Riparian Land Use Reduces Multitrophic Community Stability in Rivers.

Land use intensification threatens river biodiversity and its stability, but effects across multiple trophic levels in real river systems remain unclear. Here, we combined environmental DNA (eDNA) metabarcoding with 213 spatially and temporally stratified sampling sites across a river network to analyze the impacts of land use intensification on biodiversity and community stability across trophic levels. Our eDNA survey captured 379 families across six major organismal groups, revealing pronounced taxon-specific variation in community dynamics. Community structure exhibited significant spatiotemporal variation, whereas richness showed recurrent seasonal peaks and community stability followed distinct longitudinal patterns among organism groups. Riparian land-use intensity was negatively associated with richness, community stability, species stability and asynchrony, with generally stronger and more consistent relationships for stability-related metrics than for richness. Although richness was positively associated with stability in several organism groups, structural equation modeling explained 79% of the variation in community stability and identified stronger associations with species stability and asynchrony than with richness alone. Overall, these findings show that biodiversity-stability relationships vary across taxa and that species-level temporal dynamics provide information beyond taxonomic richness, supporting the inclusion of multitrophic and temporal dimensions in river ecosystem assessments under environmental change.