The study of litter decomposition was often tightly linked to some hot topics such as global carbon balance and climate change, but the knowledge of microbes involved in litter decomposition remains limited especially in freshwater lake wetlands. An in situ experiment (278 d) was carried out to study the decomposition processes of two typical wetland plants-Carex cinerascens and Triarrhena lutarioriparia. The litter decay rate, extracellular enzyme, and microbial community composition were all observed. The decomposition rate of C. cinerascens was faster than T. lutarioriparia. Higher contents of TOC, TN, and TP conferred higher decomposition rate to C. cinerascens, as well as the higher activities of all tested enzymes and the lower content of lignin. The alpha diversity of bacterial and fungal communities changed separately over time, but their copy numbers of the rRNA gene (qPCR) increased collectively in both litters. Betaproteobacteria, Gammaproteobacteria, Bacteroidetes, and Basidiomycota were common in the primary stage (0-37 d) of decay in both litters, while Alphaproteobacteria, Chloroflexi, Nitrospirae, and Montagnulaceae were prevailing in the later stage (212-278 d). T. lutarioriparia also had higher proportions of Actinobacteria, Acidobacteria, and Firmicutes in the later stage. Pleosporales and Hypocreales were predominant during the whole decay processes of both litters. Our results showed that the microbial community composition was mainly regulated by litter stoichiometry (hemicellulose, lignin, and AFDM), thereby reflecting the niches differentiation caused by resource partitioning on litter decomposition. This work helps to the understanding of the microbial community involved in litter decomposition in wetland ecosystems.

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