Wed, Aug 04, 2021:On Demand
Background/Question/Methods
Land-use change is a major driver of biodiversity loss, driving local species declines (loss of alpha diversity), as well as the rise of a cosmopolitan group of species and biotic homogenization (loss of beta diversity). But the role that climate plays in mediating the severity and even the direction of the resulting community change is underappreciated. The role of climate may be particularly important because microclimate often differs systematically between natural and anthropogenic habitats (e.g. cleared lands are warmer than natural forest environments), introducing the possibility that species might track their climatological niche across different land-use types. Using Neotropical bird, amphibian, and reptile communities in natural and anthropogenic habitats across climate gradients (precipitation or temperature), I first test the hypothesis that the severity of diversity loss due to land-use change is climate dependent. I then examine how climate interacts with land-use to drive biotic homogenization by altering species’ preferred habitat types along climate gradients.
Results/Conclusions I show that the consequences of land-use change, in terms of alpha and beta diversity, are strongly dependent on climatological context. Across taxa, in some climate zones alpha diversity remains unchanged between natural and anthropogenic habitats. Elsewhere, species loss is extreme. Community composition in anthropogenic habitats often “mimics” the community composition of a natural habitat from a particular climate zone, resulting in biological homogenization. For example, avian communities in tropical agriculture are most similar to those in dry forest, but highly distinct from communities in tropical wet forest. Further, some species track their climate niche regardless of land-use type. For example, in colder climate zones habitat generalist amphibians and reptiles only occupy anthropogenic habitats, even though they prefer natural habitats in warmer climates. As a consequence, so-called habitat generalist species are not always generalists, but act as habitat specialists in some climate zones. These results suggest that under climate warming even dispersal-limited lowland species may be able to rapidly colonize highland forest habitats due to preexisting anthropogenic clearings.
Results/Conclusions I show that the consequences of land-use change, in terms of alpha and beta diversity, are strongly dependent on climatological context. Across taxa, in some climate zones alpha diversity remains unchanged between natural and anthropogenic habitats. Elsewhere, species loss is extreme. Community composition in anthropogenic habitats often “mimics” the community composition of a natural habitat from a particular climate zone, resulting in biological homogenization. For example, avian communities in tropical agriculture are most similar to those in dry forest, but highly distinct from communities in tropical wet forest. Further, some species track their climate niche regardless of land-use type. For example, in colder climate zones habitat generalist amphibians and reptiles only occupy anthropogenic habitats, even though they prefer natural habitats in warmer climates. As a consequence, so-called habitat generalist species are not always generalists, but act as habitat specialists in some climate zones. These results suggest that under climate warming even dispersal-limited lowland species may be able to rapidly colonize highland forest habitats due to preexisting anthropogenic clearings.