Does habitat fragmentation affect landscape-level temperatures? A global analysis

Abstract

Habitat fragmentation per se (habitat subdivision independent of habitat loss) is a major driver of biodiversity change, potentially due to its impacts on climate. Habitat fragmentation may make landscapes hotter by increasing the amount of habitat edges, but can reduce landscape-level temperatures due to the “vegetation breeze” phenomenon. The plausibility of these two alternative hypotheses is unclear, as no study analyzed the effects of habitat fragmentation per se on temperature. We quantify, for the first time, the impacts of habitat fragmentation on landscape-level temperature across the globe. We analyzed satellite data on forest cover and three climatic variables: mean daily temperature, albedo and evapotranspiration. The analyses were performed separately for tropical, temperate, and boreal regions. We compared the climatic variables between pairs of landscapes with similar amount of forest, but different levels of forest fragmentation (number of patches). Habitat fragmentation reduced landscape-level temperature in all climatic regions. The magnitude of this cooling was stronger in the tropics and weaker in the boreal region due to different evapotranspiration rates. This landscape-scale cooling contradicts local-scale studies, which have indicated that edge effects rise local temperatures. However, habitat fragmentation may intensify vegetation breeze, resulting in final cooling at the landscape scale. Habitat fragmentation leads to colder landscapes. We propose a new conceptual model to unify local (edge-induced) and landscape-level effects of habitat fragmentation on temperature, advancing the understanding of the consequences of habitat fragmentation on climate globally.