The fate of nitrogen inputs to terrestrial ecosystems

Recent technical innovations in the use of 15N stable isotopic tracers at the ecosystem scale have produced a wealth of data on the fate of N inputs to terrestrial ecosystems. Although this analytically intensive technique has been used at over 20 sites world wide, there have been few attempts at cross-site synthesis. Here we propose a series of working group activities to synthesize ecosystem-scale 15N tracer experiments across a wide geographic range of ecosystem types. While at NCEAS, we propose to develop three products: (1) a standardized protocol for application and analysis of 15N tracer studies, (2) a meta-analysis of the fate and redistribution of N across sites and ecosystem types, and (3) an inter-site comparison with the TRACE model, a simulation model that predicts the fate of N inputs over long time scales. Through these activities, we will address questions about controls over the fate of N inputs in terrestrial ecosystems and the consequences of increased N deposition.