Secondary succession increases diversity and network complexity of soil microbial communities in subtropical and temperate forests

Abstract

Clarifying the responses of soil microbial communities to long-term forest secondary succession is useful for predicting future effects of forest restoration and protection on soil communities and ecosystem functions. In this study, high-throughput sequencing was used to investigate soil bacterial and fungal communities at early, mid, and late successional stages spanning several centuries in a temperate forest and a subtropical forest in China. Succession increased diversity and altered the structure of bacterial and fungal communities, especially those of fungal communities, in both forest types. The late successional stage favored the maintenance of microbial network complexity in both forests and increased the potential positive links between bacteria and fungi. Total soil phosphorus and litter carbon in the subtropical forest and total soil nitrogen in the temperate forest were important drivers of the variation in soil microbial communities during succession. Collectively, the results suggest the following: old-growth forests have an irreplaceable role in maintaining high soil microbial diversity and complexity; fungal communities are more sensitive than bacterial communities to succession; and changes in soil and litter properties during succession have different effects on soil microbial communities in different forests.