United States
Environmental Protection
Agency
Atmospheric Research and
Exposure Assessment Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S3-91/074 Feb. 1992
EPA Project Summary
The Role of Climate in Forest
Monitoring and Assessment: A
New England Example
Ellen J. Cooler, Sharon K. LeDuc, Lawrence Truppi, and
Donald R. Block
The development of cllmatological
Information products to support eco-
logical data collection and analysis Is
described. The scope of research is
narrowed to Issues of direct interest to
the Joint U.S. Environmental Protection
Agency Environmental Monitoring and
Assessment Program (EMAP) and U.S.
Department of Agriculture Forest Ser-
vice New England Forest Health Moni-
toring program (NDFHM).
Characteristics of cllmatological per-
sistence and recurrence that are espe-
cially critical to New England forest
health and productivity are Identified.
These Include physical disturbance
events (tornadoes, high winds, and wet
snowfall), drought, growing degree
days, and late spring freezes. Cllmato-
logical data are assembled and presen-
tations developed based on the analysis
issue to be addressed: background (sta-
tus and persistence), most recent de-
cade (short-term trends), and most
recent sampling year (near-term Im-
pacts). A Geographic Information Sys-
tem is used for presentation, data
management, and analysis.
Major research findings focus on
the application of climate data and
products to operational ecological
monitoring and analysis situations.
Possible future activities are identified
In the areas of new climatologies, pro-
gram design, database acquisition, or
development and applied research. AH
these efforts would result in signifi-
cant contributions to the development
of a more coherent theory of natural
disturbance and ecosystem response.
This Project Summary was devel-
oped by EPA's Atmospheric Research
and Exposure Assessment Laboratory,
Research Triangle Park, NC, to an-
nounce key findings of the research
project that Is fully documented in a
separate report of the same title (see
Project Report ordering Information at
back).
Project Overview
The primary goal of this report is to
define a working hypothesis of climate/
ecosystem interactions suitable for opera-
tional environmental monitoring programs.
Such an exercise is necessary before cli-
mate research and analysis can become
an integral part of these programs. Al-
though the research has focused on a
specific cooperative EPA and USDA sam-
pling project initiated during 1990, insights
are provided pertinent to the general topic
of climate/biosphere interactions.
The approach adopted is to establish a
common ground of concepts and terminol-
ogy to facilitate exchanges between the
climatological and ecological communities.
This is accomplished through the careful
definition of key terms and a discussion of
the role of climate in current ecological
theory. The discussion provides an av-
enue for identifying major environmental
policy issues, establishing which of these
are significantly climate related, and initiat-
ing the development of the necessary data
and analysis products.
The hypothesis developed is that the
relationship of climate (the synthesis of
weather) to ecosystems depends on the
Printed on Recycled Paper
-------
1
timo and space scale of the biological sys-
tem to be monitored and the analyses to
bo performed. Climatological averages and
ranges reflect one set of physical bounds
on the number of possible ecosystem states
represented within a landscape. Inter-an-
nual disturbances affect ecosystem health
and productivity as measured by changes
In growth, system energetics, plant popu-
lations, and species characteristics. Dis-
turbance events affect the persistence and
recurrence of ecological states. Disturbance
events vary with geographic location and
can be described by their frequency, size,
and magnitude. Many forest status, health,
and trend Indicators, particularly those
based on directly monitored observations,
may be incorrectly interpreted and inap-
propriate associations between observa-
tions construed unless mitigating or
compounding climatotogical factors are
considered as well.
Data and Methodology
The vast array of possible climate/eco-
system interactions that could be exam-
ined Is substantially narrowed by "targeting"
the analysis to a particular geographic set-
ting. In this case, the cooperative U.S.
EPA EMAP-Forests pilot and USDA For-
est Service New England Forest Health
Monitoring (NEFHM) project has been se-
lected (Figure 1).
Data bearing on several major catego-
ries of ecosystem disturbances facilitate
the assessment of forest response to se-
vere weather and tornadoes, hurricanes,
drought, late spring freeze, late spring
snowfall, and growing degree days. Sum-
maries of Climatological means and distur-
bance characteristics such as event
frequency, magnitude, and size are devel-
oped with particular attention to their rel-
evance to forest status and health
assessment. Given the events listed above,
Table 1 summarizes all climate disturbance
summaries pertinent to the New England
region. An "X" indicates that the character-
istic has been summarized within this re-
port. A blank entry indicates disturbance
attributes that were not characterized. The
entire set of products are stratified into
three groups defined by the analysis issue
to be addressed: background (status and
persistence), most recent decade (short-
term trends), and most recent data year
(near-term impacts).
Products that describe the long-term,
or background climate of the New England
region are the first of the three groups
discussed. Using the earlier analogy of
ecological persistence and recurrence, the
background climate defines, in part, the
"bounds'forthe recurring ecosystem states.
o o o c <» f.BV
Figure 1. The New England Forest Health Monitoring Program network of potential sampling
The second, product group, a 10-year
analysis, emphasizes short-term variability
of climate stress. This also represents more
closely the regional response time of for-
est ecosystems to chronic Climatological
stress.
Figure 2, developed as part of the dec-
adal summary, contains a summary of
drought, growing degree day (GDD) sums,
spring freezes, and warm spring snowfall
events in terms of the percent of the study
area affected. Drought, small GDD totals,
late spring freeze, and late snowfall dates
are included if, based on the entire climate
record for a station, the current value is
expected to occur fewer than once in 20
years. A one-in-100-year return period
would be more appropriate, but statistical
approximations will be needed before val-
ues for most variables and locations can
be determined.
The purposes of Figure 2 are 1) to
facilitate visual identification of short-term
trends in forest-related climate variables,
2) to identify the frequency and size of
regional-scale climate events, and 3) to
identify associations of stressful climate
conditions. This figure does not quantify
the amount of forest damage or forest
response to these stresses. The impact of
-------
Table 1. Examples of Climate Disturbance (Stress) Products Developed for New England
Climate Variable Frequency Magnitude Size
Tornadoes
Wind
Tropical cyclone
Drought
Temperature
Precipitation
Growing degree days
Late spring freeze
Late spring snowfall
intra-annual
intra-annual
X
X
X
X
X
X
X
intensity only
intensity only
intensity duration
intensity only
intensity orriy
intensity only
intensity only
intensity only
X
X
X
X
X
X
X
X
environmental stress will vary with ecologi-
cal system (although all of these measures
reflect local conditions) and combinations
of stresses may result in threshold behav-
ior (discontinuities) or nonlinear increases
in damage. The figure represents a con-
sistent intensity of stress across stressors
and permits, for this decade, some gener-
alizations of size/frequency relationships
which could be associated with monitored
forest status, health, and trend indicators.
Next, this 10-year summary is related
to the NEFHM sampling network. A distri-
bution of event/sampling area intersections
is constructed. Geographic locations that
are classified as being located in the upper
tail of the distribution represent areas ex-
periencing a large number of relatively un-
usual climate events. Monitored data from
these areas might be expected to contain
stress characteristics that could be associ-
ated with natural climate stress. Geographic
locations classified as belonging in the
lower tail of the intersection distribution
indicate relatively few climate-related dis-
turbance events. Stress-related ecosystem
characteristics in these areas could be
associated with non-climate stressors.
The final climate summary example is
developed for the most recent available
year of data. Such summaries are prima-
rily used to aid in the interpretation of the
current year's sampling program. These
products and analyses, in combination with
supplemental field observations, can help
to identify areas in need of special studies
and to suggest previously unknown sources
of stress or mortality.
Report Summary and Future
Work
Forest response research has estab-
lished that climate plays an important role
in forest ecosystems, influencing both per-
sistence and recurrence characteristics of
the landscape. Forests act as environmen-
tal integrators of both natural and anthro-
pogenic disturbances. New monitoring
programs such as EPA EMAP and the
USDA FHM program hope to capture for-
est response to changes in these stresses,
but their observations cannot be correctly
interpreted without an ability to discern
between natural climate variability and sig-
nals of permanent climatological change.
Likewise, changes in ecosystem health and
productivity cannot be accurately attrib-
uted to changes in societal behavior un-
less the ecosystem response to natural
disturbance can be better understood and
predictively modeled.
This research addresses several criti-
cal climate impact issues. First, while ex-
isting historical networks may be adequate
for landscape or regional analyses, local
geographic influences critical to the devel-
opment of accurate predictive models (a
stated goal of the FHM) may be lost or
misinterpreted by using nonrepresentative
climate observations.
Next, although there are usually far
more climate data available for analysis
than for ecosystem status and health, there
are serious quality control and representa-
tion problems. Some of these issues are
currently being addressed by the atmo-
spheric science community, but true, uni-
form quality control of cooperatively
observed weather conditions is a formi-
dable task.
Finally, new data analysis technologies
offer unique opportunities to integrate pre-
viously intractable multimedia research is-
sues. With increased flexibility come new
challenges to research problem definition.
One issue illustrated in this research is the
problem of graphically representing an in-
herently temporal process (climate/forest
interactions and dynamics) in a spatial set-
ting (regional analysis). Remotely sensed
and new ground-based monitoring pro-
grams increase analysis opportunities, but
to realize this potential, there is first the
need to establish the new data in the as-
sessment process. Even if remotely sensed
data provide improved characterization of
spatial and temporal variability of the cli-
mate, comparative relationships between
historic data sources and new sources
must be established before they are rou-
tinely incorporated into ecological assess-
ment products.
100
80
60
40
20
I I Freeze
Wk ODD
@ Snow
• Drought
_E0-
_n
1981 1982 1983 1984 1985 1986 1987 1988 1989 1990
Year
Figures. Percent of New England region impacted by climate stress, 1981-1990.
•&U.S. GOVERNMENT PRINTING OFFICE: 1991 - 648-080/40WS
-------
Elian J. Cooler (also the EPA Project Officer, see below), Sharon K. LeDuc, and
Lawrence Trupplare with Atmospheric Research and Exposure Assessment
Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC
27711. Donald R. Block is with UNISYS Corporation, Research Triangle Park, NC
27709.
Tho complete report, entitled "The Role of Climate in Forest Monitoring and Assess-
ment: A New England Example," (Order No. PB92-132869/AS; Cost: $26.00, subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Off her can be contacted at:
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triangle Park NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S3-91/074
------- |