midway between Camp 0-ongo and Snow Valley. Frost
damage increased with elevation. The frost-killed leaves were quickly
Figure 34. Examples of oxidant injury, chlorotic mottle followed by
interveinal necrosis, to leaves of black oak, Quercus
kelloggii.
116
-------
replaced by new foliage; it is difficult to assess how this may relate
to subsequent levels of oxidant injury to oak.
The distribution of ponderosa and Jeffrey pines into various
injury classes (Figure 35) with respect to the distance of the study
site along the gradient of oxidant dose (June through September) is
illustrated above the topographic projection in Figure 36. It is impor-
tant to realize that the 1974 distribution into injury classes is also
a product of earlier years when the oxidant levels were not always as
high at in 1974. The trend towards greater numbers in the very slight
(29-35) category is quite evident in the eastern plots receiving
Figure 35. A fish eye lens view of the crowns of severely oxidant
injured ponderosa pines (left) with another stand having
slight injury (right). Each tree is scored for needle
retention, needle condition, needle length, and branch
mortality by binocular inspection.
117
-------
«
O
H
OD
.c
70
E
S
o»6j0
yj 50
— CO
tt'§40
K t-
§i3D
1- 3
O o
' -I IJO
yj <
z t-
Z3 O QD
Figure 36. Topographic projection, San Bernardino Mountains, showing how ponderosa and
Jeffrey pines, in major study sites, are distributed in six injury classes
in relation to seasonal dose of total oxidant; A = dead, G = no visible
symptoms. (For absolute values, oxidant dose might be multiplied by 0.8 to
comply with a new, tentative calibration procedure.)
AIR MONITORING
STATION
-------
lower doses, e.g., Holcomb Valley (HV).
The assumption has been made that ponderosa and Jeffrey pine
respond similarly to oxidant. Ponderosa pine is replaced by Jeffrey
pine in the natural stands east of Camp O-ongo (COO) and at Barton
Flats (BF). The validity of this assumption can be partially verified
by examining the distributions of the two species where they intermix
at Barton Flats (BF Figure 36). These data indicate reasonable simi-
larity at a common site, but the influence of other environmental
variables which change continuously along the oxidant gradient,
e.g., soil moisture availability, air temperature, and humidity, must
be examined more intensively to understand how they influence oxidant
susceptibility.
Trends in Oxidant Injury and Mortality to Conifer Species in the 18
Major Study Plots from 1973 to 1974 ---
The first evaluation of oxidant injury to all tree species in the
new study plots was completed in September and October, 1973. The
second evaluation in 1974 offered the first opportunity to assess trends
of tree injury and mortality. In Table 6, the plots are arranged in the
order of decreasing injury according to the 1974 average injury score
for all ponderosa or Jeffrey pine in each plot. In the 12 plots cate-
gorized as "severe" and "moderate", all but six showed a lower score
(increased injury) which was significant (with a probability that 95
times out of 100 the difference is not due to chance). Among the
remaining 6 plots classified as "slight", "very slight", or "no vis-
ible" injury, there were three significant increases, one insignificant
increase, and two decreases, one significant and one insignificant.
119
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TABLE 6. OXIDANT INJURY SCORES AND MORTALITY RATES OF PONDEROSA AND JEFFREY PINES
AT 18 MAJOR STUDY PLOTS, 1973-1974.
a
Plot
Species
Tree
Average
injury
Mortality
Accum.
Injury
Density b
Score
Rate
Mortality
Description
(I)
(%)
1973
1973
1974
1973
1974
1974
SCR
JP
28
12.4
11.7
0.0
0.0
0.0
COO
PP
90
15.1
12.9*^
0.0
0.0
0.0
Severe
SF
PP
144
13.3
13.7
0.8
0.8
1.6
UCC
PP
309
15.5
15.6
0.0
1.5
1.5
BP
PP
236
16.3
16.0
2.7
2.7
5.5
CP
PP
217
17.1
16.4
0.0
3.1
3.1
DWA
PP
168
19.9
16.5*
1.2
0.0
1.2
TUN 2
PP
122
19.5
16.7*
0.0
1.4
1.4
Moderate
CA
PP
112
25.6
16.8*
0.0
1.5
1.5
BF
PP
200
21.4
18.7*
3.7
3.7
7.4
BF
JP
124
21.0
19.7
3.6
3.6
7.3
SV
JP
129
22.1
19.7*
0.0
1.0
1.0
GVC
JP
43
21.8
20.5*
0.0
1.5
1.5
CAO
JP
192
21.7
22.8*
0.8
7.2
8.0
Slight
BL
JP
186
29.4
31.8*
0.0
0.0
0.0
Very Slight
negv
JP
120
33.1
32.1
0.0
0.0
0.0
HB
JP
130
44.0
39.2*
0.0
0.9
0.9
No
SC
JP
56
41.3
47.3*
0.0
0.0
0.0
Visible
HV
JP
193
46.4
47.7
0.0
0.0
0.0
Symptoms
^See Figure 1 for plot locations.
^Number of trees/hectare
Significant 95 times out of 100. Ccomparisons valid otvly between years at a single plot.
-------
The general increase in injury (lower scores) in the "severe" and
"moderate" plots is probably related to the increase in June through
September, 1974 dose, (Figure 23). Tree mortality among ponderosa
and Jeffrey pines was about the same in 1973 and 1974. The largest
mortality occurred in the "moderate" injury category. Perhaps these
populations still retain greater numbers of the more susceptible
individuals. If the remaining trees comprising the populations in
the more severely injured plots are more oxidant tolerant, the
mortality rate might be less than for other plots. The percentages
of dead trees reported in Table 6 include only those killed directly
by oxidant or the oxidant-bark beetle interaction. Other small
trees were killed due to snow breakage but were not included.
Mortality of ponderosa and Jeffrey pine can be evaluated over a
longer time period from data gathered from a nucleus of 50 trees at
Dogwood (DWA) and Barton Flats (BF). These plots were first established
in 1968 and then expanded to their present size in 1972. The accumu-
lated percent of mortality in these original populations from 1968 to
1974 was 22 and 24 percent at BF and DWA, respectively. The future
prospects seem very dim when the trend of increasing oxidant dose each
year, Figures 22 and 23, is examined.
In Table 7, the average injury scores for white fir, incense cedar
and sugar pine are listed with plots in the same order of decreasing
injury employed for ponderosa and Jeffrey pine in Table 6. We do
not yet have enough experience to define the score ranges for these
species with meaningful verbal descriptions. The trend of scores from
1973 to 1974 for these species was not definite, and no mortality was
121
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TABLE 7. OXIDANT INJURY SCORES OF WHITE FIRS, INCENSE CEDARS,
AND SUGAR PINES AT 18 MAJOR STUDY PLOTS, 1973-1974.
White Fir
Average Injury
Itvcense Cedar
Average Injury
Score
1973
1974
1973
1974
197 3
SCR
52.9
52.1
a
—
—
COO
47.2
47.2
30.3
29.7
—
SF
40.7
42.5
24.4
25.2
35.5
UCC
—
—
—
—
—
BP
—
—
21 A
27.1
—
CP
—
—
—
—
—
DWA
37.9
37.1
20.7
24.2*fa
60.0
TUN 2
49.3
51.5
—
—
37.6
CA
55.6
54.8
—
—
39.0
BF
—
—
—
—
—
SV
52.7
54.0
—
—
—
GVC
53.6
52.0
29.2
27.6*
36.0
CAO
48.6
42.7
—
—
BL
58.0
56.4*
—
—
—
NEGV
66.6
64.5
—
—
—
HB
48.7
51.5
—
—
SC
62.3
59.2
—
—
—
HV
63.7
61.8
.—
—
—
Sugar Pine
Average Injury
Score
"T975
34.6
30.7*
aBlank means that the species is not present,
kSignificant, 95 times out of 100.
122
-------
observed. The larger decreases in sugar pine scores are difficult to
interpret because of the small numbers involved, e.g., only 3-15 trees
per plot.
Oxidant Injury to Broadleaf, Woody Vegetation
Both shrub and tree species were inspected throughout the summer
and autumn. Skunk bush (Amorpha califomica) was the only shrub
layer species which showed ozone-like injury. Among the trees, the
oaks (Quercus crysolepis and Q. wizlizenii) and dogwood (Cornus nutalli)
displayed no definite symptoms but black oak (Quercus Kellogii) began
to show chlorotic mottle in 1974 with some interveinal necrosis as
early in the growing season as August 9, 1974 in the western section
of the study area.
Herbaceous Vegetation
During the spring and summer, 1974 all 18 vegetation plots and
adjacent areas were routinely inspected as new plants emerged and
flowered. Ozcme or PAN type symptoms were observed on 11 species:
Bromus orcuttianus, Blymus glauca, Osmorhiza chilense, Gallium aparine,
Erigeron breweri, Potentilla glandulosa, Solidago sp., Vicia califomica,
Artemisia douglasiana, Silene verecunda, and Collomis grandifolora.
Seeds were collected from six of the above species which occur in
the greatest abundance. Ozone and PAN injury symptoms are to be con-
firmed by fumigation experiments on young plants grown in the green-
house from this seed.
123
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Oxidant Effects on Tree Growth
Objectives and Approach
The vegetation subcommittee has investigated three general param-
eters of vegetation in an effort to contribute information to the
understanding of the impact of oxidant air pollutants on the mixed
conifer forest ecosystem as shown in Figure 37. These parameters
are growth of vegetation, composition of the vegetation, and succession
of the vegetation. We first need to know how air pollutants affect
the growth of vegetation, because this will affect the ability of
different plant species to compete with one another for the resources
f
T-
W
SMALL MAMMALS h-
SPECIES
MATURE
COMPOSITION
VEGETATION
(DEAD ROOtSi—
t»«a-IBARK BEETLES!
DEAD CANOPY
SNAGS ,
PATHOGENIC
MICROBE
—Htfa
bsh&hihh3
i I PoREST PLOOft
-f- f
i—
MICRQARTHROPODS
MiiTMiii'iMii
DECOMPOSER
MICROBES
IX * CONTROL VALVE,
= MATERIAL TRANSFER,-
= CONTROLLING INFLUENCE
= OXIDANT INFLUENCE
Figure 37. Vegetation growth subsystem.
12k
-------
they require (ecosystem dynamics). As a result of this competition,
particular species compositional patterns occur (ecosystem structure).
Over time, these compositional patterns change and result in vege-
tational succession (ecosystem behavior) .
Annual Growth of Ponderosa Pine Trees
Oxidant effects on height growth in a greenhouse The impact of
oxidant air pollutants on height growth and diameter growth of ponderosa
pine has been investigated. Height growth was investigated in a study
of three groups of ten ponderosa pine saplings which were exposed to
three treatments: ambient air outside, AAO; ambient air greenhouse,
Figure 38. Aluminum framed greenhouse covered with transparent plastic
film and provided with a carbon filter-blower (upper rear).
Carbon filters were removed to obtain the ambient air treat-
ment in a second house.
125
-------
AAH; and carbon-filtered air greenhouse, FAH (Figure 38). The exposures
to each treatment lasted from April 15 to November 15, during 1969 to
1973. These naturally seeded trees were located in a heavily damaged
area 0.4 km west of Rim Forest, California. A nearby monitoring
station documented the oxidant dose during June through September each
year (Figure 23). At the outset of the experiment in August 1968,
most trees retained only 1967 and 1968 annual needle complements with
severe oxidant injury symptoms, namely, chlorotic mottle, necrosis and
Figure 39. The appearance of a typical upper crown branch (left) from
a ponderosa pine exposed to ambient oxidant air pollutants
in a greenhouse for 5 years shows fewer and shorter needles.
A similar branch exposed to carbon filtered air (right)
retains more needles which are longer; at the outset of the
experiment, this branch resembled the one on the left.
126
-------
FAH
UJI2
AAO
AAH
Z Z
197 S
YEARS
Figure 40. Injury score of current plus one-year needles, 1968-1973,
from ponderosa pine saplings maintained in filtered (FAH),
or unfiltered air greenhouse (AAH), and an outside ambient
air treatment (AAO).
premature abscission of needles shorter than normal (Figure 39, left).
In the following years, the new needles growing in the FAH treatment
failed to develop injury symptoms and were distinguished by their
longer length, healthy green color (Figure 39, right) and lower oxi-
dant injury scores compared to the AAH and AAO treatments, Figure 40.
The slightly lower level of needle injury to AAH than to AAO suggests
that enclosure in a force-ventilated greenhouse without air filtration
had some positive benefit compared to AAO saplings growing outside and
adjacent to the greenhouses.
127
-------
At the end of the 1973 growing season, the saplings were harvested
in order to explore other differences among the treatments. Needle
biomass was compared for internodes of the same age. Increases of
needle biomass in the FAH treatment for the one-year-old (1973)
needle complement compared to AAH and AAO trees (Figure 41), became
significantly greater (95 times out of 100) by 1973. Needles in inter-
nodes older than 2 years were completely absent in the AAH and AAO
treatments. The numbers of needle fascicles remaining per internode
in each polluted air treatment followed the same trend.
The dramatic decrease in needle leaf biomass in the AAO and AAH
180-r
170-
&'®0-
H
150-
<3
z
140-
tr
130-
L
120-
6
110-
a.
to
100-
3
90-
UJ
¥
80-
70-
£
2
60-
3
80-
¥
40-
u.
o
o
20-
*-
-I
®
10-
Ui
*
MASS OF NEEDLES RETAINED PER INTERNODE BY
PONDEROSA PINE SAPLINGS N 1973
1. AMBIENT AIR OUTSIDE
2. AMBIENT AIR HOUSE
3. FILTERED AIR HOUSE
n oJ.
q nrh
JLjx
<23 f 2 3 I 2 3 123
1969 1970 1971 1972
YEAR INTERNODE AND NEEDLES WERE PRODUCED
I 2 3
1973
igure 41. Average dry weight of all needle fascicles per internode in
filtered (FAH), or unfiltered air greenhouse (AAH), and an
outside ambient air treatment (AAO).
128
-------
treatments represents severe reductions of photosynthetic capacity.
Conversely, as more leaf biomass was produced in the FAH treatment,
more carbohydrates could be produced and used for the growth of woody
tissue. After a lengthy lag period, the lengths of the terminal shoot
(Figure 42, upper) and first order branches (Figure 42, lower) of the
upper half of the crowns of trees in the FAH treatment increased
significantly (95 cases out of 100). Terminal and branch growth of
trees in the AAH and AAO treatments remained the same or lower,
Figure 42. An analysis of radial growth of the saplings in this
experiment is now in process.
Oxidant effects on radial growth by age classes The influence of
oxidant air pollutants on radial growth has been investigated in
two other studies. The first of these was a comparison of the radial
growth of ponderosa pine in environments characterized by low air
pollution (1910-1914) and high air pollution (1941-1971). Two popula-
tions of trees occurring near the Dogwood plot were used in the study.
One population ranged in age from 52 to 71 years in 1972 and the other
from 20 to 39 years. Nineteen dominant trees were selected from each
population and an increment core sample was removed from the south
side of each ring. Ring widths were measured on these cores to the
nearest 0.01 mm with a dendrochronograph. An average ring width was
calculated for the 52 to 71 year old population for rings produced from
1910 to 1940 (Table 8). This period was characterized by low oxidant
concentrations in the San Bernardino Mountains. During this period, the
trees in the 52 to 71 year old population became established and pro-
129
-------
TERMINAL SHOOT GROWTH
1. AMBIENT AIR OUTSIDE
2.AMBIENT AIR HOUSE
30_ 3 FILTERED AIR HOUSE T
28- t
26-
24- T
6 22-
o _
X 20- T T--
H
o i8-
z
Ul 16- T
-I
14-
12 - r~i r-
1 o- _ __
8- T _ T
6- p-
4-1 r- r~
123 123 123 123 123
1969 1970 1971 1972 1973
YEAR
32-
30-
20-
26-
24-
E 22-
0
1 20~
O ' 8-
W 1 6-
-1
1 4-
1 2-
1 0-
e-
6-
4-
1. AMBIENT AIR OUTSIDE
2. AMBIENT AIR HOUSE
3. FILTERED AIR HOUSE
FIRST ORDER BRANCH GROWTH
2 3
1969
Figure 42,
12 3 12 3 12 3
1971 1972 1973
YEAR
Annual growth of terminal shoot (.upper) and first order
branches (lower) in upper half of sapling from ponderosa
pine maintained in filtered (FAH), or unfiltered air green-
house (AAH), and an outside ambient air treatment (AAO).
130
-------
TABLE 8. AVERAGE ANNUAL RADIAL GROWTH OF 19 PONDEROSA PINE TREES IN
TWO LEVELS OF OXIDANT AIR POLLUTANTS.
Agea Radial Growth (cm) Agea Radial Growth (cm)
(Years) 1941-1971 (Years) 1910-1940
20 0.20 60 0.52
21 0.33 55 0.49
29 0.22 55 0.61
22 0.33 57 0.34
25 0.30 64 0.40
35 0.23 63 0.55
27 0.29 60 0.44
28 0.31 65 0.46
35 0.26 60 0.75
22 0.43 71 0.67
39 0.21 63 0.71
35 0.34 71 0.65
29 0.37 66 0.78
33 0.37 63 0.53
35 0.34 60 0.33
35 0.37 70 0.38
36 0.35 61 0.32
36 0.33 62 0.37
3 4 0^ 59 CL37
Average 30.3 0.31 62.4 0.51
aAge at 1.4 m above ground in 1971.
131
-------
duced 20 to 39 annual rings. An average annual ring width was calcu-
lated for the 20 to 39 year old population for rings produced from 1941
to 1971 (Table 8). This period was characterized by high oxidant concen-
trations in the San Bernardino Mountains. During this period, the trees
in the 20 to 39 year old population became established and produced 20
to 39 annual rings. The average annual rainfall of the period from 1910
to 1940 was 110.9 cm, and from 1941 to 1971 was 117.4 cm. A difference
of 0.20 mm in average annual growth occurred between the two periods.
Average 30 year old trees grown in the two periods would have diameters
of 30.5 cm and 19.0 cm (Figure 43). The difference in these diameters
19.0cm
30 4cm-
OXIDANT POLLUTED AIR
NON-POLLUTED AIR
Figure 43. Calculated average cross-sections of two 30-year-old
ponderosa pines at breast height grown in polluted air
(left) and in non-polluted air (right) based on radial
growth samples from 1941-1971 and 1910-1940.
132
-------
is attributed to the influence of air pollutants during the period from
1941 to 1971. This information, along with the height growth data from
the previous study, can be combined to give an approximation of the
reduction in volume growth in ponderosa pine trees near the Dogwood plot
An average 30-year-old tree grown under the present air pollution con-
ditions would be 7.0 m tall, 19.0 cm in diameter at breast height and
could produce one log 1.8 m long with a volume of 0.047 m3 (Figure 44).
An average 30 year old tree grown in the absence of oxidant air pollut-
ants (i.e., 1910-1940) would be 9.1 m tail, 30.5 cm in diameter and
could produce one log 4.9 m long with a volume of 0.286 m3 (Figure 44).
Radial growth in relation to oxidant injury scores A second study
of radial growth has attempted to correlate ring width with the
oxidant injury score of individual trees near the Dogwood plot.
Increment cores were taken from the south side of 102 dominant and
co-dominant ponderosa pine trees. Annual ring width was measured to
the nearest 0.01 mm on these cores with a dendrochronograph. The cor-
relation between current (1974) annual ring width and current (1974)
oxidant injury score and the correlation between current (1974) annual
ring width and average oxidant injury score (1969-74) was determined
using a regression analysis based on the method of least squares
(Table 9).
The low r-values obtained in both tests indicate that crown charac-
teristics assessed by oxidant injury scoring (Miller, 1974) are not
closely correlated with radial growth. This result is difficult to
understand in view of the general correlation between photosynthetic
133
-------
047M3
OXIDANT POLLUTED NON-POLLUTED AIR
AIR
~WOOD VOLUME IN LOG WITH 15cm TOP(MIN.MERCHANTABLE DIAMETER)
Figure 44. Calculated average growth of 30-year-old 15 cm ponderosa
pines in polluted and non-polluted air based on radial
growth samples from 1941-1971 and 1910-1940.
13h
-------
TABLE 9. CORRELATIONS BETWEEN PONDEROSA PINE RADIAL GROWTH (Y) IN
CENTIMETERS AND OXIDANT INJURY SCORE (X).
Independent Variable Regression Equations r
Current year oxidant injury score (1974) Y™0.12 + 0.06X 0.51
Average oxidant injury score (1969-74) Y=0.10 + 0.06X 0.51
area and radial growth in forest trees as discussed by Kramer and
Kozlowski (1960). The oxidant injury scoring method used may involve
the measurement of characteristics which have little impact on radial
growth but contribute significantly to the calculated oxidant injury
score (i.e., branch mortality in the lower crown). Further investiga-
tion of the influence of air pollution on radial growth is planned
in this study. A preliminary attempt at correlating precipitation
and oxidant level with ring width was inconclusive (McBride, 1974).
A larger sample of tree cores has been collected and the annual ring
widths are being measured. Variations in temperature, precipitation,
and oxidant level will be used in a principal component analysis
(Fritts, 1974) to determine their respective effects on radial growth.
Timber volume decrease in a Jeffrey pine stand since 1952 The
longest observation of tree decline (not knowingly intended at first
to evaluate oxidant injury) began in 1952. One Forest Service plot on
Camp Osceola Road, Table 10, has been ueed as the site for nesting the
CAO plot (Figure 1) where the present level of oxidant injury has been
135
-------
TABLE 10. CHANGES OF TIMBER VOLUME AND PERCENT OF TOTAL JEFFREY PINES IN FOUR BARK BEETLE RISK
CLASSES AT TWO CONTROL PLOTS EXCLUDED FROM SANITATION SALVAGE LOGGING BETWEEN 1952 and
1972 AT BARTON FLATS IN THE SAN BERNARDINO NATIONAL FOREST. a-
Control Plot #1 (JCA Camp, Highway 38)
Risk classes ^
1952
Timber
volume c-
Percent
of trees
1963
Timber
volume
Percent
of trees
1972
Timber
volume
Percent
of trees
Total, all classes
73,040
100
63,530
100
52,730
100
Risk 1 and 2
58,520
87
38,700
73
23,780
55
Risk 3
6,740
7
14,630
13
14,140
16
Risk 4
7,780
5
10,200
7
14,810
20
Snags and
current stumps"
1
1
11
7
13
8
-------
TABLE 10. CHANGES OF TIMBER VOLUME AND PERCENT OF TOTAL JEFFREY PINES IN FOUR BARK BEETLE RISK
CLASSES AT TWO CONTROL PLOTS EXCLUDED FROM SANITATION SALVAGE LOGGING BETWEEN 1952 and
1972 AT BARTON FLATS IN THE SAN BERNARDINO NATIONAL FOREST. (Continued)
Control Plot #2
(Camp Osceola Road)
1952
1963
1972
Total, all classes
120,130
100
113,100
100
112,930
100
Risk 1 and 2
110,830
93
98,080
82
45,670
32
Risk 3
5,990
3
10,170
6
37,420
30
Risk 4
3,310
2
4,410
6
29 ,840
28
Snags and
current stumps
3
2
13
6
18
10
a These data are attributed to the U.S. Forest Service, Supervisor's Office, SBNF.
k Risk 1 and 2 are vigorous low risk; Risk 3 and 4 indicate decreasing vigor, high risk.
C Board feet
^ Accumulation during 10-year period
-------
determined (Table 6) as moderate. The JCA Camp plot also described in
Table 10 is not more than a mile to the northwest. The increases of
Jeffrey pine distributions into the high risk classes, loss of timber
volume and mortality rates between 1952 and 1972 all suggest serious
stand deterioration even though the present tree scores indicate
"moderate" injury. This is an example of the difficulty of using verbal
summaries to characterize the "severity" of stand injury. In the
stands surrounding these plots, three sanitation salvage logging oper-
ations have been carried out since 1952 to remove high risk overstory
trees. It is probable that the decline of timber volume in both plots
is the combined result of mortality and the failure of the remaining
trees to add volume through new growth.
The Climate in the Soil and the Drought Stress
In order to examine the interaction of climate with soil and
possible drought-stress which can occur simultaneously with the impact
of oxidant air pollution on the ecosystem, the first step is to docu-
ment the climate in terms of precipitation, the soil moisture regime,
the soil temperature regime, and the consequent water balance of the
system, as indicated in Figure 45. Soil cores were collected at 23
sites to the depth of hard bedrock, or to a depth of 2.75 m (9 feet),
in the spring and fall, for maximum and minimum water content, and for
physical and chemical analysis. Water content was determined by weight
differences in oven-dried samples, and the total volumetric water con-
tent calculated for the entire soil core as corrected for gravel or
138
-------
. MATURE
-VEGETATtON
SPECIES
COMPOSITION
(.
DEAD CANOPY
SNAGS
— *o i
roftesT floor
MICROARTI
RATH06ENIC
MICROBES
prr: — l_
DECOMPOSER
MICROBES
1X3 =CONTROL VALVE, CONTROLLING INFLUENCE
= MATERIAL TRANSFER, OXIDANT INFLUENCE
Figure 45. The place of the soil subsystem in the ecosystem.
stones. These data provide a true estimate of soil water storage capa-
city which is usable by plants.
Soil Moisture -—
Soil moisture-temperature sensors (fiberglas moisture blocks) were
installed at depths of 15, 30, 61, 92, 152, 214, 274 cm (6, 12, 24, 36,
60, 84, and 108 inches) in auger holes which were repacked with the same
soil to its original thickness and density as much as possible. Read-
ings have been taken every 1 to 3 weeks depending upon the rate of change
of the soil moisture since the spring or summer of 1973 (Figure 46).
Soil taken from the soil cores was used to calibrate the moisture sensor
139
-------
readings with water content.
An example of the results obtained at one site from the fiberglass
moisture-temperature sensors installed at 23 sites throughout the study
area is shown in Figure 47. The moisture curves were obtained by
comparison of field readings (conductivity converted to resistance and
corrected for temperature by computer) with the same for soil samples
from the same site at varying moisture contents. The moisture curves
for 3 depths show the drying period from March to October for 1973 and
1974. In both years, the effect of light rains wetting the upper 15 cm
(6 inches) of soil during April and May is evident, while rain in May
affected the sensor at 91 cm (36 inches) only in 1973. The total amount
of rain which produced these effects was only 20 mm (0.79 inches) in
Figure 46. Portable soil moisture meter temporarily attached to
fiberglass moisture blocks installed permanently at depths
from 15 to 274 cm (left). At the same site are cans for
collecting crown drip and screens for collecting litter
fall (right).
lUO
-------
SOIL
mTER
CONTENT
PLOT: DOGWOOD
SITE: 1
_l
200
150
250
300
350
35
25
150
80 1O0
200
300
250
MONTH APR J MAY j JUN j JUL J AUG | SEP | OCT | NOV | DEC | MAR | APR | MAY j JUN | JUL | AUG j SEP } OCT |
TEMPERATURE
PLOT: DOGWOOD
SITE : 1
20
15 cm
-* 61 cm
• 122 cm
300
DAY 100
150
250
350
200
1973
20
150
00 100
200
300
250
Figure 47. Soil moisture and temperature regime 1973-74 at Dogwood plot.
-------
1973, recorded at Lake Arrowhead about 1.5 km away. In May 1974, rain
amounting to only 7.0 mm (0.28 inches) produced the rise in the curve
in late May. The sensitivity of the method is quite evident.
The curves show clearly that the maximum rate of water use by the
vegetation occurs during June and early July, and that after mid-July,
the soil dries very slowly indicating that the upper 150 cm of soil i9
at or near permanent wilting point. At another site, sensors placed to
a depth of 275 cm (9 feet) showed moisture extraction continued slowly
into September, suggesting that the forest survives the summer drought
by moisture extracted from deep into the decomposed granite substratum.
The drastically reduced rate of water use after mid-August indicates
that the forest is essentially in a dormant state at least until the
first precipitation in autumn.
The spring period during which the soils contain available soil
moisture in 1974 is shown by black bars in Figure 48. These data were
also obtained from the sensors and indicate that essentially all avail-
able soil moisture was exhausted from the soil in 11 plots before mid-
August. The date was determined by examination of the computed resist-
ance of the moisture sensors; the first data at which the sensor was
found to have a resistance of 100,000 ohms was taken to represent the
date after which soil moisture depletion was at a minimum rate. Three
of the sites, Heart Bar (HB), Sand Canyon (SCI), and Camp Osceola (CAO)
were wet by summer thunderstorms in late July and early August. This
rain probably had little effect at Heart Bar as only the upper 30 cm (1
ft) was moistened. However, Sand Canyon and Camp Osceola were wet to
a depth of about 1 m at a time when the deep soil moisture was nearly
142
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Depth
Plot
Meters
DW
0.3 I
0.9
1.5
2.7
S22
0.3 l
0.9
1.5
2.7
CP
0.3
0.9
1.5
2.7
BP
0.3
0.9
1.5
2.7
UCC
0.3
0.9
1.5
2.7
TUN2 0.3
0.9
1.2
SF
0.3
0.9
1.5
2.7
6VC
0.3
0.9
1.5
2.7
SV
0.3
0.9
1.5
HV
0.3
0£
1.2
HB
0.3
0.9
1.5
SC
0.3
0.9
1.5
2.1
CAO
0.3
0.9
1.1
SCR
0.3
0J9
2.1
DRY
DRY
I
1974 DAY 150
MONTH may[
JUNE
200
JULY | AUGUST
250
SEPT
900
Figure 48, Time intervals during which the soil at various depths con-
tained moisture available for plants during spring and
summer 1974,
143
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exhausted. Thus, the period of active growth may be prolonged by summer
thunderstorms, which occur mainly in the eastern portion of the San
Bernardino Mountains near Big Bear Lake and in the Santa Ana Canyon.
August precipitation exceeding 25 mm at Big Bear Lake Dam occurs with a
frequency of about 23 percent, while at Lake Arrowhead it is about 14
percent.
The significance of these data in relation to air pollutant impact
is that the most dynamic growing period is from early may, when soil
temperatures begin to rise, to August when soil moisture is often
exhausted. Thus, one could expect the most severe damage to the plants
by air pollutants to take place during this period.
Soil Temperature
Soil temperature measurement at the Dogwood plot obtained with the
soil moisture-temperature sensors are also shown for 3 soil depths in
Figure 47, representative of the Lake Arrowhead area. The curves show
that the soils were colder in April, 1973 than 1974. The soil temper-
ature during 1973 rose smoothly to a maximum in August; whereas in 1974,
soil temperatures were held down by a cold period in May, followed by
a sharp rise in surface temperature with the maximum (below the Burface
layer) delayed into September. A marked soil temperature difference
due to aspect is shown by the fact that in September 1974, the soil
temperature in the upper part of the soil was 7.7 C higher at plot S22
then the Dogwood plot. Plot S22 is near the Dogwood plot but has a
south-facing slope.
Preliminary inspection of the data indicates that in September, at
144
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the Bluff Lake plot, high above Big Bear Lake at an elevation of 2260 M
(7400 feet), the soil temperature was 3.6 C lower than at Dogwood; at
Holcomb Valley on the desert side of Big Bear Lake it was about 3.8 C
higher; and Camp Angelus in the Santa Ana Canyon, but at about the same
elevation as Dogwood, was about 2.4 C higher. Detailed comparisons of
the soil temperature regimes at all plots will be completed soon.
Air Pollution in Relation to Rainwater Under Pine Tree Crowns
To examine the effect of air pollution on the forest floor (litter
layers) and the surface soil, the amount, distribution and composition
of crown drip under pine trees variously affected by air pollution injury
is being studied. Nine ponderosa pine trees at the Camp O-Ongo plot,
with oxidant injury ratings of 10 (severe) to 34 (slight), were sampled
with random radial lines of collector cans set on stakes at 0.5 m inter-
vals out from the tree trunk to 1.0 m outside the drip line, Figure 46.
Precipitation and crown drip were collected and the volume measured at
173 sites, an average of 19 samples around each tree. Of these samples,
66 (7 or 8 per tree) were selected at random and analyzed for calcium,
magnesium potassium, sodium, and phosphorus.
Crown drip and the amount of precipitation interception Crown drip was
collected immediately following the first period of precipiation in the
fall which occurred in the last week of October 1974 under ponderosa pine
trees ranging from severely damaged by air pollutants (oxidant injury
score ¦ 10) to only slightly affected (injury score ¦ 34) on the Camp
O-Ongo plot. An interesting observation is that the crown drip under the
145
-------
trees, 1.0 to 3.0 m from the trunk exceeded the precipitation measured
1.0 to 2.0 m outside the crown line of the tree. The precipitation
averaged 79.2 mm (3.12 inches) while the average crown drip was 90.2 mm
(3.55 inches). The difference is highly significant since statistical
analysis indicates this difference to be real in 99 out of 100 cases.
Generally, interception of precipitation by vegetation is thought to
decrease the amount of water reaching the ground surface. However, in
these mountain regions precipitation is generally accompanied by con-
siderable wind, and apparently the fact that the rain is falling at an
angle, rather than vertically, accounts for the fact that less than the
total precipitation reaches the ground between the trees. Presumably
the true precipitation, if it were measured above the forest, would
be between the two values of 90.2 and 79.2 mm.
Plant nutrient concentrations in tree crown drip Collected crown
drip and precipitation were analyzed for calcium (Ca), magnesium (Mg),
potassium (K) , sodium (Na), and phosphorus (P). The most striking
feature of the results is the increase in total cations (Ca, Mg, K,
and Na) with decreasing distance from trunk, although some high values
were found (>20.0 mg/1) up to 2.0 meters from the trunk. It appears
that the precipitation drips from ponderosa pine needles to limbs near
the center of the tree crown before falling to the ground. The high
values appear to be from drip from the limbs, rather than directly
from needles. The general relationship is shown clearly in Figure 49.
This variation apparently obscures any effect that the air pollu-
tant injury may have on the composition of the crown drip. The content
146
-------
-3.122 X + 15.1
.865
5 10
DISTANCE FROM TRUNK - meters
Figure 49. Crown drip cation concentration in relation to distance from
ponderosa pine tree trunk.
of total cations in the crown drip is shown in relation to oxidant
injury score in Figure 50. The two lowest values do show up on the
trees with the most severe impact (injury score 10 and 11) but the
others do not show a corresponding relationship.
Effects on Epidemiology of Forest Tree Pathogens
Pathogens have a subtle, but often profound influence on a
forest ecosystem. Their activity may affect the rate and even the
direction of successional changes (Baxter, 1952; Smith, 1970), the
11+7
-------
TREE NUMBER:
_ 20T866 864 863 852 871 868 802 853 449
CP
E
i
<
o
—J
<
o
h-
10 II 12 13 21 21 26
OXIDANT INJURY SCORE
1974
34 34
Figure 50. Crown drip cation concentration in relation to oxidant
injury score of ponderosa pine.
occurrence of plant species and the overall productivity of the plant
community. Thus, fundamental information on the effects of photochemi-
cal air pollutants on the activities of forest pathogens is essential
in the development of models to predict the long-term effects of pollu-
tants on the forest ecosystem as a whole.
There are many potential pathogens in any forest, including virus-
es, bacteria, fungi and higher plant parasites, such as the mistletoes
(Boyce, 1961). Some may infect the whole plant whereas others may be
limited to the foliage, the branches, the stem or the roots. Many
pathogens may have little effect upon the forest; others may have a
devastating effect. To determine the effects of air pollutants on all
forest pathogens is clearly beyond our practical capabilities. Thus,
lU8
-------
to limit the scope of the study while developing an initial estimate
of the effects of pollutants, we have chosen two approaches.
Objectives
General disease survey First we are attempting to develop a general
overview of the potential effects of air pollutants on disease incidence
and severity through a disease survey. All trees on 18 permanent study
sites, established across the oxidant air pollutant gradients in the
SBNF, are being examined periodically. Each tree has been examined
for diseases of the roots, stems, branches and foliage. Rates of
increase or decrease in the occurrence of disease will be determined
through periodic examinations for the duration of the study. The data
will be analyzed to determine the relationship between disease incidence
and oxidant air pollutant levels.
Specific pathogen studies The second approach involves more inten-
sive studies of selected pathogens, or pathogen types, to determine
the effects of oxidant air pollutants on their occurrence and on the
various stages of their life history. To date, studies have been
initiated on one specific pathogen, Fotnes annosus (Fr.) Cke., and on
a pathogen-type, damping-off fungi. The selection of these pathogens
is based on (a) the known or potential importance of the pathogen in
the plant community under investigation, (b) the potential importance
of the pathogen in a plant succession model, (c) interactions with
other components of the system being studied (see Figure 51), and (d)
present knowledge of the pathogen, the facility with which it can be
149
-------
studied and potential application of the results.
f
T-
-j SMALL MAMMALS H-
SPECIES
MATURE
COMPOSITION
VEGETATION
DEAO CANOPY]
SNAGS
ICOARSE UTTERl
: V
^piTHOGENlC
-
MICROBES
I FINE LITTER!
DECOMPOSER
MICROBES
FOREST FLOOR
M1CROARTHRC
1X3 = CONTROL VALVE,
= MATERIAL TRANSFER,
=CONTROLLING INFLUENCE
= OXIDANT INFLUENCE
Figure 51. The disease subsystem in the ecosystem.
Root Pathogens
F.* annosus is usually considered to be one of the most destructive
root pathogens in conifer forests of California (Bega and Smith, 1966).
Hosts include ponderosa and Jeffrey pine, both of which are adversely
affected by oxidant air pollutants. F. annosus has been found to
cause damage to these species in the San Bernardino Mountains. However,
the effects that oxidant air pollutants may have on susceptibility of
ponderosa and Jeffrey pine to infection and colonization by the fungus
150
-------
are unknown. Also, the ability of the fungus to live, proliferate and
cause disease in an environment with oxidant air pollution is unknown.
The following model (Figure 52) indicates areas where oxidant air
pollutants probably have direct and indirect effects on disease develop-
ment by the fungus.
INOCULUM
DISPERSAL
SPOROPHORE
PRODUCTION
LIVE TREE
COLONIZATION
PHOTOCHEMICAL
AIR POLLUTION
LIVE TREE ROOT
INFECTION
COLONIZATION OF
STUMPS AND ROOTS
INFECTION OF
FRESHLY-CUT
STUMP SURFACES
SYMPTOM EXPRESSION
AND DEATH
GENETIC ADAPTABILITY
OF THE FUNGUS
Figure 52. Conceptual model of oxidant effects on the Fomes annosus
root disease.
This study was established primarily to determine the effects of
pollutants on the life history of J?, annosus as outlined above. Field
studies were used as much as possible since results would be more appli-
cable to actual conditions in the forest. However, certain controlled
environment investigations were necessary to closely monitor ozone
concentration and other environmental factors, and to properly
151
-------
establish cause and effect relationships. The study sites were chosen
based on species location and presence of oxidant air pollutant injury,
Ponderosa and Jeffrey pine were the two tree species used in the study.
Mature tree susceptibility To compare £. annosus susceptibility of
existing trees showing severe and light oxidant air pollution injury,
inoculation of roots with the fungus was necessary. The 42 trees used
in this study were mostely codotninant and averaged 38 cm DBH. Two roots
of each tree were inoculated and analyzed for infection and colonization
at the end of 6 and 12 months. To date, only one root from each tree
has been analyzed, Table 11. An analysis of variance indicated no sig-
nificant differences in infection and colonization by the fungus among
trees with different levels of oxidant air pollution injury. Perhaps
definite conclusions can be made later when all of the data have been
TABLE 11. INFECTION AND COLONIZATION BY Fomes annosus OF OXIDANT INJURED
JEFFREY AND PONDEROSA PINE TREES IN NATURAL STANDS.
Tree
Species
Pollution
Injury
Infection
(%)
Average
Colonization
Jeffrey Pine
None
75.0
27.66
Jeffrey Pine
Slight
71.4
17.44
Jeffrey Pine
Moderate
66.0
17.33
Ponderosa Pine
Slight
71.4
11.34
Ponderosa Pine
Moderate
66.6
13.66
Ponderosa Pine
Severe
60.0
12.23
152
-------
collected and analyzed.
Tree seedling susceptibility A controlled environment experiment
was undertaken to determine the susceptibility to F. annosus of ponder-
osa and Jeffrey pine seedlings fumigated at ozone concentrations of
431.2 and 882.Oug/ro3. A suitable number of noninoculated and nonfumi-
gated controls were included. Seedlings used in this experiment were
grown in activated charcoal filtered greenhousses and therefore were
not exposed to ambient air pollutants. The percent of infection of
fumigated seedlings was greater than that of nonfumigated seedlings
(Table 12). A simple comparison between all ozone and control treat-
ments, showed statistically significant differences in colonization
among treatments for ponderosa and Jeffrey pine at the 5 percent and
TABLE 12. INFECTION OF OZONE FUMIGATED AND UNFUMIGATED JEFFREY AND
PONDEROSA PINE SEEDLINGS BY Fomes annosus.
Fumigation
Pine No. rate (O3) Infection
Species Seedlings (yg/m3) (%)
Jeffrey 32 0 53.1
Jeffrey 16 431.2a 75.0
Jeffrey 16 882.0 81.0
Ponderosa 32 0 62.0
Ponderosa 16 431.2 81.0
Ponderosa 16 882.0 75.0
Seedlings at each concentration were exposed for a period ranging
between 58 and 87 days.
153
-------
25 percent levels respectively.
If the data are considered according to the time of inoculation
with respect to length of ozone fumigation, it was found that the rate
of colonization of host tissue was also significantly greater at the
highest ozone doses.
For example, in the first inoculation schedule, one-third (8) of
all seedlings in each of eight fumigation cubicles were inoculated on
June 21. Fumigation began several days later and continued until
August 23 (58 days) when these seedlings were removed for confirmation
of infection and measurement of the invasion of the fungus (cm) above
and below the inoculation point. A zero was given when no infection
occurred. The total doses were 3.0 and 6.1 X 105 yg/m3 -hr, respec-
tively, and administered at the concentrations of 431 and 882 yg/m3,
respectively. Two control groups of 8 seedlings, each which had been
maintained in carbon-filtered air in identical cubicles, were removed
for evaluation at the same time. An analysis of variance shows that
95 times out of 100 there were no differences in disease development
between control and fumigated seedlings as measured by movement of
the fungus in root crown tissues. The ozone injury scores at 3.0 X
105 yg/m3 -hrs, determined by the same method as in Figure 32, were
4.0 and 6.3 for ponderosa, 10.6 and 11.1 for Jeffrey pine.
In the second inoculation schedule, eight additional seedlings in
each fumigation cubicle were inoculated on August 8, after 37 days of
ozone fumigation or filtered air treatment. The fumigation was continued
for an additional 50 days at the same concentrations after which seed-
lings were removed and disease development was determined. The total
154
-------
ozone doses were 4.5 and 9.2 X 105yg/m3-hr. In Table 13, a definite
trend toward increased disease development is indicated at the highest
ozone dose, The results show that 95 times out of 100 the largest total
dose resulted in greater disease development when the combined ponderosa
and Jeffrey pine populations from the 9.2 x 105yg/m3-hr dose were com-
pared with one control group using Duncan's multiple range test. The
needle injury scores were very similar at both doses and for both species.
TABLE 13. RELATIONSHIP OF CHRONIC OZONE INJURY OF PONDEROSA AND JEFFREY
PINE SEEDLINGS TO COLONIZATION OF ROOT CROWN TISSUE BY Fomes
annosas.
Ponderosa
Ponderosa
Combined
Treatment
Average
Oxidant
Injury
Score
Fungus
Movement
(cm)
Average
Oxidant
Injury
Score
Fungus
Movement
(cm)
Fungus
Movement
(cm)
Filtered Air, 1
0
0.3A a
0
0.5A
0.4AB
Filtered Air, 2
0
1.3A
0
1.5A
1.4ABC
Ozone, 4.5 6
16.9
0.9A
13.3
1.5A
1.2ABC
Ozone, 9.2
17.5
3.4A
14.9
3.4A
3.4BC
a Values followed by the
different 95 times out
same capital
of 100.
letters are
not significantly
^ Ozone dose as
yjg/m3-hr
x 10s.
155
-------
The eight seedlings remaining in each cubicle were not inoculated.
Each tree was observed periodically to compare ozone injury scores with
inoculated seedlings but no differences were evident. Unfumigated,
uninoculated control plants showed no evidence of foliage injury either.
Although these results cannot be extrapolated to explain disease
development in natural stands of larger trees, they did show that ozone
treatments cause a higher percentage of infection and a higher rate of
colonization of seedlings by F. annosus.
Stump inoculation studies F. annosus often spreads to new areas by in-
fecting the surface of freshly-cut stumps. Infection centers are estab-
lished when the fungus moves from infected stumps to adjacent live trees
through root grafts. To investigate this type of infection, 10 ponderosa
pine trees in each of two groups, "none" to "slight", or "severe" to
"very severe" oxidant injury were cut and their stumps inoculated with
a conidial suspension of the fungus. Infection and surface colonization
have been determined. All 20 inoculated stumps became infected.
However, the 10 stump surfaces from trees severely injured by oxidant
air pollution had surfaces colonized 36.9% compared to stump surfaces
from lightly injured trees which had 17.6% of their surface colonized.
Differences in surface area colonized appear to be real in 95 cases
out of 100. Extent of downward and lateral colonization in inoculated
stumps will soon be determined. A similar stump inoculation study
is planned for Jeffrey pine. These studies should provide an indication
of the influence of air pollution on spread of F. annosus by affecting
stump susceptibility.
156
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Decay studies annosus generally causes decay of the wood of in-
fected trees. Thus, studies evaluating the decay capacities of the
fungus on wood wood from air pollution injured trees have been initiated.
Wood from ponderosa pine trees, cut for the stump inocullations, was
used in a standard soil-block decay test to determine decay rates ex-
pressed as weight loss over time. In addition to F. annosus , Poria
monticola Murr. and Polyporus versicolor (L.) Fr., two standard decay
fungi, were used in this study. Results are not yet available.
Another related experiment is planned which will measure the direct
effects of ozone on the decay process of F. annosus. This work will be
conducted under controlled environmental conditions in specially designed
chambers. This study, plus the soil-block studies mentioned above,
should give a good indication of how decay by F. annosus is influenced by
air pollutants.
Because F. annosus as well as its hosts, is exposed to air pollut-
ants in the San Bernardino Mountains, studies have been planned to deter-
mine the direct effects of ozone on the fungus. Effects on growth, pro-
duction and germination of reproductive spores, and genetic adaptability
of the fungus will be studied. This will entail fumigating fungus cultures
in specially constructed growth chambers with various levels of ozone.
From such work, it should be possible to determine how well the fungus can
survive and maintain its pathogenicity in an air pollution environment.
To determine the influence of air pollutants on F. annosus spread
characteristics under natural field conditions, a number of F. annosus
infection centers have been located in the San Bernardino Mountains
(Figure 1). These have been mapped as to the location and fungal
157
-------
disease symptom expression. Periodic monitoring over a number of
years is planned. Perhaps correlations between such information as
rate of pathogen spread and oxidant air pollutant injury to trees can
be detected.
Damping-Off Fungi
Studies in progress We are far from a complete understanding of the
so-called healthy forest ecosystem, much less an ecosystem heavily
influenced by air pollutants. However, evidence available (Boyce, 1961)
indicated that fungi that cause damping-off of very young tree seedlings
are found everywhere and probably have an important role in seedling
establishment and subsequent stand composition.
Several studies have been initiated in the SBNF to determine what
damping-off fungi exist, where they occur, and in what numbers. A soil
dilution assay has been initiated in conjunction with a soil microarth-
ropod study being made by participating entomologists. Soil samples for
this study are collected periodically during the year adjacent to the
entomological samples. Known quantities of soil from the samples are
serially diluted and the dilutions placed onto agar media in petri
dishes. After a few days incubation, the fungus colonies are charac-
terized and counted. Since both pathogenic and saprophytic fungi are
isolated, the fungi are not identified to species or usually even to
genus; instead, they are grouped into relative broad classes. The data
will provide information on microbial populations, seasonal fluctuation®
in those populations and possible clues to the effects of air pollutants
on soil-borne fungi.
158
-------
Other studies have been designed to provide information speci-
fically on fungi that cause datnping-off. A preliminary bioassay has
been made with samples of soil and duff from seven sites. Radish, a
host that is highly susceptible to damping-off fungi, was used as the
test organism. Direct soil assays for Rhizoctonia spp. and Pythium
spp., two common genera of damping-off fungi, have been completed for
the seven sites chosen for the first study. To date, Rhizoctonia spp.
has not been found on any of the sites, while Pythium spp. has been
isolated from Breezy Point and Sky Forest, which have "moderate" to
"severe" air pollution injury. These sites were characterized by well-
developed soils (Shaver series) beneath mixed conifer stands with ponder-
osa pines (Section IV - Soils).
Oxidant Effects on Bark Beetle Infestations
Bark beetles are one of the most important groups of forest insects
in the United States. Although tree mortality due to these beetles
varies considerably from year to year, the fact remains that these
insects have tremendous potential for destruction. A breakdown of tim-
ber loss due to insects for 1952 showed bark beetles to be responsible
for almost 90 per cent of the total saw timber mortality nationally
(Graham and Knight, 1965). In California, bark beetles are considered
to be the most important forest insect pests. The three most important
species are Dendroctonus brevicomis LeConte, the western pine beetle,
ponderosae Hopkins, the mountain pine beetle, and D. jeffreyi Hopkins,
the Jeffrey pine beetle. These beetles, along with the California flat-
headed borer, Melanophila californica Van Dyke, and several other bark
159
-------
beetles were responsible for a los6 of 1676 million board feet of timber,
or a value of $23,235,000, in California in 1967*.
These beetles are not necessarily primary attackers except during
epidemics. They can usually be considered as secondaries or as symptoms
of some other stress experienced by the tree. Stresses that predispose
trees to attack by bark beetles such as flooding, drought, lightning
strikes, root disease, and photochemical air pollutants. Cobb et al.
(1968) discuss the relationship of oxidant injury, as well as other
diseases to bark beetle infestations on ponderosa pine. It has been
shown previously in the SBNP that as the severity of oxidant injury to
ponderosa pine increased, the incidence of western pine beetle and
mountain pine beetle infestation increased (Stark et al., 1968).
Oxidant injury, therefore, is an important agent predisposing pines to
bark beetle attack, and can be considered in the same way as other
predisposing agents, such as root disease, drought, flooding, over-
crowding, lightning strikes, etc. This was further substantiated by
an historical analysis of tree loss in one area, Lake Arrowhead, in the
SBNF where there have been substantial increases in tree mortality due
to bark beetles since 1951 (Wood, 1971). These previous tree mortality
records will be used along with the proposed pest damage inventory
to evaluate the overall impact of bark beetles on a forest community
stressed by oxidants. The effects of oxidant-weakened trees on the
populations of bark beetles or flatheaded borers has not been studied
previously. However, a study of western pine beetle infested ponderosa
~California Department of Pood and Agriculture, 31 July, 1968
160
-------
pine at Blodgett Forest in the central Sierra Nevada has shown populations
of beetles to be higher in non-diseased trees in all respects (Dahlsten
and Rowney, 1974). This was a comparison of trees infected and not
infected with the root pathogen, Verticicladiella wagenerii. Results
are too preliminary to draw any conclusions as to what this means in
terms of tree mortality or to associated organisms, predators and
parasitoids.
Detailed studies of the population dynamics of the mountain pine
beetle, the Jeffrey pine beetle, and the California flatheaded borer
on ponderosa and Jeffrey pines in California have not been done.
In addition, population sampling procedures have not been perfected
for these species. The western pine beetle, however, has been studied
in considerable detail. The early work has been summarized by Miller
and Keen (1960). Recent studies have concentrated on the population
dynamics of the western pine beetle and the development of population
sampling techniques (Dahlsten et al., 1974; DeMars, 1974; Stark
and Dahlsten, 1970).
It is obvious that a forest community under stress, for example
from high oxidant pollutant levels, will be predisposed to attack by
the tree-killing beetle complex. So far, only the trees most sensi-
tive to pollutants have been studied in relation to the beetles that
attack them. While the beetles are not the direct cause of the problem,
the impact on species and age composition in forest communities can be
considerable, as the entire process of change or succession can be
hastened due to the activity of beetle populations on ponderosa and
Jeffrey pines. The dramatic changes in a plant community due to this
161
-------
tree mortality has an influence on almost every aspect of the overall
study- The removal of certain tree species and the opening of a stand
will certainly influence the vegetation that follows. In addition,
there will be changes in litter fall, soil moisture and structure,
small mammal inhabitants, soil microarthropods, litter decay rates,
and regeneration. The rates of change, however, may be ameliorated
by the influence of oxidant injured trees on beetle populations. This
interaction will have to be characterized in order to model and even-
tually predict the influence and rates of change in forest communities
affected by photochemical oxidant air pollutants.
Objectives ——
The main objectives of this subproject are to characterize the
role of tree-killing beetles in stands predisposed by photochemical
air pollutants. The relationship of the beetles to other components
in the ecosystem is shown in Figure 53. Specific objectives are as
follows:
1) To determine the degree of susceptibility of oxidant
injured ponderosa pine trees to the western pine beetle
and the mountain pine beetle, and Jeffrey pine trees to
the Jeffrey pine beetle and the California flatheaded borer.
2) To investigate the influence of oxidant injured pines
on the success and productivity of broods of the four
beetle species to be studied.
3) To study the direct and indirect influence of photo-
chemical oxidant pollutants on the biology of the four
162
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HSHnfiHSISQBd
MATURE
VEGETATION
SPECIES
COMPOSITION
BE^iDiiad
FOREST FLOOR
MICROARTHROPOOS
i. I- - PATHOGENIC
r 1 ^ MICROBES
iHrastraw
DECOMPOSER
MICROBES
Cx3 » CONTROL VALVE,
'MATERIAL TRANSFER,-
- = CONTROLLING INFLUENCE
— "OXIDANT INFLUENCE
Figure 53. Bark beetle subsystem in the ecosystem.
tree-killing beetles with particular reference to insect
associates, parasitoids, and predators.
4) To develop life tables for the four beetles by oxidant
injury categories and, based on these tables, to develop
predictive models of beetle activity with reference to
stand type and pine oxidant injury level.
5) To determine the biological impact and relative impor-
tance of each of the beetle species in forest cbnununities
and what influence they have on stand change and forest
succession.
These objectives have been discussed in other EPA reports (Dahlaten^
1974a, 1974b).
163
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Techniques for Studying Bark Beetles
Western pine beetle The sampling procedures used in this study have
been developed over the past ten years (Stark and Dahlsten, 1970;
Dahlsten et al., 1974; and DeMars, 1974 [personal communication]).
The details of the sampling procedures including laboratory analytical
methods, data forms, and analytical procedures are given by Dahlsten
(1974).
The ideal situation is to locate 4 infested trees in each oxidant
injury category for each beetle generation. We use three oxidant injury
classes as defined by the oxidant injury rating score of Miller (1973b).
(See Table 6). Twelve trees are therefore sampled each generation,
Figure 1. Trees are often green and have not faded, so beetle-produced
frass (boring dust) or pitch tubes are used to find infested trees.
Local personnel of the State Division of Forestry and the U.S. Forest
Service aid in the search for trees. Once trees are found, they are
given an oxidant injury rating, and other statistics such as height and
diameter are recorded. Trees with mixed broods (more than one species ot
bark beetle present) are not selected. The mountain pine beetle and the
western pine beetle are commonly found infesting the same tree.
The various sampling procedures, the data form identification, and
the types of information recorded are diagrammed (Figure 54). The basic
sampling unit consists of paired 88 cm2 discs that are cut with a gaso-
line powered Drillgine saw. Samples are taken at 1.5 m intervals along
the length of the infestation. The following is a summary of the four
techniques used:
164
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o>
U1
Locate Beetle
Attacked Trees
FIELD SAMPLE
LAB ANALYSIS
2 egg discs/oddht -
1 TREE
Egg Disc Dissection
*EGG
2 larval disc^t
#attacks
#eggs
gallery length
early larvae
TREE
iXRAY
V
X-ray
parent adults
early larvae
predators
associates
TBUG
Rearing
brood adults
parasites
predators
associates
* REAR
^VlELD SAMPLE
2 larval discsfa f
i
TREE
TBLK3
2 emergence cartons
&TREE
X-ray
Rearir
teneral adults
pupae
late larvae
parasites
brood adults
parasites
predators
associates
Sticky Cartons
brood adults
parasites
predators
associates
&XRAY
$ REAR
$ STIK
Information
System
Figure 54.
Graphic summary of the population sampling procedures used
for the western pine beetle, showing data sets and the type
of information included for the San Bernardino study.
-------
1) Egg Discs - Paired are cut at 3.0 m intervals. (It is not
necessary to take these discs at 1.5 m intervals, so every other one is
skipped.) These discs are taken only once per generation and are used to
evaluation attacks, egg density, and egg mortality.
2) X-ray Discs - Paired discs are cut at 1.5 m intervals, are
returned to the laboratory and x-rayed, then they are placed in rearing
cartons. During the first generation, the discs are cut twice, the
first time when the beetles have reached, at most, the third instar of
larval development and the second time just prior to, or immediately
after, pupation. The second generation is treated differently since the
population overwinters in this generation. Discs are taken three times,
once at the third instar stage and then once before winter and then
again after winter in the spring of the following year. The developed
x-rays are interpreted for beetle stage, parasitoids, predators, and
miscellaneous insects. The abundance of each of these inclusion types
is recorded.
3) Rearing - Each x-ray disc is placed in a separate ice cream
container with a vial attached and placed through the lid. All insects
are reared from the bark discs, collected and identified. Approximately
75 species are reared from these samples. The discs are kept in rearing
nine to twelve months.
4) Sticky carton - Ice cream containers with a sticky substance
placed on the interior to prevent insects from voring out are placed on
trees in pairs at 1.5 m intervals at the time that the last x-ray discs
are taken. These cartons cover an area of 88 cm2. Cartons are put up
once during the first generation and are removed for analysis only after
166
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it is determined that all insects have emerged from the study trees.
Cartons are put up and removed twice in the second generation, once be-
fore and once after winter. The sticky cartons are used as a comparison
to the laboratory reared samples since rearing conditions influence the
western pine beetle as well as a number of the other insects associated
with the western pine beetle.
All of the information is punched onto cards, and programs for data
capture, summarization, and analyses have been written for each data type.
Mountain pine beetle and Jeffrey pine beetle Studies on these two
beetles were initiated in 1974 to develop sampling procedures and to rear
and identify associated insect species.
Infested trees in which broods had completed development were
selected whenever possible. Mixed broods were avoided, but often bark
beetles spp.) or the California flatheaded borer were found in por-
tions of the sample trees. Six D. jeffreyi infested Jeffrey pines from
the Big Bear and Heart Bar areas and five D. ponderosae infested ponderosa
pines from the Lake Arrowhead area were used for the determination of
sample size. Bolts were taken from one tree of each species for rearing.
Sample bolts were taken from the top, mid and bottom of each infested pine
species. Broods in both trees were in the late pupal stage, and all rear-
ing was done outside at Lake Arrowhead. Emerging insects were trapped in
KAAD (a preservative for insects) and collections made on a weekly basis
from 26 July through 14 November, 1974.
Each tree to be sampled was felled, examined for mixed broods, and
measured for standard tree and infestation characteristics. Paired samples
167
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were taken from points 1.5 m above the base of infestation, 1.5 m below
the top of the infestation, and from the mid-point between these two. The
samples were sections of bark 60 cm long by one half the circumference
of the bole.
Laboratory analysis of each sample consisted of placement of an
n
acetate overlay upon which five nested samples (rectangles of 1000 cm ,
500 cm^, 250 cm^, 100 cm^ and a circle 100 cm^) were drawn. Parameters
measured included: number of attacks, adult gallery length, number of
larval mines, pupal cells, emergence holes, and in some cases the number
of egg niches and Coeloides (a parasitoid) cocoons.
Preliminary Analyses of Bark Beetle Populations
Western pine beetle All of the information from the two generations
in 1973 has been captured, and the same is true for the two generations
in 1974 except that the rearings are still in progress. Considerable
effort has been expended to develop and debug computer programs, and to
summarize and analyze all of the completed data sets, but to date,
only the egg disc information has been partially completed. Statistical
analyses of these data is incomplete.
The trends indicated by the egg data, however, are encouraging.
Other interesting influences of oxidant air pollutants on other aspects
of western pine beetle biology are anticipated. Since populations of
the western pine beetle have been studied for the past ten years at
Blodgett Experimental Forest (Stark and Dahlsten, 1970; Dahlsten
et al., 1974), there is a base of information available to compare
with the SBNF populations. These comparisons will be interesting as
168
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many of Che ponderosa pines at Blodgett have been stressed by a root
pathogen, Verticicladiella wagenerii, but there is little, if any,
oxidant air pollutant injury to the trees.
In the SBNF, the mean attack rates of the beetles were highest in
the first generation in both years (Table 14). A similar trend was
noted at Blodgett Forest, but the differences are greatly exaggerated
in the SBNF. The mean attack rates in the first generation of 1973,
hereafter referred to as 1973-1, were higher (2.57 and 2.49/sample disc)
than any of the previously recorded highs at Blodgett (1.82/sample disc).
Not enough generations have been studied to explain this.
Mean attack rates were more variable in the SBNF, and this may be
an effect of air pollutants on the trees. Attack rates tended to be
higher in the Class III trees (slight to no visible symptoms) except
in the 1973-1 generation. However, if that generation was part of
an epidemic outbreak, this could explain the breakdown of any behavior
pattern. For example, vigorous trees, or trees that have not been
predisposed by some other factor, are often killed by beetles during
epidemic outbreaks.
Another valuable attribute for evaluating bark beetle populations
(Objective 2) is the mean number of eggs per centimeter of gallary
length. Results were extremely variable, and no consistent trend could
be found (Table 14). The values tended to be higher in the second
generation in both years. A similar trend was noted at Blodgett
(Dahlsten et al., 1974), Again the data from the SBNF is much more
variable than that from Blodgett. The values from five second gener-
ations at Blodgett ranged from 1.46 to 1.94 egga/cm gallery length and
169
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TABLE 14. WESTERN PINE BEETLE EGG DISSECTION DATA GROUPED BY GENERATION AND OXIDANT INJURY
CLASSa, EPA, SAN BERNARDINO AIR POLLUTANT STUDY, 1973-74.
No. Samples or Means 1973 1974
1st. Generation 2nd. Generation 1st. Generation 2nd Generation
Oxidant Injury Class
I
II
III
I
II
III
I
II
III
I
II
III
No. Trees
0
8
4
6
4
2
5
7
0
10
2
0
No. Discs
0
88
44
60
36
20
48
98
0
104
13
0
Discs with galleries
0
82
43
57
34
19
46
95
0
92
13
0
Attacks/disc with
galleries
0
2.57
2.49
0.78
0.89
1.69
1.84
2.23
0
0.87
0.89
0
Mean Gallery length (cm)/
disc with galleries
0
69.80
71.48
37.46
36.97
40.18
63.04
47..45
0
32.27
35.65
0
Mean No. eggs/disc with
galleries
0
63.70
60.76
31.83
43.46
'37.54
41.70
54.55
0
43.77
51.25
0
Mean No. eggs/cm gallery 0
0.89
0.88
0.85
1.17
0.90
0.66
0.82
0
1.37
1.10
0
Mean % hatched eggs
0
85.18
80.73
68.92
70.46
67.12
84.80
83.39
0
71.90
45.20
0
aTrees classed according to oxidant injury rating score (Miller, 1973b; i.e.,
Class I Score 1-14 - Very severe to severe injury
Class II Score 15-28 - Moderate to slight injury
Class III Score 29+ - Very slight to no visible symptoms of injury).
-------
for four first generations from 1.32 to 1.54. Values consistently less
than 1.0 were recorded in the SBNF (Table 14). The highest value, 1.37,
was recorded on severely injured trees in 1974-2 generation, but results
from other generations were too variable to draw any conclusions.
The percentage of hatched eggs per sample disc can often be used
as an index of egg mortality which is essential for estimates of brood
productivity (Objective 2) and for the development of meaningful life
tables (Objective 4). The egg discs can and must be taken well after
oviposition takes place to insure that all eclosion (hatching) has
occurred. The estimates of egg mortality at Blodgett vary between 15
and 25 percent. Again the data from the SBNF are more variable
(Table 14). There was a tendency for the percentage of eggs hatched
to be lower in the less severely injured trees. Since the percentage
of eggs hatched is used as an indicator of egg mortality there is a
suggestion that oxidant injured trees increase egg mortality primarily
or secondarily. Work on this facet of the egg data will be expanded
in the future (Objective 3).
Future work will concentrate on all the possible influences of
oxidant air pollutants on beetle populations in addition to analyses by
tree height and beetle generation. Initial comparison with data from
Blodgett Forest indicate that the interaction of oxidant injured trees
with western pine beetle populations is unique and that oxidants may
affect the beetles more directly than previously thought.
Mountain pine beetle and Jeffrey pine beetle Sampling procedures were
not available for either the mountain pine beetle or the Jeffrey pine
171
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beetle. The first step was to determine sample size. Preliminary
summaries and statistics for number of attacks and gallery length have
been completed for both species (Appendix J and K). The results have
not been analyzed statistically, cut the data suggest a 500 cm2 rec-
tangle would be suitable.
Counts of larval mines and pupal cells of D. jeffreyi were com-
plicated by the feeding of the California flatheaded borer which was
present to varying degrees in all samples. Estimates of the proportion
of the host sample utilized by the flathead larvae were recorded and
will be used to evaluate interspecific competition. Field observations
indicate that the flatheaded borer may be an important component in the
forest communities of southern California, particularly in Jeffrey pine.
Mountain pine beetle trees were also difficult to locate and
usually the broods were mixed with those of the western pine beetle.
There was evidence that ponderosa pines had been killed by the mountain
pine beetle but currently infested trees were rarely located in 1974.
This suggests an important interaction with western pine beetle popu-
lations. However, it appears that the most important factors in terms
of extensive pine mortality are the western pine beetle and the flat-
headed borer, and further studies should concentrate on the above named
beetles, not the mountain pine beetle or the Jeffrey pine beetle.
All of the insects reared from the sample bolts to determine the
associates of the mountain pine beetle and the Jeffrey pine beetle have
been preserved, identified, and counted (Appendix L and M). Future
analyses of rearings for both species will include the distribu-
tions of each insect through time and by height. A knowledge of the
172
-------
associate complex for each species is necessary for evaluation of the
effects of oxidant injured pines on beetle populations either directly
or indirectly through the effects of parasitoids, predators, and com-
petitors. The species lists compiled thus far are consistent with the
present knowledge of bark beetle associate complexes (Dahlsten, 1971;
Dahlsten and Stephen, 1974), and there were no unusual discoveries.
Oxidant Effect on Pine Needle Litter Production on the Forest Floor
As a result of injury to vegetation due to oxidant air pollutant
effects, reduction in tree growth, soil moisture stress, pathogenic
effects, and bark beetle interactions, as discussed in the previous sec-
tions, dead organic matter accumulates on the forest floor in the form
of needle litter and coarse woody fragments. The degree to which this
accumulation is occurring in the various forest ecosystems under study
is being investigated.
Litter fall was collected on screens (Figure 46) of 0.209 m2 area
(18 inches square) in the fall of 1973 (6 trees) and of 1974 (39 trees),
with oxidant injury ratings ranging from 3 (severe injury) to 33
(slight injury) in 1973, and from 9 (severe injury) to 44 (no injury)
in 1974. Needles were separated from other litter, and the mass per
fascicle of needles was determined to obtain a measure of the size of
the needles in the litter fall. Total needle and other litter were also
measured. Needle-fall from selected trees (1973) have been analysed for
their content of nitrogen» phosphorus, potassium, calcium and magnesium,
and will be analysed for the same elements in 1974 also.
The organic forest floor was sampled with a core-cutter at 110
173
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sites under 52 pine trees variously affected by oxidant air pollutants,
and the mass per unit area was related to thickness. Using these data
and transect measurements of thickness on 12 major plots, the total
amount of litter on the forest floor was estimated. The forest floor
was also measured in radial lines from the trunks of somewhat isolated
individual pine trees and the pattern of needle litter accumulation on
the forest floor was determined.
Rates of Pine Needle Litter Accumulation and Oxidant Injury
One of the most obvious effects of air pollutants on the ponderosa
and Jeffrey pine trees is the decrease in size and number of needles
on the tree. It is clear that as the injury to the tree increases,
the older needles fall from the tree increasing the litter-fall, until
most of the older needles are on the ground, and the production of
new needles is low. The mass of needles collected on screens placed
under the pine trees from September 10 to December 11, 1974, the
period of normal needle-fall with minimal effect of snow breakage of
the tree, is show for the Lake Arrowhead region (Camp Paivika to Camp
0-0ngo) in relation to the oxidant injury scores for the individual
trees in Figure 55.
The oxidant injury scores determined by another subproject for
these trees ranged from 9 (severe impact) to 34 (very slight impact).
It can readily be seen that needle-fall was low in the relatively
healthy trees (oxidant injury score 25), but as the injury becomes
increasingly severe, needle-fall increases to a maximum where the aver-
age injury score is about 15 and drops again to low values in the
174
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severely injured range (oxidant injury score 9 and 10). Trees with
"severe" injury retain only the current and previous year's needles, and
the needles are relatively short in length. The variation in litter
caught on the screens was quite large under those trees with oxidant
injury scores ranging from 16 to 21, but otherwise the data appear to
represent significant changes with time.
^ 500"
400'
-J
-J
2
l
LU
-J
O
UJ
UJ
300-
200-
100-
0.
1
n = 9
1
1
i
1
4
-5
J
10 15 20 25 30 35
OXIDANT INJURY SCORE 1974
Figure 55, Mass of Ponderosa pine needle litter-fall compared to
oxidant injury score, 1974; for Camp Paivika plot to
Camp 0-0ngo plot.
The oxidant air pollutants also affect the size of the needles in
the needle-drop collected. The length, or more properly the average
175
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mass per cluster of 3 needles (fascicle), is shown in Figure 56 in
relation to the oxidant injury score. The deceased mass as the impact
grows more severe is clearly shown and is highly significant. Each
point on Figure 56 represents a single tree.
22
Y" 0.00306 X + 0.131
R«.80,n «40,SE Y-.020
X- 1973 NEEDLE-FALL
0-1974NEEDLE-FALL
cn
to , _
< .16—
0.12
49
40
) 15 20
OXIDANT INJURY SCORE (X )
30
(X)
35
25
SCORE
Figure 56. Ponderosa and Jeffrey pine needle-fall compared to oxidant,
injury score, Sept. - Dec., 1973 and 1974.
Nutrient Content of Needle-Fall
Analysis of the needles which fell from the pine trees in 1974
is currently in progress, however, preliminary analysis of needles
from 5 selected trees in 1973 has been completed and the results
shown in Table 15.
The evidence for an effect of air pollutants on nutrient content
of the needle-fall is inconclusive, but it appears that the severely
affected trees with oxidant injury scores of 3 to 11 are higher in
176
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TABLE 15. CONTENT OF NUTRIENT ELEMENTS IN NEEDLE FALL COLLECTED IN
AUTUMN 1973
Oxidant
Tree Injury P K Ca Mg
Plot No. Score (g/100 g)
COO
Al-449
33
0.044
0.199
0.357
0.123
0.426
53.0
ucc
Al-448
21
0.050
0.246
0.417
0.141
0.403
53.2
COO
Go-863
11
0.066
0.336
0.355
0.103
0.444
52.1
SF
Go-1244
8
0.056
0.285
0.363
0.155
0.670
54.2
UCC
Al-405
3
0.048
0.242
0.173
0.079
0.532
52.6
nitrogen (N) content than those less affected (oxidant injury scores
21, 33). Analyses from the 1974 samples should be more definitive.
PROCESSES IN ECOSYSTEMS — IMPACTS ON LITTER DECOMPOSITION
The continuation of ecosystems depends upon natural recycling
of the dead organic material which accumulates within them. Coarse
woody fragments, as well as fine needle litter must be broken down in
several stages in decomposition. Soil microarthropods, and various
fungi work to break down the accumulated litter.
Effects on Major Decay Fungi of Woody Litter
Trees chronically exposed to oxidant pollutants lose photo-
synthetic capacity; one possible effect may be an alteration of woody
tissues and a change in the resistance of the wood to attack by decay
fungi. Such altered resistance may affect litter accumulation and
177
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nutrient cycling, in addition to various other effects on the forest
floor. On the other hand, direct exposure of decay fungi on the forest
floor to air pollutants may alter their rate of growth or ability to
decay wood which would produce similar effects on litter accumulation
and nutrient cycling. Collection sites for this subproject were coor-
dinated with other projects dealing with the soil, the litter and asso-
ciated fungi and insects. The objective of this study as indicated
in a general way in Figure 57, is to answer the question of whether
exposure to air pollutants alters wood decay resistance or the activity
of decay fungi.
j SMALL MAMMALS I--
iseedlino
MATURE
'^
VEGETATION
__y—4-
PATHOGENiCi
MICROBES
WBARK BEETLES!
DEAD CANOPY
FOREST FLOOR
MICROARTt
IXJ * CONTROL VALVE,
= MATERIAL TRANSFER,—
= CONTROLLING INFLUENCE
= OXIDANT INFLUENCE
Figure 57. Woody litter decay subsystem.
178
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Identification of the Kinds of Fungus Decomposers of Woody Litter
Pieces of large ponderosa pine wood lying on the ground were col-
lected during three seasons of the year from sites representing the
full range of long-term oxidant exposures. Isolates were screened for
ability to cause weight loss in wood by exposing wood blocks to actively
growing agar cultures (Figure 58). Decay resistance and rate of decay
are being measured by a standard soil-block method (American Society
for Testing and Materials, 1973). For the most active decayera of the
fungi isolated, decay rate and hyphal growth rate will be measured in
the laboratory under conditions of high and low ozone concentration.
Collection of wood sample material for decay resistance testing is
completed; the test for decay resistance was initiated in December 1974.
The isolation of decay fungi through three seasons of one year is com-
pleted. Screening for the ability to decay wood is continuing.
Although popular usage differs, we prefer to reserve the term "decay"
for wood destruction due to Basidiomycete fungi, whether they are
white rotters or brown rotters. This leaves soft-rot fungi, mold
fungi, blue-stain fungi and wood-inhabiting bacteria as wood-destroying
microorganisms which do not produce "decay". Despite the fact that
none of the isolates has as yet been identified, 11 of the fungi have
been shown by general screening to be wood destroying organisms, and
microscopical examination has certified that at least five definitely
are decay fungi. Superficial examination of the decay suggests that
all wood destroying isolates may be white-rot fungi. This is a sur-
prising finding since most decomposers of coniferous wood in soil
contact are brown-rot fungi.
179
-------
Figure 58. Agar-block screening test for establishing ability of fungi
to decay wood, showing a range in fungal ability to invade
wood blocks.
180
-------
The analysis of decay and growth rate under laboratory exposure to
ozone will be initiated during the coming year.
Effects on Microarthropods in Forest Litter and Soil
Litter microarthropods form an important, if rather inconspic-
uous, component of the forest ecosystem, and it is therefore necessary
to evaluate the effects of potentially disruptive environmental contam-
inants, such as oxidant air pollutants, on these abundant arthropods.
The pine needles, twigs, and other organic materials that make up the
forest floor and the underlying upper layers of the mineral soil
contain a complex and diverse community of small (often less than
2-3 millimeters) animals belonging to the phylum Arthropoda, which
includes insects, mites, spiders, centipedes and a variety of other
less well known animals which, taken together, can be termed "litter
microarthropods." Litter microarthropods can occur in very large
numbers, with population estimates in pine forest soils ranging from
102,000/m2 in Tennessee, (Crossley and Bohnsack, 1960), to 200,739/m2
in California (Price, 1973).
The primary role of litter and soil microarthropods, aa shown in
Figure 59, in conjunction with the soil microflora (fungi, actinomy-
cetes, and bacteria) is to decompose and reduce the organic residues,
both plant and animal, which fall to the forest floor (Edwards et al.
1970; Millar, 1974). They can contribute directly to the decomposi-
ition process by mechanically breaking down these organic materials,
such as pine needles, into smaller fragments. The activity and move-
ments of the microarthropods helps to further reduce these fragments
181
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BSfifflgMSEOB
MATURE
VEGETATION
COMPOSITION
i=75aaE™i^
DEAD CANOPY
SNAGS
(goftBSE yrf
PATHOGENIC
MICROBES
u\ $1 £ i?Z£? Z&%*£*
IMMeHiH
DECOMPOSER
MICROBE?
(X ¦ CONTROL VALVE,
'MATERIAL TRANSFER,-
»CONTROLLING INFLUENCE
= OXIDANT INFLUENCE
Figure 59. Litter microarthropod decomposer subsystem.
into humic substances and then mix these and other breakdown products
with the mineral soil below. These processes make the nutrients, which
are contained in the undecotnposed organic material, available for utili"
zation by other plants and animals in the ecosystem. Furthermore, these
disintegrating and reducing activities can increase the surface area of
organic material and create microhabitats and substrates that are more
easily attacked by the soil fungi and bacteria. These microflora in
turn chemically decompose and change the organic residues which benefits
the microarthropods. Thus, both directly and indirectly, through
decomposition and mechanical mixing and with complex interactions with
182
-------
soil microflora, soil microarthropods affect overall soil fertility
and nutrient cycling.
At the same time, species composition and abundance of litter micro-
arthropods can be influenced by the various soil and litter properties
such as the quantity and quality of the organic litter, its rate of
accumulation, soil water availability and the pH of the soil. Litter
microarthropods are also affected by the biological components of the
soil, including the soil microflora. Chemicals released by the action
of the soil fungi may inhibit or enhance litter microarthropods and
some of these arthropods feed on, and hence are dependent on, certain
fungi. From a long-term standpoint, these complex feedback interrela-
tionships between litter microarthropods and the physical and biological
attributes of the soil can significantly affect forest succession
through natural seed bed preparation, seed germination success and
seedling survival as well as the basic role of decomposition.
Consequently, any disruption which affects, directly or indirectly,
the microfauna and flora can potentially affect the entire ecosystem.
Long-term implications of such an ecological imbalance have particular
significance for a forest ecosystem, in contrast to a typical agro-
ecosystem since it depends almost entirely on natural processes for
maintenance of fertility and recycling of nutrients, rather than artifi-
cial inputs such as energy dependent fertilizers.
Stable forest ecosystems are generally considered to have a rela-
tively constant rate of litter production (Burges, 1967), and any factor
that could potentially affect this balance warrants investigation. This
disturbance could involve not only change in the rate and amount of lit-
183
-------
ter fall but also the quality of the organic matter itself and other
factors, such as the composition and amounts of dissolved organic matter
in the rain water passing through the canopy. These changes could take
several years as ponderosa or Jeffrey pine gradually became weaker due
to continued exposure to oxidants or could be accelerated by disease or
bark beetles or an interaction of factors. Ultimately, under natural
conditions, the dead trees themselves fall to the forest floor and are
decomposed.
The response of the litter microarthropods and other components of
the forest floor to these changed conditions can influence the nature of
forest regeneration through nutrient availablity. The overall objective,
then, of this study is to determine the effects, primarily indirect, of
photochemical air pollution on the litter microarthropod component of
the ecosystem and to evaluate the effect of this component on the other
elements of the system.
Objectives
1. Determine species abundance and diversity in the forest floor
under selected individual trees.
2. Relate these population characteristics to soil and litter
properties.
3. Determine how photochemical air pollutants influence litter
microarthropod populations: a) through their effect on litter
quantity and quality, and b) through their effect on microbial
activity.
4. Relate litter microarthropod populations with soil microbial
184
-------
populations under selected individual trees: a) by correlating
raicroarthropod and microbial species composition and relative
densities, b) by determining the succession of soil microarthropods
and microflora in the decomposition of forest litter and their
effect on gross decomposition rates.
5- Determine and compare characteristics of ecological disruptions
of litter microarthropods caused by oxidant air pollutants with
undisturbed (natural) sites and with disruptions caused by other
factors, i.e., pesticides, fire, and logging.
6. Identify specific components of the litter microarthropod
community as indicators of an ecosystem disrupted by oxidant air
pollutants.
Identification of Microarthropod Decomposers
The plots and individual sample trees were selected primarily on
the basis of oxidant injury ratings in an attempt to compare plots and
individual trees with different oxidant levels. An attempt, largely
unsuccessful, was made to choose isolated undisturbed (other than by
oxidant air pollutants) trees relatively uninfluenced by adjacent trees
to minimize possible sources of variation. In addition, an effort was
made to work with trees, at least within plot, that were of similar
size and age class.
Sampling Samples were taken with a rectangular shaped soil corer,
32.26 cm2 (5 sq. in.) in area. Samples were taken at six week
intervals, with some variation in time due to snow and weather
conditions. Ten cores per tree are taken on each sample data and
185
-------
where appropriate, the different forest floor layers (litter, fermen-
tation, humus) and the top 0-5 cm of mineral soil were measured and
stored separately for individual extraction. The forest floor beneath
each sample tree was divided into eight quadrants based on cardinal
direction, the exact dimensions of which depend on crown size, ground
cover and disturbances of the forest floor. Samples were taken by
randomly selecting the quadrat and specific direction from the tree
bole, and the location of each individual core was mapped as precisely
as possible using the angle (from N, 0-360 ) and the distance from the
bole. (This sampling is directly coordinated with the Litter Decomposi-
tion and Nutrient Cycling subproject.)
Extraction All cores taken in the field were stored at low tempera-
tures until extraction. The microarthropods were extracted from the
soil using a high heat gradient modified Berlese funnel system (Price,
1973). This system uses a combination of heat, light and drying action
on the individual soil samples to drive the microarthropods from the
soil core through steep walled plastic funnels sprayed with a dry sili-
cone lubricant into alcohol filled vials where they are preserved for
later analysis and counting. The temperature in the funnel units was
controlled by a voltage regulator and increased gradually from an
initial temperature of 32 C in order to avoid excessively rapid heating
and drying of the soil cores which could result in microarthropods
being killed in place, rather than being driven into the alcohol vial.
Each core was extracted in the system for a minimum of three days.
186
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Data Processing and Analysis
Different data set types have been developed for this subproject -
Forest Floor Depth Data (FFDD) and Soil Microarthropod Data (SBUG). The
initial data analysis routines will be able to yield basic statistics
on various soil microarthropod taxonomic and functional groups combined
according to horizon and date.
Litter Microarthropods Under Trees Differing in Oxidant Injury
A preliminary list of specimens collected during the initial phases
of the study is given in Appendix N. The systematica of many of these
groups, especially the Acarina, are poorly understood, and at this point
many groups have not been identified beyond their family level.
Since the data could only be summarized for the first three sample
dates in 1973 (August 16; October 4; November 27), the results can only
be considered as preliminary and are presented to show trends. The data
are from three of the six plots presently being used (Snow Valley (SV),
N. E. Green Valley (NEGV), and Breezy Point (BP).
Table 16 gives comparisons for selected taxonomic groupings between
the plots with different oxidant air pollutant injury ratings: SV (16)
and BP (21) being "moderate" and NEGV (33) having "very slight" injury.
The results are consistent with the least injured plot, NEGV, averaging
more total microarthropods than the two "moderate" plots on each sample
date. The sample at BP taken initially on 27 November, 1973, was inter-
mediate in total microarthropod density.
These results must be considered in light of individual tree varia-
tion (Table 17). With the exception of BP, where the "healthy" #394 had
187
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TABLE 16. MEAN NUMBER OF MICROARTHROPODS IN SELECTED TAXONOMIC GROUPINGS
IN LITTER SAMPLES FROM BENEATH TWO TREES AT THREE MAJOR PLOTS,
NE GREEN VALLEY (NEGV), SNOW VALLEY (SV) , AND BREEZY POINT (BP)
(10 SAMPLES PER TREE)
Plot
1973 Oxidant injury
NEGV
(Very Slight)
SV
(Moderate)
BP
(Moderate)
Collection dates
Aug. 16
Oct. 4
Nov. 27
Aug. 16
Oct. 4
Nov. 27
Nov. 27
Total Cryptostigmatid
adults
20.5
20.3
28.7
13.2
6.2
24.8
34.3
Total Cryptostigmatid
inmatures
11.6
11.2
7.4
7.7
3.0
2.9
4.4
Prostigmatid adults
23.6
26.9
54.6
12.6
41.7
17.3
9.7
Miscellaneous
Prostigmatids
36.2
52.4
12.2
24.6
7.7
12.5
20.6
Total Prostigmatids
60.0
79.3
66.8
37.5
49.3
29.8
30.2
Total Insects
4.4
3.4
14.1
9.0
2.3
9.9
29.1
Total Microarthropods
156.3 193.5 183.8
104.6 110.2 97.2
128.1
-------
TABLE 17. MEAN NUMBER OF TOTAL MICROARTHROPODS UNDER INDIVIDUAL TREES
OF DIFFERENT OXIDANT INJURY AT NORTHEAST GREEN VALLEY (NEGV),
SNOW VALLEY (SV), AND BREEZY POINT (BP), 1973.
Oxidant Total
Tree Injury Cryptostig Total Total
Plot No. Score matids Prostigmatids Mesostigmatids Insects Others Microar-
Adult/Immature Adult/Misc ./Total Adult/Immature thropods
16 AUGUST
NEGV
614
24
32.0
14.2
17.7
62.7
80.4
0.0
0.0
5.0
0.3
211.9
618
26
9.0
9.0
29.4
9.6
39.0
0.0
0.0
3.8
0.1
99.9
SV
753
14
14.1
7.9
5.8
17.1
23.9
0.1
0.0
5.9
0.0
74.8
785
12
12.2
7.4
19.4
31.6
51.0
0.0
0.0
12.0
0.5
134.1
4 OCTOBER
NEGV
614
24
27.4
15.1
21.1
99.9
121.0
0.2
0.0
4.2
0.1
289.0
618
26
13.1
7.2
32.6
4.9
37.5
0.0
0.0
2.6
0.2
98.1
SV
753
14
6.7
0.8
25.6
9.5
35.1
0.0
0.0
1.8
0.0
79.5
785
12
5.7
5.1
57.7
5.8
63.5
0.0
0.0
2.8
0.1
140.7
27 NOVEMBER
NEGV
614
24
40.9
10.8
91.4
13.0
104.4
0.8
0.5
18.1
0.5
280.4
618
26
16.5
4.0
17.8
11.3
29.1
0.8
0.6
10.1
0.1
90.3
SV
753
14
12.1
1.5
16.1
16.8
32.9
0.6
1.3
4.8
0.5
89.3
785
12
37.5
4.2
18.5
8.1
26.6
0.4
0.0
15.1
1.0
111.3
BP
394
29
42.5
5.7
9.7
27.4
37.1
0.9
1.4
43.2
0.8
168.7
397
9
26.1
3.0
9.6
13.7
23.3
1.5
1.5
15.0
0.4
94.1
-------
a higher total density than the "injured" #397, the results were not
consistent. For example, although the NEGV trees #614 and 618 had very
similar oxidant injury ratings, there was a considerable difference in
total microarthropod density. This differential may be due primarily to
disturbance of the forest floor by human activity. The two trees at SV
also had different abundance levels. In this case, the higher density
of microarthropods under #785 may in part be due to the fact that the
f
tree is not particularly isolated and litter fall from nearby healthier
trees could have influenced the forest floor under the sample tree.
Without these disturbances, differences between oxidant air pollutant
"injured" and "healthy" trees might have been greater, as with the
trees at Breezy Point, and emphasize the importance of critically
evaluating between-tree variation.
Effects on Microbial Activity in Needle Litter Decomposition and Nutri-
ent Cycling
In the forest, there is a constant turnover of tree biomass as old
foliage, branches and trees die and fall and others grow to replace
them. Litter decomposition and nutrient cycling are the means by which
the living forest recovers much of the nutrient tied up (incorporated)
in this organic matter. The recovery of these vital nutrients is the
function of the vast populations of litter and soil microflora and
microfauna. This portion of the overall study is directed toward de-
termining the influence of oxidant air pollution on microfloral popula-
tions and leaf litter decomposition (primarily ponderosa and Jeffrey
pines) as indicated in Figure 60, Previous work in this field is
190
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ATURE
VEGETATION
SPECIES
COMPOSITION
HBARK BEETLES]
DEAD_CANOPY
SNAGS
J r5
wiaioii-i
[COARSE UTTER]
* FOREST FLOOR
* IMICROARTHROPODS
PATHOGENIC
MICROBES
[MINERALS^
Dx3 1 CONTROL VALVE, "CONTROLLING INFLUENCE
MATERIAL TRANSFER, = OXIDANT INFLUENCE
Figure 60. Needle litter decomposition subsystem.
relatively sparse. Recent reviews are available (Dickinson and Pugh,
1974) .
Needle Litter Decomposition in Natural Stands
Quantification of integrated needle litter decomposition in the
field is in progress. Data from this type of experiment will help de-
termine how oxidant air pollution affects the quality of needles as
substrates for decomposers and as sources of nutrients for cycling, and
how it affects the capacity of naturally-occurring populations of litter
microorganisms to decompose pine needle litter.
For such a study, co-dominant or dominant, relatively isolated
191
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trees have been selected. Two of the least, and two of the most, oxi-
dant injured Jeffrey pine trees were selected. The selected sites
included Holcomb Valley, "no" oxidant injury, and at Camp Osceola,
"moderate" oxidant injury. Similar selections of ponderosa pines were
made at Barton Flats, "moderate" oxidant injury, and at Camp O-ongo,
"moderate - heavy" oxidant injury. These sites represent the range of
oxidant injury represented in each species on the study plots.
Freshly fallen litter was collected from each selected tree and
subsamples were randomly made. One subsample was taken for subsequent
nutrient analysis. In fall, 1974, twenty subsamples were placed in
nylon mesh envelopes. One subsample each was taken for microarthropod
census prior to and approximately five weeks after placement in the
field. Figure 61 relates the sources and disbursement of the mesh
decomposition envelopes.
After one year in the field, one-half of the replicates of each
treatment will be retrieved and a) the microarthropod population will
be recensused, b) change in dry weight for each replicate will be de-
termined, and c) the change in nutrient status of the needles will be
determined. The remaining envelopes will be retrieved after two years
in the field and will be handled in the same manner as the first year
envelopes.
This type of experiment ties in broadly with other aspects of the
overall project. The soil moisture and temperature data being collected
by the soils group, as well as precipitation and air temperature esti-
mates for the involved sites will be used in the interpretation of
data collected. The cooperative efforts of the microflora and micro—
192
-------
JEFFREY PINE
HOLCOMB VALLEY
(no oxidant injury)
CAMP OSCEOLA
(moderate oxidant injury)
Go
1537 - 51
Go
1561 - 20
Go
1598 - 40
T i
Go
1574 - 20 ^
Go
1934 - 39
Go
1964 - 10
Gr
807 - 66
t 1
Go
1865 - 15
PONDEROSA PINE
CAMP O-ONGO
(moderate-heavy oxidant injury)
BARTON FLATS
(moderate oxidant injury)
Go 894 - 23
Go 852 - 14
Go 875 - 13
Go 2755 - 11
Go 2755 - 11
Go 868 - 24
Go 2600 - 53
Go 2625 - 46
ure 61. Source and location of decomposition study envelopes.
Left portions of codes represent tree tag number; right
portion indicates 1973 oxidant injury score of tree.
Arrows represent 10 litter envelopes and point from
sources to present locations.
193
-------
fauna are under study here. In the sense that many pathogenic fungi
have active saprophytic roles, their decompositional efforts are in-
cluded in the total observed rates.
Analysis of the materials now in the field will be completed in
approximately two years. Further similar experiments involving the
same, and perhaps additional, trees will be necessary in order to sub-
stantiate the results of this first run. Some of these are planned to
begin in the fall of 1975.
Laboratory Decomposition of Conifer Needle Litter With Various Degrees
of Oxidant Injury
A pilot experiment on pine needle decomposition in the laboratory
was begun in December, 1973. This experiment tested a method and also
provided information on relative differences in needle decomposition
rates between four sites, two trees of different oxidant injury scores
on each of those sites, and incubation at two different temperatures.
Relatively isolated co-dominant to dominant trees were selected on each
of four plots: Breezy Point (ponderosa pine, "moderate" oxidant in-
jury), Dogwood (ponderosa pine, "moderate" oxidant injury), Snow Valley
(Jeffrey pine, "moderate" oxidant injury), and U.C. Conference Center
(ponderosa pine, "moderate" oxidant injury). Twenty equal lengths of
needle from one of the trees were weighed (air-dried to a constant
weight at approximately 22 C and 42 percent relative humidity) for each
replicate. One-half of the replicates were sterilized with propylene
oxide. Each replicate was then placed on one gram of hand-crumbled
duff from its source tree on clean paper towelling inserted into a
large test tube (o.d. 2.5 cm). One—half of the replicates were incu—
194
-------
bated at room temperature; the other half at 12 C. Distilled water was
added four times during the winter and withheld for the remainder of
the experiment. Fourteen months after initiation of the experiment,
the needles were separated from the duff, air-dried and weighed. Air-
dry weight losses were calculated as percent of original weight and
analyzed by one-way analysis of variance.
Average percent weight loss was significantly greatest (95 times
in 100) for needles from Breezy Point (33%) , insignificantly different
between U.C. Conference Center (26%) and Snow Valley (25%), and sig-
nificantly least for Dogwood (20%). At Breezy Point, needles from the
healthier of the two trees (oxidant injury scores 17 and 6) lost sig-
nificantly more weight. The two trees involved at U.C. Conference
Center (oxidant injury scores 11 and 7) and Snow Valley (oxidant injury
scores 27 and 13) did not differ significantly. At Dogwood, needles
from the less healthy tree (oxidant injury scores 25 and 6) lost sig-
nificantly more weight. Analysis of the effect of incubation tempera-
ture on percent weight loss suggests that temperature can be a factor
in needle decomposition rate. Where there was a significant difference
between incubation at 12 C and room temperature (the unhealthy tree at
Breezy Point and the healthy tree at Snow Valley) , greater decomposition
occurred at room temperature.
This type of needle decomposition test in the laboratory shows
promise for future use. Plans are developing for experiments on the
effects of fumigation on decomposition. Sterilized needles from trees
involved in the integrated field needle decomposition study will be
inoculated with individual isolates of predominant organisms and sub-
195
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jected to fumigated or filtered air as well as incubation at room
temperature or 12 C.
Oxidants and Decomposer Microorganism Populations on Needle Litter in
Natural Stands
Oxidant air pollution may alter the rate of pine needle decomposi-
tion by affecting the composition of microbial populations on senescing
and fallen needles. To study the succession of litter microorganisms,
three lines of investigation are being followed in the field.
One square meter of nylon mesh material has been placed (September
and early October, 1974) approximately two-thirds of the crown radius
out from the stem beneath each of 29 trees on seven major plots, in-
cluding all trees involved in the integrated field needle decomposition
study and most of the trees in the cooperative microorganism survey.
In addition, four trees have been tagged at each of two locations
on the University of California Blodgett Experimental Forest, El Dorado
County, California. They are tagged Gr 1-8, and each has a nylon mesh
square under it. Blodgett was selected as a mixed conifer area with
very little air pollution damage. It is felt that ponderosa stands
outside the SBNF must be considered for comparison in terms of air
pollution impact. Periodic samples of litter from these nets will be
incubated and analyzed for diversity and populations of microorganisms
present. Additional mesh squares will be set out annually beneath each
tree, separating annual litter increments. In this way, the annual and
seasonal succession of microflora will be elucidated.
In order to determine the degree of colonization of needles while
still on the trees, the lowest healthy twig on the north, east, south,
196
-------
and west sides of the stem was clipped from the trees involved in the
field gross needle decomposition study and from each of the eight trees
tagged at Blodgett. The annual needle complements were separated in the
field, and their fungal populations are being characterized and esti-
mated in the lab. Data for one tree (Barton Flats Go 2600, P.
ponderosa, oxidant injury score 53) has been compiled. Twenty-four
categories of fungi were isolated. Alternaria sp., Cladosporium sp.,
Aureobasidium sp., Penicillium spp., and an unidentified fungus desig-
nated "tan fruiting body" occurred at all aspects. Of these five,
Cladosporium sp. and Penicillium spp. were probably surface contaminants
in most cases as surface sterilization (one minute drench in 10% chlorox
drastically reduced their numbers. Aureobasidium sp. and, to a lesser
extent, Alternaria sp. may have considerable internal as well as exter-
nal populations, as surface sterilization had much less effect on their
numbers. "Tan fruiting body" was virtually unaffected by surface ster-
ilization and may well exist internally. Of the four directions stud-
ied, southern exposure appeared to be harshest. Only Alternaria sp. and
Aureobasidium sp. were abundant on this aspept.
Samples of the organic matter horizons are being collected in con-
junction with, and immediately adjacent to, samples for microarthropods.
Direct plating of litter and fermentation zones, coupled with dilution
plating of humus, will relate the occurrence of fungal and microarthro-
pod pupulations to each other. Available data on precipitation, air
and soil temperature and soil moisture will be incorporated into the
analysis. This cooperative litter microorganism survey will increase
in value as the data base expands.
197
-------
The nature of the studies outlined above dictates that a number of
years of data are requisite for the substantiation of results obtained.
Response of Selected Fungal Species and Fungus/Mite Associations to
Ozone Fumigations in the Laboratory
This phase of the project is designed to determine how air poll-
ution a) affects growth and reproduction of microbial species involved
in litter decomposition, b) affects rates of needle decomposition by
major microorganisms and c) affects selected litter mites cultured with
litter fungi.
Species of fungi isolated from litter samples will be fumigated at
a number of concentrations of ozone. The effects of ozone will be quan-
tified on such factors as a) colony growth rate, b) rate of spore pro-
duction and c) percent spore germinability. Two clear plexiglass fumi-
gation chambers were designed and constructed for this use inside the
two walk-in growth chambers on the Oxford Field Tract, University of
California, Berkeley. These two walk-in chambers are nearly renovated
to permit control of light, temperature, relative humidity and ozone
concentration. Twelve similar opaque plexiglass fumigation chambers
have been designed for fumigation of woody litter decay tests and Forney
annosus soil block decay tests.
A technique similar to the laboratory gross needle decomposition
method reported above will be employed for the fumigation of various
needle/fungus combinations.
As techniques for culturing mites with important litter fungi be-
come worked out, cooperative in vitro tests of the effects of ozone on
these associations will be possible.
198
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CONSEQUENCES FOR RENEWAL OF BIOLOGICAL RESOURCES FOR HUMAN WELFARE
Cone and Seed Production for Dominant Conifer Tree Reproduction
To persist, a forest must reproduce itself. This involves the pro-
cess of seed production, seed germination, and seedling establishment.
In coniferous forest species, seed production is accomplished by the
production of an annual cone crop whose abundance varies widely each
year (Pearson, 1923; Roeser, 1941; Boe, 1954; Fowells and Schubert,
1956; Daubenmire, 1960; Larson and Schubert, 1970). The causes of these
annual fluctuations are unknown, but they are thought to be partially
the result of weather patterns (Maguire, 1956; Daubenmire, 1960; Lowry,
1966; Puritch, 1972). Furthermore, each species differs in the amount
and frequency of the cone crops it produces (Fowells and Schubert,
1956). This difference, coupled with differing requirements for seed
germination, seedling establishment and seedling survivorship by each
species, determines the rate of change in the species comprising a
stand. Measuring the cone crop patterns of each species thus become
important in understanding stand succession.
The mixed conifer forests of the SBNF have had a history of photo-
chemical oxidant air pollution exposure, principally ozone (Miller and
Millecan, 1971). Of the species comprising this forest type, ponderosa,
Pinus ponderosa, Lawson, and Jeffrey pine, P. Jeffreyi, Greville and
Balfour are the two species most sensitive (Miller and Millecan, 1971).
In these pines, exposure to ozone reduces the rate of photosynthesis
and injures the needle tissue. Both of these effects lead to prema-
ture needle abscission (Miller et al., 1969; Evans and Miller, 1972;
199
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Miller, unpublished data). Ponderosa and Jeffrey pines injured by ozone
have crowns which appear similar to those used to define the low vigor
classes employed in rating pines subjected to higher risks of bark
beetle attack (Keen, 1936) and in evaluating the growth potential of
P
pines following selective logging (Hornibrook, 1939; Thomson, 1940).
Larson and Schubert (1970) using the vigor classes employed to evalu-
-------
fewer seeds per cone, and lower seed viability. This subsystem is
indicated in Figure 62.
Ob ject ives
One objective of this study is to test the hypothesis that cone
crop abundance and frequency in ponderosa and Jeffrey pine are affected
by ozone injury. A second objective is a description of the probability
of a given tree producing a cone crop in a given year. A number of fac-
tors are known to affect cone production (Powells and Schubert, 1956;
Larson and Schubert, 1970); hence, this description will require the
identification of certain tree characteristics, such as species, age
class, vigor class, ozone injury class, and other variable such as
temperature patterns or soil moisture depletion rates which are likely
to affect that probability. The description will be used in a submodel
of cone production and can be integrated with a stand succession model.
Estimating Cone Crops
The cones within the crowns of all conifers on the 18 established
plots were visually counted with the aid of binoculars. Although these
counts underestimate the actual number of cones within the crown, they
reveal the pattern of annual cone production, identify those trees which
produce cones, and provide an order of magnitude estimate of cone abun-
dance (Roeser, 1941; Fowells and Schubert, 1956, Daubenmire, 1960).
Their inaccuracy, however, suggests the need for a second estimate of
cone abundance. This second estimate will be obtained by counting the
cones after they have fallen to the ground. They will be recorded by
assigning them to the trees from which they fell. In cases where the
201
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crowns of two or more trees are Interlaced, the cones will be parti-
tioned among the trees in proportion to the number of cones counted
in each of their crowns. (This latter point suggests a fourth reason
for the need of visual cone counts.) The cones will be collected
periodically in the spring and summer of the year following a given
cone crop. Very few cones from the previous year's crop remain in the
tree crowns by the time the next crop is produced (Larson and Schubert,
1970). Counts of cones on the ground are applicable only to the pines
(sugar pine, ponderosa pine, Jeffrey pine), and possibly to incense
cedar, Libocedrus decurrens Torrey. Cones can be counted on the
ground and their year of production determined (Pearson, 1923; Lar-
son and Schubert, 1970). The cones of white fir, Abies concolor,
disintegrate in the process of seed dispersal.
Cones collected in the 18 plots are used to estimate the incidence
of cone insects, the incidence of predation on cones by squirrels, and
the frequency distribution of seeds produced per cone. The incidence
of cone insects is obtained by placing a number of cones, individually,
in containers and rearing out the insects they contain. The specimens
which emerge are identified and their damage characteristics determined.
An estimate of the number of seeds per cone is made by counting the
number of seed niches present in the bracts in fifty cones. These
cones are also cut along the axis and the presence or absence of
insect damage noted. Incidence of cone predation by squirrels is
evidenced as the number of immature cones on the ground upon which
feeding has occurred. The effect of squirrel predation is being
studied in conjunction with investigations on small mammals.
202
-------
Additional information is being taken from trees on all of the
plots. Trees are classified on the basis of their age, height, crown
class (Table 18), vigor class (Figure 63), length of live crown and
location within a stand (ori the margin or in the interior).
TABLE 18. DESCRIPTION OF CROWN CLASS CHARACTERISTICS
Crown Class Description
Dominant Trees whose crowns extend above the general
crown level.
Codominant Trees whose crowns form the general crown
level.
Intermediate Trees whose crowns extend into the general
crown level.
Intermediate Open Trees substantially smaller in diameter and
height than those that generally character-
ize the stand but are isolated, free to grow
on all sides.
Intermediate Suppressed Trees which are of similar diameter as those
which generally characterize the stand but
whose crown lies entirely below the general
crown level.
Suppressed Trees which are smaller in diameter than
those which generally characterize the stand
and whose crown lies entirely below the
general crown level.
All these factors are known to be associated with cone abundance and
cone crop frequency (Fowells and Schubert, 1956; Larson and Schubert,
1970). These additional data have been taken on 8 of the 18 plots.
Additional plot and tree data will be obtained from the other subpro-
jects and this subproject will supply data to them in return. Multi-
203
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JHr.
t»0
\M U"
sc
Jl L
4C
C
|a
r
V; f«*
so
40
0
Examples of Keen's tree age and growth vigor classes for
east side Sierra Nevada and southern California ponderosa
pine (Keen, 1936).
204
-------
variate analysis (multiple regression, stepwise regression or variance-
covariance analysis, for example) will be used to identify the relation-
ship of cone crop to the independent variables discussed above.
Counts of Cone-Bearing Trees and Cone Production
Most of the data presented below is preliminary. The 1974 cone
crop was the first crop visually counted in the 18 plots. Only a por-
tion of the plots were counted in 1973 because plot establishment was
not completed prior to the loss of many of the cones from the trees.
Lack of these counts prevented assigning the fallen cones to the trees
from which they came, in those tree groups whose crowns interlaced.
Furthermore, cone data for 1973 do not include losses due to insects
or squirrels. The 1973 cone data, however, provide a reliable estimate
of the number of trees which produced a cone crop. Ground counts of
the cone crop will begin in spring 1975 and will represent the count of
the 1974 cone crop. Cones lost to insects, squirrels, and unknown
sources will be incorporated into these counts. It should be noted
that most all of the additional tree and plot data are still being
acquired; thus the effect of oxidants on cone production in ponderosa
and Jeffrey pine cannot be addressed, as the data are still in var-
ious stages of analysis.
Table 19 summarizes the visual cone counts for both the 1973 and
1974 cone crops. The characteristics of the crown classes are listed
in Table 18. The visual counts for Jeffrey and ponderosa pine are
summarized by plot in Appendix 0.
A greater percentage of trees in the dominant crown class produced
205
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TABLE 19.
Year
Numbers
# trees
INFLUENCE OF CROWN CLASS ON THE NUMBER OF TREES WHICH PRODUCED CONES
AND THE NUMBER OF CONES PRODUCED BY PONDEROSA AND JEFFREY PINE IN
1973 AND 1974 IN 18 PLOTS.
Crown Class
Intermediate Intermediate
Dominant Codominant Intermediate Open Suppressed Suppressed
# trees
with cones
1973 total cones
X trees
with cones
average #
cones/cone
tree
357
144
4,230
40.34
29.38
277
45
800
16.24
17.77
122
3
9
2.46
3.0
151
6
15
3.97
2.5
68
0
0
0
28
0
0
# trees 482 425
# trees
with cones 285 139
1974 total cones 18,645 4,183
X trees
with cones 59.13 32.70
average #
cones/cone
tree 65.41 30.09
329
20
320
6.08
16.0
235
6
108
2.55
18
73
2
2
2.74
1.0
165
0
0
-------
cones. Codominant trees were the second most frequent bearers (Table
19). In those trees that bore cones in 1973 or 1974, dominant trees
produced a little more than double those produced by codominant trees.
In 1973, of the 198 trees, 73 percent were dominant, 23 percent were
codominant, 1.5 percent were intermediate, while the remainder, 3 per-
cent, were intermediate open. A similar pattern was evident in the
1.974 cone crop. Of the 452 trees which bore cones in 1974, 63 percent
were dominant; 31 percent were codominant; 4.4 percent were intermedi-
ate; 1.3 percent were intermediate open, 0.01 percent were intermediate
suppressed. Clearly, the dominants are the greatest contributors to
the cone crop. These findings agree with those of Pearson (1923),
Fowells and Schubert (1956), and Larson and Schubert (1970). One other
point should be emphasized regarding the class of trees which are the
greatest contributor to the cone crop; the larger the tree, the greater
the number of cones produced, and the relationship appears to be non-
linear (Pearson, 1923; Larson and Schubert, 1970). Appendix 0
provides a further breakdown of cone production by plot and species.
Tentatively, the type of trees contributing the most cones to a
given annual crop are those which have a large diameter (larger than
50 cm), are isolated from their neighbors or on a margin of a stand,
have a good complement of needles, and belong to the dominant crown
class.
Seed Production
Cones were collected from seven plots to estimate the number of
seeds produced per cone in 1973. The plots and the resultant data are
207
-------
shown in Table 20.
TABLE
20. CONIFER
SEED PRODUCTION
FROM SELECTED STUDY
SITES
Plot
Seeds/Cone
(Mean Standard Deviation)
No. of Cones
in Sample
Pine
Species
Tun 2
45.70
+
12.31
50
PP
GVC
28.26
+
13.17
50
JP
CAO
41.16
+
13.41
50
JP
BF
53.18
+
22.57
50
JP,PP
SF
66.92
+
26.56
50
PP
CA
52.90
+
23.95
50
PP
BP
42.50
¦f
40.95
12
PP
Ignoring Breezy Point because of the small sample size, 12 cones,
the remaining six plots can be divided into two groups based on the
standard deviations of the number of seeds per cone. The reasons for
these two groups are unclear. It is not based on tree species, since
the trees at Tunnel Two are predominantly ponderosa pine and those at
Green Valley Creek and Camp Osceola are Jeffrey pine. Moreover, the
trees at Sky Forest and Camp Angelus are ponderosa pine, while those
at Barton Flats are a mixture of Jeffrey and ponderosa. More data
collected from a larger number of plots and from a number of years will
be needed before the consistency of these relationships can be accepted.
Agents of seed mortality; insects Insect damage to cones produced in
1973 was assessed in six plots. The results were variable: Tun 2 had
2 percent of its cones infested, SF had 22 percent, CA had 6 percent,
208
-------
and the remaining three plots showed no sign of cone insect activity.
All of the infested cones in this year were from ponderosa pine. The
majority of insect damage was caused by the cone moth Lasperysia sp.
(Lepidoptera: Olethreutidae), but the moth damage was less than 15 per-
cent of the seeds in the infested cones. The larvae of this moth bore
into the seed while the cone is immature, consuming the seed content
in the process of developing. The moth larvae leave the seeds by boring
into the cone axis, where they pupate and emerge. They leave the hol-
lowed out seeds firmly attached to the cone axis, along with larval
mines and cast skins (shed following the moths' pupation) as evidence
of their presence.
A second insect Ernobius fissuratus Fall(Coleoptera: Anobiidae)
has been found infesting cones in the SF plot. Fourteen percent of the
cones collected from the SF plot showed evidence of damage. Cone bracts
riddled with holes were the damage characteristics of this insect.
Agents of seed mortality: squirrels Squirrels accounted for the
greatest single loss of cones. This loss, however, occurs only in the
last summer of cone maturation- Ponderosa and Jeffrey pine take two
years to develop and mature (Roeser, 1941; Mirov, 1967). The impact of
squirrel predation on the cone crop has not yet been analyzed. For fur-
ther discussion of squirrel predation see the following section on wild-
life. The amount of data collected to date, and the stage of their
analyses, prevents discussion of the two main objectives outlined in
the introduction. Cone crop frequency can only be obtained after a
number of cone crops have been followed (Fowells and Schubert, 1956;
209
-------
Larson arid Schubert, 1970). The .1974 cone crop was larger than usual
according to personnel familiar with the area. It is too early to
judge what a large cone crop means in terms of established seedlings,
or how frequently such a crop occurs.
Distribution and Role of Wildlife Populations Under Oxidant Stress
Wildlife species form an important component of all forest
ecosystems. As consumers, for example, wildlife often have a major
influence on forest plant succession patterns (Lawrence, 1958; Hooven,
1969). Changes in wildlife abundance, or species mix, induced by the
direct or indirect effects of oxidant air pollution potentially could
affect forest plant succession.
Objectives and Study Procedures
The goal has been to describe the terrestrial vertebrate community
within this mixed conifer forest, particularly in relation to ponderosa
and Jeffrey pine; and to determine the effects of oxidant air pollutants
upon this vertebrate community
Field work was conducted during the summers of 1972, 1973, and
1974. Initially, we prepared preliminary lists of vertebrates found in
the study area (White and Rolb, 1973). Small mammals were chosen for
detailed study because of their important interactions within this forest
system, Figure 64, because they are numerous and widespread through the
forest, and because this group of vertebrates can be studied easily with
simple procedures. Standard Calhoun Type B snaptrap lines were used
(Calhoun, 1959). Lines were established on each of the six plots
210
-------
trapped in 1972 (Kolb and White, 1974), and on an additional eleven
plots in 1973 (White, 1974). This widespread trapping provided a
f
T-
j
CLIMATE
SPECIES
COMPOSITION
MATURE
VEGETATION
i
|SHi?3P31Sll=0
DEAD CANOPY
SNAGS
PATHOGENIC
MICROBES
—
1C0ARSE UTTER!
-4
forest floor
MICR0ARTHR9PQP?
decomposer
MICROBES
(X * CONTROL VALVE,
= MATERIAL TRANSFER.-—
- «CONTROLLING INFLUENCE
— = OXIDANT INFLUENCE
Figure 64. Wildlife subsystem.
sample of small mammal distribution and abundance throughout the
forest, in addition to data on sex and age ratios, reproductive per-
formance, health, physical condition, and food habits of these pop-
ulations. The ecology of the western gray squirrel (Sciurus griseus),
and its impact upon conifer seed crops, also has received detailed
study because of its abundance and the important role it plays in the
functioning of this forest.
211
-------
Small. Mammal Distribution and Oxidant Concentrations
We captured 405 small mammals on the permanent study plots in 1972—
1974, Table 21. There was considerable variation in the number of small
mammals captured year to year and from one plot to another (Figure 65).
Overall, the greatest number was captured in 1974 and the fewest ani-
mals were captured in 1973. Much of the fluctuation can be accounted
for by fluctuations in the numbers of deer mice (Peromyscus spp.) and
harvest mice (Reithrodontomys megalotis). For example, the number of
deer mice captured on the six original plots was 45 in 1972, 15 in 1973,
and 118 in 1974. Harvest mice increased in incidence of capture from
0 in 1972 and 1 in 1973, to 9 in 1974.
The paucity of larger species, dusky-footed woodrat (Neotoroa
fuscipes) and golden-mantled ground squirrel (Callospermophilus
lateralis), in 1972 was largely a result of using only small museum
special (mouse) traps during this first trap-year. The marked in-
crease of both species in 1973 and 1974 is coincident with the use of
rat traps in addition to the museum special traps.
Deer mouse populations characteristically fluctuate dramatically
(Hooven, 1969). v/e are currently comparing the amplitude and pattern
of these fluctuations in the San Bernardino National Forest with
fluctuations reported in other forests.
The data suggest a relationship between oxidant air pollutant con-
centrations and the number of small mammals captured (Figure 66). Dur-
ing trap-years 1972-1974, 238 animals were trapped on plots with "no"
or light pollution, 120 on "moderate" plots, and 48 on plots with
heavy oxidant air pollution. In 1974, we did additional trapping
212
-------
TABLE 21. SMALL MAMMAL SPECIES CAPTURED PER PLOT, 1972-1974
(Number)
PLOT SPECIES TOTAL
P. sp.
E. sp.
C.l.
N.f.
M.c.
R.m.
S.b.
G.s.
D.a.
sc
72
17
3
18
0
0
1
0
0
111
HB
28
26
11
4
3
0
0
0
2
74
SV
40
9
8
5
5
0
1
0
0
68
CA
19
0
1
0
0
0
0
1
0
21
BF
16
0
0
0
2
0
1
0
0
19
DW
3
4
0
0
0
10
0
0
0
17
BL
13
9
4
0
0
0
0
1
0
27
NEGV
5
3
0
0
3
0
0
0
0
11
TUN 2
9
1
0
0
0
0
0
0
0
10
GVC
8
0
0
0
0
0
1
0
0
9
UCC
0
9
0
0
0
0
0
0
0
9
SCR
8
0
0
0
0
0
0
0
0
8
BP
6
0
0
0
0
1
0
0
0
7
COO
1
3
0
0
1
0
0
0
0
5
HV
4
0
1
0
0
0
0
0
0
5
NWCP
1
0
0
0
0
1
0
1
0
3
SF
jO
J)
JO
_0
J)
_0
J)
J)
_1
TOTAL
234
81
28
27
14
12
4
3
2
405
P.sp. ~ Peromyscus sp. R.m. - Reithrodontoroya megalotis
E.sp. - Eutaroias sp. S.b. - Spermophilus oeecheyi
C.l. ~ Callospermaphilus lateralis G.s. - Glaudomys sabrinus
N. f. - Naotoma £usc i pe a D.a. - Dipodomys agilis
M.c. - Microtus calirornicus ———
213
-------
¦ 1972
B 1973
~ 1971*
n
_ra
r~i
SV
sc
HB
BF
DWA
CA NEGV HV
PLOTS
BL BP GVC UCC CP COO TUN2 SF SCR
Figure 65. Number of small mammals caught per year per plot
-------
500 -1
CO
u
a>
&
S3
~J
~J
cn
*~00
% 300
1
200 -
100 -
shaded = on-plot
open = off-plot
Light Moderate Heavy
RELATIVE OXTDANT T.F.VFT.9
Figure oo. Number of small mammals caught on plots with light, moder-
ate, and heavy oxidant air pollutant levels. A value equal
to the average catch per moderate plot was added to the
moderate level column because only five moderate plots were
sampled compared to six for both light and heavy plots.
On-plot, 1972-74; off-plot, 1974.
215
-------
in adjacent off-plot locations; 233 animals were trapped on plots with
"no" to "light" pollution, 116 on "moderate" plots, and 74 on "heavy"
plots (Figure 66).
This relationship also appears to exist between the oxidant air
pollutant injury rating for the plots (White and Kolb, 1973; White,
L974) and the number of animals captured. It is likely that the
abundance of small mammals is affected more importantly by other
aspects of habitat quality (e.g., food and cover abundance) than
directly by levels of oxidant air pollution. However, we are con-
tinuing to investigate these relationships.
Conifer Seed Predation by Squirrels
Detailed study of the ecology of the western gray squirrel began
in 1973 and will continue through 1975-76. Abundant throughout the
conifer forest, the gray squirrel depends on the yellow pine - black
oak (Pinus ponderosa - Quercus kelloggii) vegetation mosaic for food,
cover, and nest sites (Figure 67). The seed-squirrel relationship is
very important in this forest system. Other factors of importance in
controlling seed availability for conifer tree reproduction have been
discussed in a preceding section of this report. An alteration of the
balance between pine and oak through the agency of oxidant air pollution,
or a change in the squirrel population directly due to oxidants, will
affect the balance of the seed-squirrel relationship and have a signifi-
cant influence on the forest, especially pine and oak reproduction. We
are comparing what is found in the SBNF with what is reported elsewhere
in forests not affected by oxidants.
216
-------
Immature cones stripped of seed by tne gray squui
compared to a single mature cone of ponderosa pine
We live-trapped and ear-tagged 43 squirrels (2.) male . 20 female)
on six study plots. Preliminary census results indicates a large, wide
spread population of gray squirrels, with small areas of unusual density.
For example, on the Sky Forest plot, 18 individuals were tagged in six
trap-days on an area of less than 0.2 hectares.
According to our measurements, yellow pine cone production increased
in 1974 over 1973. The number of cones destroyed for seed eating by
gray squirrels also was higher in 1974 than in 1973 (figure 68).
Squirrels generally utilized the same trees in both years. Only four
trees that were heavily utilized in 1973 were not used in 1974. All
other trees heavily used in 1973 produced cones and were utilized in
217
-------
ec
<
UJ
>-
a:
LU
a.
o
<
UJ
i
o
5000
~
1973
1974
AOOO
CO
ac
C
a
LU
>-
o
oc
Y~
CO
UJ
o
CO
UJ
z
o
<_>
3000
2000
cc
LU
CO
1000 -
B77a
COO
GVC
i
BP
I
TUN 2
SCR
iL
CA
PLOTS
Figure 68. Comparison of cone utilization by gray squirrels in 1973
and 1974 by plot.
218
-------
1974. A good example of this "favorite tree" syndrome is Jeffrey
pine #1718 on the Schneider Creek plot. In 1973, 753 cones were cut;
in 1974, 2034 cones were cut.
In both years, the bulk of the cone utilization occurred on only a
few of the 50 overstory yellow pine trees on each plot. The cones cut
from tree #1718, mentioned above, represent 85% and 90% respectively,
of the total cone production for that plot in 1973 and 1974.
Gray squirrels began to cut green cones in June. In 1973, the
first signs of cone-cutting appeared during the last week in June on the
west side of the mountains. In 1974, workers on the west side noticed
freshly cut cones by 10 June. Cone-cutting on the east side started
somewhat later both years, but was underway by early July. Relatively
few cones are cut during this early period through mid-July. From mid-
July through mid-August the greatest amount of cone-cutting occurred.
In Figure 69, we separate the three plots with the greatest amount
of cone utilization from the four lowest. The salient difference be-
tween the two groups was the sustained plane of high utilization on
the three heavily utilized plots during this peak period. Cone-cutting
dropped off in the weeks after mid-August. On Green Valley Creek and
Schneider Creek, cone-cutting ceased in late August. On all other plots,
cone-cutting continued at a low level in September and October.
In total, 14,844 cones were counted on the seven study plots in
1974. All cones were cut prior to seed maturity. This large loss of
seed prior to maturity may be a factor acting in concert with oxidant
air pollutant injury to depress the regeneration of yellow pine. In
areas unaffected by oxidants, western gray squirrels are regarded as
219
-------
2500 -I
Ui
tii
£
oc
UJ
a.
o
UJ
(N
_J
F
3
V)
UJ
z
o
o
o
z
2000 -
1500 -
1000
500
Three most heavily
uti1tzed plots
Four least
uti11 zed plots
a>
a
3
LT\
CM
>»
*3
—)
CM
>•
•
•
•
>»
>•
o>
o>
W
o.
3
3
3
3
4)
3
3
3
->
<
<
«£
(/)
—)
—>
—>
OO
OO
V0
— CM
CONE COLLECTION DATES
Figure 69. Extremes of weekly cone utilization by gray squirrels in
1974.
usually having limited effect on the overall regeneration potential
of yellow pine (Moore, 1940; Fowells and Schubert, 1956; Larson and
Schubert, 1970). Squirrel cone cutting in the oxidant injury areas
220
-------
in the SBNF may be contributing to a hastening of vegetation change.
Long-Term Change in Forest Composition; Succession of the Vegetation
Continued high levels of oxidant air pollutants in the San
Bernardino Mountains will affect both the rate and direction of plant
succession. The vegetation subcommittee is concerned with developing a
model of plant succession that can be used to predict the species com-
position and structure of forest stands subjected to different levels
of air pollution. This model will require the cooperation of many of
the investigators collecting data on other components of the ecosystem.
The vegetation subcommittee's contribution to the development of this
model involves the development of a conceptual (non-mathematical) model
of plant succession and the field measurement of certain vegetation
parameters needed to "run" the mathematical model.
Fire History
In order to develop a meaningful conceptual model, the vegetation
subcommittee has initiated a study of plant succession following fire
in the ponderosa and Jeffrey pine dominated forest types in the San
Bernardino Mountains. This study is identifying variables which have
influenced the rate and direction of plant succession in the past. In
the summer of 1974, eighty—five plots were established in this study
(Figure 1). The date of the last major fire on each plot was determined
from basal fire scars on trees in or adjacent to the plots. Quadrant
and line interception methods, the same as those used to characterize
the vegetation on the 18 permanent plots, were used to measure the vege-
221
-------
tation. The age of each tree on the plot was also determined by ring
counts. Analysis of the field data has not been completed. The 85
plots may be arranged as a chronological series based on date of the
last major fire. Changes in species composition and age structure along
this chronological sequence will reveal the pattern of plant succession
following fire in the San Bernardino Mountains.
General observations made during the previous field season suggest
that fire has been a selective factor in forests of mixed species com-
position. White fir and incense cedar are more vulnerable to wildfire
than the pine species. Similar observations have been made in other
7
parts of California (Biswell, 1969) and the southwest (Weaver, 1964).
Other mortality factors operating in the San Bernardino Mountains,
including air pollution, are also selective. Any model of plant suc-
cession must take into account the rate at which these mortality fac-
tors remove trees from a forest stand. Since mortality rates differ
according to the age of the plants, it is necessary to know the age
structure of the stand. With knowledge of the initial age structure,
expected mortality rates from various factors (insects, pathogens, air
pollutants, fire, herbivores), and reproductive rates (seed production
and establishment), one could approach the modeling of plant succession
using a modification of the life table method introduced by Leak (1970).
With this approach in mind, the vegetation subcommittee has initiated
a study of age structure of stands in the San Bernardino Mountains.
Initially, the age structure of the 18 permanent plots was determined
using ring counts on cores taken with increment borers. Tree age was
also determined on the 85 fire succession plots. These data, along with
222
-------
additional samples to be taken in the coming field season, will build
up an important data source to be used in the modeling of plant suc-
cession .
Two age distribution curves are present in Figures 70 and 71 as
examples of the variations thus far observed in the analysis of age
structure. Age distribution of trees on the Dogwood plot is shown in
Figure 70. These data suggest that events around the turn of the
century set the stage for establishment of tree seedlings. Ponderosa
pine and incense cedar became established at that time and continued
to successfully establish seedlings for the next 40 years. Subsequent
to the 1930's, the establishment of ponderosa pine has declined.
Establishment of incense cedar continued to increase until about 1960.
Since 1960, no successful regeneration of incense cedar has taken
place. Establishment of black oak seedlings in the 0-9 year age class
suggests this species may eventually dominate the plot, assuming the
decrease in conifer regeneration is to continue.
An examination of the age distribution of the coniferous species
on Sand Canyon plot suggests a pattern of continuous tree replacement
(Figure 71). The periodic successful establishment of a few individuals
of Jeffrey pine, white fir, and Sierra juniper have lead to a balanced
all-age stand. The situation with mountain mahogany is somewhat dif-
ferent. In this species, there is an abundance of younger age classes,
especially the 0-9 and 10-19 age classes. This may indicate an improve-
ment in conditions for seedling establishment of mountain mahogany in
recent times. The abundance of mountain mahogany seedlings impresses
the observer with the species1 potential for dominating the plot.
223
-------
AGE DISTRIBUTION: DOGWOOD
192 -i
168-
144-
120-
96-
- 72
U_
O
q:
m 48
24-
1
O O PONDEROSA PINE
~ ~ SUGAR PINE
& A WHITE FIR
A A INCENSE CEDAR
¦ B BLACK OAK
0)
I
o
i r
o>
CM
I
o
CM
I
9
I
9
i i i i
$
1
(0
0)
00
o
00
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§
i
8
i i » i
129
149
169
681
l
O
CSJ
l
O
160-
180-
l—i—r
0)
8
i
o
o
«M
AGE CLASS
Figure 70. Age distribution for various tree specie*, at Logwood plot
22k
-------
AGE DISTRIBUTION:SAND CANYON
LU
0^192-
<1
1—
Q
yi
68-
X
a:
44-
120-
<
z>
a
9 6-
>
o
2
72-
U-
O
ct;
48-
UJ
03
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2
•—• JEFFREY PINE
A—A WHITE FIR
O-O SIERRA JUNIPER
0—0 MOUNTAIN MAHOGANY
4
V*\
IT I II I II I I
1
I I I I I I n IT
SO) o> ff> o> ffl o>
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U U ¦ T - " " N "
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0) 01
<0
CM CM
I I I 11
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ON*
(O 10 K1
i — 777"" "NNNwionio
§ S H H H H ^ n s
CM cm CM CM CM lO fO
AGE CLASS
Figure 71. Age distribution for various tree species at Sand Canyon
plot.
225
-------
SECTION VI
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SECTION VII
GLOSSARY
(An underlined word in a definition implies that this word is
defined in another part of this glossary),
AAH - Ambient air house; a greenhouse experiment to evaluate tree
growth in which ambient air was drawn into the house by fans.
AAO - Ambient air outdoors; used in reference to the outdoor control in
an experiment on tree growth.
Absciss ion - Act or process causing leaves or needles to detach from
the stem and fall to the ground; it occurs following advanced oxidant
injury to leaves.
Accumulated Oxidant Dose - The sum of all the hourly average concentra-
tions of total oxidant for any specified period, e.g., a month or a
growing season, expressed as micrograms per cubic meter -hours (pg/m3
-hrs) .
Agar Media - A gelatinous nutrient substrate for growing microorganisms
in the laboratory.
A1luvial - Deposited by running water, as soil material deposited
during a flood.
Ambient Air - Air surrounding a given location; the outside air.
APCD - Air pollution control district, a county agency.
Attack - The point on a tree where the female bark beetle (Dendroctonus
spp.) bores through the bark to feed and begin egg laying.
Available Water Storage Capacity - The total amount of water which a
soil is capable of holding and which the plants can use.
Background Concentration (of ozone) - The world-wide background or
natural concentration of tropospheric ozone injected downward from the
stratosphere or formed by photochemical reactions in the troposphere;
generally considered to be 59yg/m3 (0.03 ppm).
Basal Area - The area of cross section of a tree, expressed in square
meters, and referring to the section at breast height.
Basal Fire Scars - Area of charred wood at the base of a living tree
caused by a wildfire.
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Bioindicator - Biological organisms which have specific sensitivity to
a single pollutant and thus are useful as indicators for the presence
of that pollutant.
Biomass - The total quantity at a given time of living organisms of one
or more species per unit of space (species biomass), or of all the
species in a community (community biomass).
Bole - The trunk or stem of a tree.
Bolt - A relatively small cylindrical section cut from the stem of a
tree.
Branch Order - The arrangement of branches on a tree. The following
terms are used to identify branches according to their order: main
stem is referred to as the leader; any branch growing out of the leader
is a first order branch; any branch growing out of a first order branch
is a second order branch; any branch growing out of a second order
branch is a third order branch, etc.
Cat ion - An ion which is positively charged in solution; typical+ +
cat ions in soils are potassium, sodium, calcium and magnesium (K , Na ,
Ca , and Mg"^") .
Chlorotic Mottle - Irregular, diffuse patterns of yellow areas inter-
spersed with normal green tissue.
Climax - Vegetation existing in a relatively stable equilibrium with its
environment and with good reproduction of the dominant plants.
Codominant - Trees that share dominance of the canopy of a forest stand.
Colluvial - Deposited at least in part as a result of gravitational
movement of material; occurs at the base of slopes and is sometimes
stony or rubbly.
Colonization - Spread of a fungus throughout a substrate.
Complement - See leaf complement and needle complement.
Conidial - Of or pertaining to conidia which are asexual spores of many
fungi.
Cores - Cylindrical samples of wood removed from a tree with a tool
known as an increment borer.
Cover - The ground area covered by the individuals of one species.
Crown - The portion of a tree containing limbs, branches and foliage.
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Crown Drip - Liquid which falls to the ground under the crown of a tree
or other plant during precipitation or dew-format ion onto the crown.
Crumb Structure - Same as granular structure except that the soil
aggregates are relatively porous; common in the surface of forested
so il s.
Damping-off - The lethal effect of certain fungi on germinating seeds
or seedlings.
Data Form - A standardized form upon which a certain type of information
is recorded, mostly in the field.
Data Set - An identifiable complete unit of information composed of
several individual entries.
DBH - Diameter of the trunk of a tree measured at breast height above
the ground surface.
Debug (. . .computer program) - The identification and elimination of
problematical errors in a computer program so that the computer may
perform the intended functions.
Density - Number of individuals per unit area.
Dilution Plating - A known weight of humus or mineral soil is suspended
and diluted in sterile distilled water; a portion of the suspension is
swirled in water agar medium; developing fungal colonies are identified
and counted.
Direct Plating - A known weight of litter or fermentation zone material
is distributed evenly over the surface of water agar medium; developing
fungal colonies are identified and counted.
Dose - A measured concentration of a toxicant for a known duration of
time to which vegetation is exposed.
Duff - A collective term that includes the litter layer (fresh or
slightly altered organic matter), fermentation layer (partially decom-
posed organic matter), and humus layer (amorphous organic matter) of
the soil,
Eclosion - The emergence of the adult insect from the pupa or the act
or process of hatching from the egg.
Ecosystem - A level of biological organization that includes the total
array of plant and animal life in an environment and also the matter
which cycles through the system and the energy used to power the system.
238
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Egg Niche - A small notch chewed by the adult bark beetle in the side o£
a gallery into which an egg is deposited.
Epidemiology - The study of spread or increase of disease.
Exchangeable Cation - A cat ion which is held mainly by the colloidal
portion of the soil (clay and organic matter) which is not soluble in
pure water but is easily exchanged with the cation of a neutral salt
solut ion.
FAH - Filtered air house; used in reference to the greenhouse treatment
in an experiment on tree growth in which filtered air (ozone removed)
was forced into the house by fans.
Fascicle - A bundle of 1-5 needle leaves all originating from a common
growth point; a characteristic of the foliage of pine trees.
Forest Floor - All dead vegetable matter or organic matter resting on
the surface of the mineral soil, including leaves, branches, needles
and humus not incorporated into the mineral soil; under forest
vegetat ion.
Frass - A combination of boring dust and excrement or feces produced by
feeding insects.
Gallery (length) - The tunnel created by adult bark beetles as they feed
and deposit eggs in the phloem layer of a tree.
Granular Structure - Soil aggregates generally spheroidal in shape and
less than 10 mm in diameter and relatively nonporous.
Gruss - Any rock that is granulated but not decomposed by weathering.
Partially weathered granitic rocks are often gruss.
Herbaceous - Refers to plants that die back to the ground each year;
for example, grasses and forbs are distinct from shrubs and trees in
this regard.
Host - The plant, or animal, on, or in which a parasite exists.
Human Welfare Effects - Includes, but is not limited to, effects on
soils, water, crops, vegetation, man-made materials, animals, wildlife,
weather, visibility, and climate, damage to and deterioration of
property, and hazards to transportation, as well as effects on economic
values and on personal comfort and well-being. (Clean Air Act, 1970).
Hypha - One of many cellular filaments making up the thallus of a
fungus.
Importance Value - A measure of the degree to which a species occurs in
a vegetation type and exerts influence on the microclimate of the type.
239
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Inclusion Type - This refers to images in the x-rays of the bark samples
that are categorized by form and developmental stage of the insect
inclusions. There are six categories used in this study.
Infect ion - Establishment of a physiological relationship between a
host andpathogen.
Ins tar - The period or stage between molts in the larva, numbered to
designate the various periods; e.g., the first instar is the stage
between the egg and the first molt, etc.
Internode - The portion of a woody stem produced in a single growing
season.
Isolate - The product of culturing a small portion of a microorganism
to yield a new individual.
Lachrymator - An atmospheric chemical compound which induces tears to
run from the human eyes, and possibly from the eyes of various animals.
Larva - The young individuals in an insect population, which are due to
undergo changes in their structural form.
Larval Mine - The small tunnels created by bark, beetle larvae as they
feed in the phloem or bark of a tree, generally perpendicular to the
parent adult gallery.
Leaf Complement - A subjective evaluation of numbers of leaves present
on all living branches of an oak tree as average, or less than average,
for the stand.
Life Table - Similar to the actuarial tables kept by life insurance
companies for humans. As adapted for insects, it is a convenient method
to account for mortality during each developmental stage of an insect.
Line Interception Method - The sampling of vegetation by recording the
plants intercepted bya measured line placed close to the ground, or by
vertical projection on the line.
Loam - A textural class of soil containing 7 to 27 percent clay, 28 to
50 percent silt, and 23 to 52 percent sand.
Main Leader - The central trunk of a tree, usually refers to the
youngest or tip portion.
Metamorphic Rock - Rock formed from pre-existing rock by mineralogical,
chemical and structural alteration due to geologic processes originat-
ing within the earth.
240
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Mesoscale Meteorological Patterns - A scale of observation of meteoro-
logical elements, namely winds and temperatures, which is intermediate
between very local observations such as up-canyon or down-canyon
breezes in a single canyon and the synoptic scale observations describ-
ing conditions over a broad area like the southwestern United States.
The density of observing stations for mesoscale interpretation is
typically 50 miles apart.
Micrograms Per Cubic Meter, yg/m^-A measure of the concentration of a
pollutant in micrograms per cubic meter of air at standard temperature
and pressure.
Minimum Moisture Content - Measured soil water content at the driest
period of the year; corresponds approximately to permanent wilting
point.
Mixed Brood - A situation in bark beetle infested trees in which more
than one species of bark beetle offspring is present in the same tree.
Model - A description of the system which it represents.
Molt - The process of certain organisms shedding their outer covering,
to be succeeded by new growth.
Mortality - A standing tree whose current year buds are dead; a conif-
erous tree may be defoliated without being dead.
Needle Complement - The total number of needle fascicles retained on
each branch lnternode, which were formed in any one growing season.
Needle Injury Score - The score or index is the sum of individual rat-
ings for chlorotic mottle, necrosis and abscission, each on a scale of
0 to 4. The score, or index, may be as high as 12 for a single annual
needle complement. Scores for current and one-year-old needle comple-
ments are often added together; this scoring procedure is adequate for
seedlings and small saplings only.
Necrosis - An advanced stage of tissue injury indicated by brown, dead
tissue, involving all or parts of a leaf or needle; necrosis develops
following chlorotic mottle, especially in older leaf tissues.
Oviposition - the act of depositing eggs.
Oxidant Air Pollutants - Gas phase molecules and compounds capable of
oxidizing a reference substance, namely the liberation of iodine from
potassium iodide solutions; these include ozone (more than 90 percent)
and smaller amounts of nitrogen dioxide and peroxyacetyl nitrate and its
homologs, e.g., propionyl and butyrl.
Paradigm' - The basic pattern underlying the functioning of a system.
241
-------
Parameter - A characteristic which can be easily quantified.
Parasitoid - An insect, generally a wasp or fly, which lays its own
eggs on the eggs, larvae, or adults of other species of insects (hosts)
so that the larvae may develop by feeding within or upon the body of the
host.
Particle Size Distribution - See soi1 texture.
Pathogen - Organism capable of causing disease.
Pathogen Type - An organism, not usually considered a pathogen, which
behaves like a pathogen under special circumstances.
Pathophysiology - The altered metabolic state of pathogen infected, or
toxicant injured tissues.
Permanent Wilting Point - The soil moisture content at or below which
plants can absorb water only very slowly or not at all; sunflower used
as a test plant wilts and does not recover over night.
pH (soil) - A measure of the acidity or alkalinity of a soil expressed
as the negative logarithm of the hydrogen-ion activity of the soil.
The general range of soil pH is 4.0 (very strongly acid), 7.0 (neutral),
10.0 (strongly alkaline).
Phenology - The study of the time of appearance of characteristic peri-
odic events in the life cycles of organisms in nature.
Phloem - The complex tissue of higher plants which forms a spongy layer
between the protective outer layer and the inner structurally sup-
portive portion. Its function is to transport food materials.
Photosynthetic Capacity - The ability of a plant to convert inorganic
carbon in the air, from carbon dioxide, into organic carbon molecules
in a given environment.
Phytotoxicant - Any chemical agent that causes injury to plants.
Pitch Tube - A small resinous tube projecting from the bark of a tree
as a result of a beetle boring into the tree. A successful attack is
indicated by frass in the resin while an unsuccessful attack produces
a pitch tube without frass.
Plot - An area of land surface within which vegetation, soil, and
animal life is periodically inventoried and studied for determining
dynamic interactions among them. In this study, 18 plots were delin-
eated on the ground during 1972 in the San Bernardino Mountains. The
range of individual plot area sizes runs from 0.2 ha to 1.2 ha.
242
-------
Pollinator - An organism, usually an insect, which carries pollen from
one flower to another.
ppb - Parts by weight, or volume, of pollutant per billion parts by
volume of air (usually refers to volume of pollutant if not so stated).
pphm - Parts by weight, or volume, of pollutant per hundred million
parts by volume of air (usually refers to volume of pollutant if not so
stated).
ppm - Parts by weight, or volume, of pollutant per million parts by
volume of air; it usually refers to volume of pollutant if not so
stated.
Pupal Cell - A cavity in the bark or phloem created during the final
feeding of the larvae of bark beetles and in which the larvae go into
a non-feeding, and often immobile, transformed stage of development.
Quadrat - A sampling area 0.1 m square used to sample herbaceous
vegetation.
r-Value - The coefficient of correlation between a dependent and an
independent variable. When there is no association between two vari-
ables, the correlation coefficient is 0; when there is perfect positive
association, the coefficient is +1; and when there is perfect negative
association, the coefficient is -1.
Rearing - Raising insects in the laboratory. This allows insects to
complete their development to the adult stage before being collected
and identified. Immature insects are difficult to identify so this
is an important procedure.
Rearing Carton - A paper ice cream carton with a glass vial attached to
the lid. It is used to capture insects as they emerge from the bark
samples. The insects are attracted to light and fall into the glass
vial.
Ring Count - A method used to determine tree age by counting annual
growth rings of the bole, usually at DBH.
Sanitation Salvage - A forest management technique with the objective
of periodic removal of ponderosa and Jeffrey pines judged to have re-
duced vigor and to be more susceptible to fatal attack by bark
beetles; the selection and cutting process is repeated every 10 years.
Sapling - A tree that is more than one meter in height and less than 10
cm in diameter at breast height.
Saprophyte - An organism utilizing an organic source of food which is
dead.
243
-------
Senescence - The combined processes by which leaves or needles on a
tree age, and undergo abscission.
Simulation - The process of using a dynamic model on an electronic
computer to mimic the functioning of a system or process by repeated
step-by-step solution of the equations describing the system.
Soil Bulk Density - The mass of dry soil per unit volume of soil in its
natural state which may be moist at the time the volume is determined.
Soil Core - A cylindrical sample of soil, usually circular in horizontal
cross section.
Soil-dilution Assay - See dilution plating.
Soil Moisture Regime - The variation of soil moisture content through-
out the soil through an entire year.
Soil Texture - A classification of soil material based upon particle
size distribution of the mineral grains in the soil, the relative pro-
portions of sand, silt, clay and gravel.
South Coast Air Basin (SCAB) - One of the five principal airsheds
(atmospheric basins) in the State of California and partially located
within the six counties of Santa Barbara, Ventura, Los Angeles,
San Bernardino, Orange and Riverside.
Species Composition - The relative percentage of the total number of
individuals in a vegetation type represented by a certain species.
Species Dominance - The degree of influence a species exerts over a
vegetation type.
Spore - A reproductive body capable of developing into a new individual
fungus thallus.
Subsoi1 - A general term for soil material from about 25 to 100 cm
depth below the surface, although these depths may vary considerably.
Succession - The replacement of one vegetation type by another.
Synoptic meteorological patterns - Typically a description of air pres-
sure patterns at the surface and at higher elevations over a broad
area (see mesoscale meteorological patterns). Synoptic scale stations
are usually more than 100 miles apart, e.g., Los Angeles, California
and Tonapah, Nevada.
System - A set of elements together with relations among the elements
and among their states.
244
-------
Systems Ecology - The application of the philosophy and techniques of
systems analysis to ecological problems.
Temperature Inversion - When air temperature decreases from the surface
up at a rate greater than 5.5 F per 1,000 ft. or 1.0 C per 100 m, there
is pronounced vertical mixing. But if the temperature increases with
height, vertical air movements are suppressed. This temperature pro-
file is "inverted" from the normal condition and it is a temperature
inversion. Air pollutants are trapped near the ground by temperature
inversions.
Terminal Shoot - The uppermost section of the main leader of a tree.
Thallus - The vegetative structures comprising body of lower plant
forms, for example, fungi.
Troposphere - The layer of air extending 7 miles above the earth's sur-
face and containing 80 percent of the total atmospheric mass.
Vegetation Type - A plant community of definite floristic composition,
presenting a uniform physiognomy and growing in uniform habitat
conditions.
Volumetric Water Content - The volume water content of soil per unit
volume of soil; expressed as percent by volume.
Water Balance - A complete accounting of the soil moisture regime;
water gams and losses from, and to, the atmosphere, and losses to
runoff and deep percolation into the groundwater system.
245
-------
SECTION VIII
APPENDIX
Appendix Page
A Ambient air quality standards 247
B Classification of soils of major plots in the San
Bernardino Mountains 249
C Particle size distribution and pH of representative
soil samples from major study plots 252
D Bulk density of soils of major study plots 254
E Exchangeable and soluble cations of surface soils 255
F Exchangeable and soluble cations of representative
subsoil layers 256
G Organic carbon and nitrogen in the surface soils to a
depth of 25 cm 257
H Available soil water storage capacity of major study plots 258
I Vegetation zones, vegetation types, and major species
in the San Bernardino Mountains 259
J Preliminary analysis of number of attacks and gallery
length for the Mountain Pine Beetle from varying bark sample
sizes (data converted to 1000 cm2 for comparison) 1974 264
K Preliminary analysis of number of attacks and gallery
length for the Jeffrey Pine Beetle from varying bark sample
sizes (data converted to 1000 cm2 for comparison) 1974 265
L Total arthropods reared from Mountain Pine Beetle
infested Ponderosa Pine bolts from three heights in
1974, San Bernardino 266
M Total arthropods reared from Jeffrey Pine Beetle infested
Jeffrey Pine bolts from three heights in 1974, San Bernardino 268
N Taxonomic list of specimens collected from the study plots,
1973-1974 270
0 The number of cones produced by Jeffrey and Ponderosa pine of
different crown classes during 1973 and 1974 273
246
-------
Appendix A. AMBIENT AIR QUALITY STANDARDS
California Standards
National Standards'*
Pollutant
Averaging
Time
Concentrationb
Method c-
Primary
Secondary
Method ^
Photochemical
Oxidants
(Corrected
for NO )
1 hour
0.10 ppm
(200 yg/m3)
Neutral
Buffered
Potassium
Iodide
160 d
]ig/m3
(0.08 ppm)
Same as
Primary
Std.
Chemilumines-
cent Method
Carbon
Monoxide
12 hour
10 ppm
(11 mg/m3)
Non-
-
Same as
Non-
8 hour
—
dispersive
Infrared
Spectro-
10 mg/m3
(9 ppm)
Primary
Std.
Dispersive
Infrared
Spectro-
1 hour
40 ppm
(46 mg/m3)
scopy
40 mg/m3
(35 ppm)
scopy
Nitrogen
Dioxide
Annual
Average
—
Saltzman
100 yg/m3
0.05 ppm)
Same as
Primary
Proposed:
Modified J-H
1 hour
0.25 ppm
(470 ug/m3)
Method
—
Standards
Saltzman
(O3 corr.)
Chemilumin-
escent
-------
Appendix A. AMBIENT AIR QUALITY STANDARDS (Continued)
NOTES:
a
National standards, other than those based
on annual averages or annual geometric means,
are not to be exceeded more than once per
year.
Concentration expressed first in units in
which it was promulgated. Equivalent units
given in parentheses are based upon a ref-
erence temperature of 25C and a reference
pressure of 760 mm of mercury. All measure-
ments of air quality are to be corrected to
a reference temperature of 25C and a refer-
ence pressure of 760 mm of Hg (1,013.2 milli-
bar); ppm in this table refers to ppm by
volume, or micromoles of pollutant per mole
of gas.
Any equivalent procedure which can be shown
to the satisfaction of the Air Resources
Board to give equivalent results at or near
the level of the air quality standard may be
used.
National Primary Standards: The levels of
air quality necessary, with an adequate
margin of safety, to protect the public
health. Each state must attain the primary
standards no later than three years after
that state's implementation plan is approved
by the Environmental Protection Agency (EPA).
National Secondary Standards: The levels
of air quality necessary to protect the
public welfare from any known or antici-
pated adverse effects of a pollutant.
Each state must attain the secondary
standards within a "reasonable time"
after implementation plan is approved by
the EPA.
Reference method as described by the EPA.
An "equivalent method" of measurement may
be used but must have a "consistent rela-
tionship to the reference method" and must
be approved by the EPA.
Corrected for SO2 in addition to NO2•
REPRINTED IN PART FROM THE CALIFORNIA
AIR RESOURCES BOARD BULLETIN:
October 1974
-------
Appendix B. CLASSIFICATION OF SOILS OF MAJOR PLOTS IN THE
SAN BERNARDINO MOUNTAINS.
Plot
Lake Arrowhead Region
Dogwood
Sky Forest
NE13
S22
UC Conf. Cen.
NW Camp
Paivika
Breezy Point
Tunnel Two
Soil Series
Shaver
Unnamed-1
Shaver
Unnamed-1
Shaver
Crouch
Unnamed-2
Shaver
Shaver
Stump Springs
Classification: Soil
Taxonomy (197^)
Pachic Ultic Haploxeroll,
coarse loamy, mixed, mesic
See below
See above
Pachic Ultic Argixeroll,
fine loamy, mixed, mesic
See above
Ultic Haploxeroll, coarse
loamy, mixed, mesic
Ultic Argixeroll, fine
loamy, mixed, mesic
See above
See above
Ultic Haploxeralf, fine
loamy, mixed, mesic
East of Lake Arrowhead Region
Camp O-Ongo
25M, 13 M R.
76M, 7 M R. Unnamed-3
58M, 11 M L.
142M, 2 M R.
Unnaraed-4
Utmamed-5
Typic Xerorthent, coarse
loamy, mixed, frigid
Entic Xerumbrept, coarse
loamy, mixed, frigid
Pachic Xerumbrept, coarse
loamy, mixed, frigid
249
-------
Appendix B. CLASSIFICATION OF SOILS OF MAJOR PLOTS IN THE
SAN BERNARDINO MOUNTAINS. (Continued)
Plot
Green Valley Creek
(Valley)
(Hill)
Snow Valley
0-156M
156-249M
NE GREEN VALLEY
0- 60M
60-175M
Soil Series
Unnamed-6
Unnamed-7
Heitz
Chiquito
Corbett
Heitz
Classification; Soil
Taxonomy (1973)
Entic Xerumbrept, sandy,
mixed , raesic
Typic Xerorthent, sandy,
mixed, tnesic
Lithic Xeropsamment,
mixed, frigid
Entic Xerumbrepts, coarse
loamy, mixed, frigid
Typic Xeropsamment, mixed,
frigid
Lithic Xeropsamment,
mixed, frigid
Big Bear Lake Region
Bluff Lake
Holcomb Valley
Gefo Variant
Ducey Variant
Domingo
Unnamed-10
Typic Xerombrupt, sandy,
mixed, frigid
Typic Xerumbrept, coarse
loamy, mixed, frigid
Typic Argixeroll, fine
loamy, mixed, mesic
Typic Haploxeroll, coarse
loamy, mixed, mesic
250
-------
Appendix B. CLASSIFICATION OF SOILS OF MAJOR PLOTS IN THE
SAN BERNARDINO MOUNTAINS. (Continued)
Plot
Sand Canyon
(Granite area)
Soil Series
(Mixed alluvial area)
Heitz
Unnamed-8
Delleker Variant
Unnamed-3
Unnamed-9
Gefo Variant
Classification: Soil
Taxonomy (1373)
Lithic Xeropsamment,
mixed, frigid
Lithic Xerorthent, coarse
loamy, mixed, acid, frigid
Typic Haploxeralf, fine
loamy, mixed, frigid
Typic Xerorthent, coarse
loamy, mixed, frigid
See above
Typic Xerumbrepts, sandy,
mixed, frigid
Santa Ana Canyon Region
Camp Angelus Cahto Variant
Unnamed-10
Schneider Creek
Heart Bar
Crouch Variant
Gearson Variant
Unnamed-11
Pachic Ultic Haplixeroll,
loamy-skeletal, mixed,
mesic
Typic Haploxeroll, coarse
loamy, mixed, mesic
Ultic Haploxeroll, sandy,
mixed, mesic
Typic Haploxeroll, sandy,
mixed, frigid
Typic Xerochrept, sandy,
mixed, frigid
251
-------
Appendix C.
PARTICLE
SIZE
DISTRIBUTION
AND pH
OF REPRESENTATIVE
SOIL
SAMPLES
FROM
MAJOR STUDY
PLOTS.
F ine
Plot-site
Depths
Sand
Silt
Clay
Gravel
Gravel
2-. 05
.05-.002
<.002
2-12mm
> 12mm
PH
mm
mm
mm
(cm)
U)
(%)
(%)
(%)
(%)
Dogwood-1
0-23
71.6
20.3
8.1
29.0
1.3
5.83
77-99
62.7
19.1
18.1
62.3
0.6
5.73
122-141
69.2
19.6
11.2
38.3
0.4
5.59
Dogwood-2
0-19
72.8
20.7
6.6
21.7
0.0
6.05
112-126
67.7
16.9
15.4
51.6
2.7
5.53
173-198
74.6
20.5
4.8
28.0
0.3
5.52
Dogwood-3
0-25
69.2
18.2
12.6
42.2
0.9
5.40
29-112
71.4
16.7
12.0
42.8
1.3
5.70
119-140
69.1
14.2
16.7
42.3
0.6
5.50
S 22
0-20
74.0
18.1
7.9
0.2
4.9
6.75
41-58
74.2
18.1
7.6
7.0
5.0
5.80
79-99
77.5
14.8
7.7
6.9
0.6
5.33
NE 13
0-24
74.7
15.8
9.5
29.2
7.7
6.28
109-133
74.2
13.8
12.0
36.8
0.0
5.50
246-272
78.3
15.6
6.1
37.1
0.4
5.21
UC Conf.
0-25
69.1
24,9
6.1
24,7
1.9
5.91
Cen .
71-99
58.3
21.6
20.1
41.0
0.0
5.58
250-268
73.8
19.7
6.5
34.2
0.0
4.88
Sky Forest
0-15
71.2
18.5
10.3
0.0
2.2
5.53
R.S.
91-107
71.9
20.7
7.4
6.4
2.0
5.80
208-231
76.2
18.1
5.7
5.2
0.3
5.50
Breezy
0-29
69.9
20.6
9.5
20.6
0.8
5.92
Point
102-127
73.0
19.2
7.8
25.5
0.0
5.68
208-231
82.2
12.6
5.1
27.9
0.0
5.65
Camp
0-24
67.0
24.8
8.2
30.0
0.5
5.94
O-Ongo
72-93
65.0
22.2
12.9
50.0
4.4
5.63
110-128
55.5
28.4
16.1
55.2
0.5
5.35
128-149
56.9
35.0
8.2
93.4
0.0
5.36
252
-------
Appendix C. PARTICLE SIZE DISTRIBUTION AND pH OF REPRESENTATIVE SOIL
SAMPLES FROM MAJOR STUDY PLOTS. (Continued)
Fine
Plot-s ite
Depths
Sand
Silt
Clay
Gravel
Gravel
pH
2".05
.05-.002
<.002
2-12mm
> 12mm
mm
mm
mm
(cm)
(%)
(%)
(%)
(%)
(%)
Green
0-29
76.6
16.1
7.3
48.8
1.9
6.05
Valley
98-121
78.7
17.2
4.1
52.8
0.6
5.78
Creek
212-234
84.2
13.0
2.8
28.6
0.1
5.21
NE Green
0-22
82.4
11.5
6.1
37.6
0.8
6.00
Valley
81-104
84.7
12.6
2.8
31.4
0.0
6.13
Snow
0-14
75.3
16.1
8.6
28.1
0.0
5.40
Valley
33-46
74.4
16.1
9.5
40.0
0.0
5.00
Bluff Lake
0-28
79.4
14.0
6. 6
34.8
0.2
5.74
103-127
78.2
15.2
6.6
44.4
0.7
5.79
189-211
82.2
11.2
6. 6
47.0
0.0
5.89
Hoicomb
0-13
69.4
18.8
11.8
30.0
3.7
6.18
Valley
28-43
67.3
16.2
16.5
71.0
0.3
6.43
94-110
70.7
14.8
14.5
83.1
2.3
7.70
Sand
0-25
79.9
12.6
7.5
39.6
0.1
6.52
Canyon
87-110
82.0
14.9
3.2
34.1
0.0
6.08
Schne ider
0-14
79.8
14.1
6.1
104.2
0.9
6.51
Creek
81-104
81.7
12.9
5.3
63.1
0.1
6.4,5
166-189
81.4
13.1
5.6
58.2
0.0
6.46
Barton
0-15
71.2
19.4
9.4
4.2
ND
6.15
Flat
61-76
69.5
22.4
8.1
7.4
ND
6.45
Heart Bar
0-15
84.8
9.9
5.3
5.2
ND
6.81
91-107
81.8
8.1
10.1
7.3
ND
6.11
122-137
81.4
8.9
9.1
5.6
ND
6.13
Camp
0-15
17.9
21.7
10.4
5.2
ND
5.93
Osceola
61-76
67.6
21.0
11.4
7.4
ND
5.98
91-107
67.5
18.2
14.3
10.1
ND
5.78
253
-------
Appendix D.
BULK DENSITY (Db)
OF SOILS OF MAJOR
STUDY PLOTS
Plot Site
Sur f ace
Subsoil
Substratum
Depth
Depth
°b
Depth Djj
(cm)
(gm/cc)
( cm)
(gm/c c)
(cm) (gm/cc)
DW 1
0-46
1.09
41-157
1.46
—
DW 2
0-43
1.13
43-147
1.64
147-267 1.57
DW 3
0-51
1.13
51-157
1.94
NE 13
0-50
1.07
50-189
1.61
189-272 1.53
S 22
0-20
1.20
20-145
1.53
145-290 1.70
SF
0-61
1.05
61-160
1.53
160-277 1.47
UCC
0-25
1.40
25-152
1.69
152-250 1.68
CP
0-2 7
1.12
27-80
1.65
—
BP
0-29
0.74
29-147
1.17
147-284 1.57
TUNE
0-28
1.18
28-90
1.67
—
COO
0-51
1.15
51-149
1.68
—
GVC
0-29
1.11
29-156
1.85
150-246 2.10
NEGV
0-22
1.31
22-150
2.15
—
SV
0-14
1.24
14-55
1.56
—
HV
0-13
1.46
13-117
1.77
—
BL
0-55
1.15
55-147
1.67
147-255 1.74
SC 1
0-25
1.30
25-110
1.80
—
SCR
0-20
1.19
20-145
1.75
145-234 1.73
254
-------
Appendix E. EXCHANGEABLE AND SOLUBLE CATIONS OF SURFACE SOILS
Plot Site Depths Exchangeable Cations Soluble Cations
(cm)
Ca Mg K Na Ca Mg K Na
(Meg/lOOg)
(Meq/lOOb)
1:1 Extract
DW
1
0-24
3.64
0.72
0.499
0.032
0.028
0.011
0.018
0.012
DW
2
0-19
5.46
1.30
1.970
0.055
0.018
0.008
0.049
0.006
DW
3
0-25
2.92
0.59
0.482
0.030
0.020
0.010
0.019
0.013
NE 13
0-24
5.25
0.79
0.655
0.020
0.023
0.010
0.019
0.008
S 22
0-20
6.72
1.08
0.613
0.099
0.024
0.008
0.017
0.010
SF
0-15
7.31
1.39
0.493
0.006
0.073
0.029
0.020
0.014
UCC
0-25
4.87
1.23
0.566
0.081
0.023
0.010
0.015
0.009
CP
0-27
8.18
3.01
1.240
0.088
0.053
0.034
0.038
0.012
BP
0-29
10.44
2.78
0.914
0.052
0.060
0.031
0.027
0.012
TUNE
0-28
5.33
1.04
0.767
0.026
0.041
0.016
0.051
0.021
COO
0-24
10.47
2.06
1.140
0.076
0.057
0.019
0.039
0.006
GVC
0-29
3.75
0.79
0.352
0.018
0.016
0.004
0.010
0.007
NEGV
0-22
5.28
0.84
0.370
0.045
0.030
0.010
0.010
0.007
SV
0-14
6.17
1.65
0.261
0.008
0.014
0.005
0.011
0.006
HV
0-13
9.41
2.13
0.486
0.014
0.038
0.011
0.011
0.006
BL
0-28
3.32
0.44
0.266
0.028
0.034
0.015
0.011
0.006
SC
1
0-25
4.35
2.93
0.134
0.052
0.021
0.008
0.005
0.012
SC
2
0-24
13.55
2.24
0.227
0.012
0.148
0.041
0.012
0.009
SCR
0-14
9.92
1.32
0.610
0.014
0.277
0.046
0.070
0.016
BF
0-15
11.05
1.45
0.770
0.023
0.072
0.028
0.033
0.016
CAO
0-15
4.27
0.96
0.393
0.043
0.031
0.013
0.020
0.006
HB
0-15
5.00
0.88
0.520
0.015
0.024
0.009
0.015
0.008
-------
Appendix F. EXCHANGEABLE AND SOLUBLE CATIONS OF REPRESENTATIVE SUBSOIL LAYERS
Plot Site Depths Exchangeable Cations Soluble Cations
(cm)
Ca
Mg
K
Na Ca
(meq/100 gm)
Mg
K
Na
DW
1
77-99
2.83
1.53
0.347
0.056
0.008
0.005
0.004
0.014
DW
2
67-91
2.93
1.14
0.609
0.068
0.005
0.003
0.011
0.006
DW
3
89-111
0.71
0.36
0.317
0.040
0.004
0.003
0.007
0.014
NE 13
84-109
1.79
0.52
0.529
0.033
o.ooz.
0.003
0.008
0.007
S 22
79-99
3.47
1.54
0.340
0.084
0.008
0.004
0.008
0.009
SF
76-91
4.48
1.63
0.432
0.023
0.016
0.008
0.007
0.011
UCC
71-99
7.45
2.12
0.609
0.108
0.003
0.001
0.004
0.006
UCC
216-250
16.30
4.29
0.068
0.305
0.003
0.001
0.001
0.015
CP
64-80
6.09
2.48
1.250
0.021
0.015
0.009
0.020
0.006
BP
80-102
7.68
2.52
0.860
0.059
0.014
0.007
0.012
0.011
BP
231-264
14.35
2.97
0.134
0.215
0.006
0.002
0.001
0.019
TUN 2
79-90
3.08
0.92
0.515
0.018
0.014
0.006
0.014
0.008
COO
93-110
12.89
2.66
0.155
0.121
0.011
0.003
0.002
0.009
GVC
137-156
7.38
1.27
0.045
0.180
0.003
0.001
0.001
0.013
NEGV
81-104
6.64
0.46
0.072
0.070
0.018
0.002
0.002
0.010
SV
46-55
5.57
1.01
0.142
0.006
0.009
0.002
0.006
0.009
HV
62-80
23.55
2.14
0.256
0.017
0.095
0.018
0.006
0.010
BL
103-127
1.21
0.20
0.084
0.048
0.005
0.001
0.001
' 0.012
sc
1
89-110
13.60
4.01
0.049
0.085
0.007
0.002
0.002
0.012
SC
2
89-112
8.12
1.52
0.119
0.025
0.077
0.028
0.005
0.007
SCR
81-104
2.59
0.40
0.505
0.011
0.016
0.004
0.016
0.008
BF
61-76
5.68
0.79
0.602
0.030
0.024
0.007
0.011
0.009
CAO
76-91
3.10
1.00
0.418
0.036
0.007
0.004
0.006
0.008
HB
91-107
3.17
0.90
0.227
0.026
0.008
0.005
0.006
0.012
-------
Appendix G. ORGANIC CARBON (C) AND NITROGEN (N) IN THE SURFACE SOILS
TO A DEPTH OF 25 cm.
Plot Site
C
N
C/N
(g/lOOg)
(g/lOOg)
Dogwood 1
2.56
0.094
27.3
Dogwood 2
1.88
0.069
27.2
Dogwood 3
3.46
0.105
33.0
NE 13
2.70
0.097
27.9
S 22
1. 70
0.071
23.9
Sky Forest R.S,
2.03
0.076
26.8
U.C. Conference
Center
1.10
0.040
27.5
Camp Paivika
1.78
0.081
22.0
Breezy Point
2.08
0.102
20.4
Tunnel-2
1.63
0.051
32.0
Camp O-Ongo
1.72
0.122
14.1
Green Valley Creek
0.93
0.036
25.8
N.E. Green Valley
1.47
0.061
24.1
Snow Valley
0.83
0.041
20.4
Hoicomb Valley
1.14
0.054
21.1
Bluff Lake
3.42
0.118
29.0
Sand Canyon 1
0.65
0.031
21.0
Sand Canyon 2
1.78
0.084
21.1
Schneider Creek
2.15
0.092
23.5
Barton Flat
2.99
0.119
25.1
Camp Osceola
1.14
0.043
26.8
Heart Bar
0.87
0.034
25.6
257
-------
Appendix H. AVAILABLE SOIL WATER STORATE CAPACITY OF MAJOR STUDY PLOTS
Soil Soil Total
Plot-Site Depth Available Water Depth Available
Water
(cm) (Vol.%) (cm) (cm) (cm)
Breezy Point
152
15.4
23.4
256
39.2
Sky Forest
152
14.3
21.8
208
30.6
Green Valley Creek
152
14.3
21.7
203
28.9
Bluff Lake
152
13.9
21.2
223
28.4
Dogwood-2
152
13.5
20.6
267
29.0
Dogwood-1
152
13.4
20.4
Not
sampled
NE 13
152
12.9
19.6
272
37.4
U.C, Conf. Cen.
152
12.4
18.9
269
27.9
Dogwood-3
152
12.2
18.5
Not
sampled
S 22
152
10.6
16.1
208
18.4
Schneider Creek
152
8.9
13.5
221
28.8
Camp O-Ongo
152
8.6
13.1
152
13.1
Sand Canyon
152
7.7
11.7
262
13.8
Tunnel-2
12.5
86
10.8
NE Green Valley
10.3
121
12.4
Camp Paivika
8.1
80
6.5
Holcomb Valley
8.4
116
9.7
Snow Valley
16.3
61
9.9
Range
7.7-15.4
11.7-23.4
6.5-39
Mean
11.9
18.5
21.6
258
-------
Appendix I. VEGETATION ZONES, VEGETATION TYPES, AND MAJOR SPECIES IN THE SAN BERNARDINO MOUNTAINS.
Vegetation Horton's vegetation Minnich's vegetation Major species
zone0- typea type ^
Chamise-
Chaparral
Woodland-
Chaparral
Pure chamise-
chaparral
Chamise-ceanothus
chaparral
Chamise-manzanita
None
Soft chaparral
Hard chaparral
Scrub oak
chaparral
Coastal
sagebrush
Live oak
chaparral
Live oak
woodland
Oak chaparral
Coastal sage
scrub
Emergent oak
woodland
Interior oak
wood1and
Adenostoma fasciculatum
Adenostoma fasciculatum, Ceanothus
crassifolius, C. leucodermis,
Quercus dumpsa, Photinia
arbutifolia, Rhus ovata
Adenostoma fasciculatum,
Arctostaphylos glauca, A.
glandulosa, Ceanothus crassifolius,
C. leucodermis
Quercus dumosa, Q. wislizenii,
Cercocarpa betuloides, Ceanothus
leucodermis, Garrya veatchii,
Arctostaphylos glandulosa
Artemisia californica, Salvia
apiana, Eriogonum fasciculatum,
Encelia farinosa, Salvia mellifera,
Deplacus longiflorus
Quercus wislizenii, Q. chrysolepis
plus hard chaparral species
Quercus wislizenii, Q. chrysolepis,
Pseudotsuga macrocarpa, Cercocarpus
ledifolius
-------
Appendix I. VEGETATION ZONES, VEGETATION TYPES, AND MAJOR SPECIES IN THE SAN BERNARDINO MOUNTAINS.
(Continued)
Vegetat ion
zone a
Horton's vegetation
type
Minnich's vegetation
type
Major species
Pinyon-
Juniper
Wood1and
Timberland
Chaparral
Coniferous
Forest
Big-cone Douglas
fir forest
Great Basin
sagebrush
none
none
Timberland
chaparral
Pine forest
Big-cone Douglas
fir forest
Great Basin
sagebrush
Joshua Tree
woodland
Juniper-Joshua
Tree woodland
Timberland
chaparral
none (see Coulter
pine forest, dry
forest)
Pseudotsuga macrocarpa, Quercus
chrysolepis
Artemisia tridentata, Artemisia
arbuscula nova, Chrysothamnus
nauseousus, Colegyne ramossias-
sima, Eriogonum spp., Salvia spp.
Yucca occidentalis, Yucca brevi-
folia, Chrysothamnus nauseosus
Juniperus occidental is, Yucca
brevifolia, Artemisia tridentata,
Chrysothamnus nauseous
Arctostaphylos patula, Ceanothus
cordulatus, Castanopsis
sempervirens
Pinus ponderosa, Pinus jeffreyi,
Pinus coulteri, Quercus kelloggii
Ponderosa pine-
white fir forest
Mixed yellow pine-
white fir forest
Pinus ponderosa, Pinus jeffreyi,
Abies concolor, Pinus lambertiana,
Libocedrus decurrens, Quercus
kelloggii
-------
Appendix I. VEGETATION ZONES, VEGETATION TYPES, AND MAJOR SPECIES IN THE SAN BERNARDINO MOUNTAINS.
(Continued)
Vegetation
zonea
Horton's vegetation
type °~
Minnich's vegetation
type k
Major species
Sugar pine-
white fir forest
none (see pure yellow
pine-white fir
forest)
Pinus 1ambertiana, P^. j effreyi,
Abies concolor, Quercus chryso-
lepis, plus timberland chaparral
species
Coniferous
Forest
Grassland
Black oak
woodland
Alpine forest
Barren areas
Grassland or
meadow
none (see dry
forest)
Subalpine forest
Krunmholz
Bromus spp., Carex spp., Juncus
spp.
Quercus kelloggii, Quercus
chrysolepis, Pinus ponderosa,
Pseudotsuga macrocarpa, Ceanothus
mtegerr imus
Pinus contorta, P. flexilus, plus
timberland chaparral species
Pinus contorta, Pinus flexilus,
plus stunted timberland chaparral
species
Barren
none
none
none (see Pine
forest, ponderosa
pine-white fir forest)
Marginal conifer
forest
Pure yellow pine-
white fir forest
A mixture between pure yellow
pine-white fir forest and timber-
land chaparral species
Pinus ponderosa, P. jeffreyi, £.
1ambertiana, Libocedrus decurrens ,
Abies concolor
-------
Appendix I. VEGETATION ZONES, VEGETATION TYPES, AND MAJOR SPECIES IN THE SAN BERNARDINO MOUNTAINS.
(Continued)
Vegetation
CL
zone
Horton's vegetation
type
Minnich's vegetat
type
ion
Major species
All zones
Woodland-
Chaparral
Desert
Chaparral
Pinyon-
Juniper
Woodland
none (see Pine forest,
black oak woodland)
none
Knobcone pine
forest
none (see pine
forest
Desert
chaparral
Pinyon-Juniper
woodland
Dry forest
River ine
vegetation
Knobcone pine
forest
Coulter pine
forest
Desert
chaparral
Western Juniper-
mountain mahogany
woodland
Pinus coulteri, Quercus
kelloggii
Platanus racemosa (below 4,000 ft),
Populus trichocarpa (below 4,000 ft),
Alnus rhamnifolia (4,000-7,000 ft),
Salix spp. (above 7,000 ft),
Populus tremuloides (Fish Creek)
Pinus attenuata, Adenostoma
fasciculatum, Arctostaphylos
glandulosa, Ceanothus leucodermis,
Pickeringia montana
Pinus coulteri, Quercus
wislizenii, Q. chrysolepis, plus
hard chaparral species
Cercocarpus ledifolius, Quercus
wislizenii, (}. dumosa,
chrysolepis, Ceanothus greggii,
C. crassifolius, Fremontia
californicus,"Garrya veatchii
Juniperus occidental is,
Cercocarpus ledifolius, Artemisia
tridentata, Chrysothamnus
nauseosus
-------
Appendix I. VEGETATION ZONES, VEGETATION TYPES, AND MAJOR SPECIES IN THE SAN BERNARDINO MOUNTAINS.
(Continued)
Vegetation
zone
a.
Horton1s vegetation
type
a
Minnich's vegetation
type b
Major species
N3
U>
All Zones
none
Pinyon pine
woodland
Pinyon-Juniper
woodland
Subclimax
vegetation
Pinus monophylla, P. Quadrifolia,
Juniperus californica, J.
occidentalis, Cercocarpus ledi-
folius, Artemisia tridentata,
Chrysothamnus nauseosus
Pinus monophylla, P. quadrifolia,
Juniperus californica, .J.
occidentalis, Cercocarpus ledj-
folius, Artemisia tridentata,
Chrysothamnus nauseosus,
Arctostaphylos glauca, Quercus
duroosa
Varies with site
Outside of
Above Zone
none
Open desert
vegetation
a Horton (1960)
k Minnich and others (1969)
-------
Appendix J. PRELIMINARY ANALYSIS OF NUMBER OF ATTACKS AND GALLERY LENGTH
FOR THE MOUNTAIN PINE BEETLE FROM VARYING BARK SAMPLE SIZES
(DATA CONVERTED TO 1000 cm* FOR COMPARISON), EPA, SAN
BERNARDINO AIR POLLUTANT STUDY, 1974.
Number of Attacks Gallery Length
Location of Sample Number Mean Standard Number Mean Standard
Sample Size of Deviation of (cm) Deviation
(ctij2) samples samples (cm)
100 10 3.00 6.75 10 246.0 182.9
100 10 4.00 9.66 10 278.0 198.3
Base of
250 10 3.60 3.98 10 243.6 155.9
Infestation
500 10 3.00 3.43 10 230.8 123.5
1000 10 3.00 2.71 10 195.5 95.1
100
9
5.56
5.27
10
230.0
114.8
100
9
5.56
5.27
10
266.0
130.8
Middle of
250
9
4.00
3.46
10
253.2
120.4
Infestation
500
9
2.89
1.76
10
243.8
87.0
1000
8
3.00
2.45
9
216.8
78.2
100
10
0
0
10
142.0
99.4
100
10
0
0
10
160.0
113.2
Top of
250
10
0
0
10
141.6
80.8
Infestat ion
500
8
1.00
1.51
8
159.8
93.9
1000
6
1.50
1.97
5
147.8
129.3
264
-------
Appendix K. PRELIMINARY ANALYSIS OF NUMBER OF ATTACKS AND GALLERY LENGTH
FOR THE JEFFREY PINE BEETLE FROM VARYING BARK SAMPLE SIZES
(DATA CONVERTED TO 1000 cm* FOR COMPARISON), EPA, SAN
BERNARDINO AIR POLLUTANT STUDY, 1974.
Number of Attacks Gallery Length
Location of Sample Number Mean Standard Number Mean Standard
Sample Size of Deviation of (cm) Deviation
(cm2) samples samples (cm)
100
12
3.33
4.92
12
146.7
89.98
100
12
3.33
4.92
12
156.7
96.42
Base of
250
12
2.00
2.09
12
144.3
63.04
Infestat ion
500
12
3.33
2.31
12
144.5
56.90
1000
12
2.83
1.58
12
136.7
52.81
100
12
3.33
6.51
12
135.8
107.7
100
12
3,33
6.51
12
141.7
112.4
Middle of
250
12
2.67
4.29
12
133.3
78.32
Infestation
500
12
2.83
3.01
12
117.7
67.30
1000
12
2.91
2.57
12
112.8
57.05
100
12
2.50
4.52
12
71.67
59.52
100
12
4.17
5.15
12
89.17
69.86
Top of
250
12
2.33
3.17
12
82.00
62.93
Infestat ion
500
12
2.67
2.87
12
80.00
59.60
1000
12
2.42
2.35
12
84.25
52.47
265
-------
Appendix L. TOTAL ARTHROPODS REARED FROM MOUNTAIN PINE BEETLE INFESTED
PONDEROSA PINE BOLTS FROM THREE HEIGHTS IN 1974, SAN
BERNARDINO.
Ar achnida
Araneae
Pseudoscorpion ida
Chernet idae
Insecta
Hemiptera
Anthocoridae
Lyctocoris sp.
Species #2
Unknown nymphs
Neuroptera
Inocelliidae
Inocellia sp.
Raphidiidae
Agulla sp.
Chrysopidae
Species #1
Unknown larvae
Coleoptera
Histeridae
Plegaderus sp.
Platysoma sp.
larva #1
larva #2
Scaphidiidae
Species #1
Staphylinidae
Nudobius sp.
Species #2
Dermestidae
Species #1
Os torn idae
Temnochila sp.
Tenebroides sp.
Cleridae
Enoclerus sp.
Species #4
Rhizophagidae
Rhizophagus
Cryptophagidae
Salebius sp.
Nitidulidae
Species #1
Lathridiidae
Corticaria sp.
Colyd i idae
3
Lasconotus sp
10
AuIonium sp
138
68
Othniidae
Othnius sp
28
Tenebrionidae
Corticeus sp.
38
2
Melandryidae
1
Rushia sp.
127
8
Bostrichidae
Species #1
14
Curculionidae
14
Cossonus sp.
293
Lechriops sp.
1
52
Scolyt idae
Dendroctonus
1
valens LeC.
1
2
D. brevicomis
11
Pityokteines sp.
307
Gnathotrichus sp.
32
338
Unknown larvae
10
Species #3
256
18
Lepidoptera
2
Unknown species
Diptera
2
1
Ceratopogonidae
Species #1
233
4
Sciaridae
1
Species #1
Scatopsidae
21
2
Species #1
Cecidomyiidae
1
119
Species #1
5
4
Stratiomyidae
Zabrachia sp.
289
171
Scenopinidae
4
Belosta sp.
Erapididae
27
2
Drapetis sp.
Dolichopodidae
11
3
Medetera sp.
7
Species #2
2
1
Phoridae
Species #1
51
12
266
-------
Appendix L. TOTAL ARTHROPODS REARED FROM MOUNTAIN PINE BEETLE INFESTED
PONDEROSA PINE BOLTS FROM THREE HEIGHTS IN 1974, SAN
BERNARDINO. (Continued)
Diptera (continued)
Londraeidae
Species #1 33
Milichi idae
Species #1 22
Drosophilidae
Species #1 8
Sarcophagidae
Species #1 2
Unknown larvae
Species #1 116
Hymenoptera
Braconidae
Species #1 2
Species #2 1
Encyrt idae
Species #1 8
Species #4 2
Species #6
Toryraidae
Roptrocerus sp.
Pteromalidae
Species #1
Bethy1idae
Species #1
Formic idae
Species #2
Sphecidae
Pemphredon sp.
267
-------
Appendix M. TOTAL ARTHROPODS REARED FROM JEFFREY PINE BEETLE INFESTED
JEFFREY PINE BOLTS FROM THREE HEIGHTS IN 1974, SAN
BERNARDINO
Arachnida
Araneae
Pseudoscopt ionid a
Chernetidae
Insect a
Neuroptera
Inocelliidae
Inocellia sp.
Raphxdixdae
Agulla sp.
Coleoptera
Scaphidiidae
Species #1
Staphylinidae
Species #L
n
#4
larvae
Clambidae
1 species
Dermest idae
Megatoma sp.
larvae #1
Maiachiidae
Species #1
Ostomidae
Temnochila sp.
Clendae
Enoclerus sp.
Species #3
Buprest idae
Larvae #1
Rhizophagidae
Rhizophagus sp,
Cryptophagidae
Salebius sp.
Nit ldul idae
Species #1
Colydiidae
Lasconotus sp.
Aulonium sp.
OthnTTcTae
Othnius sp.
156
31
3
2
1
1
1
25
1
13
1
44
57
15
12
1
8
2
3
1
21
Tenebrionidae
Larvae #1 26
Curculionidae
Cossonus sp. 1
Scolyt idae
Ips pini Lanier 1
Ips latidens (LeC) 2
Pityokteinels
ornatus (Swaine) 3
Gnathotrichus sp 189
Unknown Larvae #1 1
Lepidoptera
Larva #1 1
Species #2 1
Diptera
Ceratopogonidae
Species #1 2,993
Mycetophilidae
Species #1 1
Sciar idae
Species #1 40
Scatopsidae
Species #1 1
Cecidomyiidae 7
Stratiomyidae
Zabrachia sp. 28
Scenopinidae
Belosta sp. 2
Empid idae
Drapetis sp. 9
Dolichopodidae
Medetera sp. 7
Species #2 1
Phoridae
Species #1 224
Milichiidae
Species #1 23
Unknown larvae
Species #1 91
Species #2 28
Species #4 27
268
-------
Appendix M. TOTAL ARTHROPODS REARED FROM JEFFREY PINE BEETLE INFESTED
JEFFREY PINE BOLTS FROM THREE HEIGHTS IN 1974, SAN
BERNARDINO (Continued)
Hymenoptera
Braconidae
Species #1
Encyrt idae
Species #1
#2
#3
#4
#5
Avetienella sp.
Eurytomid ae
Eurytoma sp.
Diapr ndae
Species #1
Formic idae
Species #1
Collet idae
Species #1
12
10
1
10
2
1
3
2
1
24
1
269
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Appendix N. TAXONOMIC LIST OF SOIL MICROARTHROPODS COLLECTED FROM THE
BREEZY POINT, SNOW VALLEY AND NEGV STUDY PLOTS, 1973-74.
Insecta
Protura
Campode idae
Japygidae
Lepismatidae
Collembola
Istomidae
Entomobryidae
Podur idae
Onychiuridae
Sminthur idae
Thysanoptera
Pscocoptera
Hymenoptera
Diptera
Coleoptera
Staphylinidae
Silphidae
Curculionidae
Lathridiidae
Raphidiidae
Myriapoda
Diplopoda
Ch ilopoda
Geophilidae
Scut igeromorpha
Symphyla
Pauropoda
Arachnid a
Araneida
Chelonethida
Acar ina
Prost igmata
Lab idostornidae
Eupod idae
Bdellidae
Nanorchestidae
St igmaeidae
Cunaxidae
Ragidiidae
Erythraeidae
Anyst idae
Neophylobiidae
270
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Appendix N. TAXONOMIC LIST OF SOIL MICROARTHROPODS COLLECTED FROM THE
BREEZY POINT, SNOW VALLEY, AND NEGV STUDY PLOTS, 1973-74
(Continued)
Arachnida (continued)
Tyde idae
Cryptognathidae
Raphignathidae
Cheyletidae
Linotetranidae
Paratydeidae
Trombidiidae
Caeculidae
Mesostigmata
Zerconidae
Trachyt idae
Phytose idae
Asc idae
Hypoaspidae
Pachylaelapt idae
Rhodacar idae
Cryptost igmata^
Gymnodamaeidae
Jacotella sp.
a Cryptostigmatid identifications
New York, Syracuse Campus
° Genus and species numbers refer
271
Gymnodamaeus sp.
Damaeidae^
Genus 1 sp. 3
Genus I sp. 6
Genus 2 sp. 5
Genus 5 sp. 3
Eremae idae
Eremaeus stiktos Higgins
Eremaeus sp. (two species)
Or ibatulidae
Scheloribates sp.
Hemileius sp.
Liacaridae
Liacarus sp. nr.
Charassobatidae
Ametroproctus sp.
Cepheidae
Eupterotegaeus sp.
by R. A. Norton, State Univ. of
to Norton terminology.
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Appendix N. TAXONOMID LIST OF SOIL MICROARTHROPODS COLLECTED FROM THE
BREEZY POINT4 SNOW VALLEY, AND NEGV STUDY PLOTS, 1973-74
(Continued)
Passalozetidae
Passalozetes sp.
Hermanniellidae
Hermanniella sp.
Palaeacar idae
Palaeacarus sp.
Cosmochthonoidea
Cosmochthonius sp.
Aphelacar idae
Aphelacarus sp.
Camisiidae
Camisia sp.
Ceratozet idae
Propelops sp.
Galuranidae
Philogalumna sp.
Tectocepheidae
Tectocepheus sarekensis Tragardh
272
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Appendix 0. THE NUMBER OF GONES PRODUCED BY JEFFREY AND PONDEROSA PINES OF DIFFERENT CROWN CLASSES
DURING 1973 AND 1974.
Part A. Ponderosa pine.
Plot name Year
Dom.
Co-Dom.
Inter.
Crown classes
Inter. Inter.
Open Suppr.
Suppr,
Total
Cones
Number of Cones/Number of Trees
CP
1973
137/37(7)^
0/24
0/5
0/10
0/0
0/0
137
1974
275/37(19)
26/24(5)
0/5
0/10
0/0
0/0
301
BP
1973
1/25(1)
0/24
0/8
0/9
0/6
0/0
1
1974
165/25(10)
90/24(6)
0/8
0/9
0/5
0/0
255
DWA
1973
0/6
0/8
0/3
0/4
0/0
0/0
0
1974
609/16(9)
79/19(5)
0/25
1/11(1)
0/0
0/19
689
TUN 2
1973
1624/25(14)
144/20(6)
0/7
0/7
0/12
0/1
1768
1974
1698/25(20)
432/20(10)
0/7
0/7
0/12
0/1
2120
SF
1973
98/31(16)
14/22(5)
0/23
1/16(1)
0/21
0/0
113
1974
2022/31(24)
582/22(13)
35/23(2)
8/16(1)
0/20
0/0
2648
UCC
1973
11/16(4)
1/25(1)
0/11
0/9
0/4
0/0
12
1974
300/15(9)
175/25(8)
0/11
8/9(1)
0/4
0/0
483
COO
1973
9/29(3)
0/16
0/2
0/5
0/5
0/0
9
1974
382/29(2)
18/16(1)
0/3
0/5
0/5
0/0
400
CA
1973
1395/9(9)
388/17(3)
0/5
8/4(1)
0/0
0/4
1706
1974
1317/12(13)
1276/17(19)
28/12(3)
86/5(2)
0/0
0/9
2701
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Appendix 0. THE NUMBER OF CONES PRODUCED BY JEFFREY AND PONDEROSA PINES OF DIFFERENT CROWN CLASSES
DURING 1973 AND 1974 (Continued)
Plot name Year Inter. Inter. Total
Pom. Co-Pom. Inter. Open Suppr. Suppr. Cones
SCR 1973 NO DATA TAKEN
1974
5735/31(30)
402/17(2)
63/1(1)
0/0
0/0
0/0
6208
BF
1973
0/10
8/8(1)
0/3
0/4
0/0
0/0
8
1974
534/11(8)
327/4(3)
0/4
0/4
0/1
0/0
361
Part B. Jeffrey Pine.
GVC
1973
452/35(24)
0/12
0/9
0/5
0/0
0/4
452
1974
3903/35(28)
0/12
26/9(1)
0/5
0/0
0/4
3929
SV
1973
37/24(7)
45/23(6)
0/3
2/9(1)
0/0
0/9
84
1974
119/28(11)
87/25(5)
0/13
0/27
0/0
0/9
206
NEGV
1973
100/20(18)
113/15(7)
7/18(2)
0/6
0/5
0/1
220
1974
600/20(13)
189/15(16)
16/18(3)
5/6(2)
1/5(1)
0/1
811
BL
1973
170/22(19)
33/23(4)
2/32(1)
3/31(2)
0/14
0/13
208
1974
119/22(11)
79/23(8)
0/32
0/31
0/14
0/13
198
HV
1973
NO DA
T A TAKEN
1974
199/34(21)
58/37(14)
4/48(2)
0/29
0/0
0/18
261
sc
1973
219/21(14)
137/12(6)
0/1
1/6(1)
0/0
0/0
357
1974
62/21(9)
1/12(7)
7/5(3)
0/9
0/0
0/6
70
HB
1973
27/43(6)
2/28(1)
0/1
0/26
0/7
0/5
19
1974
321/44(19)
18/28(5)
0/1
0/29
1/7(1)
0/5
340
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Appendix 0. THE NUMBER OF CONES PRODUCED BY JEFFREY AND PONDEROSA PINES OF DIFFERENT CROWN CLASSES
DURING 1973 AND 1974 (Continued)
Plot name Year
Dom.
Co-Dom.
Inter.
Inter. Open
Inter.
Suppr.
Suppr.
Tot a
Cone
CAO 1973
1974
1238/16(10)
163/30(8)
NO DATA TAKE
138/34(4) 0/11
H
0/1
0/29
1541
BF 1973
1974
0/4
50/23(4)
0/0
185/44(9)
0/0 0/0
5/68(1) 0/11
0/0
0/0
0/0
0/50
0
240
SCR 1973
NO DATA TAKE
N
1974
109/3(2)
0/0
0/0 0/1
0/0
0/1
109
a Number in
parenthesis
is number of
trees in that crown class
which produced cones.
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