Shifting community assembly mechanisms in soil eukaryotes over successional time and their implications for restoration.

Integration of soil biodiversity restoration into reforestation strategies is important to accelerate the restoration process given the interplay between belowground and plant community dynamics. Research on the mechanisms underlying the temporal changes that occur in soil communities has been limited, and this is especially true for eukaryotes. Understanding these processes can help us to manipulate soil communities in a way that promotes recovery and stability. Here, we test the importance of selection, dispersal, and drift in structuring community composition of taxonomic and functional groups of soil eukaryotes in croplands and planted forests, and their relationships with successional time. We observed a link between functional/taxonomic groups of soil eukaryotes, the importance of ecological processes in their community compositional patterns, and successional time. To optimize the effectiveness of soil restoration, we suggest implementing additional measures that target specific groups of soil organisms, account for the key ecological processes structuring their communities, and address how these processes correlate with successional time. Our findings advance both theoretical understanding and practical guidelines for restoring soil biodiversity.