Local diversity, beta diversity and climate influence the regional stability of bird biomass across North America

Biodiversity often stabilizes aggregate ecosystem properties (e.g., biomass) at small spatial scales. However, the importance of species diversity within communities and variation in species composition among communities (β-diversity) for stability at larger scales remains unclear. Using a continental-scale analysis of 1,657 North American breeding-bird communities spanning 20-years and 35 ecoregions, we show local species diversity and β-diversity influence two components of regional stability: local stability (stability of bird biomass within sites) and spatial asynchrony (asynchronous fluctuations in biomass among sites). We found spatial asynchrony explained three times more variation in regional stability of bird biomass than did local stability. This result contrasts with studies at smaller spatial scales – typically plant metacommunities under 1 hectare – that find local stability to be more important than spatial asynchrony. Moreover, spatial asynchrony of bird biomass increased...