Compared with pure forest, mixed forest alters microbial diversity and increases the complexity of interdomain networks in arid areas

Abstract

Soil microbial communities are key to material cycling and energy exchange in forest soils. As the Tianshan Mountains in Xinjiang are rich in tree species, it is important to understand the impact of tree species composition on soil microbial community structure and co-occurrence networks in arid mountain habitats. In this study, soil microbial community structure of five typical vegetation types in the Tianshan Mountains of Xinjiang, China, was investigated using bacterial 16S rRNA and fungal ITS sequences. The results showed that the relationship between the fungal community and tree species was strong, while the bacterial community was mainly affected by soil carbon. The dominant bacterial composition was Ascomycota, which had the highest relative abundance in herbaceous soils (27%–41%); the dominant fungal phylum was Ascomycota (50.22%–63.95% of the total sequences), followed by Stramonium (8.99%–28.09%). The fungal community structure of mixed coniferous and broadleaf forests was similar to that of conifers, while the bacterial community structure was similar to that of pure broadleaf forests. Mixed forests (mean connectivity: 812.50, clustering coefficient: 8.89) showed a more complex co-occurrence network and a significant increase in microbial structure related to soil carbon and nitrogen than pure forests (broad: mean connectivity: 710.69, clustering coefficient: 6.94; coniferous: mean connectivity: 730.79, clustering coefficient: 7.76). The results contribute to the understanding of the interactions between soil microorganisms and soil factors in different forest ecosystems and provide new insights into the interactions among forest microorganisms in arid zones. IMPORTANCE The results provide a comparative study of the response of soil microbial ecology to the afforestation of different tree species and deepen the understanding of the factors controlling soil microbial community structure.