Understanding how local climatic changes modify the response of biodiversity to land-use changes

Abstract

Anthropogenic changes to Earth’s ecosystems are putting global biodiversity under ever-increasing pressure. Land-use and climate change are two of the biggest pressures facing terrestrial species. These environmental changes, however, are not occurring in isolation and, consequently, may interact. One route by which these two pressures could interact is through the local-scale climatic changes that occur due to land-use change. Human-altered land uses are often hotter and drier than natural habitats, which may lead to these land uses (such as agricultural areas) favouring certain species. Moreover, environmental changes do not impact species uniformly across their distributions. Populations’ climatic positions (i.e., how close the environmental climatic conditions populations experience are to their species’ climatic tolerance limits) have been found to influence populations’ responses to global climate change, but whether they impact responses to land-use change remains unknown. By using three of the most comprehensive assemblage databases to date (the PREDICTS, Living Planet and BioTIME databases), this thesis investigates the impact of local climatic changes on vertebrate responses to land-use changes. I find that human-altered land uses are reshaping communities by favouring species affiliated with more extreme climatic conditions, especially at tropical latitudes. Further, responses differ across species ranges, with populations’ climatic positions influencing abundances within human-altered land uses. In particular, those populations experiencing temperatures closer to their thermal limits are filtered out of human-altered land uses. In addition, population trends were influenced by interactions between land use, habitat loss, climatic position, and climate change. These results are likely, at least in part, due to the local climatic changes ensuing land-use change. Overall, accounting for these local climatic differences between land uses is essential if we are to fully understand the impacts of environmental changes on biodiversity, set up suitable conservation and management plans to mitigate their effects, and minimise future biodiversity loss

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