Shaping River Resilience: Insights from the Multidimensional Beta Diversity of Macroinvertebrates

Understanding how biodiversity mediates ecological resilience is fundamental to sustaining the stability and functionality of river ecosystems. While previous studies have linked biodiversity to resilience, the specific contribution of beta diversity remains insufficiently elucidated. In this study, we quantified taxonomic, functional, and phylogenetic beta diversity in macroinvertebrate communities along the upper Qin River, partitioning each dimension into turnover and nestedness components. Using partial least squares path modeling, we investigated how these components relate to ecological resilience, indexed by the secondary productivity-to-biomass ratio (P/B ratio). We further assessed the mediating roles of aquatic plant distribution and abiotic environmental factors in shaping biodiversity-resilience dynamics. Our findings reveal that taxonomic turnover and nestedness, as well as phylogenetic turnover, exert significant and contrasting effects on the P/B ratio, while functional beta diversity exhibited no significant influence. These results suggest that species and lineage turnover enhance resilience by introducing taxa with broader environmental tolerance and divergent evolutionary strategies, whereas nestedness may constrain ecosystem function by reflecting non-random species loss. The lack of a functional beta diversity effect likely stems from trait redundancy, which buffers functional composition against taxonomic shifts. Abiotic variables emerged as key drivers of beta diversity patterns across all dimensions, whereas aquatic plant distribution had limited influence, likely due to structural redundancy and niche overlap among dominant aquatic plant forms. Collectively, these findings highlight the importance of promoting species and phylogenetic turnover and maintaining functional redundancy as mechanisms for enhancing ecological resilience. This multidimensional perspective offers an integrative framework for informing riverine biodiversity conservation and adaptive management under increasing environmental pressures.