Acclimation of the Nitrogen Cycle to Changes in Precipitation

Abstract Climate change drivers elicit ecosystem responses that vary through time. We propose that the mismatch between equilibrium and transient ecosystem response defines ecological acclimation. As precipitation is expected to shift under climate change, we asked how both increases and decreases in water availability elicit ecological acclimation of the N cycle and how long does this acclimation take. Using foliar δ 15 N as a proxy for N cycling processes, we found that the slope of foliar δ 15 N decreases with mean annual precipitation across continents. However, within a desert grassland, slopes of interannual foliar and soil δ 15 N increased with precipitation amount. Using precipitation manipulation field experiments, we then assessed trends in foliar and soil δ 15 N as duration of the precipitation manipulation increased, from 5 to 14 years. When parsed temporally, the δ 15 N-precipitation slopes showed initially increasing trends that decr