June 10th USGCRP Seminar Flyer on Forests - Final

[Tony Socci]

                U.S. Global Change Research Program Second Monday Seminar Series 

         FOREST RESPONSES TO CHANGES IN ATMOSPHERIC COMPOSITION AND CLIMATE 

     What is the response of forests to increasing concentrations of carbon 
   dioxide and other gases?  What impact has climate change had on forests? 
   What are the combined effects of these influences on soil fertility, forest 
   productivity, and forest ecosystems?  Do forests in different regions 
  exhibit different responses to these influences?  What  is the outlook for 
                             forests 25 to 50 years from now, and beyond? 

                                                      Public Invited 

                                   Monday June 10, 1996, 3:15-4:45 PM 
                   Rayburn House Office Bldg., Room B369, Washington, DC 
                                                   Reception Following 


INTRODUCTION 

Dr. Jerry Sesco, Deputy Chief of Forest Service for Research, U.S. 
Department of Agriculture (USDA), Washington, DC 

SPEAKERS 

Dr. Richard Birdsey, Program Manager, Northern Global Change Program, USDA 
Forest Service, Radnor, PA 

Dr. J. G. Isebrands, Project Leader, North Central Forest Experiment 
Station, USDA Forest Service, Rhinelander, WI. 

Background 

        Carbon dioxide (CO2) is the most important of the greenhouse gases 
that are influenced directly by human activities. The rising atmospheric 
concentration of carbon dioxide is predicted to enhance photosynthesis of 
some plants and to warm the climate. The CO2 concentration in the atmosphere is 
determined by the emissions from combustion of fossil fuels and by CO2 
uptake and release by the Earth's oceans, vegetation, and soils.  Carbon 
dioxide is taken up by land plants, which annually consume about twelve 
times the world's fossil fuel emissions.  The biosphere also gives off about 
the same amout of CO2 through respiration and plant decay.  This makes 
land plants a critical part of the global carbon cycle. 

Global observations clearly indicate atmospheric concentrations of CO2 are 
increasing. However, the rate of increase in atmospheric CO2 is not as high 
as expected based on the increase in fossil fuel emissions.  This "missing" 
carbon is being taken up by either the oceans or the terrestrial biosphere 
(plants and soils), or both.  Understanding these carbon transfers is 
critical to predicting the importance of global climate change and its 
consequences.  Recent studies have pointed to  carbon accumulation in 
temperate forests of the Northern Hemisphere as a likely explanation for 
the imbalance in the global carbon budget. It is thought that several 
factors may be accounting for the increase in the carbon uptake by the 
terrestrial biosphere - the regrowth of forests in regions where farming is 
being reduced, increased plant growth due to the increase in the CO2 
concentration of the atmosphere, and increased forest productivity as a 
result of nitrogen deposition. 

                                 Atmospheric Changes and Forest Responses 

        Trees and ecosystems are affected by an array of environmental 
factors that vary in space and time, and so a particularly important area 
of research has been the simultaneous effects of multiple factors on 
forests. While simple experiments may show the effects of a single factor, 
it is the timing and intensity of interactions between multiple factors 
that determine how a tree responds to environmental change. There are also 
genetic factors that determine the sensitivity of individual trees to 
stress, and their adaptability to a new environment. 

It is generally accepted that scientists need to study more natural systems 
because of significant difficulties with exposure chamber techniques.  Under 
the auspices of the U.S. Global Chnage Research Program, a multi-agency 
terrestrial ecology program, augmented by funding from private sources, a 
new chamberless experimental facility is under development at a U.S. Forest 
Service site in Rhinelander, Wisconsin.  This will be the largest "free air CO2 
enrichment" (FACE) experimental facility in the U.S., consisting of 12 exposure 
rings, several different tree species, and the capability to simulate exposures 
to CO2 and ozone, singly and in combination. 

In multi-factor, multi-year experiments using exposure chambers, different 
tree species have shown very different responses to elevated ozone levels, 
alone and in combination with elevated CO2 levels. For example, aspen is 
highly sensitive to ozone and there are strong genotypic differences. Ozone 
reduces biomass production and root growth in aspen, and an increase in the 
CO2 concentration does not compensate for the reduction. This negative 
interaction between CO2 and ozone decreases aspen photosynthesis rates more 
than ozone stress alone. In contrast, white pine and yellow poplar show no 
significant detectable adverse effects of exposure to ozone, and growth has 
been stimulated with the simultaneous addition of CO2. 

                                       Models of Forest Behavior and Response 

        Integrated models of physical, biological, and social systems are 
being used to address the effects of different scenarios of climate change 
on forest productivity, carbon storage, and the timber economy.  Initial 
projections from these models suggest that increases in productivity are 
likely for northern forest types, while southern forest types may show 
small increases or decreases in productivity.  In one extreme scenario for 
the southeastern U.S., much of the dense pine forest would be replaced by a 
pine savanna of low productivity.  Forests in the western U.S. may be 
highly sensitive to small climate changes because they often grow at or 
near the limits of climate tolerated by tree species. 

When the ecosystem models are linked with economic models, results show 
that projected increases in productivity may not lead to increases in 
harvest at the national scale because the market responds to many different 
factors besides timber growth.  The models project some redistribution of 
harvest among regions, which would in turn lead to some changes in fiber 
types and the ownership of lands from which wood is harvested.  Harvested 
timber will add to a growing pool of carbon in wood products.  Byproducts 
from timber production, which are burned for energy, reduce the combustion 
of fossil fuels that adds long-stored carbon back into the atmosphere. 

Retrospective applications of the models have explored uptake and release 
of carbon by forests and forest products.  Results suggest that U.S. 
forests are currently a net sink for carbon. Increases in biomass on U.S. 
forest lands over the last 40 years are estimated to have added 281 million 
metric tons per year of stored carbon, enough to offset 25 percent of U.S. 
emissions for the period.  Most of this additional carbon is found in 
regrowing forests on abandoned agricultural land in the eastern U.S. These 
estimates indeed suggest that some of the "missing" carbon can be accounted 
for by storage in northern temperate forests. 

        The integrated models are currently undergoing extensive revisions 
in preparation for another round of projections based on updated forest 
inventory data, new climate projections, and developments in modeling 
techniques. An international model intercomparison study known as VEMAP 
(Vegetation Ecosystem Model Analysis Project) has compared the results of 3 
biogeochemistry models for simulating the response of 21 different U.S. 
vegetation types to climate change scenarios. This exercise has helped the 
model developers understand the strengths and weaknesses in representing 
key ecosystems processes, and will facilitate analytical review of 
uncertainty in projections of vegetation change. 

                                Forest Management to Offset CO2 Emissions 

Opportunities to increase carbon storage above the expected baseline have 
been identified and are beginning to influence landowner decisions. 
Studies have shown that CO2 emissions can be effectively offset by 
sequestering additional carbon at various steps in the life cycle of wood 
growth, harvest, use, and disposal. Typical practices to offset carbon 
emissions include (1) tree planting on marginal agricultural land, (2) 
increasing timber growth on forests now used for timber production, (3) 
increasing the use of wood in place of fossil fuels, and (4) improving wood 
utilization. 

Several U.S. agencies, in partnership with American Forests, a nonprofit 
organization that represents many land owners, have been quantifying how 
various management practices used in different regions and forest types may 
impact carbon storage over long periods of time. This information has been 
used by utility companies to design carbon offset projects to compensate 
for CO2 emissions that are a byproduct of energy generation from fossil 
fuels. Other landowners have begun to use estimates of carbon storage under 
different forest conditions to quantify accomplishments under the 
Department of Energy's "Voluntary Reporting of Greenhouse Gas Reductions" 
Program. 


                                                                Biographies 

Dr. Richard Birdsey is Program Manager of the Northern Global Change 
Research Program within the U.S. Department of Agriculture, Forest Service, 
Northeastern Forest Experiment Station. He is a specialist in quantitative 
methods for large-scale forest inventories and has pioneered the 
development of methods to estimate national carbon budgets for forest lands 
from forest inventory data. He spent 10 years as team leader for forest 
inventory research in the Midsouth States. He was a principal contributor 
to several regional and national assessments of future timber supply in the 
South and the Nation. He designed the first comprehensive inventories of 
forest resources in Puerto Rico and St. Vincent, West Indies.  He is a 
contributor to the ongoing inventory of U.S. greenhouse gases and sinks 
compiled by USDA, EPA, and DOE. He also cooperates with the Sukachev 
Institute of the Russian Academy of Sciences in a project to estimate the 
Russian carbon budget. He was a major contributor to the most recent 
assessment of climate change impacts on America's forests conducted as part 
of the decadal Resources Planning Act Assessment. In his current role as 
Program Manager, Dr. Birdsey is coordinating a national effort to link 
biological and economic models with atmospheric models to assess the 
impacts of global change on U.S. forests, and to analyze mitigation and 
adaptation strategies. He manages a large basic research program involving 
a dozen U.S. Forest Service Laboratories and Experimental Forests in the 
Northeast and North Central States, with research emphases on basic plant 
processes, ecosystem nutrient cycling, and measurement and modeling 
techniques. Dr. Birdsey has degrees in quantitative methods and world 
forestry from the State University of New York, College of Environmental 
Science and Forestry. 

Dr. J. G. Isebrands is Project Leader of a research project in the USDA 
Forest Service (FS), North Central Forest Experiment Station entitled 
"Physiological mechanisms of growth and multiple stress responses in 
northern forests" located in Rhinelander, Wisconsin. His research expertise 
is tree physiology with emphasis on carbon allocation, tree canopy 
architecture and physiological growth process modeling. He is currently the 
FS representative to the Global Change and Terrestrial Ecosystems Core 
Project (GCTE) of the International Geosphere-Biosphere Program (IGBP) as 
well as the FS representative to the FAO-sponsored International Poplar 
Commission. He was involved in the formation of the current FS Global 
Change Program and is currently on the technical advisory committee of the 
FS Northern Global Change Program. He has received an award from this group 
for fostering cooperative research. For 8 years he was the chairman of the 
International Union Forest Research Organization (IUFRO) Working Group on 
"Forest tree canopies" and has been the cochairman of the international 
meetings for that group in Italy, New Zealand, and the U.S. He currently 
holds adjunct research professorships at four universities including 
University of Minnesota, Michigan Tech University, University of 
Washington, and Swedish University of Agricultural Sciences. He holds 
graduate degrees in forestry and forest science from Iowa State University, 
Ames, IA and is the author and/or co-author of over 100 scientific 
publications. 


                     PLANNED TOPIC FOR NEXT SEMINAR on Monday, July 15, 1996 

                                  A Look at Climate Feedbacks and Controls 


For more information please contact: 

Dr. Anthony D. Socci, U.S. Global Change Research Program Office 
300 D St., SW, Suite 840, Washington, DC 20024 
Telephone: (202) 651-8244; Fax: (202) 554-6715 
E-Mail: TSOCCI at USGCRP.GOV. 

Additional information on the U.S. Global Change Research Program (USGCRP) 
and this Seminar Series is available on the USGCRP Home Page at: 
http://www.usgcrp.gov. Normally these seminars are held on the second 
Monday of each month.