Intensified rainfall in the wet season alters the microbial contribution to soil carbon storage

Aims Precipitation patterns in the tropics of southern China are predicted to change with an increase of the rainfall in the wet season (WW) and a delay of the wet season into autumn (DW). To explore how soil C cycles respond to a changing precipitation pattern, we established a precipitation manipulation experiment through water exclusion or addition.

Methods We assessed soil physicochemical properties, microbial communities, glomalin-related soil protein (GRSP), and microbial residual carbon (MRC) to indicate whether there are differences in soil C cycling after altered precipitation patterns.

Results Changes in precipitation patterns did not affect soil properties at 0-10 cm soil depth. However, the WW treatment significantly increased microbial biomass (by 52%) at 10-20 cm soil depth owing to its long-term promotion. At the same time, the increment of microorganisms significantly decreased the contribution of fungal MRC to SOC (by 32%), and there was an increasing trend in bacterial MRC and SOC.

Conclusions Over a long time, the facilitation of microbes and the alteration of microbial contribution to SOC by intensified precipitation in the wet season will enhance the carbon sequestration capacity of tropical forest soils, which is of great importance in mitigating global warming.