The relationship between biological diversity and ecological
stability has fascinated ecologists for decades. Determining
the generality of this relationship, and discovering the mechanisms
that underlie it, are vitally important for ecosystem management.
Here, we investigate how species richness affects the temporal stability
of biomass production by reanalyzing 27 recent biodiversity experiments
conducted with primary producers. We find that, in grasslands,
increasing species richness stabilizes whole-community biomass
but destabilizes the dynamics of constituent populations.
Community biomass is stabilized because species richness impacts
mean biomass more strongly than its variance. In algal communities,
species richness has a minimal effect on community stability because
richness affects the mean and variance of biomass nearly equally.
Using a new measure of synchrony among species, we find that for
both grasslands and algae, temporal correlations in species biomass
are lower when species are grown together in polyculture than when
grown alone in monoculture. These results suggest that interspecific
interactions tend to stabilize community biomass in diverse communities.
Contrary to prevailing theory, we found no evidence that
species’ responses to environmental variation in monoculture predicted
the strength of diversity’s stabilizing effect. Together, these
results deepen our understanding of when and why increasing species
richness stabilizes community biomass.
- ecosystem stability
- statistical inevitability
- fluctuating environments
- competitive communities
- ecological communities
- underlying mechanisms
- aquatic microcosms
- plant diversity