PROGRAM TITLE: Global Change Research in Earth's Drylands ACTIVITY STREAM: Process Studies SCIENCE ELEMENTS:Solid-Earth Processes, Earth System History SMITHSONIAN INSTITUTION NATIONAL AIR AND SPACE MUSEUM SCIENTIFIC MERIT: Over three-quarters of Earth's land surface is arid or semi-arid. We are studying the interactions between landforms, soils, climate, and vegetation in these environments in order to understand the relationships between dryland surface processes and both past and present climate variations. Current long-term study sites include locations in Africa, the Middle East, North America and Europe with plans to add sites in South America. The two major courses of study under this program focus on (1) dryland sediment transport and climate change, and (2) dryland vegetation dynamics and climate change. Sediment transport studies encompass the effects of climate change on the rates, directions, and timing of desert sand transport, and the development, preservation and erosion of dryland soils. Vegetation dynamics studies include determining seasonal and longer-term reflectance variations due to vegetation and surface processes across a range of dryland environments. The objective of these studies is to determine linkages between drought, sand transport, soil stability and vegetation dynamics, all of which are important components of change in areas prone to land degradation (desertification), deforestation, and consequent loss of ecological complexity. The methodology used in these studies combines computer analysis of digital satellite data with ground observations and laboratory studies of the vegetation, soils and sediments from the field areas. A combination of data from various sensor systems is used, depending on specific objectives of each study. Heavy use is made of visible and reflected infrared wavelength multispectral image data (e.g., Landsat TM and MSS, SPOT, and AVHRR data) and imaging radar (e.g., Seasat and Shuttle Imaging Radar (SIR-A, -B, and -C). These studies include the development of baseline reflectance data and supporting field and lab work for dryland soils and vegetation in true desert (e.g. Egypt, Namibia), Sahelian grasslands (e.g. Mali) and tree and shrub savanna (e.g. Kenya and Botswana). Studies of temperate forest loss (e.g. Czechoslovakia) are conducted using similar techniques. STAKEHOLDERS: The research within this program of study involves U.S. and international collaborators. These include scientists at the University of Arizona, the University of New Amphoras, Boston University, the University of New Hampshire, the National Aeronautics and Space Administration, and colleagues in Egypt, Mali, Botswana, Kenya, Namibia and Czechoslovakia. The research is directly related to the goals of several Core Projects within the IGBP, including LOICZ, BAHC, GCTE, PAGES, and GAIM. POLICY RELEVANCE: The program directly contributes to the study of two high-priority USGCRP milestones; specifically Forests and Deforestation, and Desertification; under Global Water, Energy Cycles, and Sea Level Change: Linkages between climate and surface hydrologic conditions identified, Continental scale energy and water exchange processes characterized for mid- latitude regions, Watershed fluvial processes characterized. Under Ecological Systems and Population Dynamics: this program will contribute Decadal (and interdecadal) measurements of African deserts. PROGRAM CONTACTS:SI SGCR Representative: Ted A. Maxwell NASM MRC 315 Smithsonian Institution Washington, D.C. 20560 202 357 1424 FAX: 202 786 2566 Email: tmaxwell@ceps.nasm.edu Bureau Representative: Pat Jacobberger NASM MRC 315 Smithsonian Institution Washington, D.C. 20560 202 357 1424 FAX: 202 786 2566