Biogeographical patterns of rhizosphere microbial communities in Robinia pseudoacacia forests along a north–south transect in the Loess Plateau

•Restored forests were associated with distinct rhizosphere microbiota across space.•Microbial richness peaked at lower latitudes with distance decay in community similarity.•Fungi exhibited a more prominent spatial pattern in the rhizosphere than bacteria.•Deterministic processes dominated microbial community assembly.•Co-occurrence patterns of sensitive taxa demonstrated prominent regional effects.