Plant litter decomposition in wetlands is closely associated with phyllospheric fungi as revealed by microbial community dynamics and co-occurrence network

Phyllospheric microbes play a crucial role in the biological decomposition of plant litter in wetland ecosystems. Previous studies have mainly focused on single stages of decomposition process, and to date there have been no reports on dynamic changes in the composition of phyllospheric microbes during the multiple stages of decomposition from living plant to death. Here we investigated fungal and bacterial community succession in the leaf litter of Schoenoplectus tabernaemontani, a wetland plant species using sequencing of the both fungal ITS and bacterial 16S genes. Our results revealed that, over the whole period of decomposition, the fungal communities underwent more distinct succession than did the bacterial communities. Proteobacteria dominated throughout the entire period, while, across different decomposition stages, the Ascomycete fungi were gradually replaced by the Ciliophora and Rozellomycota as the dominant fungi. Network analysis revealed higher degrees of species segregation and shorter average path lengths between species of fungi compared with species of bacteria. This suggests that fungal communities may harbor more niches and functional diversity and are potentially more susceptible to external interference than are bacterial communities. During decomposition, the contents of leaf cellulose, hemicellulose and lignin in the litter were significantly (p < 0.01) correlated with the fungal communities, and abiotic factors accounted for 89.8% of the total variation in the fungal communities. In contract, abiotic factors only explained 6.10% of the total variation in bacterial communities, suggesting external environments as drivers of fungal community succession. Overall, we provide evidence that the complex litter decay in wetlands is the result of a dynamic cross-kingdom succession, and this process is accompanied by distinct phyllospheric fungal community dynamics.