Climate Variability Modulates the Temporal Stability of Carbon Sequestration by Changing Multiple Facets of Biodiversity in Temperate Forests Across Scales

Climate variability poses a significant threat to ecosystem function and stability. Previous studies suggest that multiple facets of biodiversity enhance the temporal stability of forest ecosystem functioning through compensatory effects. However, as climate change intensifies, two key questions remain unresolved: (1) the mechanisms by which different biodiversity facets sustain the temporal stability of carbon sequestration across spatial scales and (2) how climate variability influences biodiversity and stability at different scales. In this study, based on data from 262 natural communities in the temperate forests of northeastern China, we aggregated metacommunities at varying spatial extents. Using ordinary-least squares regression, we examined the relationships between different facets of biodiversity and the temporal stability of carbon sequestration (hereafter, "stability") across scales. We then employed mixed-effects models to assess how multiple facets of biodiversity influence biotic stability mechanisms at different scales. Additionally, we applied piecewise structural equation modeling to disentangle the relationships among climate variability, multiple facets of biodiversity, and stability across scales. Our findings indicate that biodiversity facets (taxonomic, functional, and phylogenetic diversity) enhance ecosystem stability at multiple scales primarily through insurance effects. Temperature variability was negatively correlated with all biodiversity facets, and declines in biodiversity were associated with reduced ecosystem stability at different scales. Precipitation variability, in contrast, was negatively correlated with α diversity facets but positively correlated with β diversity facets. Unexpectedly, precipitation variability exhibited an overall positive correlation with stability across scales. These results suggest that increasing temperature variability may pose a greater threat to temperate forest ecosystems in the future. Thus, preserving multiple facets of biodiversity across spatial scales will be critical for mitigating the adverse effects of climate warming. Furthermore, the impact of precipitation variability cannot be overlooked in arid and semi-arid regions. Our study provides novel insights into biodiversity conservation under global climate change.