Interactive effects of precipitation manipulation and nitrogen addition on soil properties in California grassland and shrubland

摘要: Abstract Soil microbial communities and pools of carbon (C) nitrogen (N) play an important role in ecosystem responses to precipitation variability N deposition. In southern California, vulnerability these environmental change drivers may differ for grassland versus shrubland vegetation types. We hypothesized that (1) types would their manipulation; (2) reduced (“drought treatment”) have a negative effect on soil abundance alter community composition, (3) changes be associated with reductions C pools, (4) addition increase as well (5) combined drought deposition offsetting effects properties. tested hypotheses at the Loma Ridge Global Change Experiment California. Across types, we found biomass based phospholipid fatty acids declined addition. Microbial composition differed more strongly by type than treatments. Added had little but labile pools; were mitigated Drought forms N, whereas increased all pools. Negative additive biomass, which could inhibit cycling if both occur together. interacted significantly most pool under drought + N treatment, suggests build-up available conditions. These results imply multiple combine non-additively affect below-ground microorganisms consequences services such productivity, biodiversity, quality Mediterranean climate regimes North America.