Microbial community structure of decayed trunks of Populus euphratica desert riparian forests in the lower Tarim River, Xinjiang, China

Rich microbial communities are associated with tree decay, and they markedly impact the degradation of tree species and material cycling within ecosystems. The native Populus euphratica forests along the lower Tarim River of China are mostly mature or over-mature, with many tree trunks exhibiting features of extensive cavity decay and slow regeneration. In this study, a growth cone was used to drill a wood core at varying degrees of decay, and 16S and internal transcribed spacer techniques were used to identify the microbial structure (fungi and bacteria) within the wood core. Changes in the trunk microbial community under varying decay conditions were also examined. For healthy, lightly decayed, and heavily decayed trunk, the dominant bacterial and fungal phyla were Firmicutes and Actinobacteria, Ascomycota, and Basidiomycota, respectively. As decay progressed, the alpha diversity index of the microbial community tended to decline. The maximum number of differential species was found in healthy trunks, where leaner discriminant analysis effect size (LEfSe) of fungi and bacteria revealed 1 and 15 different species, respectively. Species network analysis showed that interspecific linkages were more complex within bacterial communities than within fungal communities, with the complexity of fungal interspecific relationship increasing as decay progressed. The microbial communities of P. euphratica trunks differed significantly with the varying degrees of decay. Microbes such as Ralstonia may also play key roles in the decay process. In addition to providing a foundation for the sustainable management of desert riparian forests, investigating the mechanisms through which microbial communities influence the deterioration of P. euphratica trunks provides information about the general health of P. euphratica forests.