Soil organic matter dynamics under changing precipitation regimes

Current and predicted changes in global precipitation regimes, characterized by increasing extreme events and wet-dry cycles, present critical uncertainties for terrestrial biogeochemical cycling and soil organic matter (SOM) dynamics. Here, we highlight individual and interactive effects of abiotic and biotic factors on SOM dynamics under changing precipitation amount, timing, and frequency. Particularly, we identify the mechanisms and magnitude by which changes in precipitation regimes alter different fractions of SOM, that is particulate, mineral-associated, and dissolved organic matter, across temporal and spatial scales. We also discuss how precipitation and other environmental changes interactively affect the formation, decomposition, and stability of SOM. Finally, we propose future research directions to better assess and predict SOM dynamics in a changing world.