Soil microbial biomass and community responses to experimental precipitation change: A meta-analysis

Abstract

The activity of soil microbes is strongly constrained by water availability. However, it is unclear how microbial activity responds to spatial and temporal changes in precipitation, particularly to long-term precipitation changes. To identify the spatiotemporal patterns of microbial responses to precipitation changes of differing durations, we conducted a meta-analysis of data from 95 field studies with drought treatments and 109 field studies with elevated precipitation treatments. Our results indicated that microbial biomass carbon (MBC) decreased by 17% under drought and increased by 18% under elevated precipitation. Across all studies, the phospholipid fatty acid (PLFA) biomarkers for fungi and bacteria decreased significantly under drought but increased under elevated precipitation. In addition, the negative effect of drought on MBC tended to be greater at sites with a high aridity index, but the effect of elevated precipitation on MBC did not differ among sites. More importantly, the responses of MBC, fungal and bacterial PLFA abundance did not vary with treatment duration under drought, but under elevated precipitation, they increased in the first five years of treatment and declined thereafter. These results are important for our prediction of microbial responses to long-term precipitation change, because they imply that microbes acclimate to long-term elevated precipitation.