Dominant woody plants alter soil microbial community composition during succession

Abstract

Belowground assemblages are closely related to the aboveground vegetation and edaphic properties, which are also driven by dominant plants due to direct and indirect influences. However, the effects of dominant woody plants on the belowground organisms along successional gradients remain poorly understood. Plant and soil samples were collected from an initial herbaceous stage (i.e. alpine meadows) and four stages dominated by woody species, beneath and between patches of the dominant woody plants, to assess the effects of dominant woody plants on the succession of microbial communities along a secondary successional gradient. We quantified herbaceous, edaphic, bacterial, and fungal dissimilarities between stages to explore how dominant woody plants affect bacterial and fungal dissimilarities between stages using structural equation modeling. We found that dominant woody plants generally increase the succession of microbial communities in early stages, but decrease it in late stages. Our results further suggest that the herbaceous dissimilarity between stages plays more important roles than the edaphic one in mediating the effect of dominant woody plants on both bacterial and fungal dissimilarities between stages. Our results provide insight into the relative role of direct and indirect influences on microbial dissimilarity between stages and highlight the importance of dominant woody plants in driving microbial succession. As woody encroachment increases in alpine meadows, the dominant woody plants may have strong consequences on the dynamic of microbial communities, thereby affecting ecosystem functioning.