Do climate factors govern soil microbial community composition and biomass at a regional scale?

Abstract

Soil microbial communities play important role in organic matter decomposition, nutrient cycling and vegetation dynamic. However, little is known about factors driving soil microbial community composition at large scales. The objective of this study was to determine whether climate dominates among environmental factors governing microbial community composition and biomass at a regional scale. Here, we compared soil microbial communities using phospholipid fatty acid method across 7 land use types from 23 locations in North-East China Transect (850 km × 50 km). The results showed that soil water availability and land use changes exhibited the dominant effects on soil microbial community composition and biomass at the regional scale, while climate factors (expressed as a function of large-scale spatial variation) did not show strong relationships with distribution of microbial community composition. Likewise, factors such as spatial structure, soil texture, nutrient availability and vegetation types were not important. Wetter soils had higher contributions of gram-positive bacteria, whereas drier soils had higher contributions of gram-negative bacteria and fungi. Heavily disturbed soils had lower contributions of gram-negative bacteria and fungi than historically disturbed and undisturbed soils. The lowest microbial biomass appeared in the wettest and driest soils. In conclusion, dominant climate factors, commonly known to structure distribution of macroorganisms, were not the most important drivers governing regional pattern of microbial communities because of inclusion of irrigated and managed practices. In comparison, soil water regime and land use types appear to be primary determinants of microbial community composition and biomass.