Andean grassland stability across spatial scales increases with camelid grazing intensity despite biotic homogenization

Abstract

Intensive land use and changing environmental conditions are reshaping the biodiversity, functioning and stability of local Andean grassland communities. It remains unclear whether these effects propagate to larger spatial scales that are most relevant for policy and conservation. Using a multiscale framework, we quantified the influence of grazing intensity and environmental factors on the diversity and temporal stability of productivity in Andean grassland plant communities at both the local (within communities) and larger (among neighbouring communities) spatial scales. We found that higher grazing intensity and soil total nitrogen were related to greater stability at both the local (alpha stability) and larger (gamma stability) scales. Higher gamma stability at higher grazing intensity resulted from enhanced spatial asynchrony of productivity among communities despite biotic homogenization. That is, while higher grazing intensity reduced compositional differences among communities (beta diversity) which in turn decreased spatial asynchrony, this indirect effect was not strong enough to counteract the direct positive influence of grazing on spatial asynchrony and gamma stability. Additionally, local diversity (alpha diversity) decreased with increasing soil acidification but did not influence alpha or gamma stability. Synthesis: Our results emphasize the necessity of considering the complex influences of grazing intensity on diversity and stability at different spatial scales for the effective management of Andean grasslands.