Wood decomposition is mediated by microbial activity. As decay proceeds, the composition and function of the resident bacterial communities change in response to shifting resource availability and interspecific interactions. However, we lack studies unravelling the effects of interspecific interactions from abiotic drivers of bacterial community composition. Here, we identified (i) how bacterial taxa changed along a chronosequence of wood decay stages; (ii) bacterial community succession dependency on the wood chemical characteristics.. Wood characteristics determine bacterial assembly

Wood decomposition is a continuum of physical and chemical changes that are largely mediated by microbial activity. As decay proceeds, the composition and function of the resident bacterial communities change in response to shifting resource availability and interspecific interactions. However, we lack studies disentangling the effects of interspecific interactions, such as cooperation and facilitation, from abiotic drivers of bacterial community composition, especially in relation to changing wood decay status. Here, we identified how (i) the diversity and abundance of bacterial taxa changed along a chronosequence of Populus grandidentata Michx. (bigtooth aspen) decay stages; (ii) bacterial community succession was dependent on the chemical characteristics of the downed wood; (iii) interspecific bacterial interactions may mediate community structure. Bacterial community succession displayed two stages of decomposition: an early stage of decomposition characterized by bacteria present in the original tree tissue microbiome along with nitrogen fixing bacteria that colonized the wood, and a late stage of decomposition characterized by bacterial taxa that displayed a gradual progression toward resembling soil communities. The shifts in bacterial assemblage and abundance paralleled changes in wood C and N-content, moisture, and pH. We report an increase in interspecific interactions in both total number and coefficient intensity in the late stage of aspen wood decomposition, suggesting the emergence of a more complex community structure as wood decay progresses.