A mathematical partitioning of the effects of habitat loss and habitat degradation on species abundance

Context: Worldwide, anthropogenic habitat loss and degradation have led to substantial biodiversity declines. Preserving biodiversity requires an understanding of how habitat loss and degradation interact to impact species populations, and how land-use decisions can limit these losses. Objectives: We present a mathematical partitioning of changes in landscape-level population abundance in response to land-use change using a modified version of the Price equation from evolutionary biology. Methods: The Price equation partitions changes in species abundance into multiple drivers related to habitat loss, habitat degradation, and their interaction. We describe its development and exemplify its applicability using simulated data. Results: Applying the Price equation to simulated data reveals the roles of habitat loss, habitat degradation, and their interaction in driving population change in patchy landscapes undergoing complex land-use change processes. Conclusions: The Price equation is a theoretical tool that may enhance our understanding of the effects of land-use change on populations by accounting for the specific processes by which land-use change operates across landscapes.