The ultimate goal of this research is to develop a method that will allow repeated inventories of land-use and land-cover from space and then to evaluate the ecosystem consequences of observed and predicted land-cover changes in the Great Plains. Without an understanding of the biogeochemical consequences of such major land-cover change as in the eastern Great Plains, it will not be possible to manage resources to insure their sustainability. To achieve this goal, we are using aerial photos, remote sensing and GIS techniques coupled with in situ process-level biogeochemical and ecosystem flux studies. We will link the biogeochemical studies to land-cover change using the Marine Biological Laboratory-General Ecosystem Model (GEM) and GIS techniques and ultimately predict long-term changes on a regional scale. Specific objectives of this proposal are to: · 1. assess the current distribution of land-cover, document the historical change in land-cover (especially forest cover) using aerial photographs and remote sensing (using both historical and present data), linked to a GIS data base which will have important information on the potential forcing factors (socioeconomic vs climatic, ecological), · 2. quantify the effects of forest expansion on biogeochemical processes controlling the quantity, quality, and distribution of soil organic matter and soil C, and N cycling and availability, · 3. determine how these life-form shifts alter ecosystem C balance and fluxes of CO2, H2O, and energy, and · 4. incorporate a spatially-explicit model (GEM) that will link our in situ biogeochemical and ecosystem studies with spatial information on land-cover change to predict ecosystem consequences of the impact of future forest expansion. In only the last 9 months since receiving our NASA funding, we have made significant progress in meeting our stated goals and objectives. We have established three paired forest-grassland study sites in which we have begun conducting our intensive, process-level in situ biogeochemical measurements and C flux studies. These three forests range in age from 40 (Dobson, Carlson sites) to 60 years old (Borg forest) and represent the ecological endpoint of the shift from grassland to forest. Additionally, we have begun acquiring and processing the necessary remote sensing imagery and GIS data which will allow us to scale up the ecosystem consequences of forest expansion to the regional level of eastern KS. Our progress is also documented on our web page (http: //climate.konza.ksu.edu /general nasalandcover/landuse.html established in March 1998). Below we provide specific details as to our progress.