EPA 600/R
95/037
INSTALLATIONS:
lN EXPLORATORY,
-------
EPA ERL-Corvallis Library
I 1 I
00007512
CARBON SEQUESTRATION AND
FOREST MANAGEMENT AT DOD
INSTALLATIONS: AN EXPLORATORY
STUDY
Jerry R. Barker
ManTech Environmental Research Services Corp.
EPA Environmental Research Laboratory - Corvallis
Greg A. Baumgardner
ManTech Environmental Research Services Corp.
EPA Environmental Research Laboratory - Corvallis
Jeffrey J. Lee
U.S. Environmental Protection Agency
Environmental Research Laboratory - Corvallis
J. Craig Mc Farlane
U.S. Environmental Protection Agency
Environmental Research Laboratory - Corvallis
March 1995
EPA/600/R-95/037
ERL-COR 826
U.S. Environmental Protection Agency
Environmental Research Laboratory
200 S.W. 35th Street
Corvallis, Oregon 97333
Library
9.S. Environmental Protection Agtnof
National Kcc:::i c~r1. environmental
Bllects nosccrc'i " ' Moratory
200 S.W. SCili Cl'.c-!
Corvallis, Oregon 97333
-------
DISCLAIMER
The information in this document has been funded under the Strategic Environmental Research
and Development Program (SERDP) through the U.S. Environmental Protection Agency. This
document has been prepared at the EPA Environmental Research Laboratory in Corvallis,
Oregon through contract 68-C8-0006 to ManTech Environmental Research Services Corpora-
tion. It has been subjected to the Agency's peer review and administrative review and it has
been approved for publication. Mention of trade names or commercial products does not consti-
tute endorsement or recommendation for use. Furthermore, the forest management scenarios
presented herein do not represent planned action by the U.S. Department of Defense on any
military installation. The scenarios are hypothetical and do not necessarily reflect those cur-
rently being considered at Camp Shelby.
ii
-------
Table of Contents
Acknowledgments iv
Tables v
Figures vi
Boxes vii
Executive Summary viii
1.0 INTRODUCTION, SCOPE OF WORK, AND POLICY BACKGROUND 1
1.1 Introduction 1
1.2 Scope of Work 2
1.3 Policy Background 3
2.0 BACKGROUND: CLIMATE CHANGE, VEGETATION, AND CARBON BUDGETS 5
2.1 Climate Change 5
2.2 Potential Consequences of Climate Change to Vegetation 5
2.3 Terrestrial Carbon Budgets 7
2.4 Forest Management and Carbon Sequestration 10
3.0 CAMP SHELBY: AN EXPLORATORY STUDY OF ATMOSPHERIC CARBON
SEQUESTRATION BY FORESTS . 15
3.1 Camp Shelby Forests -.15
3.2 Methods Used to Evaluate the Carbon Dynamics of Camp Shelby 17
Carbon Pools 17
Carbon Flux 19
Forest Management Scenarios 19
3.3 Results 21
Scenario 1 - No-Action Management 21
Scenario 2 - Tree Harvesting 25
Scenario 3 - Biofuel 27
Scenario 4 - Deforestation 29
Scenario 5 - Restoration 30
On-Site Carbon Benefit 32
Off-Site Carbon Benefit 34
3.4 Discussion of Simulation Results 35
Carbon Pools 35
Carbon Flux 35
Management Considerations 36
Offsetting C02 Emissions 37
4.0 DOD FOREST MANAGEMENT AND CARBON SEQUESTRATION 39
4.1 Management 39
4.2 Carbon 41
5.0 SUMMARY AND CONCLUSIONS 43
LITERATURE CITED 45
iii
-------
Acknowledgments
The authors gratefully acknowledge all those whose contributions led to the completion of this
document. Thanks is extended to the following:
Technical Advisors
A. Anderson, US Army Corps of Engineers
C. Bagley, US Army Corps of Engineers
B. Culpepper, ManTech Environmental Research Services Corp.
T. Craven, US Army Corps of Engineers
T. Droessler, ManTech Environmental Research Services Corp.
P. Miller, ManTech Environmental Research Services Corp.
W. Sprouse, US Army Corps of Engineers
D. Turner, ManTech Environmental Research Services Corp.
J. White, USFS National Forests in Mississippi (retired)
Document Production
R Miller, ManTech Environmental Research Services Corp.
M. Schuft, ManTech Environmental Research Services Corp.
Reviewers
Internal
T. Droessler, ManTech Environmental Research Services Corp.
D. Turner, ManTech Environmental Research Services Corp.
K. West, ManTech Environmental Research Services Corp.
External
C. Bagley, US Army Corps of Engineers
D. Price, US Army Corps of Engineers
D. Wergowske, USFS National Forests in Alabama
J. White, USFS National Forests in Mississippi (retired)
S. Winnett, US Environmental Protection Agency
IV
-------
Tables
Table 1. Past and predicted future rates of temperature change 6
Table 2. Forest age-class distribution by land area for Camp Shelby forests 17
Table 3. Percent of total carbon within the various carbon pools by forest type for 1990 under
the no-action scenario 23
Table 4. Percent of total carbon within the various carbon pools per forest type for the year
2040 under the no-action scenario 24
Table 5. Carbon benefits of Camp Shelby forests during 10-year (2000-2009) and 50-year
(1990-2039) periods as affected by five hypothetical management scenarios 34
v
-------
Figures
Figure 1. Military installations within the United States with more than 4,032 ha of forestland. 2
Figure 2. Concentrations of atmospheric C02 measured at Mauna Loa, Hawaii, and Niwot
Ridge, Colorado 6
Figure 3. The global carbon cycle 8
Figure 4. Carbon sequestration in various ecoregions of the world 10
Figure 5. The location of Camp Shelby 16
Figure 6. Examples of stand-level carbon budgets for the coniferous, deciduous, and mixed
forests of Camp Shelby 18
Figure 7. Projections of carbon pools for Camp Shelby forests under the no-action scenario. .. 22
Figure 8. The modeled partitioning of carbon among the various pools of the forests of Camp
Shelby in 1990 under the no-action scenario 22
Figure 9. The modeled partitioning of carbon among the various pools for Camp Shelby forests
in the year 2040 under the no-action scenario 23
Figure 10. The modeled average annual carbon net flux projections by decadal intervals for the
forest of Camp Shelby assuming no-action management 24
Figure 11. Projections of carbon pools for Camp Shelby forests under the harvesting scenario. 25
Figure 12. The modeled average annual carbon flux projections by decadal intervals for the
forests of Camp Shelby under the harvesting scenario 26
Figure 13. The modeled projections of carbon pools for Camp Shelby forests under the biofuel
scenario 27
Figure 14. The modeled average annual carbon flux projections by decadal intervals for the
forests of Camp Shelby under the biofuel scenario 28
Figure 15. The modeled carbon pool projections for the forests of Camp Shelby under the
deforestation scenario 28
Figure 16. The modeled average annual carbon flux projections by decadal intervals for the
forests of Camp Shelby assuming the deforestation scenario 30
Figure 17. The modeled carbon pool projections for the forests of Camp Shelby assuming the
reforestation scenario 31
Figure 18. The modeled average annual carbon flux projections by decadal intervals for the
forests of Camp Shelby under the reforestation scenario 31
Figure 19. A comparison of (A) total carbon, (B) net carbon gain, and (C) carbon sequestration
rate of Camp Shelby forests as influenced by five hypothetical management scenarios 33
vi
-------
Boxes
Box 1. What Is a Forest-Sector Carbon Budget (from Turner et al. 1993)? 9
Box 2. Global View of Carbon Conservation/Sequestration (from Turner et al. 1993) 11
Box 3. The Biosphere Reserve Management Concept (from Dixon et al. 1991) 40
vii
-------
Executive Summary
Scientific assessments carried out by the Intergovernmental Panel on Climate Change show that
carbon dioxide (C02) and other radiatively important trace gases (RITGs) such as methane (CH4)
are increasing in the atmosphere and may result in a rapidly changing climate with increased
temperatures and altered precipitation patterns (EPCC 1990, 1992). A rapidly changing climate
could adversely impact forest vegetation composition, structure, and productivity resulting in
widespread forest dieback and the redistribution of forest vegetation to regions with favorable
climates. One policy option for offsetting the increase of atmospheric C02 and mitigating a
rapidly changing climate is carbon sequestration and conservation by forest vegetation and soil
(Schwengels et al. 1990, National Academy of Science 1991, Dixon et al. 1994). Forests located
on U.S. Department of Defense (DOD) training installations throughout the United States offer
promising opportunities to sequester and conserve atmospheric carbon because many lands could
be reforested, other lands could receive management practices that would improve tree growth,
while additional lands support mature forests that are vast carbon reservoirs (American Forestry
Association 1992).
The DOD manages approximately 12.3 Mha of land throughout the United States (American
Forestry Association 1992). Of this, an estimated 2.4 Mha are forest that are used mainly for
carrying out realistic training missions for troop preparedness. In many instances, the stress from
tactical vehicles and combat training have degraded the usefulness of forests for military
purposes. Consequently, the DOD has established programs targeted to improve or maintain the
environment on lands under its jurisdiction. The Strategic Environmental Research and
Development Program (SERDP) is one program charged to address concerns that include global
environmental change and ecological restoration through research and technology development
to improve the environmental quality of military installations. This research was conducted
under the auspices of SERDP.
The primary purpose of this report is to explore the influence of management practices such as
tree harvesting, deforestation, and reforestation on carbon sequestration potential by DOD forests
by performing a detailed analysis of a specific installation. Camp Shelby, Mississippi was
selected for analysis because (1) it is a large installation within a prime forestry area, (2) it has
been degraded by military training, and (3) its forests are managed by the U.S. Forest Service
(FS) so forest-stand data are available for analysis. The specific research goals were (1) to
quantify forest carbon pools and flux at Camp Shelby from 1990 through 2040, (2) to evaluate
carbon sequestration as influenced by hypothetical management scenarios, and (3) to account for
on-site and off-site carbon benefits.
Carbon pool estimates were based on Camp Shelby's forest-stand area, age class, and stocking
level. A stand-level carbon budget was developed for each of the three major forest types based
on growth and yield tables from the Aggregate Timberland Assessment System (ATLAS), a
-------
12000
11000
10000
8000
7000 ¦¦
1_
>.
o
•
a>
0
X
3
LL
C
1
(0
O
6000
1990
80 ¦¦
60
40
20 ¦¦
0
-20 ¦¦
-40
(B)
—i—
2000
1990-1999
—I
2030
2000-2009 2010-2019
Years
2020-2029
—I
2039
2010
2030-2039
150 T
^ 100--
L
>»
E
o
•
3
c
o
2
V>
®
3
CT
(8
50 -¦
¦50 ¦¦
-100 ¦¦
-1 50
(C)
1990-1999
2010-2019
Years
2000-2009
2020-2029
2030-2039
-A-— No Mgt.
-X Deforestation
Harvesting
Reforestation
Biofuel
Figure 1. A comparison of (A) total oarfoon, (B) net carbon gain, and (C) carbon se-
questration rate of Camp Shelby forests as influenced by five hypothetical manage-
ment scenarios. Positive and negative values are respectively net carbon gain or loss.
ix
-------
timber inventory model developed by the FS (Mills and Kincaid 1992). Each carbon budget
specified the density of carbon (kg-C nv2) within each carbon pool (live tree, soil, forest floor,
understory, vegetation, woody debris) for each age class (Turner et al. 1993). Carbon pools were
then calculated by taking the product of the land area of the inventory and the carbon densities
from the stand-level carbon budgets.
Flux is the transfer of carbon among the forest pools and the atmosphere in either direction, and
carbon loss due to harvesting. Net flux is the average annual change in the total carbon pool
since the previous decade, and was calculated by dividing the difference of the ending and
beginning carbon pools by 10 years.
Five different hypothetical management scenarios were simulated to assess their consequences
on forest carbon pools and flux from 1990 through 2040. Scenario 1 (no-action) was an
assessment of carbon dynamics for the year 1990 and then projected to the year 2040 with no
forest management action such as harvesting or reforestation. This scenario was the benchmark
for comparison with the others. Scenario 2 (harvesting) assumed that commercial tree harvesting
occurred at a rate defined as normal management by the FS, Black Creek Ranger District which
includes Camp Shelby (Department of the Army 1991). Scenario 3 (biofuel) assumed that trees
were harvested to support a biofuel program for Camp Shelby as proposed for many DOD
installations by the American Forestry Association (1992). Scenario 4 (deforestation) assumed
that deforestation of 8,593 ha was necessary to develop new training areas and maintenance
facilities during the 1990s (Department of the Army 1991). Scenario 5 (reforestation) assumed
that 4,050 ha of previously harvested land were reforested during the 1990s (Department of the
Army 1991)
Management action profoundly affected the carbon pools and sequestration potential of Camp
Shelby's forests as simulated during the 50-year period (Figure 1). Tree harvesting decreased
carbon pools and sequestration potential, and reforestation increased carbon pools and
sequestration potential. Tree harvesting at the rate defined as normal management (scenario 2),
resulted in a smaller total carbon pool in 2040 and a 25% loss in the rate of carbon sequestration
compared with scenario 1. Deforestation of 8,593 ha resulted in a reduction of total carbon and a
96% loss in on-site carbon sequestration potential. The reforestation of 4,050 ha of land
significantly increased carbon storage and resulted in a 29% increase in the rate of on-site carbon
sequestration during the 50 years. Thus, management practices that promote reforestation and
discourage deforestation will provide the maximum carbon sequestration and conservation.
Potential ancillary benefits include enhanced wildlife habitat, increased biodiversity, decreased
soil erosion, and improved water quality.
Under the harvesting, biofuel, and deforestation scenarios, harvested wood was assumed to be
transferred off-site for production of lumber or fuelwood. Long-term wood products and
fuelwood can provide a benefit in offsetting the built-up of atmospheric carbon (Table 1). The
lumber that is used in construction projects provides long-term carbon storage. Even when
lumber is discarded into landfills it will retain its carbon for many more years. Harvesting trees
to support a biofuel program also provides a carbon benefit in that fossil fuel is displaced with
x
-------
Table 1. Carbon benefits of Camp Shelby forests during 10-year (2000-2009) and
50-year (1990-2040) periods as affected by five hypothetical management scenarios.
Management Net On-site Carbon On-site Carbon Off-site Carbon Combined Carbon
Scenario Sequestration Benefit3 Benefit315 Benefit3
(Gg-C yr1)
10-year 50-year 10-year 50-year 10-year 50-year 10-year 50-year
No-action
52
39
0
0
0
0
0
0
Harvesting
42
31
-10
-8
2.6
2.6
-7.4
-5.4
Biofuel
40
30
-12
-9
10.1
10.1
-1.9
+1.1
Deforestation
41
10
-11
-29
12.2
4.9
+1.2
-24.1
Reforestation
64
51
+12
+12
0
0
+12.0
+12.0
a
Compared with the no-action scenario.
Assumes a 0.4 and 0.9 conversion efficiency to long-term wood products/landfill and biofuel energy
production, respectively, for C transferred off-site.
modern, fuelwood technology. The ideal situation is where carbon emissions from energy
production approximates carbon sequestration by the trees that will eventually become fuelwood.
Consequently, an equilibrium in carbon flux between energy production and tree sequestration is
eventually established.
Under the Climate Change Action Plan the United States is committed to reduce RITG emissions to
their 1990 levels by the year 2000 (Clinton and Gore 1994). If Mississippi were to adopt the Action
Plan as a state goal, then 3,640 Gg-C yr"1 of emission reductions or offsets would be required.
Reforestation of Camp Shelby (scenario 5) could provide 0.3% of the necessary offsets during the
2000-2009 decade.
xi
-------
Xll
-------
1.0 INTRODUCTION, SCOPE OF WORK, AND POLICY BACKGROUND
1.1 Introduction
Scientific assessments carried out by the
Intergovernmental Panel on Climate Change
(IPCC) show that carbon dioxide (C02) and
other radiatively important trace gases (RITGs)
such as methane (CH4) and nitrous oxide (N20)
are increasing in the atmosphere and may
result in a rapidly changing climate with
increased temperatures and altered precipita-
tion patterns (IPCC 1990,1992). A rapidly
changing climate could adversely impact forest
vegetation composition, structure, and produc-
tivity resulting in widespread plant dieback and
the redistribution of forest vegetation to re-
gions with favorable climates. One policy
option for offsetting the increase of atmo-
spheric C02 is carbon sequestration and con-
servation by forest vegetation and soil
(Schwengals et al. 1990, National Academy of
Science 1991, Dixon et al. 1994). Forests
located on U.S. Department of Defense (DOD)
training installations throughout the United
States offer promising opportunities to seques-
ter and conserve atmospheric carbon because
many lands could be reforested, other lands
could receive management practices that
would improve tree growth, while additional
lands support mature forests that are vast
carbon reservoirs (American Forestry Associa-
tion 1992).
The U.S. Environmental Protection Agency
(EPA) has been evaluating potential changes in
climate that may result from increasing atmo-
spheric RITGs and addressing mitigating
options that could reduce the threat of elevated
RITG concentrations (e.g., Smith and Tiipak
1989, Lashof and Tirpak 1990, Dixon et al.
1991, Turner etal. 1993). These reports
recommend management practices to im-
prove the potential for natural forests, tree
plantations, and urban trees to sequester and
conserve atmospheric carbon. Such action
could include increasing the growth of forest
stands through practices such as tree thinning,
the reforestation of marginal croplands, and
encouraging urban tree plantings throughout
the United States (Sampson 1993). A recent
publication jointly sponsored by the EPA,
DOD and the American Forestry Association
(AFA) assessed management options to
improve carbon sequestration and conserva-
tion on military installations through im-
proved management of existing forests,
reforestation of degraded lands, and land-
scaping cantonment areas with trees (Ameri-
can Forestry Association 1992). The research
reported herein evaluated the influence of
management practices on carbon dynamics at
a specific facility. The research is of value to
installation commanders and land managers
as they plan the management of DOD forests
in conjunction with military training.
The DOD manages approximately 12.3 Mha
of land throughout the United States (Ameri-
can Forestry Association 1992). Of this, an
estimated 2.4 Mha is forest that is used
mainly for carrying out realistic training
missions for troop preparedness (Figure 1).
In many instances, the stress from tactical
vehicles and combat training have degraded
the usefulness of forests for military pur-
poses. In addition, military training has
caused the destruction of vegetation cover
and soil erosion. Consequently, DOD has
established programs targeted to improve or
l
-------
A > 20,161 ha
o 4,032 - 20,161 ha
Figure 1. Military installations within the United States with more than 4,032 ha of
forestland. Data are from the American Forestry Association (1992).
maintain the environment on lands under its
jurisdiction. The Strategic Environmental
Research and Development Program (SERDP)
is one program charged to address concerns
that include global environmental change and
ecological restoration through research and
technology development to improve the envi-
ronmental quality of military installations.
This research was conducted under the aus-
pices of SERDP.
1.2 Scope of Work
The primary purpose of this report is to explore
an approach at a specific military installation
for evaluating the influence of forest manage-
ment on the carbon sequestration potential of
DOD forests. Section 2 provides background
information on climate change, vegetation, and
carbon cycles. Section 3 is the detailed analy-
sis of five hypothetical forest-management
scenarios including no-action, tree harvesting,
biofuel, deforestation, and reforestation. Camp
Shelby, a tactical-vehicle training installation
in Mississippi, was selected for the exploratory
study because (1) it is a large installation in a
prime forestry area, (2) it has been physically
degraded by training activities, and (3) its
forests are managed by the U. S. Forest Service
(FS) so that stand inventory data are available.
The approach used to quantify carbon dynam-
ics was to link the forest-stand inventories with
stand-level carbon densities to calculate cur-
rent and future carbon pools and fluxes (Turner
et al. 1993). The specific research goals were
(1) to quantify forest carbon pools and flux at
Camp Shelby from 1990 through 2040, (2) to
evaluate carbon sequestration as influenced by
various hypothetical management scenarios,
2
-------
and (3) to account for on-site and off-site
carbon benefits. Section 4 presents manage-
ment practices that may improve the potential
for carbon sequestration and storage by DOD
forests throughout the United States. Conclu-
sions of the research are presented in
Section 5.
U Policy Background
The Climate Change Action Plan (CCAP)
commits the United States to reducing RITGs
to their 1990 levels by the year 2000 (Clinton
and Gore 1994). This means implementing a
combination of reduced emissions and in-
creased carbon sinks amounting to approxi-
mately 1% of the 1990 rate, or 106 Tg-C
equivalent for all gases combined. Carbon
emissions for the years 1990 (in the absence of
a RITG-reduction policy) and 2000 in the
United States are estimated to be 1,462 and
1,568 Tg-C, respectively. Managing DOD
forests to optimize carbon sequestration can
contribute to achieving the 1% reduction.
3
-------
4
-------
2.0 BACKGROUND: CLIMATE CHANGE, VEGETATION, AND CARBON
BUDGETS
2.1 Climate Change
Rising levels of atmospheric C02 (Figure 2)
and other RITGs (e.g., CH4, N20) from anthro-
pogenic activity (e.g., fossil-fuel combustion,
deforestation, industrial emissions) are likely
to induce changes in the earth's climate over
the coming decades (IPCC 1990,1992). Even
though considerable uncertainty remains about
the rate and magnitude of the possible climate
change, there is an emerging consensus that
policies relevant to stabilizing or reducing the
level of atmospheric C02 and other RITGs
should be explored (National Academy of
Science 1991, Rubin et al. 1992). One option
that shows considerable promise is to increase
the potential for forest vegetation and soil to
sequester atmospheric carbon and conserve it
for long periods of time (Houghton et al.
1993, Wisniewski et al. 1993, Dixon et al.
1994).
The relationship between increased concentra-
tion of RITGs in the atmosphere and observ-
able changes in climate and potential ecologi-
cal effects have been the subject of numerous
investigations and much debate. Global
circulation models cannot accurately predict
the magnitude and timing of changes in cli-
mate on regional scales, but a widely viewed
estimate is that average surface atmosphere
temperatures will increase by 1.5-4.5°C within
the next few decades (Schneider et al. 1992,
Shugart 1993). Temperature changes of this
magnitude have occurred in past geological
times, such as in the current interglacial period
after the last ice age (Table 1). However, a
change in climate of this magnitude and
occurring in a few decades rather than over
millennia may have dramatic effects on forests
and agricultural productivity, sea levels, water
resources, and human health (National Acad-
emy of Science 1991, Peters and Lovejoy
1992).
2.2 Potential Consequences of Climate
Change to Vegetation
The consequences of a rapidly changing
climate will have both direct and indirect
effects on forest systems (Smith 1992, Smith et
al. 1992, King 1993, Smith and Shugart 1993).
The main effect could be the redistribution of
vegetation (Webb 1992, Grabherr et al. 1994).
The reconstruction of past wanning and cool-
ing periods from the paleoecological record
demonstrates that vegetation distributions
varied significantly from those of today. For
example, vegetation in the northern hemi-
sphere has migrated northward or southward in
response to warming or cooling periods,
respectively. During the ice age that ended
10,000 years ago, Arctic tundra extended into
the Great Lakes region and northern spruce
trees grew as far south as Georgia and Texas.
During the most recent wanning period ap-
proximately 6,000 to 9,000 years ago when the
atmosphere was 1.5°C warmer than at present,
many North American plant associations
shifted approximately 300 km northward.
In addition to the paleoecological record, plant
distribution models have been used to predict
the breakup and reassortment of future vegeta-
tion associations. Davis and Zabinski (1992)
project that a global warming of approximately
3°C would cause the demise of sugar maple,
beech, yellow birch, and hemlock from the
5
-------
360 -r
350 --
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990
YEAR
Mauna Loa Niwot Ridge
Figure 2. Concentrations of atmospheric C02 measured at Mauna Loa, Hawaii and
Niwot Ridge, Colorado. Data are from Boden et al. (1991).
Table 1. Past and predicted future rates of temperature change. Data are from
Hinkley and Tierney (1992).
Time Period
Warming Rate
(°C) (°C/century)
15,000 BP (Last Glacial) to 11,500 BP Allerod) 10
10,500 BP (Younger Dryas) to 7,000 BP (Climatic 7
Optimum)
5000 BP to 2,500 BP 4
Last 10,000 years 5
Last 100 years 0.5
Next 100 years 2.5
Next 100 years (High Latitudes) 5
0.3
0.2
0.2
0.05
0.5
2.5
5
6
-------
southern parts of their ranges in the eastern
United States. A subsequent northern shift of
several hundred kilometers in the species
distribution of these ranges would then occur.
The explanation for changes in vegetation
distribution during warming and cooling
periods is that plant processes such as photo-
synthesis, respiration, flower and seed set, seed
germination and seedling establishment occur
optimally within specific temperature and soil-
water ranges (Barker et al. 1991, Woodward
1992). Species respond individually to tem-
perature and soil water conditions. Above or
below the optimum, plant growth, develop-
ment, and reproduction will suffer depending
on the magnitude of departure from the norm.
An increase in the growing season will allow
plants greater time to complete life cycles with
increased biomass production. However, drier
soil conditions in some regions may offset the
longer, warmer, growing season by reducing
seed production and seedling establishment.
Furthermore, increases in temperature over
long periods may be detrimental to cool-season
species because they require cold temperatures
for flowering, seed set, or seed germination to
occur. Therefore, cool-season plants may
migrate northward or to a higher elevation to
be associated with favorable temperatures
conducive with phenological requirements
(Peters and Darling 1985, Grabherr et al.
1994).
The ability for plant species to migrate to new
areas with suitable climatic zones will depend
mainly on propagule dispersal mechanisms and
the presence of physical barriers. According
to Davis and Zabinski (1992), the average
migration rate for North American tree species
is about 20 to 40 km per century. This rate of
migration is much too slow to track a rapidly
changing climate. In addition, barriers such as
roads, cities and agricultural fields will present
obstacles to vegetation migration (Myers
1992).
The indirect effects of a rapidly changing
climate on forest vegetation will probably
include increased insect and other pathogen
outbreaks, and increased fire frequency and
intensity (Franklin et al. 1991, Smith 1992).
Insect and pathogen outbreaks may increase
because they are usually associated with
extreme weather patterns and forest dieback.
Both causal agents will be common with a
rapidly changing climate. In addition, foliage
consumption by insects may increase with
conditions of warm temperatures and elevated
C02 (Oechel and Strain 1985, Bazzaz 1990).
Forest fire intensity and frequency may also
increase with warmer and drier conditions and
extensive tree dieback in many areas (Franklin
et al. 1991).
23 Terrestrial Carbon Budgets
The movement of carbon between the atmo-
sphere and biosphere is known as the global
carbon cycle (Figure 3). The biosphere can be
further subdivided to include oceans, vegeta-
tion, and soil. The general nature of the global
carbon cycle is well documented. However,
relatively large uncertainties exist in the
magnitude of the various carbon pools and the
transfer of carbon among them (Post et al.
1990, Dixon and Turner 1991, Simpson and
Botkin 1992, Smith et al. 1993). The oceans
store the largest amount of caibon at 38,500
Pg-C (Pg=1015 g). Fossil fuels are the second
largest carbon pool at 5,000-10,000 Pg-C. The
next largest reservoir is soil, estimated at
1,170-1,740 Pg-C. The vegetation and atmo-
spheric pools are the smallest and are esti-
mated at 560-830 and 740 Pg-C, respectively.
The annual transfer or flux of atmospheric
7
-------
TERRESTRIAL ECOSYSTEMS
Photosynthesis
110 Pg
Vegetation
560-830 Pg
; ^ ^ ^Soil, Litter, & Peal
1170-1740 Pg
ATMOSPHERE
740 Pg
OCEANS
Respiration &
Decompostion
109 Pg
Fossil
fuels
93 Pg
2 Pg Biol°9'cal
t Chemical
Processes
Deforestation
90 Pg
Fossil Fuels
\ vS \S vS vS \S \N \N \S A\N\' ...
\\\Nv\\\A\\\\s\\S\Ss\ W\>
\\v\ \\\\\\A\N\Nv\\\AV " "
s \ V .v\\\s\\\s\s\\S n\\\n\\V
' • \ \N W \N \N
i 3 Pg:
. A\S\S .
. \S \V . .
. .S \\ \\ v\ s\
38,500 Pg;
Figure 3. The global carbon cycle.
carbon with the biosphere is about 30%. The
flux between the terrestrial biosphere (i.e.,
vegetation and soil) and atmosphere is about
equal to that between the oceans and the
atmosphere.
Our understanding of the global carbon cycle
suggests that managing terrestrial ecosystems,
especially forests, to sequester and conserve
carbon may contribute to moderating the rise
in atmospheric C02 (Sampson and Hair 1992,
Wisniewski et al. 1993, Houghton et al. 1993,
Dixon et al. 1994). However, better knowl-
edge of forest carbon pools and transfer rates is
needed (Box 1). Such information will be
crucial in formulating national and interna-
tional policy to reducing the risks of altering
the composition of the atmosphere (National
Academy of Science 1991).
Forest dieback and the redistribution of vegeta-
tion to new areas will likely release large
amounts of stored carbon into the atmosphere,
resulting in a significant positive feedback to
climate change (Neilson 1993, Smith and
Shugart 1993). Forest vegetation is critical in
the carbon cycle because of the processes of
photosynthesis, respiration, and decomposition
(Woodwell 1992). The rate of photosynthesis
is sensitive to many environmental factors such
as C02 concentration, light intensity, soil
water, and soil nutrients. However, photosyn-
thesis is not very sensitive to ambient tempera-
ture. On the other hand, the rate of plant
respiration and decomposition of organic
matter is sensitive to temperature. Tempera-
ture changes of a few degrees can increase the
rate of respiration by 10-30% while photosyn-
thesis remains approximately constant. There-
fore, plant respiration and organic matter
decomposition could greatly increase with
8
-------
Box 1. What Is a Forest-Sector Carbon Budget (from Turner et al. 1993)?
A carbon budget is a bookkeeping system for tracking the amount of carbon in various
reservoirs ("pools"), and the amount of carbon transferred among the reservoirs and
between the reservoirs and the atmosphere ("flux"). Important carbon pools within forests
are trees, other vegetation, soil, the forest floor, and woody debris. "Net flux" is the differ-
ence between total uptake into a pool and total output from the pool, and is equal to
the change in the pool size during some time interval. Post-harvest use of wood products
and landfills are also substantial carbon pools.
The main uptake of carbon into forests is through photosynthesis, the fixation of at-
mospheric CO by green plants ("primary producers"). Carbon loss from forests is mainly
through respiralion by green pjants and other organisms, through burning, and through
harvest of wood by humans. The first two processes result in the direct release of carbon
to the atmosphere. The difference between photosynthesis and respiration by green
plants is Net Primary Production (NPP). The difference between photosynthesis and
respiration by all organisms, including decomposers is the total change in the carbon
content of forests due to biological processes (i.e., Net Ecosystem Production, NEP). Thus,
NEP is also the net flux of carbon from the atmosphere to the forest from biological
processes. The "net accumulation" by forests is NEP minus carbon removed by harvest.
The NPP, NEP, and the flux among the carbon pools within the forest, are determined by
stand characteristics such as tree species, age class, and site productivity. Regional and
national estimates are obtained by combining forest stand NEP estimates with forest
inventory data. In contrast, the harvest and reforestation rates are determined by exter-
nal economic and policy factors.
Unlike the forests, there are no systematic inventories of the product and landfill pools or
of the net annual transfer into or out of these pools. The national net change in the pool
of forest products in landfills can be estimated as the difference between the amount of
forest products transported to landfills and the carbon emissions to the atmosphere from
landfills due to forest products.
Photosynthesis
Burning
Burning
Respiration, Burning
Harvest
Products
Biofuel
Planting
Landfills
C02
C02
Internal
Forest
Dynamics
9
-------
r
Swamp and marsh
Agricultural
Extreme desert
Desert shrub [
Tundra and alpine
Temperate grassland
Tropical savannah
Woodland & shrubland
Boreal forest
Temperate forest
Tropical forest
~ Carbon in soil
I Carbon in vegetation
100 200 300 400 500
Sequestered Carbon (Pg)
600
700
Figure 4. Carbon sequestration in various ecoregions of the world. Data are from
Waring and Schlesinger (1985).
global warming and release large amounts of
C02 and methane into the atmosphere, adding
to the problem of anthropogenic emissions.
In contrast, the direct effect of elevated C02 on
plants might reduce the rate at which C02
accumulates in the atmosphere. In controlled
environments with elevated C02, many plants
tend to have increased photosynthesis, de-
creased respiration, and increased water-use
efficiency. However, it is not clear that in-
creased plant growth rates could be sustained
by natural vegetation because of soil, water,
and nutrient limitations (Luxmoore et al.
1993).
2.4 Forest Management and Carbon
Sequestration
Forests are extremely important in the global
carbon cycle because they cover approximately
29% of the total land area of the world (World
Resource Institute 1990) and store far more
carbon than any other terrestrial ecosystem
(Figure 4). Furthermore, forests account for a
vast amount of the annual carbon flux between
the atmosphere and terrestrial sphere (e.g.,
Apps and Kurz 1991, Kauppi et al. 1992,
Turner et al. 1993). Obviously, forest manage-
ment practices can be extremely important in
influencing the carbon dynamics of the terres-
trial biosphere (Smith et al. 1993, Winjum et
al. 1993). However, according to the World
Resources Institute (1990) only about 10% of
forests throughout the world are managed to
increase tree growth and productivity.
10
-------
Box 2. Global View of Carbon Conservation/Sequestration (from Turner et al. 1993)
In 1991, a global assessment was undertaken of the potential of forest management
practices to store atmospheric carbon (Dixon et al. 1991; Winjum et al. 1993; Dixon et al.
1993: Schroeder et al. 1993). The assessment was based on information on the rates of
carbon storage per hectare for many practices, their implementation costs, and esti-
mates of the amounts of land suitable for forest management. Information was com-
piled through a survey of current published technical literature for forested nations
representing boreal, temperate, and tropical regions of the world. Key findings of the
assessment are highlighted in the following paragraphs. Because of the geographic
scope of the 1991 assessment, it was necessary to use generalized representations of
ecoregions and data. Thus, the results are broadly applicable for comparing ecoregions
and countries. However, they lack the spatially detailed basis needed for within-country
analyses. Also, the data for the 1991 assessment did not consider change over time so
that it was not possible to estimate carbon flux.
Carbon Storage
The assessment indicated that the most promising forest management practices to
sequester carbon in the terrestrial biosphere include reforestation in the temperate and
tropical latitudes, afforestation in the temperate regions, and agroforestry and natural
reforestation in the tropics. Least promising from a carbon storage standpoint were the
application of silvicultural practices, such as thinning, fertilization and other stand im-
provement treatments, at all latitudes.
The potential carbon storage ranges of forestation and silvicultural practices by major
latitudinal biomes were as follows;
Forestation Silviculture
t-C/ha
Boreal
15-40 3-10
Temperate
30-180 10-45
Tropical
30-130 14-70
Costs of Storing Carbon
The median cost efficiency for all management practices in terms of establishment costs
was about $5/t-C, with an interquartile range (middle 50% of observations) of $1 to $19/
t-C. The most cost-efficient forestry and agroforestry practices, based on establishment
costs, within zones of latitude are shown in the following table.
Total cost per ton of carbon sequestered, which includes land rental, would be consider-
ably higher. The magnitude of the total cost is difficult to estimate because of economic
uncertainties regarding factors such as land rental.
11
-------
Recent research shows that improved manage-
ment of temperate forests could sequester
considerable amounts of carbon and offset the
buildup of atmospheric C02 (Box 2). Temper-
ate forests currently cover approximately 600
Mha, about 50% of their potential range.
Deforestation during the last two centuries for
crop production, pastures and urbanization
resulted in these forests being a carbon source.
However, with a greatly reduced rate of defor-
estation and the establishment of new forest
stands through plant succession, reforestation,
and afforestation, temperate forests are cur-
rently a carbon sink (Heath et al. 1993, Turner
et al. 1993). Presently, the greatest threat to
temperate forests is not deforestation but
degradation resulting from poor management
practices, soil erosion, air pollution, fire,
insects and other pathogens, and wind fall.
Improved management must be practiced to
minimize these disturbances.
Management practices that could potentially
improve carbon sequestration in temperate
forests are (Heath et al. 1993, Kauppi and
Tomppo 1993):
• reducing the rate of forest degradation and
deforestation,
• increasing the rate of reforestation and
afforestation,
• implementing practices that stimulate carbon
sequestration by forest vegetation and soil,
and
• improving the management of post-harvest
wood products.
Forest carbon sinks can be greatly expanded by
planting additional areas such as marginal
cropland with trees and by increasing the
growth of existing forest stands (Sampson
1993, Wisniewski et al. 1993). However,
trade-offs may exist between high rates of
carbon sequestration and large amounts of
carbon in wood storage (Heath et al. 1993).
Young trees have fast growth rates, but store
little carbon. On the other hand, mature forest
stands have reduced growth rates, but store
large amounts of carbon in woody vegetation
and soil. Forest stands must be managed
through tree harvesting and reforestation to
maximize both carbon sequestration and
storage for optimal carbon benefit.
According to Heath and Birdsey (1993) the
amount of land in the United States suitable for
reforestation is difficult to estimate because of
numerous socioeconomic and ecological
aspects that need addressing. The potential
land base for reforestation in the United States
is estimated to be 100 Mha. To encourage
reforestation, programs similar to the Conser-
vation Reserve Program or Forests for the
Future need to be established (Cubbage 1992,
Sampson 1993). These programs provide a
carbon sequestration benefit, while also ad-
dressing other environmental concerns such as
soil erosion and wildlife habitat. The Conser-
vation Reserve Program provided an economic
incentive for farmers to establish forest trees
on large tracts of environmentally sensitive
land and maintain the trees for 10 years. The
Conservation Reserve Program resulted in the
largest tree-planting effort ever achieved in the
United States. Forests for the Future is an
international program to encourage large-scale
afforestation in less developed countries to
offset carbon emissions of the industrialized
nations and improve the environment of the
cooperating countries. In addition to large-
scale efforts, small projects such as planting
trees for windbreaks, soil-erosion control,
snow guards, improved landscaping, and
biofuel plantations are all opportunities to
12
-------
increase tree numbers and carbon sequestration
(Sampson 1993).
Silvicultural practices have proven valuable for
improving tree growth on sites with adverse
environmental conditions such as limited water
or poor soil fertility. These practices can
continue to be used to improve the environ-
ment for tree growth given a rapidly changing
climate (Smith 1992). Such practices include
stand thinning, pruning, pest control, irrigation,
fertilization, understory plant control, fire
management, and harvesting practices. Pro-
viding an environment that optimizes tree
growth will stimulate carbon sequestration by
vegetation and soil and promote long-term
storage.
Proper soil management is also crucial to
increase carbon sequestration and conserva-
tion. Fertile, moist, cool soils provide an
environment conducive for carbon storage
(Johnson 1992). Consequently, fertilization,
mulching, erosion control, and maintaining
plant cover are important management tools to
encourage soil carbon sequestration and
conservation. Frequent tilling and other
similar practices that disturb the soil and
reduce vegetation cover, promote the loss of
carbon through oxidation and erosion (Cole et
al. 1993, Kern and Johnson 1993).
The improved management and extensive use
of post-harvest wood products can also pro-
mote a substantial carbon sink (Heath et al.
1993, Turner et al. 1993). Wood products such
as construction lumber and wood furniture
provide long-term carbon storage. Therefore,
the extensive use of wood products should be
encouraged and expanded in the commercial
market. The recycling of waste paper and
cardboard also provides a conservation of
carbon service. However, even with prolonged
use, building materials, paper, and cardboard
will eventually become waste products and
need to be disposed. One option is the use of
biofuels to offset the need for fossil fuels
(Sampson et al. 1993). Biofiiel technology
can greatly reduce C02 emissions in compari-
son with fossil fuels (Wright and Hughes 1993,
Sampson 1993). An additional benefit is that
wood products can still serve as a carbon sink
if disposed of in such a manner to minimize
C02 and methane emissions (Heath et al.
1993).
13
-------
14
-------
3.0 CAMP SHELBY: AN EXPLORATORY STUDY OF ATMOSPHERIC
CARBON SEQUESTRATION BY FORESTS
Approximately 20% of DOD land within the
United States supports forest ecosystems.
These lands could make a significant contribu-
tion in mitigating increasing atmospheric C02
levels through carbon sequestration and con-
servation (American Forestry Association
1992). Camp Shelby was selected for the
exploratory study to illustrate the influence that
management and land use can have on carbon
sequestration by DOD forests. The manage-
ment scenarios used for the carbon-sequestra-
tion simulations are hypothetical and do not
represent planned action by DOD on any
military installation.
3.1 Camp Shelby Forests
Camp Shelby is the largest National Guard
training installation (land area 56,048 ha) in
the United States and is located in southcentral
Mississippi near Hattiesburg (Figure S). Camp
Shelby was developed for military training
during World War I and is currently a tactical-
vehicle training center. The five main vegeta-
tion associations are grassland (13%), swamp
(< 0.1%), coniferous forest (70%), deciduous
forest (7%), and mixed (coniferous and decidu-
ous) forest (10%).
Climatic patterns at Camp Shelby are influ-
enced by weather systems that develop in the
Gulf of Mexico (Department of the Army
1991). High humidity, heavy precipitation,
and mild temperatures are typical. Average
annual precipitation is approximately 1,520
mm and fairly evenly distributed throughout
the year. The daily mean temperature is
18.8°C and ranges from 27.4°C in July to
9.1°C in January. Prevailing winds are from
the south.
Camp Shelby soils were formed from poorly
consolidated sandstone and sediment rock.
(Department of the Army 1991). Ultisols are
the predominant soil while Alfisols are of
secondary importance. The four major soil
associations in order of prevalence are:
• McLaurin-Heidel-Prentiss Association
OVpic Paleudult-Typic Paleudult-Glossic
Fragiudult) is located on gently sloping to
steep slopes, and consists of well drained
and moderately well-drained sands and
loams.
• Benndale-McLaurin-Heidel Association (all
Typic Paleudults) is located on gently
sloping to steep slopes, and consists of well-
drained sands and loams.
• Prentiss-Susquehanna-Falkner Association
(Glossic Fragiudult-Vertic Paleudalf-Aquic
Paleudalf) is located on sloping lands, and
consists of moderately well-drained loamy
soils.
• Poarch-Susquehanna-Saucier Association
(Plinthic Paleudult-Vertic Paleudalf-
Plinthaquic Paleudult) is located on ridge
tops and side slopes, and consists of well-
drained to moderately well-drained loamy
soils.
Most of Camp Shelby lies within the longleaf-
slash pine belt of the southern mixed forest,
although mixed pine and hardwood forests also
15
-------
Mississippi
Alabama
Georgia
Louisiana
Camp
Shelby
Area
Florida
Figure 5. The location of Camp Shelby.
occur (Department of the Army 1991).
Longleaf pine grows on the drier, upland sites
and slash pine is found on the moist sites.
Loblolly pine is found on the moderate to
moist sites. These species are generally found
in association with other species such as
shortleaf pine. Longleaf pine may occur in
almost pure stands if the area is frequently
burned. On dry sites, longleaf pine may be
associated with a sparse mixture of various oak
species. Well-drained floodplains and stream
terraces support hardwoods including southern
red oak, cherrybark oak, white oak, sweet gum,
yellow poplar, and hickory. The drainages and
bottom lands and floodplain areas that are
usually wet are dominated by sweetbay,
swamp tupelo, and red maple.
Forestry is the main nonmilitary activity that
occurs within the confines of Camp Shelby.
The FS, Black Creek Ranger District, DeSoto
National Forest (Camp Shelby resides in this
District) is managed for longleaf pine, loblolly
pine, and slash pine and hardwoods with slash
pine and longleaf pine the predominant species
(Department of the Army 1991). Most of the
forest is managed on an even-aged basis, with
rotations of 60, 50, and 40 years, respectively,
for longleaf, loblolly, and slash pine. At
rotation age, longleaf pine (dry sites) will
range from 35 to 51 cm diameter at breast
height (DBH) while slash and loblolly pine
(moist sites) will range from 30 to 40 cm DBH.
Hardwood stands (wet and wetland sites) are
managed primarily for wildlife habitat and are
seldom harvested. Prescribed burning is used
to control understory plant growth and occurs
usually on a 5-year cycle in the coniferous
forest. Site preparation (e.g., chemical, me-
chanical, fire) is used to promote development
of new tree stands in a cut area and reduce
competition for commercial species.
16
-------
Table 2. Forest age-class distribution by land area for Camp Shelby forests.8
Age Class
Forest Type
(years)
(hectares [%])
Coniferous
Deciduous
Mixed
5-10
262 (1)
< 1 (< 1)
60 (1)
10-20
4,165 (8)
337 (7)
136 (3)
20-30
3,521 (10)
195 (6)
422 (8)
30-50
14,359 (38)
1,049 (26)
1,813 (43)
50-70
16,163 (41)
2,211 (53)
2,768 (39)
70 -100
943 (20)
151 (8)
384 (6)
"Data Source: U.S. Department of Agriculture Forest Service, Black Creek Ranger
District.
3.2 Methods Used to Evaluate the
Carbon Dynamics of Camp Shelby
Carbon Pools
Carbon pool estimates were based on forest-
stand area, age class, and stocking level (Table
2). A stand-level carbon budget was developed
for each of the three major forest types of
Camp Shelby (Figure 6) based on growth and
yield tables from the Aggregate Timberland
Assessment System (ATLAS), a timber inven-
tory model developed by the FS (Mills and
Kincaid 1992). Each carbon budget specified
the density of carbon (kg-C m 2) within each
carbon pool (live tree, soil, forest floor, under-
story, woody debris) for each age class using
an approach similar to that developed by
Turner et al. (1993). Carbon pools were then
calculated by multiplying the land area of the
inventory and the carbon densities from the
stand level carbon budgets. Partitioning
among the various carbon pools was deter-
mined as follows:
Tree carbon pool. The ATLAS growth and
yield tables include only growing stock volume
for commercial trees. To account for non-
commercial species an adjustment factor of
1.01 and 1.14 for softwoods and hardwoods,
respectively, was applied (Thompson 1989).
The growing stock volume was then converted
to whole tree carbon based on the relative
proportion of hardwood and softwood volume
(Cost et al. 1990, Harmon 1993). Carbon from
sapling trees (< 12.5 cm DBH) was also
included and estimated according to the biom-
ass statistics developed by Cost et al. (1990).
The tree pool accounts for leaves, twigs, limbs,
bole, and coarse roots. A full tree stocking
level was assumed for the simulations.
Understory carbon pool. The carbon pool
size for understory vegetation was estimated
based on data presented by Birdsey (1992).
Understory vegetation usually grows rapidly
after tree harvesting or other disturbances such
as fire but then slows with subsequent tree
growth and canopy closures. Understory
vegetation growth again increases as the forest
17
-------
Coniferous Deciduous
u
Tr*a carbon
13
U
11
ID
9
6
s
e
6
4
9
2
I
0
12
11
10
D
S
7
SoU
0
4
3
foody debru
Fore*t floor
8
1
0
o 20 40 60 eo 0 20 40 60 BO
Stand A«e (Year) Stand Age (Year)
Mixed Coniferous and Deciduous
Soil
to
0
Figure 6. Stand-level carbon budgets for the coniferous, deciduous, and mixed
forests of Camp Shelby.
18
-------
stand matures and canopy gaps occur from tree
fall.
Woody debris carbon pool. A modeling
approach developed by Harmon (1993) was
used to estimate age-specific carbon pools.
The woody debris pool consists of standing
dead trees, dead coarse roots (> 2 mm diam-
eter), and dead woody material (> 2 cm diam-
eter) lying on the forest floor.
Forest floor carbon pool. Estimates of initial
forest floor carbon and the age-specific in-
creases in pool size were based on data pro-
vided by Vogt et al. (1986) and evaluated by
Plantinga and Birdsey (1993). The forest floor
component is composed of dead plant material
lying on the soil surface that cannot be classi-
fied as woody debris.
Soil Carbon Pool. The starting level for mean
soil carbon in the modelsimulations was
derived from Kern (W&j and was 7.0, 7.0,
and 7.8 kg-C m 2 to a one meter depth for the
coniferous, deciduous, and mixed forests,
respectively. Soil carbon was assumed to be
constant over the course of stand development
based on research conclusions of Johnson
(1992) for all simulations except for the defor-
estation scenario that is described later.
Carbon Flux
Flux is the transfer of carbon between the
forest and the atmosphere in either direction,
and carbon loss due to harvesting. Net flux is
the average annual change in the total carbon
pool since the previous decade, and was
calculated by dividing the difference of the
ending and beginning carbon pools by 10
years. Fire is an important management tool in
the coniferous forest (Department of the Army
1991); however, a separate estimate of fire
emissions was not attempted since all mortality
was transferred to the woody debris pool
(Turner et al. 1993).
Forest Management Scenarios
Five hypothetical forest management scenarios
were simulated to assess their consequences on
carbon pools and flux from 1990 through 2040.
Scenario 1 (no-action) assumed no active
management such as harvesting or reforesta-
tion occurred during the years 1990 to 2040.
Scenario 1 was the benchmark to which the
other scenarios were compared.
Scenario 2 (harvesting) assumed that tree
harvesting occurred within the coniferous
forest of Camp Shelby at a rate defined as
normal management by the Black Creek
Ranger District (Department of the Army
1991). Tree harvesting of merchantable logs
was restricted to the clear cutting of the oldest
age class first and occurred at the historical
average rate of approximately 14,750 thousand
board feet (MBF) per year from 1990 to 2040.
This represented a carbon loss of 6.6 Gg-C yr'
with a harvested area of 93 ha yr1. Scenario 2
assumed that only the bole was carried off-site
for the production of lumber and that all
woody debris remained on-site. A conversion
factor of 0.4 was used to calculate the carbon
benefit of the off-site, wood-products pool
created from the harvested trees (Heath and
Birdsey 1993, Turner et al. 1993). Natural tree
regeneration occurred after harvesting.
Scenario 3 (biofuel) assumed that trees were
harvested to support a biofuel program as
proposed for many DOD installations by the
American Forestry Association (1992). Tree
harvesting was restricted to the coniferous
forest; however, no harvesting other than for
19
-------
biofuel occurred. The clearcut harvest was
25,000 MBF per year and occurred on 98 ha
yr1 using the oldest age class first. This
represented an annual carbon loss from the tree
pool of 11.2 Gg-C yr1. Scenario 3 differs from
scenario 2 in that 80% of aboveground tree
biomass was collected for fuelwood production
with 20% woody debris left on site. An effi-
ciency factor of 0.9 was used to calculate the
off-site carbon benefit of generating energy
from the wood biomass instead of from fossil
fuel (Sampson et al. 1993). Scenario 3 as-
sumed natural tree regeneration after harvest-
ing.
Scenario 4 (deforestation) assumed that tree
removal from 8,593 ha (1,368, 948 MBF) was
necessary to develop new training areas and
corridors with the establishment of new main-
tenance facilities during the 1990s (Depart-
ment of Army 1991). For this simulation, the
coniferous forest was clear cut from 1900 to
1999 and 8,390 ha were seeded to grass while
203 ha were paved for roads or received some
type of permanent construction facility. No
other harvesting of trees occurred during the
simulation. These trees were commercially
harvested; therefore, only the boles were
removed off-site (61.3 Gg-C yr*1) and all slash
was burned. A conversion factor of 0.4 was
used to calculate the carbon benefit of the off-
site, wood-products pool created from the
harvested trees (Heath and Birdsey 1993,
Turner et al. 1993). The soil carbon was
maintained throughout the simulation at 80%
for forestland converted to grasslands and 50%
for forestland converted to permanent struc-
tures.
Scenario 5 evaluated the affect of reforestation
on carbon sequestration. This scenario as-
sumed that 4,050 ha of land that had been
previously clearcut for military training or had
been commercially harvested (Department of
the Army 1991) were reforested during the
1990s at the ATLAS full stocking rate and
composition consistent with a coniferous forest
within the Black Creek Ranger District. Dur-
ing the 1980s, 4,505 ha of coniferous forest
were developed for tracked vehicle maneuver-
ing. For the purposes of this scenario, 3,590 ha
were assumed to have been cleared of timber
for development and available for reforesta-
tion. In addition, from 1986 to 1990, 460 ha of
coniferous forest were commercially harvested
with the land available for reforestation.
Under this scenario, no trees were harvested
between the years 1990 to 2040.
These five scenarios are management options
that could occur at Camp Shelby, as well as
many other DOD installations. Tree harvesting
(scenario 2) and reforestation (scenario 5) are
normal management practices at Camp Shelby
(Department of the Army 1991). The biofuel
(scenario 3) program is proposed by the AFA
(1992) to reduce C02 emissions and reduce
overall energy costs on many DOD installa-
tions. This scenario differs from scenario 2 in
that the carbon of the harvested trees is re-
turned immediately to the atmosphere through
fuel combustion. This is considered to be a
carbon benefit because the carbon released
during combustion has been recently seques-
tered by the growing trees and no net carbon is
released to the atmosphere. On the other hand,
the combustion of fossil fuels releases carbon
into the atmosphere that has been stored in an
inert form for thousands of years. Proposed
improvement of training facilities would result
in tree removal on some forestland (scenario 4)
with the conversion to grassland and the
thinning of additional forest stands to allow for
the maneuvering of tactical vehicles (Depart-
ment of the Army 1991). Under this scenario,
the management plan would be to harvest and
20
-------
thin forest stands as required for the training
area development and reduce or eliminate
harvesting in other areas so as to not increase
total forest harvests. Carbon sequestration
occurs in grass swards and associated soils but
at a much lower rate in comparison with forest
trees and soils (Barker et al. 1995).
3.3 Results
Scenario 1 - No-Action Management
Forest carbon pools -1990. The total carbon
stored in the forests of Camp Shelby in 1990
was calculated to be 9,048 Gg-C (Gg=109 g,
Figure 7). The majority of carbon resided in
the coniferous forest (80%) because of its large
land area. The deciduous and mixed forests
stored 8 and 12% of the total carbon, respec-
tively. Average carbon storage per unit area for
the three forests was approximately 19 kg-C
m2.
The distribution of carbon among the forest
components varied considerably (Figure 8).
Approximately 48% of all carbon resided in
the tree pool which included living leaves,
woody material, and coarse roots. The second
largest carbon pool was the soil at 38%. Car-
bon storage within the forest floor, understory
vegetation, and woody debris pools was 5,1,
and 8%, respectively. The partitioning of
carbon among the five carbon pools was
almost identical across forest types (Table 3).
The main differences were in the tree and
woody debris pools.
Forest carbon pools - 2040. The carbon pool
for Camp Shelby forests increased steadily
from 1990 to 2040 because of the growing
trees. The total carbon pool in the year 2040
was calculated to be 10,981 Gg-C (Figure 7).
The distribution of carbon among the three
forests was the same as in 1990. Carbon
storage per unit area averaged 22 kg-C m 2.
The distribution of carbon among the various
pools was similar as in 1990 in that the tree
and soil dominated (Figure 9). However, the
proportion of carbon in the tree pool increased
to 53% while the soil pool decreased to 31 % of
total carbon. The forest floor, understory, and
woody debris pools jointly represented 16% of
total carbon.
The distribution of carbon within the various
pools varied by forest type, but was partitioned
similarly as in 1990 (Table 4). However, for
all forest types the proportion of carbon within
the tree pool increased with a proportional
decrease in soil carbon. The carbon stored
within the woody debris, forest floor, and
understory pools were essentially the same as
in 1990.
Carbon flux. During the 50-year simulation,
there was a net flux of 1933 Gg-C into the
Camp Shelby forests. Total carbon flux into
the forest was the greatest during the first
decade and then decreased somewhat linearly
through the fifth decade (Figure 10). This
pattern of carbon flux resulted from the rapid
growth of the young forest stands during the
first portion of the simulation and increased
respiration as the stands matured. Without tree
harvesting and the subsequent establishment of
seedlings, the rate of forest-stand growth
decreased along with net carbon gain as the
forest matured.
The majority of carbon during the simulation
was sequestered by the tree pool which in-
creased in size by 36% and was consistently a
carbon sink. The forest floor and woody
21
-------
12,000 j
10,000 --
0
1
CD
g. 8,000 --
§
^ 6,000 --
3 4,000 --
2,000 --
1990
2000
4-
2010 2020
Year
2030
2040
El Soil
~ Forest floor I Understory ID Woody debris ~ Living tree
Figure 7. Projections of carbon pools for Camp Shelby forests under the no-
action scenario.
Living tree
4 8%
Forest Floor
5%
Forest Soil
3 8%
Understory
Woody debris 1 %
8%
Figure 8. The modeled partitioning of carbon among the various pools of the
forests of Camp Shelby in 1990 under the no-action scenario.
22
-------
Table 3. Percent of total carbon within the various carbon pools by forest type for
1990 under the no-action scenario.
Forest Type
Carbon Pool Coniferous Deciduous Mixed
Tree
46
51
Soil
38
39
Understory
2
1
Forest floor
5
4
Woody Debris
9
5
Forest Floor
Living tree
53%
Forest Soil
31%
Understory
Woody debris 1 %
9%
Figure 9. The modeled partitioning of carbon among the various pools for Camp
Shelby forests in the year 2040 under the no-action scenario.
23
-------
Table 4. Percent of total carbon within the various carbon pools per forest type
for the year 2040 under the no-action scenario.
Forest Type
Carbon Pool
Coniferous
Deciduous
Tree
Soil
Understory
Forest floor
Woody Debris
52
31
1
6
10
58
31
1
5
5
Mixed
56
32
1
5
7
80 -r
^ 60 --
U. 30 --
O 10 --
lllllllllllll
¦¦¦¦¦¦¦¦mm
1990-1999
2000-2009
2010-2019
2020-2029
2030-2039
Decade
Forest Soil O Forest floor I Understory ID Woody debris D Living tree
Figure 10. The modeled average annual carbon net flux projections by decadal
intervals (e.g., 1990-1999 = average annual carbon flux for the years 1990
through 1999) for the forest of Camp Shelby assuming no-action management.
Positive and negative values are respectively net carbon gains or losses.
24
-------
12,000 -J
¦
10,000 ¦
-
o
6) 8,000 -
o
¦
S 6,000 •
CL
¦
1 4,000 -
CO
mum
milium
nm M
1,,
||
|
o
2,000 ¦
n
¦
¦
B
B
B
111
¦
__ J
1990
2000
2010
Year
2020
2030
2040
8
Soil ED
Forest floor
H Understory
CD Woody debris G Living tree
Figure 11. Projections of carbon pools for Camp Shelby forests under the
harvesting scenario.
debris pools were also carbon sinks and in-
creased by 39 and 30%, respectively. The
understory vegetation was a small carbon
source during the first 10 years, and thereafter
a sink with an overall decrease of approxi-
mately 2%. Competition for sunlight, soil
water, and soil nutrients between the trees and
understory vegetation resulted in the latter
being a carbon source (luring the first decade
when the former were rapidly growing. As the
forest stands matured, the tree canopy opened
with the death of some trees which, in turn,
allowed the understory vegetation to grow and
become a carbon sink.
The 50-year average net carbon sequestration
of the Camp Shelby forests was 39 Gg-C yr1.
Total carbon sequestration by the coniferous,
deciduous and mixed forests averaged 31,3,
and 5 Gg-C yr1, resipectively. The rate of
carbon sequestration per unit area averaged 79,
87, and 89 g-C m2 yr1 for the coniferous,
deciduous, and mixed forests, respectively.
Scenario 2 - Tree Harvesting
Forest carbon pools - 2040. The total carbon
pool for Camp Shelby forests with tree har-
vesting was 10,617 Gg-C in 2040 (Figure 11).
The partitioning of carbon among the three
forest types and among the five carbon pools
by forest type was essentially the same as in
scenario 1. Apparently, the rate of tree harvest-
ing was not sufficient to adversely affect the
partitioning of carbon among the various
pools. Carbon storage per unit area averaged
21.6kg-Cm'2.
25
-------
80 T
70 ¦¦
60 --
50 --
40 --
30 -¦
20 ¦¦
^ 70 +
»
O
¦
O)
O 50
x
3
C
o
-O
k.
n
O 20
**
u
z
1990-1999 2000-2009 2010-2019 2020-2029 2030-2039
Decade
E3 Forest Soil ~ Forest floor I Understory CD Woody debris D Living tree
Figure 12. The modeled average annual carbon flux projections by decadal
intervals (e.g., 1990-1999 = average annual carbon flux for the years 1990 through
1999) for the forests of Camp Shelby under the harvesting scenario. Positive and
negative values are respectively net carbon gains or losses.
Carbon flux. The impact of tree harvesting on
carbon dynamics is the immediate removal of
carbon from the tree pool. However, the loss
of carbon is offset by the concurrent growth of
trees in non-harvested forest stands and the
subsequent establishment and growth of
seedlings from natural regeneration on the
harvested land. Consequently, the net decrease
in sequestration of carbon in the tree pool
resulting from harvesting during the 50-year
simulation was 113 Gg-C in comparison to the
no-action scenario and 364 Gg-C for all pools
combined.
During the 50-year simulation from 1990 to
2040, there was a net carbon flux of 1,569
Gg-C into the Camp Shelby forests. This is
19% less in net carbon gain compared with
scenario 1. Total carbon flux into the forest
was the greatest during the first decade and
then decreased somewhat linearly through the
fifth decade (Figure 12). This pattern of
carbon flux resulted from the rapid growth of
the young forest stands during the first portion
of the simulation. As the forest stands ma-
tured, the rate of tree growth declined. The
tree pool was the strongest carbon sink
throughout the simulation and increased by
29%. The forest floor and woody debris pools
were also carbon sinks and increased in size by
30 and 27% respectively. Once again, the
understory pool was a carbon source during the
first decade and then a small carbon sink for
the remaining time.
The calculated 50-year net annual carbon gain
for the Camp Shelby forests averaged 31 Gg-C
yr1. Averaged carbon sequestration by the
coniferous, deciduous and mixed forests was
23, 3, and 5 Gg-C yr1, respectively. The rates
26
-------
12,000 T
10,000 ¦¦
|
$ 8,000 -¦
s
Q.
6,000 • ¦
c
o
¦E 4,000
(B
o
2,000 ¦ ¦
lllllllllll
llllllltlllHlllllllllll
4-
+
1990 2000 2010 2020 2030 2040
Year
ESoil
0 Forest floor I Understory d Woody debris D Living tree
Figure 13. The modeled projections of carbon pools for Camp Shelby forests under
the biofuel scenario.
of carbon sequestration per unit area for the
coniferous, deciduous, and mixed forests were
58, 87, and 89 g-C m"2 yr1. The rate of carbon
sequestration in the coniferous forest decreased
by 25% in comparison with scenario 1.
Scenario 3 - Biofuel
Forest carbon pools - 2040. The total carbon
pool for Camp Shelby forests after yearly tree
harvesting to support a biofuels program in
2040 was 10,530 Gg-C (Figure 13). The
partitioning of carbon among the coniferous,
deciduous and mixed forests was respectively
79, 8 and 13%. The distribution of carbon
within the various pools by forest type for the
deciduous and mixed forests was essentially
the same as scenario 1.
Carbon flux. The goal of tree harvesting to
support a biofuel program is to offset carbon
emissions from fuel combustion through
carbon sequestration by the establishment and
growth of new trees. The ideal situation would
be where carbon emission from burning fuel-
wood equals carbon sequestration by the
forest. Tree harvesting to support the biofuel
program resulted in the immediate loss of
carbon from the tree pool. This loss, however,
was partially offset by the growth of new
seedlings on the harvested land. The net
decrease in carbon sequestration in the tree
pool during the 50-year simulation in compari-
son to scenario 1 was 326 Gg-C and 451 Gg-C
for all pools combined.
During the 50-year simulation, there was a net
flux of 1,482 Gg-C carbon into the Camp
Shelby forests. This is a 23% loss in net
carbon gain in comparison with scenario 1.
27
-------
>»
0
1
o>
o
x
3
C
O
n
i-
-------
Carbon storage per unit area averaged 21 kg-C
m-2 in 2040. The majority of carbon accumula-
tion occurred in the tree pool which increased
by 28% and was a carbon sink throughout the
simulation (Figure 14). The forest floor and
woody debris pools were also carbon sinks and
increased in size by 30 and 18%, respectively.
The understory pool was a carbon source
during the first decade and then a carbon sink
thereafter.
The 50-year average net carbon gain for Camp
Shelby forests was 30 Gg-C yr1. Carbon
sequestration by the coniferous, deciduous and
mixed forests averaged 22,3, and 5 Gg-C yr1,
respectively. The rates of carbon sequestration
for the coniferous, deciduous, and mixed forest
averaged 55, 87, and 89 g-C m2 yr*1. The rate
of sequestration for the coniferous forest was
27% less in comparison with scenario 1.
Scenario 4 - Deforestation
Forest carbon pools - 2040. The overall
carbon pool for Camp Shelby forests after
deforestation of 8,593 ha of coniferous forest
was calculated to be 9,533 Gg-C in 2040
(Figure 15). The partitioning of carbon among
the coniferous, deciduous, and mixed forests
was 72,9, and 14%, respectively. This repre-
sents an 8% decrease for the coniferous forest
and a 2 and 1% increase for the deciduous and
mixed forests, respectively, in comparison with
scenario 1. The distribution of carbon among
the five carbon pools varied slightly compared
with scenario 1. The most significant changes
were in tree carbon that changed from 53% to
50% and soil carbon that increased from 31%
to 35%. The partitioning of carbon by pool
and forest type was similar to the no-action
scenario.
Carbon flux. Deforestation resulted in all
pools being a carbon source during the first
decade when the land-use change occurred
(Figure 16). The tree pool was the largest
source in decade 1, but recovered quickly in
the second decade to be a carbon sink for the
remainder of the simulation. Tree carbon in
2040 was 996 Gg-C less than in scenario 1 and
total carbon was 1448 Gg-C less. Understory
vegetation, woody debris, and forest floor also
were carbon sinks for the remainder of the 50
years. The soil-carbon pool was carbon neutral
for the remaining 40 years. The rate of carbon
flux into the forests decreased linearly from
decade 2 through decade 5. The loss of carbon
in the tree pool was partially offset by concur-
rent tree growth in other forest stands. Tree
seedling establishment did not occur because
the deforested areas were seeded to grass or
became roads and facility sites.
During the simulation period, there was a net
carbon flux of 485 Gg-C into Camp Shelby
forests, a 75% decrease in comparison with
scenario 1. Carbon gain was the greatest in
decade 2 and decreased with time due to a
decrease in tree growth and increased respira-
tion. The majority of carbon accumulation
occurred in the tree pool which increased by
13%. The forest floor and woody debris pools
also increased by 13 and 5%, respectively. The
amount of carbon in the soil pool decreased by
4% in the first decade due to the conversion of
the forestland to grassland and then remained
constant for the remaining time. The under-
story pool was a carbon source the first two
decades and a small sink the last three decades
with a 19% decrease.
The 50-year average net carbon gain for Camp
Shelby forests was 10 Gg-C yr1. Carbon
sequestration by the coniferous, deciduous, and
mixed forests averaged 1,3, and 5 Gg-C yr1,
29
-------
50 j
40 --
_ 30 -¦
-40 --
-50 --
-60 --
1990-1999 2000-2009 2010-2019 2020-2029 2030-2039
Decade
E3 Forest soil ~ Forest floor B Uriderstory [D Woody debris ~ Living tree
Figure 16. The modeled average annual carbon flux projections by decadal intervals
(e.g., 1990-1999 = average annual carbon flux for the years 1990 through 1999) for
the forests of Camp Shelby assuming the deforestation scenario. Positive and
negative values are respectively net carbon gains or losses.
respectively. The rates of sequestration for the
coniferous, deciduous, and mixed forest
averaged 3, 87, and 89 g-C m"2 yr1. This is a
96% lower carbon sequestration rate for the
coniferous forests as compared with
scenario 1.
Scenario 5 - Reforestation
Forest carbon pools -1990. The 1990 carbon
pool under this scenario.differs from that of the
under scenario 1 because of the land (4,050 ha)
that was reforested to coniferous forest. The
additional land enrollment provided 141 Gg-C
carbon to the 1990 soil pool that was not part
of the assessment for the previous scenarios.
We assumed that this additional land had
negligible amounts of carbon in the tree and
understory pools. Consequently, the 1990 non-
soil carbon pools as described in scenario 1 are
also applicable to this scenario. Thus, the 1990
carbon pool was 9,189 Gg-C for this scenario
(Figure 17).
Forest carbon pools - 2040. The 2040 carbon
pool for the forests of Camp Shelby after
reforestation of 4050 ha was 11,737 Gg-C
(Figure 17). The partitioning of carbon among
the coniferous, deciduous, and mixed forests
was 81,7 and 12%, respectively. Average
carbon storage for the coniferous, deciduous,
and mixed forests was 22, 23, and 23 kg-C m2,
respectively. Carbon storage for the coniferous
forest was 3% less than in scenario 1 because
of the young forest stands associated with the
30
-------
I
0
o>
1
£L
C
I
8
12,000 j
10,000 ¦¦
8,000
6,000
4,000
2,000
0
imiim hiimiuiiH iiiiiiiiiHIIHIllll
1990 2000 2010 2020
Year
2030
2040
E3 Soli
~ Forest floor B Understory Dl Woody debris ~ Living tree
Figure 17. The modeled carbon pool projections for the forests of Camp Shelby
assuming the reforestation scenario. New land enrollment provided an additional
141 Gg to the 1990 soil pool.
*
o
x
3
H
c
2
k.
CB
o
80 j
70 -¦
60 ¦¦
50 -¦
40
30
20 ¦¦
10
0
-10
lllllllllllll
1990-1999
AWWWWW
2000-2009
2010-2019
Decade
lllllllllllll
2020-2029
lllllllllllll
2030-2039
~ Forest soil 0 Forest floor H Understory DDI Woody debris G Living tree
Figure 18. The modeled average annual carbon flux projections by decadal
intervals (e.g. 1990-1999 = average annual carbon flux for the years 1990 through
1999) for the forests of Camp Shelby under the reforestation scenario. Positive and
negative values are respectively net carbon gains or losses.
31
-------
reforested land. The partitioning of carbon
among the five pools was similar to scenario 1.
Carbon flux. Reforestation resulted in all
pools being a carbon sink throughout the
simulation (Figure 18). Carbon flux into the
Camp Shelby forests was the greatest during
decade 1 and decreased linearly through
decade 5. Reforestation provided increased
potential to sequester atmospheric carbon
because of the rapid growth of the young trees.
Consequently, average net sequestration of
carbon by the tree pools was 377 Gg-C more
than in scenario 1 and 615 Gg-C for all pools
combined.
During the 50-year simulation, there was a net
carbon flux of 2,548 Gg-C into the forests of
Camp Shelby. This is a 32% increase in
carbon sequestration in comparison with
scenario 1. The majority of carbon accumu-
lated in the tree pool which increased by 45%.
In addition, the soil, forest floor, understory
vegetation, and woody debris pools also
increased their carbon storage by 4,48, 6, and
36%, respectively. Unlike scenario 1, the
understory vegetation was never a carbon
source.
The 50-year carbon gain per annum for Camp
Shelby forests averaged 51 Gg-C yr'1. Carbon
sequestration by forest was 43, 3, and 5 Gg-C
yr"1 for the coniferous, deciduous, and mixed
forests, respectively. The rates of carbon
sequestration per unit area for the coniferous,
deciduous, and mixed forests averaged 99, 87,
and 89 Gg-C m2 yr"1 The carbon sequestration
rate for the coniferous forest was 29% higher
than in scenario 1.
On-Site Carbon Benefit
According to the model simulations, tree
harvesting whether for commercial, biofuel, or
land-use change decreased carbon pools and
the rate of carbon sequestration in comparison
with no-action management, while reforesta-
tion increased carbon pools and sequestration
(Figure 19). The pattern of carbon flux into
the forest during the simulation was a decrease
from one decade to the next as exemplified by
the no-action scenario. The only exception to
this pattern was the net flux of carbon to the
atmosphere during the first decade under the
deforestation scenario. Thereafter, net carbon
flux was into the forest but at a much lower
rate than the no-action scenario. The reforesta-
tion scenario also showed the same pattern of
carbon flux as the benchmark, but at a much
higher rate.
The no-action scenario provided a benchmark
to compare the carbon sequestration of the
other management scenarios (Table 5). Har-
vesting trees at a rate considered normal
management by the Black Creek Ranger
District could reduce on-site carbon sequestra-
tion by -8 Gg-C yr' for the 50-year period.
Thus, this scenario is slightly carbon negative.
In contrast, the deforestation scenario is decid-
edly carbon negative as it results in an average
decrease in on-site sequestration of -29 Gg-C
yr1. Reforestation is the only scenario that is
carbon positive because average sequestration
is increased by +12 Gg-C yr1.
Furthermore, the scenarios differ in the timing
of their impacts on carbon sequestration. For
example, the harvesting, biofuel, and defores-
tation scenarios have similar on-site carbon
gains for the decade 2000-2009 (Table 5).
However, for the entire 50-year period, the on-
site carbon gains are more negative for defor-
32
-------
12000 t
11000 ¦¦
O) 10000
(3
9000
8000
7000
6000
1990
2000
2010 2020
Year
2030
2039
>>
0
1
O)
o
x
3
(0
O
CD
z
2030-2039
>»
CM
E
0
1
o>
S
-------
Table 5. Carbon benefits of Camp Shelby forests during 10-year (2000-2009) and
50-year (1990-2039) periods as affected by five hypothetical management scenarios.
Management Net On-site Carbon On-site Carbon Off-site Carbon Combined Carbon
Scenario Sequestration Benefit3 Benefitab Benefit3
(Gg-C yr1)
10-year 50-year 10-year 50-year 10-year 50-year 10-year 50-year
No-action
52
39
0
0
0
0
0
0
Harvesting
42
31
-10
-8
2.6
2.6
-7.4
-5.4
Biofuel
40
30
-12
-9
10.1
10.1
-1.9
+1.1
Deforestation
41
10
-11
-29
12.2
4.9
+1.2
-24.1
Reforestation
64
51
+12
+12
0
0
+12.0
+12.0
a Compared with the no-action scenario.
b Assumes a 0.4 and 0.9 conversion efficiency to long-term wood products/landfill and biofuel energy
production, respectively, for C transferred off-site.
estation than for the harvesting and biofuel
scenarios. This reflects the primary loss of
carbon sequestration potential by trees through
the conversion of forestland to grassland.
The management scenarios are independent,
and carbon gains (compared with the bench-
mark) change linearly with land area. Thus, it
is possible to estimate carbon gains for sce-
nario combinations for the forests of Camp
Shelby or other forests with similar mixes of
tree species and stand-age distribution
(Table 5). For example, combining reforesta-
tion with tree harvesting would result in a
carbon gain of +4 Gg-C yr"1 for the 50-year
period. Deforestation of 4,297 ha instead of
8,593 ha would be less carbon negative,
resulting in a carbon gain of -14 Gg yr1. A
concurrent program of deforesting 8,593 ha
and reforesting 4,050 ha would be slightly
carbon positive for the decade 2000-2009 and
carbon negative for the 50-year period.
Off-site Carbon Benefit
Under the harvesting, biofuel, and deforesta-
tion scenarios, harvested wood was transferred
off-site for production of lumber or fuelwood.
Long-term wood products/landfill or fuelwood
can offset atmospheric carbon emissions
(Table 5). For example, under the harvesting
scenario, merchantable logs (representing 6.6
Gg-C yr*1) were removed off-site during the
2000-2009 decade. With the conversion of the
wood into lumber, approximately 2.6 Gg-C yr"1
is placed into long-term storage and kept out of
the atmosphere. Similarly, under the biofuel
scenario, wood biomass (representing 11.2
Gg-C yr1) was removed off-site for fuelwood
production during the 2000-2009 decade. This
will offset 10.1 Gg-C yr"1 that would have been
released into the atmosphere from fossil-fuel
combustion. Biofuels contain carbon that has
been recently removed from the atmosphere
and will be returned upon combustion. How-
ever, fossil fuels store inert carbon that was
sequestered thousands of years ago and upon
34
-------
combustion releases this "new" carbon into the
atmosphere. Thus, there is no not increase in
atmospheric carbon with the use of biofuels,
while the use of fossil fuels will increase
atmospheric carbon.
3.4 Discussion of Simulation Results
The modeling simulation under the no-action
scenario suggests that Camp Shelby forests are
a net carbon sink. During the 50-year simula-
tion, carbon accumulated into the tree, woody
debris, and forest floor pools. The understory
vegetation pool was a carbon source to the
atmosphere during the first decade of the
simulation but then became a small carbon
sink. Tree harvesting had a modest effect on
reducing carbon sequestration in comparison to
the no-action scenario. On the other hand, the
conversion of forestland to grassland resulted
in a significant flux of carbon to the atmo-
sphere and also reduced the potential for future
carbon sequestration. Reforestation signifi-
cantly improved the long-term carbon seques-
tration potential.
Carbon Pools
Turner et al. (1993) show that the forests of the
FS South Central region (in which Camp
Shelby is located) are second only to the
Northeast region in the amount of total carbon
accumulation because of the large land area.
Their estimate of current carbon storage in the
forests of the South Central region is 6.7 Pg-C.
However, Turner et al. (1993) found that the
average quantity of carbon per unit area for the
South Central region was the lowest in the
United States at approximately 14.5 kg-C m2.
The highest region was the Pacific Northwest
West at approximately 33 kg-C m2.
Our estimate of carbon storage per unit area for
Camp Shelby forest in 1990 was 19.0 kg-C
m'2. The forests of Camp Shelby should be
more productive than those elsewhere in the
region because of favorable growing condi-
tions such as abundant precipitation throughout
the year (Department of the Army 1991).
Potential carbon storage in the longleaf pine-
slash pine forests that occur on DOD land was
estimated to be 19 kg m*2 by the AFA (1992).
The agreement in carbon storage between the
AFA calculation and our independent analysis
gives confidence to the modeling approach that
we used.
Turner et al. (1993) also provided data to
estimate the partitioning of carbon among the
various pools for the forests of the South
Central region. Their data show that the
majority of carbon resides in the soil (50%)
and within tree biomass (34%). The remaining
carbon is found in woody debris (10%), forest
floor (3%), and understory (2%). Our calcula-
tions of carbon partitioning within the forests
of Camp Shelby suggest that approximately
52% of total carbon resides in tree biomass
while soil stores 31%. Much of the land within
Camp Shelby is protected from all or limited
use by the general public because of the dan-
gers associated with military training and the
rate of tree harvesting is less than in the other
forests of the region (Department of the Army
1991). Heath and Birdsey (1993) provide data
that show 54% of forest stands on private lands
in the region that includes Camp Shelby are
less than 30 years old with the 25-year age
class dominating. The age-class distribution of
Camp Shelby forests is much older in that
approximately 20% of forest stands are less
than 30 years old while the 50-70 age class
dominates (Table 3). Consequently, a rela-
tively large amount of carbon has been stored
in the tree pool.
35
-------
Carbon Flux
Carbon flux into forests depends on stand age
or disturbance regime. Net carbon flux is
balanced through plant photosynthesis, plant
respiration, and tissue decomposition
(Houghton et al. 1993). A disturbance to the
forest such as tree harvesting or tree blow
down from strong winds produces considerable
woody debris. Therefore, carbon flux to the
atmosphere is high because of elevated rates of
decomposition of woody debris. A young,
rapidly-growing tree stand will sequester large
amounts of atmospheric carbon. As the tree
stand recovers from disturbance through
seedling establishment and growth, the rate of
carbon sequestration will exceed the rate of
carbon emissions. As the stand matures, the
rate of carbon sequestration approaches carbon
loss to the atmosphere. Then as the stand
continues to age carbon loss to the atmosphere,
through elevated rates of respiration and
woody debris decomposition, may exceed the
rate of carbon sequestration. However, carbon
storage in an old tree stand is much greater
than in a young tree stand.
Commercial- and biofuel-tree harvesting in
this study had a modest effect on carbon
sequestration in this modeling study. This
occurred because of the concurrent growth of
the non-harvested tree stands and the subse-
quent establishment and growth of seedlings
on the harvested land. Also, only a relatively
small proportion of the coniferous forest was
harvested in any given year. A higher rate of
harvesting would eventually result in the forest
being a carbon source instead of a carbon sink
as exemplified by the deforestation scenario.
Management Considerations
Management to sequester carbon should target
long-term forest stand growth and productivity
through ecosystem management as proposed
by the Society of American Foresters (1993).
Tree harvesting should be coupled with imme-
diate reforestation or natural seedling estab-
lishment in a timely manner. However, if
deforestation of large tracts of land is neces-
sary for military training purposes, only the
minimal area necessary for vehicle maneuver-
ing should be clear cut. Where possible "is-
lands" of trees should be left intact. The
establishment of a vigorous grass cover on
training areas that were deforested will im-
prove carbon sequestration but at a much lower
rate in comparison with forest stands (Barker
et al., unpublished data). The grass cover will
also help maintain soil carbon through the
addition of biomass and erosion control. After
training events, disturbed areas should again be
reseeded to establish grasses as quickly as
practical to maintain plant cover and reduce
erosion. Finally, all lands that can support tree
growth and will not interfere with training
should be reforested.
The greatest carbon sequestration potential will
come from rapidly growing tree stands. How-
ever, carbon storage is greatest in older tree
stands. Therefore, a trade-off between seques-
tration and storage must be considered (Heath
et al. 1993). Sustainable tree harvesting will
reduce carbon sequestration by Camp Shelby
forests compared with no harvesting. The
reforestation of harvested stands can greatly
increase carbon assimilation. Forest manage-
ment to encourage carbon sequestration and
conservation will provide other benefits such
as improved wildlife habitat, decreased soil
erosion, improved realism in military training,
and improved overall environmental quality
(American Forestry Association 1992).
Tree harvesting for lumber or fuelwood is
advantageous to carbon sequestration and
conservation (American Forestry Association
36
-------
1992, Kauppi et al. 1992, Heath and Birdsey
1993, Kauppi and Tomppo 1993, Sampson et
al. 1993). The lumber that is used in construc-
tion projects will still provide long-term carbon
storage. Even when lumber is discarded to
landfills it will retain its carbon for many more
years while decomposition slowly occurs.
Another advantage is that the establishment
and subsequent growth of tree seedlings on the
harvested land will sequester carbon at a much
higher rate than older tree stands. However,
harvesting old forest stands tends to create a
long-term overall carbon source because of the
release of carbon from decaying woody debris
(Harmon et al. 1990).
Harvesting trees to support a biofuel program
is advantageous to carbon sequestration in that
fossil-fuel use is displaced with modern tech-
nology that can be more efficient and thus
result in lower carbon emissions (Sampson et
al. 1993, Wright and Hughes 1993). Also, the
reforestation of the harvested land will seques-
ter carbon released from combustion of the
biofuel. Consequently, an equilibrium in
carbon flux between the atmosphere and trees
can be established as shown under the biofuel
scenario.
Offsetting C02 Emissions
Total C02-C emissions for the State of Missis-
sippi for 1990 were estimated to be 52,000
Gg-C (based on the 1985 emissions estimates
of Piccot and Saeger [1990] plus a 1% yr1
increase). If Mississippi were to adopt the
CCAP target as a state goal, then 3640 Gg-C
yr1 in reduced C02 emissions or increased
carbon sinks would be required.
For the decade 2000-2009, average net carbon
flux into the Camp Shelby forests was calcu-
lated to be 52,41, and 64 Gg-C yr"1 respec-
tively under the no-action, deforestation, and
reforestation scenarios (Table 5). The refores-
tation scenario would provide about 1.8%
(0.3% above the no-action scenario) of the
carbon offset needed to obtain the CCAP goal
in Mississippi through carbon sequestration.
In contrast, deforestation would reduce seques-
tration by 11 Gg-C yr1, and require additional
offsets to attain the CCAP goal by the year
2000.
The carbon sequestration data for the reforesta-
tion scenario can be extrapolated to all national
forests (403,225 ha) within Mississippi be-
cause of similarity in forest-stand age class
distribution and composition with Camp
Shelby forests (J. White, DeSoto National
Forest, personal communication). Therefore,
for the decade 2000-2009, a proactive refores-
tation program throughout the national forests
in Mississippi at the same intensity as the
reforestation scenario would sequester 122
Gg-C yr1 more carbon in comparison with the
no-action scenario. This would account for
3.4% of the C02-C offset needed to meet the
CCAP goal within Mississippi.
The 50-year average flux provides a measure
of the long-term implications of these manage-
ment scenarios. Reforestation would, on
average, increase sequestration by +12 Gg-C
yr1 compared to no management (Table 5). In
contrast, deforestation would decrease average
sequestration by -29 Gg-C yr1. Thus, over the
long-term, these scenarios would either pro-
vide 0.3% of the required offset, or require an
additional 0.8%, respectively.
37
-------
38
-------
4.0 DOD FOREST MANAGEMENT AND CARBON SEQUESTRATION
The research presented in Section 3 demon-
strated that forest management can have both
immediate and long-term consequences on
atmospheric carbon sequestration. This section
briefly presents management options that could
improve the potential for atmospheric carbon
sequestration by forests on DOD land with
associated economic benefits.
4.1. Management Practices for Carbon
Sequestration
Conservation efforts through the ITAM pro-
gram could be employed to sequester and
conserve carbon in terrestrial ecosystems on
DOD land. Most notably, proactive manage-
ment should call for the reforestation of land
degraded by training activities and improved
land-use practices that would reduce further
vegetation and soil destruction. The biosphere
reserve concept is one approach to forest
management that has been implemented
successfully in many parts of the world and
perhaps may be of promise on DOD forestland
(Box 3). The biosphere reserve concept helps
preserve primary forests while integrating
multiple use endeavors into surrounding lands.
Impact areas and sensitive wildlife habitat on
DOD land could serve as the core area that
receives the maximum protection. The buffer
zone would be reserved for military training
that results in minimal environmental damage.
The restoration zone would be those areas
recovering from environmental degradation.
Finally, the developed zone could contain the
cantonment facilities and other intense training
areas. Of course, the biosphere reserve con-
cept would have to be adapted to the unique
needs of each installation.
Cantonment areas include administrative,
housing, maintenance, medical and other
support facilities. These areas are usually
landscaped with grass, shrubs, and trees.
Semi-developed areas include airfields, han-
gars, equipment storage, transportation and
utility corridors, and other modified areas.
These lands receive periodical mowing and
woody plant control treatments. Unimproved
lands include maneuver areas, buffer strips,
drop zones, firing ranges, and ammunition
impact areas and are generally left in natural
vegetation. Unimproved lands are frequently
managed for timber production or are grazed
by livestock.
All land-use areas can be managed to increase
the potential for carbon sequestration and
reduce energy costs by the appropriate planting
of trees and shrubs (U.S. Environmental
Protection Agency 1992, Sampson 1993).
Minimizing soil erosion will also improve
carbon sequestration potential on these areas.
The management strategy in cantonment areas
should be to use trees and shrubs to beautify,
reduce heating and cooling costs, and store
carbon. Wind breaks have been shown to
significantly reduce heating costs and also
reduce C02 emissions while the trees sequester
atmospheric carbon. Playgrounds, parks, and
other recreational areas could benefit from
landscaping with trees and shrubs to provide
shade. Soil carbon sequestration and storage
can be enhanced through maintaining plant
cover, irrigation, and fertilization (Johnson
1992). Woody vegetation on the semi-devel-
oped sites should be allowed to grow if it does
not present a safety hazard or interfere with
normal, daily activities. Areas that require
mowing or herbicides to control plant size and
growth could be planted with trees and shrubs
capable of growing within the plant size
restriction. Unimproved lands offer the great-
est opportunity for carbon sequestration by
39
-------
Box 3. The Biosphere Reserve Management Concept (from Dixon et al. 1991).
~
Core
m
Buffer
z
Restoration
Developed
o
Human settlements
*
Research station
T
Tourism/recreation
E
M
Education/training
Monitoring
Figure a
Figure b
The origin of Biosphere Reserves
can be traced to the mid 1970s and
UNESCO's Man and the Biosphere
Program (MAB). However, the
concept has evolved from one aimed
at preserving a worldwide network
of areas for basic ecological re-
search, to one where development
and management of the surrounding
region is viewed as essential to the
maintenance of the preserve area.
Three specific management objec-
tives are implicit in this concept: (1)
habitat preservation (providing
protection of genetic resources on a
worldwide basis), (2) logistical
coordination (interconnected
facilities for research and monitor-
ing), and (3) sustainable develop-
ment of a range of economically
viable and sustainable options for
rural peoples living in proximity to
the preserves) (Batisse 1980, 1990).
Four Major Zones
Miller (1978) identifies four major
zones which should be in each
biosphere reserve: The protected
core serves as the baseline or
scientific study area and includes the
most pristine habitat in the region.
This zone must be as laige as
possible to permit natural ecosystem
functioning and is generally sur-
rounded by a buffer zone in which
limited anthropogenic activities can be
permitted as long as they do not
compromise the ecological integrity of
the core. Resource extraction, tourism
and other forms of resource conver-
sion can be undertaken under strict
controls. Often the buffer zone is
adjacent to restoration zones, areas
which have been severely altered but
for which management is being
intensified as a means of contributing
to the sustained and economically
viability of the region. Finally, there
are the developed zones, including
villages and related infrastructure.
In theory, each reserve has all four
zones forming a gradient of manage-
ment intensities aimed at protecting
the ecological structure and function
of the core (Figure a). The manage-
ment of the entire region would
ideally respond to a unified manage-
ment structure and be protected by
national law. In practice however, it
seldom works out that way, due to the
scarcity of natural habitat, existing
management and jurisdictional
structures and boundaries, established
land use patterns, etc. (Figure b). In
fact, most of the initial reserve
"designations" were in existing
protected areas. Professor Batisse
claims this was initially seen as a
"quality label", providing additional
prestige or clout in the scientific-
political arena. Today there are
some 285 reserves in 72 countries
representing a range of scale,
ecological importance, management
objectives and success (Batisse
1990, MacKinnon et al. 1986).
The major obstacles to proper
management of biosphere reserves
are not technical or scientific but
managerial and institutional
(Batisse 1990). Perhaps the real
importance of the biosphere reserve
concept is that it helps focus the
issues involved in collaborative
management of a natural resource
base. Many groups, including the
Department of Regional Develop-
ment and Environment of the
Organization of American States,
The Nature Conservancy, Conserva-
tion International and others, have
tested and improved upon the basic
MAB model and achieved definitive
results in both preservation of
habitat and resource management
for economic development.
40
-------
vegetation and soil. Silvicultural practices
could be used to improve stand tree productiv-
ity such as the control of understory vegetation
and maximizing stem density. Reforestation of
degraded lands would greatly improve the
potential for carbon sequestration in addition to
providing soil erosion control and improve
wildlife habitat quality and recreational oppor-
tunities. Maintenance of vegetation will also
enhance the carbon sequestration of soil.
Another management option for DOD installa-
tions that would provide a carbon-sequestra-
tion benefit is the establishment of a biofuel
program (American Forestry Association 1992,
Sampson 1993). The biofuel philosphy is that
the carbon emitted from fuel combustion is
sequestered by growing trees and other vegeta-
tion. Then the biomass is harvested and
becomes the biofuel. Tree seedlings are then
planted to take the place of the harvested
vegetation. Thus, an equilibrium between
carbon emissions and sequestration is estab-
lished with no net loss of carbon to the atmo-
sphere. Another benefit of a biofuel program
is the displacement of fossil fuels which results
in less carbon emissions into the atmosphere
using biomass-energy technology (Wright and
Hughes 1993).
4.2 Carbon Sequestration and Economic
Benefits for DOD Installations
Proactive management of DOD forests can
have immediate and long-range carbon and
economic benefits. According to the American
Forestry Association (1992) some of the
advantages are:
• Proactive management of 193,548 ha of
underutilized forestland could result in the
sequestration of SO to 60 Mg per acre of
carbon over the next 40 years.
• Proactive management on approximately
354,839 ha of forestland could result in a net
return of $200 million by 2032.
• Lumber is a form of long-term carbon
storage that may be kept indefinitely in
building structures or land fills and will only
return carbon to the atmosphere upon de-
composition or burning.
• Establishing or expanding biofuel programs
on many military bases could result in a 10-
year savings of up to $600 million and a 40-
year savings of $1.8 billion and significantly
reduce carbon emissions to the atmosphere. .
• Landscaping with trees and shrubs in can-
tonment areas can significantly reduce
heating and cooling costs, reduce carbon
emissions, and sequester large amounts of
atmospheric carbon.
• Improve recreational areas and wildlife
resources by increasing vegetation cover,
improving habitat and water quality, de-
creasing soil erosion and increasing soil
carbon.
• Tree and shrub plantings around fuel and
ammunition storage areas can improve
overall safety by absorbing the impacts of
explosions.
• Tree and shrubs plantings around target
ranges and artillery impact areas would
decrease the frequency of accidents by
stopping stray bullets and flying shrapnel.
• Planting woody vegetation on runway and
road medians, buffers, and approaches can
reduce maintenance costs, reduce soil
erosion, and improve overall safety.
41
-------
42
-------
5.0 SUMMARY AND CONCLUSIONS
The terrestrial biosphere is a significant com-
ponent of the global carbon cycle. As such,
forest vegetation and soil are important carbon
pools. An understanding of changes in forest
carbon dynamics as affected by land use is
critical to predict changes in atmospheric C02
concentrations. Forests located on DOD
training installations throughout the United
States offer promising opportunities to seques-
ter and conserve atmospheric carbon because
reforestation opportunities, land-use practices,
and large land tracts support mature forests
that are vast carbon reservoirs. The influence
of land-use practices such as tree harvesting,
deforestation, and reforestation on carbon
sequestration of Camp Shelby forests were
evaluated through model simulations.
Carbon pools estimates of living tree, under-
story vegetation, soil, forest floor, and woody
debris were based on Camp Shelby forest-
stand area, age class, and stocking level. A
stand-level carbon budget was developed for
the coniferous, deciduous, and mixed forests
based on growth and yield tables from the
Aggregate Timberland Assessment System
(ATLAS), a timber inventory model developed
by the FS. Flux is the average annual change
in the total carbon pool since the previous
decade and was calculated by dividing the
difference of the ending and beginning carbon
pools by 10 years. Carbon pools and flux for
five management scenarios were simulated
from 1990 through 2040.
Forest management profoundly affected the
carbon pools and sequestration potential of the
forests. The no-action scenario provided the
baseline for comparing harvesting, biofuel,
deforestation, and reforestation scenarios. A
general conclusion from the scenarios is that
tree harvesting decreased carbon pools and
sequestration rate and reforestation increased
carbon pools and sequestration rate. Tree
harvesting, even at the rate defmed as normal
management, resulted in a reduction in the
total carbon pool and a 25% loss in the rate of
carbon sequestration. Deforestation of 8,593
ha resulted in a dramatic reduction in total
carbon and a 75% loss in on-site carbon se-
questration potential. On the other hand, the
reforestation of 4,050 ha of land significantly
increased the carbon storage and resulted in a
31% increase in the rate of carbon sequestra-
tion. Thus, management practices that pro-
mote reforestation and discourage deforesta-
tion will provide the maximum carbon seques-
tration potential. In addition, other conserva-
tion benefits will include enhanced wildlife
habitat, increased biodiversity, decreased soil
erosion, and improved water quality.
Under the harvesting, biofuel, and deforesta-
tion scenarios, harvested wood was transferred
off-site for production of lumber or fuelwood.
Tree harvesting for lumber and other wood
products is advantageous to carbon sequestra-
tion and conservation. The lumber that is used
in construction projects will still provide long-
term carbon storage. Even when lumber is
discarded into landfills it will retain its carbon
for many more years while decomposition
slowly occurs.
Harvesting trees to support a biofuel program
also provides a carbon benefit in that fossil fuel
is displaced with modern, fuelwood technology
that can lower carbon emissions. The ideal
43
-------
situation is where carbon emissions from
energy production approximates carbon se-
questration by the trees that will eventually
become fuelwood. Consequently, an equilib-
rium in carbon flux between energy production
and tree sequestration is eventually established.
Under the CCAP, the United States is commit-
ted to reducing RITGs emissions to their 1990
levels by the year 2000. If Mississippi were to
adopt the national target as a state goal, then
3,640 Gg-C yr1 of emission reductions or
offsets would be required. Reforestation of
Camp Shelby could provide 0.3% of the
44
-------
LITERATURE CITED
American Forestry Association. 1992.
Enhancing management of forests and
vegetation on Department of Defense
lands: Opportunities, benefits, and
feasibility. 230-R-005, US EPA Office of
Planning and Evaluation, Washington, DC.
Apps, M.J. and W.A. Kurz. 1991. Assessing
the role of Canadian forests and forest
sector activities in the global carbon
balance. World Resources Review 3:333-
344.
Barker, J.R., G.A. Baumgardner, D.P. Turner,
and J.J. Lee. 1995 (in press). Potential
carbon benefits of the Conservation
Reserve Program in the United States.
Global Ecology and Biogeography Letters.
Barker, J.R., S. Henderson, R.F. Ross, and D.T.
Tingey. 1991. Biodiversity and human
impacts. P 353-361 In: W.A. Nierenberg
(ed.), Encyclopedia of Earth System
Science, Vol. 1, Academic Press, Inc., San
Diego, CA.
Batisse, M. 1980. The relevance of MAB.
Environmental Conservation 7:179-184.
Batisse, M. 1990. Development and
implementation of the biosphere reserve
concept and its applicability to coastal
regions. Environmental Conservation
17:111-116.
Bazzaz, F.A. 1990. The response of natural
ecosystems to the rising global C02 levels.
Ann. Rev. Ecol. Syst. 21:167-196.
Birdsey, R.A. 1992. Carbon storage and
accumulation in United States forest
ecosystems. General Technical Report WO-
59, US Department of Agriculture Forest
Service, Washington, DC.
Boden, T.A., R.J. Sepanski, and F.W. Stoss.
1991. Trends '91: A compendium of data
on global change. Publ. No. ORNL/
CDIAC-46, Oak Ridge National
Laboratory, Oak Ridge, TN.
Clinton, W.J. and A. Gore. 1993. The climate
change action plan. The White House,
Washington, DC.
Cole, C.V., K. Flach, J. Lee, D. Sauerbeck and
B. Stewart. 1993. Agricultural sources and
sinks of carbon. Water, Air and Soil
Pollution 70: 111-122.
Cost, N.D., J.O. Howard, B. Mead, W.H.
McWilliams, W.B. Smith, D.D. VanHooser,
E.H. Warton. 1990. The biomass resource
of the United States. General Technical
Report WO-57, US Department of
Agriculture Forest Service, Washington,
DC.
Cubbage, F.C. 1992. Federal land conversion
programs. P 177-194 In: R. N. Sampson
and D. Hair (eds.), Forests and Global
Change, Vol. 1, American Forests,
Washington, DC.
Davis, M.B. and C. Zabinski. 1992. Changes in
geographical range resulting from
greenhouse wanning: Effects on
45
-------
biodiversity in forests. P 297-308 In: R.L.
Peters and T.E. Lovejoy (eds.), Global
Warming and Biological Diversity. Yale
University Press, New Haven, CT.
Department of the Army. 1991. Military
training use of national forest lands, Camp
Shelby, Mississippi. Draft Environmental
Impact Statement, Vol. 1, National Guard
Bureau and Mississippi Army National
Guard.
Dixon, R.K. and D.P. Turner. 1991. The global
carbon cycle and climate change:
Responses and feedbacks from below-
ground systems. Environmental Pollution
73:245-262.
Dixon, R.K., P.E. Schroeder, and J.K. Winjum
(eds.). 1991. Assessment of promising
forest management practices and
technologies for enhancing the
conservation and sequestration of
atmospheric carbon and their costs at the
site level. EPA/600/3-91/067, US EPA
Environmental Research Laboratory,
Corvallis, OR.
Dixon, R.K., J.K. Winjum, and P.E. Schroeder.
1993. Conservation and sequestration of
carbon: The potential of forest and
agroforest management practices. Global
Environmental Change 40:159-173.
Dixon, R.K., S. Brown, R. A. Houghton, A.M.
Solomon, M.C. Trexler, and J. Wisniewski.
1994. Carbon pools and flux of global
forest ecosystems. Science 263:185-190.
Franklin, J.F., F.J. Swanson, M.E. Harmon,
D.A. Perry, T.A. Spies, V.H. Dale, A.
McKee, W.K. Ferrell, J.E. Means, S.V.
Gregory, J.D. Lattin, T.D. Schowalter, and
D. Larsen. 1991. Effects of global climate
change on forests in northwestern North
America. P 7049-7962 In: G. H. Orians
(ed.), The Northwest Environmental
Journal, Institute for Environmental
Studies, University of Washington, Seattle,
WA.
i
Grabherr, G., M. Gottfried, and H. Pauli. 1994.
Climate effects on mountain plants. Nature
369:448.
Grainger, A. 1991. Overcoming constraints on
assessing feasible afforestation and
revegetation rates to combat global climate
change. In: D. Howlett and C. Sargent
(eds.), Proceedings of a technical
workshop to explore options for global
forest management. International Institute
for Environment and Development,
London, UK.
Harmon, M. 1993. Woody debris budgets for
selected forest types in the U.S. In: D.P.
Turner, J.J. Lee, G.J. Koerper, and J.R.
Barker (eds.). The Forest Sector Carbon
Budget of the United States: Carbon Pools
and Flux under Alternative Policy Options.
EPA/600/3-93/093, US EPA Environmental
Research Laboratory, Corvallis, OR.
Harmon, M.E., W.K. Ferrell, and J.F. Franklin.
1990. Effects on carbon storage of
conversion of old-growth forests to young
forests. Science 247:699-702.
Heath, L.S. and R.A. Birdsey. 1993. Carbon
trends of productive temperate forests of
the conterminous United States. Water, Air,
and Soil Pollution 70:279-294.
Heath, L.S., P.E. Kauppi, P. Burschel, H-D.
Gregor, R. Guderian, G.H. Kohlmaier, S.
Lorenz, D. Overdieck, F. Scholz, H.
46
-------
Thomasius, and M. Weber. 1993.
Contribution of temperate forests to the
world's carbon budget. Water, Air, and Soil
Pollution 70:55-69.
Hinckley, D. and G. Tierney. 1992. Ecological
effects of rapid climate change. P 291-300
In: S.K. Majumder, L.S. Kalkstein, B.
Yarnal, E.W. Miller, and L.M. Rosenfeld
(eds.), Global climate change:
Implications, challenges and mitigation
measures. The Pennsylvania Academy of
Science.
Houghton, R.A., J.D. Unruh, and P.A.
Lefebvre. 1993. Current land cover in the
tropics and its potential for sequestering
carbon. Global Biogeochemical Cycles
7:305-320.
IPCC (Intergovernmental Panel on Climate
Change). 1990. Scientific Assessment of
Climate Change. World Meteorological
Organization/UN Environmental Program.
Cambridge University Press, Cambridge,
UK.
DPCC (Intergovernmental Panel on Climate
Change). 1992. Climate Change:
Proceedings of a workshop on assessing
technologies and management systems for
agriculture and forestry in relation to
global climate change, Australian
Government Publishing Service, Canberra,
Australia.
Johnson, D.W. 1992. Effects of forest
management on soil carbon storage. Water,
Air, and Soil Pollution 64:83-120.
Kauppi, P.E. and E. Tomppo. 1993. Impact of
forests on net national emissions of carbon
dioxide in West Europe. Water, Air, and
Soil Pollution 70:187-196.
Kauppi, P.E., K.K.K. Mielikainen, and K.
Kuusela. 1992. Biomass and carbon budget
of European forests, 1971 to 1990. Science
256:70-74.
Kern, J.S. 1994 (in press). Estimation of soil
water retention modeled from texture,
organic matter, and bulk density. Soil
Science Society of America Journal.
Kern, J.S. and M.G. Johnson. 1993.
Conservation tillage and impacts on
national soil and atmospheric carbon
levels. Soil Science Society of America
Journal 57:200-210.
King, G.A. 1993. Conceptual approaches for
incorporating climatic change into the
development of forest management options
for sequestering carbon. Climate Research
3:61-78.
Lashof, D.A. and D.A. Tirpak (eds.). 1990.
Policy options for stabilizing global
climate. 21P-2003.1, Report to Congress.
US EPA Office of Policy, Planning and
Evaluation, Washington, DC.
Luxmoore, R.J., S.D. Wullschleger and P.J.
Hanson. 1993. Forest responses to C02
enrichment and climate warming. Water,
Air and Soil Pollution 70: 309-323.
MacKinnon, J., K. MacKinnon, G. Child and J.
Thorsell (eds.). 1986. Managing protected
areas in the tropics. International Union for
the Conservation of Nature and Natural
Resources, Gland, Switzerland.
47
-------
Miller, K.R. 1978. Planning national parks for
ecodevelopment: Methods and cases from
Latin America. Center for Strategic
Management Studies, School of Natural
Resources, University of Michigan, Ann
Arbor, MI.
Mills, J.R. and J.C. Kincaid. 1992. The
aggregate timberland assessment system-
ATLAS: a comprehensive timber
projection model. General Technical
Report PNW-GTR-281, U.S. Department
of Agriculture Forest Service , Pacific
Northwest Research Station, Portland, OR.
Moulton, R.J. and K.R. Richards. 1990. Costs
of sequestering carbon through tree
planting and forest management in the
United States. General Technical Report
WO-58, US Department of Agriculture
Forest Service, Washington, DC.
Myers, N. 1992. Synergisms: Joint effects of
climate change and other forms of habitat
destruction. P 344-354 In: R.L. Peters and
T.E. Lovejoy (eds.), Global Warming and
Biological Diversity. Yale University Press,
New Haven, CT.
National Academy of Science. 1991. Policy
implications of greenhouse warming.
National Academy Press, Washington, DC.
Neilson, R.P. 1993. Vegetation redistribution:
A possible source of C02 during climatic
change. Water, Air, and Soil.Pollution
70:643-674.
Oechel, W. and B.R. Strain. 1985. Native
species responses to increased carbon
dioxide concentration. P 117-154 In: B.R.
Strain and J.D. Cure (eds.), Direct effects of
increasing carbon dioxide on vegetation.
DOE/ER-0238, US Department of Energy,
Washington, DC.
Peters, R.L. and J.D. Darling. 1985. The
greenhouse effect and nature reserves.
Bioscience 35:707.
Peters, R.L. and T.E. Lovejoy (eds.). 1992.
Global Warming and Biological Diversity,
Yale University Press, New Haven, CT.
Piccot, S., and M. Saeger. 1990. National- and
state-level emissions estimates of
radiatively important trace gases (RTTGs)
from anthropogenic sources. EPA-600/8-
90-073. US EPA, Air and Energy
Engineering Research Laboratory,
Research Triangle Park, NC.
Plantinga, A.J., and R.A. Birdsey. 1993.
Carbon fluxes resulting from U.S. private
timberland management. Climatic Change
23:37-53.
Post, W.M., T-H Peng, W.R. Emanuel, A.W.
King, V.H. Dale, and D.L. DeAngelis.
1990. The global carbon cycle. American
Scientist 78:310-326.
Rubin, E.S., R.N. Cooper, R.A. Frosch, T.H.
Lee, G. Marland, A.H. Rosenfield, and
D.D. Stine. 1992. Realistic mitigation
options for global warming. Science
257:148-149, 261-266.
Sampson, R.N. 1993. Forest management and
biomass in the U.S.A. Water, Air, and Soil
Pollution 70:519-532.
Sampson, R.N., and D. Hair (eds.). 1992.
Forests and Global Change. Volume One:
Opportunities for Increasing Forest Cover.
48
-------
American Forestry Association,
Washington, DC.
Schneider, S.H., L. Mearns, and P.H. Gleick.
1992. Four climate scenarios for impact
assessment. P 38-58 In: R.L. Peters and
T.E. Lovejoy (eds.). Global Warming and
Biological Diversity, Yale University Press,
New Haven, CT.
Schroeder, P.E., R.K. Dixon, and J.K. Winjum.
1993. Forest management and agroforestry
to sequester and conserve atmospheric
carbon dioxide. Unasylva 44:52-60.
Schwengals, P., B. Solomon, C. Ebert, J.
Scheraga, M. Adler, D. Ahuja, J. Wells, S.
Seidel, K. Andrasko, and L. Burke. 1990.
Technical options for reducing greenhouse
gas emissions. VI-VI67 In: D.A. Lashof
and D.A. Tirpak (eds.). 21P-2003.1. Policy
options for stabilizing global climate,
Report to Congress. US EPA Office of
Policy, Planning and Evaluation,
Washington, DC.
Shugart, H.H. 1993. Global Change. In: A.M.
Solomon and H.H. Shugart (eds.).
Vegetation Dynamics & Global Change,
Chapman & Hall, New York, NY.
Simpson, L.G. and D.B. Botkin. 1992.
Vegetation, the global carbon cycle, and
global measures. P 411-425 In: D.A.
Dunnette and R.J. O'Brien (eds.), The
Science of Global Change: The Impact of
Human Activities on the Environment.
American Chemical Society, Washington,
DC.
Smith, S.H. 1992. United States forest
response and vulnerability to climate
change. School of Forestry and
Environmental Studies, Yale University,
New Haven, CT. Report prepared for the
Office of Technology Assessment,
Washington, DC.
Smith, T.M. and D. Tirpak (eds.). 1989. The
potential effects of global climate change
on the United States. EPA-230-05-89-050,
Report to Congress, US EPA, Office of
Policy, Planning and Analysis, Washington,
DC.
Smith, T.M. and H.H. Shugart. 1993. The
transient response of terrestrial carbon
storage to a perturbed climate. Nature
361:523-526.
Smith, T.M., H.H. Shugart, G.B. Bonan, and
J.B. Smith. 1992. Modeling the potential
response of vegetation to global climate
change. Advances in Ecological Research
22:93-116.
Smith, T.M., W.P. Cramer, R.K. Dixon, R.
Leemans, R.P. Neilson, and A.M. Solomon.
1993. Water, Air, and Soil Pollution 70:19-
38.
Society of American Foresters. 1993. Task
force report on sustaining long-term forest
health and productivity. Society of
American Foresters, Bethesda, MD.
Thompson, M.T. 1989. Forest statistics for
Georgia, 1989. Resource Bulletin SE-109,
US Department of Agriculture Forest
Service, Washington, DC.
Trexler, M.C. 1991. Minding the carbon store:
Weighing US forestry strategies to slow
global warming. World Resource Institute,
Washington, DC.
49
-------
Turner, D.P., J.J. Lee, G.J. Koerper, and J.R.
Barker (eds.). 1993. The forest sector
carbon budget of the United States:
Carbon pools and flux under alternative
policy options. EPA/600/3-93/093, US EPA
Environmental Research Laboratory,
Corvallis, OR.
U.S. Army Corps of Engineers. 1989.
Integrated training area management. Fact
Sheet EN-13, U.S. Army Corps of
Engineers, Construction Engineering
Laboratory, Champagne, IL.
U.S. Environmental Protection Agency. 1992.
Cooling our communities. 22P-2001, US
EPA Office of Planning and Evaluation,
Washington, DC.
Vogt, K.A., C.C. Grier, and D.J. Vogt. 1986.
Production, turnover, and nutrient
dynamics of above- and below-ground
detritus of world forests. Advances in
Ecological Research 15:303-377.
Volz, H., W.U. Kriebitzsch, and T.W.
Schneider. 1991. Assessment of potential,
feasibility and costs of forest options in the
temperate and boreal zones. In: D. Howlett
and C. Sargent (eds.). Proceedings of a
technical workshop to explore options for
global forest management. Bangkok,
Thailand, April 24, 1991. International
Institute for Environment and
Development, London, UK.
Waring, R.H., and W.H. Schlesinger. 1985.
Forest ecosystems: Concepts and
management. Academic Press, Inc.,
Orlando, FL.
Webb, ID, T. 1992. Past changes in vegetation
and climate: lessons for the future. P 59-75
In: R.L. Peters and T.E. Lovejoy (eds.)
Global Warming and Biological Diversity,
Yale University Press, New Haven, CT.
Winjum, J.K., R.K. Dixon, and P.E. Schroeder.
1993. Forest management and carbon
storage: An analysis of 12 key forest
nations. Water, Air, and Soil Pollution
70:239-258.
Wisniewski, J., R.K. Dixon, J.D. Kinsman,
R.N. Sampson, and A.E. Lugo. 1993.
Carbon dioxide sequestration in terrestrial
ecosystems. Climate Research 3:1-5.
Woodward, F.I. 1992. A review of the effects
of climate on vegetation: Ranges,
competition, and composition. P 105-123
In: R.L. Peters and T.E. Lovejoy (eds.).
Global Warming and Biological Diversity.
Yale University Press, New Haven, CT.
Woodwell, G.M. 1992. How does the world
work? Great issues of life and government
hinge on the answer. P 31-37 In: R.L.
Peters and T.E. Lovejoy (eds.), Global
Warming and Biological Diversity. Yale
University Press, New Haven, CT.
World Resources Institute. 1990. World
resources 1990-91. Oxford University
Press, Oxford, UK.
Wright, L.L. and E.E. Hughes. 1993. U.S.
carbon offset potential using biomass
energy systems. Water, Air, and Soil
Pollution 70:483-498.
50
------- |