Greenhouse gas fluxes under drought and nitrogen addition in a Southern California grassland

摘要

Climate and regional air quality models predict that Southern California will experience longer and more severe droughts, and possibly wetter, more intense storms and changing nitrogen (N) deposition. We investigated how the three major soil greenhouse gas (GHG) fluxes respond to 4-6 years of exposure to a full-factorial experiment of reduced and augmented precipitation crossed with increased N in a semi-arid grassland in Irvine, CA, USA. The mean emission fluxes across all treatments were 249.8 mg CO2 m(-2) h(-1), -16.41 mu g CH4 m(-2) h(-1), and 2.24 mu g N2O m(-2) h(-1). Added N plots released 3.5 times more N2O than ambient N plots, and N treatment and soil moisture interacted, such that volumetric soil moisture in added N plots correlated positively with N2O release. Soil moisture, which was higher in the added water plots, correlated positively with respiration. CH4 consumption increased with soil moisture in the drought treatment, an opposite trend to that observed in most other studies.