Human activities have introduced massive quantities of nitrogen to both terrestrial and aquatic environments with detrimental effects on forests, rivers, and estuaries. Consequently, it is important to understand how and where natural processes retain and transform nitrogen as it moves across the landscape. Our research will focus on how headwater streams function as sites for retention of nitrogen with emphasis on microbial processes that return nitrogen to the atmosphere. The program design compares headwater streams that differ in their terrestrial settings and the degree with which streams interact with groundwater. Study sites in New Mexico, Tennessee, and North Carolina will be established to compare the influence of forest type (open or dense) and subsurface processes (streams on bedrock vs streams that exchange water with subsurface sediments) to assess how the biota of stream ecosystems effectively retain nitrogen and how these processes vary across the landscape.
