Scaling of population resilience with dispersal length and habitat size

TL;DR

This paper investigates how population resilience to environmental fluctuations diminishes with reduced dispersal length and habitat size, revealing key scaling laws that highlight dispersal length as critical for extinction risk mitigation.

Contribution

It introduces a quantitative analysis of how dispersal length and habitat size influence population resilience, establishing scaling laws that identify dispersal length as a critical factor.

Findings

Resilience decreases as dispersal length or habitat size are reduced.

Extinction threshold scales with the ratio of dispersal length to environmental synchrony.

Habitat reduction lowers resilience, especially when habitat size is comparable to dispersal distances.

Abstract

Environmental fluctuations can create population-depleted areas and even extinct areas for the population. This effect is more severe in the presence of the Allee effect (decreasing growth rate at low population densities). Dispersal inside the habitat provides a rescue effect on population-depleted areas, enhancing the population resilience to environmental fluctuations. Habitat reduction decreases the effectiveness of the dispersal rescue mechanism. We report here how the population resilience to environmental fluctuations decreases when the dispersal length or the habitat size are reduced. The resilience reduction is characterized by a decrease of the extinction threshold for environmental fluctuations. The extinction threshold is shown to scale with the ratio between the dispersal length and the scale of environmental synchrony, i.e., it is the dispersal connection between non-environmentally-correlated regions that provides resilience to environmental fluctuations. Habitat reduction also decreases the resilience to environmental fluctuations, when the habitat size is similar to or smaller than the characteristic dispersal distances. The power laws of these scaling behaviors are characterized here. Alternative scaling functions with spatial scales of population synchrony are found to fit the simulations worse. These results support the dispersal length as the critical scale for extinction induced by habitat reduction.