Program Goal

Research provides scientific knowledge of terrestrial components of the global carbon cycle – for the purposes of accurate predictions of atmospheric CO₂ change, evaluating terrestrial sources and sinks for CO₂, and assessing effectiveness of ecosystem processes for controlling and squestering CO₂ – thereby slowing the rate of atmospheric CO₂ increase.

Program Objectives

(1) To advance the scientific understanding of terrestrial processes that regulate carbon balance of ecosystems, including mechanistic controls on exchanges of CO₂ with the atmosphere;
(2) To understand fundamental carbon cycling mechanisms of the atmoshere and biosphere as a basis for enhancing carbon sequestration by terrestrial ecosystems;
(3) To measure changes of carbon quantities of ecosystems in relation to the rising concentration of atmospheric CO₂, and altered temperature and precipitation regimes;
(4) To model terrestrial carbon processes, and use terrestrial ecosystem models coupled with atmosphere-ocean carbon models to estimate rate and timing of atmospheric CO₂ change.

Program Description and Components

Terrestrial Carbon Processes (TCP) research provides the scientific underpinnings for predicting future concentrations of CO₂ in the atmosphere. In particular, TCP research focuses on (i) understanding the processes controlling exchange rate of CO₂ between atmosphere and terrestrial biosphere; (ii) developing process-based models of atmosphere-terrestrial carbon exchange; (iii) evaluating source-sink mechanisms for atmospheric CO₂; and (iv) improving reliability of global carbon models for predicting future atmospheric concentrations of CO₂. The research focuses on natural systems that regulate the abundance of CO₂ in the atmosphere, including the role of terrestrial ecosystems in determining exchanges of CO₂ with the atmosphere. Focus of the research is on the processes and mechanisms that influence quantities fixed by terrestrial ecosystems, and the potential for long-term carbon sequestration is evaluated. This research is distinct from, yet complimentary to continental scale carbon cycle observations of the National Oceanic and Atmospheric Administration (NOAA) and other laboratories. BER's TCP research responds to the U.S. Carbon Cycle Science Plan, and significantly contributes to the Interagency Carbon Cycle Implementation Plan. The research supports AmeriFlux measurements and modeling, and experiments on the effects of CO₂ and changing climate variables on plants and ecosystems. Research also investigates plant physiological controls that affect exchange of CO₂ between the atmosphere and terrestrial biota, changes of carbon content of plants and soil, and mechanisms of carbon transformation in soil. A major uncertainty of the greenhouse gas and potential climate change issue is what happens to the excess CO₂ generated from the burning of fossil fuels. Rate and magnitude by which excess carbon is assimilated into sinks affects the balance that remains in the atmosphere. Terrestrial ecosystems play an important role in this process and fundamental TCP research provides the scientific foundation for estimating the capacity of ecosystems to sequester and store the considerable quantities of CO₂ anticipated from fossil sources in the future. At the larger scale, the research focuses on ecosystem productivity and structural and functional properties of ecosystems, including roles of plant-animal-microbial communities that process carbon. Fundamental plant processes (e.g., photosynthesis, carbon metabolism and water balance) and ecosystem processes (e.g., productivity and nutrient turnover) are examined as they might be affected directly by CO₂ and indirectly by changing climate conditions. Components of field and modeling activities include:

• Carbon (CO₂) flux and biometric measurements in terrestrial ecosystems for evaluating changes of carbon quantities.
• AmeriFlux, the network of CO₂ flux, for directly estimating net ecosystem production (NEP), and carbon sequestration by terrestrial ecosystems.
• Experiments for determining effects of CO₂, climate and other environmental variables on carbon uptake, sequestration by ecosystems (focus is on different environments and biogeochemical and climate-related feedbacks); FACE represents multi-disciplinary experiments to evaluate the responses of terrestrial plants and ecosystems to increased concentrations of atmospheric CO₂ and changing climate variables.
• Mechanistic terrestrial carbon models for evaluating the role of the biosphere in atmospheric CO₂ changes, and the influence of climate and other feedbacks on the biogeochemical cycle of carbon.

Program Announcements

No additional Program Announcement is anticipated in 2003.

Program Linkages

The TCP research is central to DOE's policy concerns about excess CO₂, which is the anticipated major human cause of climate change. Experiments and measurements of TCP provide critical data for tracking atmospheric CO₂ changes, and for quantifying the terrestrial term of the excess CO₂ budget. TCP data contribute to integrated Programs of the U. S. Global Change Research Program, particularly the "Carbon Cycle" interdisciplinary research element. The experiments contribute measurably to IGBP research on Global Change and Terrestrial Ecosystems (GCTE), and the AmeriFlux Network represents the North American component of the international FLUXNET Program. Carbon Cycle research contributes fundamental scientific information that underpins carbon sequestration and management programs in the Office of Science and the Office of Fossil Energy. TCP research contributes to the Administration's National Climate Change Technology Initiative (NCCTI) to quantify carbon affects due to carbon sequestration by terrestrial ecosystems. The TCP Program, especially AmeriFlux, contributes to the planned North American Carbon Program.

Program Manager

Dr. Roger C. Dahlman
Climate and Environmental Sciences Division, SC-23.1
Department of Energy, GTN Bldg.
1000 Independence Ave, SW
Washington, DC 20585-1290
(301) 903-4951
Fax: (301) 903-8519
Internet: roger.dahlman@science.doe.gov