The dynamics of bacterial communities during leaf decomposition of various species combinations in riparian forest buffers in China

Abstract

Leaf litter decomposition determines nutrient cycling and soil formation in forests, driven largely by bacterial community composition and diversity. However, the roles of leaf types and altitude in shaping bacterial communities and leaf decomposition remain unclear in riparian forest buffers within karst river systems. This study investigated bacterial community composition across various leaf types (broad-leaved: Salix matsudana Koidz; pine-leaved: Taxodium distichum (Linn.) Rich., Taxodium ascendens Brongn.) and altitudes to clarify their roles in decomposition. Leaf samples, including single-species and mixed-species types, were collected at altitudes of 60 m, 110 m, and 800 m. High-throughput 16S rRNA gene sequencing was used to identify bacterial communities at the phylum and genus levels. Bacterial richness and diversity were assessed using alpha diversity indices (Chao1, Shannon, and Simpson). Leaf chemical properties were analyzed to determine their relationships with bacterial community structure and decomposition rates. Results showed significant differences in bacterial richness, diversity, and phylogenetic diversity across leaf types and altitudes. Mixed-species samples exhibited greater bacterial diversity than single-species samples, suggesting that substrate heterogeneity enhances bacterial abundance and functionality. Bacteroidetes were the dominant decomposers due to their ability to degrade complex polymers like lignin. Redundancy analysis revealed that leaf chemical characteristics strongly influence bacterial community structure and decomposition. Environmental factors in conjunction with altitude also shape bacterial composition. This study emphasizes the complex interactions between bacterial diversity, substrate quality, and environmental factors during decomposition. Understanding these dynamics provides the basis for predicting nutrient cycling and forest ecosystem functioning.