Changes in soil microbial activity and their linkages with soil carbon under global warming

Abstract

Soil microorganisms play an important role in the carbon (C) cycling of terrestrial ecosystems. However, changes in soil microbial activity and their linkages with soil C under global warming remain unclear. Here, a global meta-analysis of 1272 pairwise observations was conducted to explore the effects of warming on soil microbial activity and their linkages with soil C under different warming duration (0–5, 5–10, and > 10 yr), warming magnitudes (<2 and ≥ 2 °C), ecosystem types (cropland, grassland, shrub, and forest), mean annual precipitation (MAP: 0–400, 400–800, and > 800 mm), and mean annual temperature (MAT: 0–5, 5–10, 10–20, and > 20 °C). Warming overall positively affected soil microbial C, bacteria diversity, fungi richness, and soil C content. Moreover, the positive effects of warming on microbial and soil C gradually weakened and even inhibited with increasing warming duration and magnitudes. Additionally, the soil microbial biomass and microbial diversity shifted from positive to negative relationships with increasing MAP and MAT. Warming mainly affected soil microbial biomass and bacteria diversity in grasslands. Finally, warming induced significant linear relationships of microbial variables with soil C. In conclusion, our results indicated that warming had significant influences on soil microbial activity and soil C cycling, depending on warming duration, magnitudes, ecosystem types, MAP, and MAT. Such findings underscore the important effects of warming on soil C cycling in global ecosystems, which may improve our ability to predict soil biogeochemical cycles in this biome.