Abstract
The worldwide biodiversity crisis has intensified the need to better
understand how biodiversity and human disturbance are related. The
'intermediate disturbance hypothesis' suggests that disturbance regimes
generate predictable non-linear patterns in species richness. Evidence
often contradicts intermediate disturbance hypothesis at small scales,
and is generally lacking at large regional scales. Here, we present the
largest extent study of human impacts on boreal plant biodiversity to
date. Disturbance extent ranged from 0 to 100% disturbed in vascular
plant communities, varying from intact forest to agricultural fields,
forestry cut blocks and oil sands. We show for the first time that
across a broad region species richness peaked in communities with
intermediate anthropogenic disturbance, as predicted by intermediate
disturbance hypothesis, even when accounting for many environmental
covariates. Intermediate disturbance hypothesis was consistently
supported across trees, shrubs, forbs and grasses, with temporary and
perpetual disturbances. However, only native species fit this pattern;
exotic species richness increased linearly with disturbance.
Nincsenek megjegyzések:
Megjegyzés küldése