Nature restoration shifts the abundance and structure of soil nematode communities in subtropical forests

Soil nematode community is an important component of the soil food web, which has been widely recognized as a key bio-indicator for assessing the influence of nature restoration on ecological functions. However, the dynamics of the abundance, structure of soil nematode community remain unclear under nature restoration. The soil nematode community of natural secondary forests was investigated using a chronosequence approach in subtropical forests in China. Six succession stages of nature restoration were sampled to represent forest stand age groups with 4-5, 8-12, 18-22, 25-30, 35-40 and over 100 years. To enhance our understanding of the factors influencing soil nematode communities, we also examined the relationships between plant community, soil microbial community, and soil properties by structural equation modeling. Soil nematode abundance gradually increased with forest stand ages, which reached a peak value (574 individuals 100 g−1 dry soil) in the oldest stands. Soil available nitrogen and phosphorus were key factors influencing soil nematode abundance and diversity during secondary forest succession. The plant parasite index decreased with forest stand ages, which indicated that ecosystem function and health would be improved as nature restoration. The structure of soil nematode community was more sensitive to microbial community compared to plant community. The bottom-up effects of microbial communities on soil nematode communities were important drivers of nematode communities in subtropical forests. This study demonstrates the active responses of soil nematode community to nature restoration and highlights the importance of the above-ground and below-ground interactions to the soil food web.