Long-Term Soil Warming Increases K-Strategy Microbes Inducing High Potential of Soil Carbon Decomposition

Abstract

Soil microorganisms are fundamental for regulating the carbon (C) cycle in ecosystems. Changes in soil microbial communities caused by climate warming could have a significant impact on terrestrial ecosystem C cycle. However, how soil microbial community, a key player in C cycle in subtropical forests, responds to long-term warming is poorly characterized. We conducted a long-term soil warming experiment in a subtropical forest to examine the response of microbial community structure, C-associated metabolic function, and respiration to two levels of soil warming. Both bacterial and fungal alpha-diversity declined under warming condition. C-degradation genes abundance and associated enzyme activities increased by soil warming. Moreover, warming decreased soil organic C and increased soil microbial respiration under both warming levels. The increased microbial ratio of K- to r-strategists suggesting that warming promoted the dominance of K-strategy microbes. Our findings indicate that future global warming can accelerate soil C decomposition in subtropical forests through altering the structure of microbial communities and promoting the C-associated metabolic function.

Keywords: C-degradation gene, Climate change, Metabolic function, microbial diversity, Microbial life strategy, Soil microbial respiration