Disturbance Interacts with Dispersal and Niche Breadth to Shape Scale-Dependent Diversity Change in Metacommunities

AbstractEnvironmental disturbance can drive biodiversity change at both local (α) and regional (γ) scales, yet its effects on spatial turnover (β diversity) are often inconsistent. Using a process-based metacommunity model, we show how dispersal and niche breadth jointly structure scale-dependent diversity dynamics in response to disturbance. Our results reveal that dispersal determines the balance of diversity loss between α and γ scales, leading to either homogenization (β diversity decreases) or differentiation (β diversity increases) after disturbance. High dispersal promotes rapid local recovery but accelerates regional extinctions, while dispersal limitation impedes recolonization. Niche breadth mediates sensitivity to disturbance, with specialist-dominated communities suffering greater diversity loss. We show how the interaction between dispersal and niche breadth structure the dynamics of scale-specific diversity dynamics, which determine β diversity change following disturbance. These results offer a mechanistic framework for predicting when and how communities reorganize across scales following environmental perturbation.