Nutrients and herbivores impact grassland stability across multiple
spatial scales through different pathways
Abstract
Nutrients and herbivores have independent effects on the temporal
stability of aboveground biomass in grasslands; however, their joint
effects may not be additive and may also depend on spatial scales. In an
experiment adding nutrients and excluding herbivores in 34 globally
distributed grasslands, we found that nutrients and herbivores mainly
had additive effects. Nutrient addition consistently reduced stability
at the local and larger spatial scales (aggregated local communities),
while herbivore exclusion weakly reduced stability at these scales.
Moreover, nutrient addition reduced stability primarily by causing
changes in local community composition over time and by reducing local
species richness and evenness. In contrast, herbivore exclusion weakly
reduced stability at the larger scale mainly by decreasing asynchronous
dynamics among local communities, but also by weakly decreasing local
species richness. Our findings indicate disentangling the influences of
processes operating at different spatial scales may improve conservation
and management in stabilizing grassland biomass.