PROGRAM TITLE: Ecological System Dynamics (ECODYN) ACTIVITY STREAMS: Process/Observations, Modeling, Assessment SCIENCE ELEMENT:Ecological Systems and Dynamics U.S. DEPARTMENT OF AGRICULTURE Forest Service DESCRIPTION: The Ecosystem Dynamics research component of our mission focuses on the response of terrestrial and aquatic ecosystems--forest, range, and wildland; wetlands, lakes, and rivers--to global change. Research is conducted at the local and regional levels. It is directed at (1) understanding basic ecosystem processes, such as elemental cycling and responses to a changing physical and chemical environment; (2) determination of plant and animal species composition and the critical characteristics that ensure viable functioning of each component of the whole ecosystem; (3) evaluation of water quality and quantity and the impact of changes in these characteristics on biological diversity as well as the role of forests and rangeland in protecting water quality and quantity; and, (4) assessment of environmental impacts on vegetation and soil and the resulting effects on ecosystem dynamics. The objective of this research is to understand and anticipate the ecosystem changes that will result from altered environmental conditions and to understand the sensitivity of key ecosystem processes and components to different levels of stress. Species migration and ecosystems composition changes will be predicted based on climate, weather, and air pollution scenarios derived from general circulation models and other sources. Threshold limits of ecosystem stability and diversity will be determined. Life histories, population dynamics, competitive interactions, and community dynamics of plants and animals under altered environments are being studied. Threatened, endangered, and sensitive species are also being studied. Accomplishments to date include an extensive information base on current forest and rangeland health, experimental results defining health and function of forest tree species and ecosystem process under current and estimated future climate and pollution. Numerous modeling research projects have provided distribution and productivity for major vegetation types. Modeling projects have also identified how individual plant and communities are impacted by pollution and climate. Ecosystem and biome- level projection of soil-water balance and streamflow have also been completed. A number of projects have analyzed the role of forests (both vegetation and forest soils) as sinks and sources of greenhouse gases. Management and adaptation strategies are being investigated. Scientists in the program are active participants in the Intergovernmental Panel for Climate Change assessments and USDA Forest Service global change summaries for the Resource, Planning, and Assessment five-year reports to Congress. The products and performance measures are peer reviewed publications from this effort numerous peer reviewed publications have been completed and many more are being compiled or are planned. STAKEHOLDERS: Forest land managers, policy makers, producers and consumers of forest products (both market and non-market), and federal agencies. SHORT-TERM POLICY PAYOFFS: Input to President's greenhouse gas emission policy, sound management of this critical sector of the economy.