Abstract: Litter decomposition is a critical component of nutrient cycling in forest ecosystems. Betula platyphylla is a dominant tree species in the Wudalianchi volcanic forest ecosystem. We investigated the eco-stoichiometric characteristics, bacterial community composition, and diversity during the decomposition of leaf litter using in situ litterbag incubation and high-throughput sequencing. The results showed that after one year of decomposition, the mass remaining of B. platyphylla leaf litter was 62.6%. Decomposition time significantly influenced carbon (C), nitrogen (N), and phosphorus (P) contents, as well as C/N, C/P, N/P ratios (P<0.05). During decomposition, the relative abundance of Cyanobacteria decreased significantly, whereas that of dominant bacterial taxa, including the phyla Proteobacteria, Bacteroidota, and Actinobacteria, as well as the genera Sphingomonas and Massilia, significantly increased (P<0.05). The relative abundances of bacterial functional groups, such as chemoheterotrophy and aerobic chemoheterotrophy, increased over time (P<0.05). Litter P content, C/P, and N/P were key factors shaping bacterial community structure. However, due to the unique nature of the volcanic lava environment, litter bacterial community was driven by both litter stoichiometry and environmental filtering. Our results provide deeper insights into the driving mechanisms of stoichiometry on litter-associated bacteria during litter decomposition in volcanic forest ecosystems.

Key words: Betula platyphylla, litter decomposition, bacteria, community structure, volcanic forest ecosystem