Abstract: Aims Elucidating the mechanisms of underlying microbial biomass and extracellular enzyme activity responses to the seasonal distribution change of precipitation during litter decomposition is of great significance for understanding the material cycle of forest ecosystems in the context of global climate change. Methods A precipitation manipulation experiment including a control (CK) and treatments with decreased precipitation in the dry season and extremely increased precipitation in the wet season (IE) and decreased precipitation in the dry season and proportionally increased precipitation in the wet season (IP) was conducted in a subtropical evergreen broad-leaved forest in China from October 2020 to October 2021. The microbial biomass and extracellular enzyme activities of foliar litter from two dominant shrub species, Phyllostachys violascens and Alangium chinense, were investigated using litterbag methods. Important findings The results demonstrated that: (1) the seasonal distribution pattern of precipitation (IE and IP) in “drier dry season and wetter wet season”, which significantly decreased microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) content and the activities of β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG), acid phosphatase (ACP) and cellulase (CL) in dry season, At the same time, the results of the wet season were opposite to those of the dry season. (2) Compared with IE, the effects of IP on foliar litter microbial biomass and extracellular enzyme activity were significantly higher in wet season. (3) MBN and foliar litter water content (LMC) were the main factors affecting extracellular enzyme activity during foliar litter decomposition, and compared with foliar litter water content (8.8%), MBN (56.4%) was a higher explanation of extracellular enzyme activity. The above research results indicated that the precipitation pattern of “drier dry season and wetter wet season” will significantly change the microbial biomass and extracellular enzyme activity during foliar litter decomposition in a subtropical forest, but the size of the effect will vary with the form of future seasonal distribution of precipitation. This study also provides an important theoretical basis for revealing the microbial mechanisms driving the decomposition of foliar litter in subtropical forest areas under precipitation seasonal distribution change in the future.

Key words: microbial biomass, extracellular enzyme activity, subtropical forest, global change, biogeochemical cycle, dry and wet seasons