Regional boreal biodiversity peaks at intermediatehuman disturbance

摘要

The worldwide biodiversity crisis has intensified the need to better understand howbiodiversity and human disturbance are related. The ‘intermediate disturbance hypothesis’suggests that disturbance regimes generate predictable non-linear patterns in speciesrichness. Evidence often contradicts intermediate disturbance hypothesis at small scales,and is generally lacking at large regional scales. Here, we present the largest extent studyof human impacts on boreal plant biodiversity to date. Disturbance extent ranged from 0 to100% 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 speciesrichness peaked in communities with intermediate anthropogenic disturbance, as predictedby intermediate disturbance hypothesis, even when accounting for many environmentalcovariates. Intermediate disturbance hypothesis was consistently supported across trees,shrubs, forbs and grasses, with temporary and perpetual disturbances. However, only nativespecies fit this pattern; exotic species richness increased linearly with disturbance.