PS 24-45 - Global scale differention in the effects of altered precipitation regimes on soil nitrogen cycling

Background/Question/Methods

Changes in precipitation regimes can strongly affect soil nitrogen (N) cycling in terrestrial ecosystems. However, whether altered precipitation regimes may differentially affect soil N cycling between arid and humid biomes at the global scale is not clear. We conducted a meta-analysis using 1036 pairwise observations from 194 publications to examine the effects of increased or decreased precipitation on the input (N return from plants), storage (N retained in soil), and output (gaseous N emissions) of soil N at the global scale.

Results/Conclusions

We found that (1) increased precipitation increased N input (+12.1%) and output (+34.9%), but decreased N storage (-13.7%), while decreased precipitation decreased N input (+10.7%) and output (+34.8%), but increased N storage (-11.1%); (2) the sensitivity of soil N cycling to increased precipitation was higher in arid than in humid regions, while that to decreased precipitation was lower in arid than in humid regions; (3) the effect of altered precipitation regimes on soil N cycling was independent of precipitation type (i.e., rainfall vs. snowfall); and (4) in precipitation alteration experiments, mean annual precipitation regulated soil N cycling at the global scale. We conclude that the response of soil N cycling to altered precipitation regimes depends not only on the direction of the alteration (increased or decreased precipitation) but also on the regional climate (arid or humid). Our research suggests that under future global change scenarios, ecosystem models need to consider the differential responses of N cycling to altered precipitation regimes in ecosystems in different climatic conditions.