Rates of woody debris movement downstream will be compared among four streams in Coweeta Experimental Forest (a site operated by the U.S. Department of Agriculture's Forest Service). These will then be compared with analogous results from a pair of streams in Puerto Rigo's Luquillo Experimental Forest. The locations of marked (tagged) wood added to headwaters of these tributary streams are to be mapped after major rainfall events in order to determine how quantity and sizes of these pieces influence their downstream movement. The greater amont and diversity of sizes of wood expected in streams meandering through older forests will more often lead to formation of debris dams, which decrease water flow rates and increase retention of leaf litter within the stream, thereby altering physico-chemical conditions of the stream. Such differences have a profound influence on the species composition and abundances of benthic community members. A major component of this study is the application of Geographical Information System (GIS) technology to record sequential changes in positions of natural and added woody debris. Some of the GIS software being developed will be used to simulate movement of materials downstream in natural catchment basins by using digital data on topography, elevation, and slope. This methodology has been developed to manipulate digitized data available from remotely sensed (aircraft and satellite) imagery. The capacity to store and handle large comparative data sets is finding wide use in ecological studies but has not yet been applied to analysis of detrital materials. Dr. Alan P. Covich, of the University of Oklahoma, will devote twelve months of Mid- Career Fellowship in Environmental Biology tenure to this research. The host institution is the University of Georgia.
