The relative importance of deforestation, precipitation change, and temperature sensitivity in determining the future distributions and diversity of Amazonian plant species
biodiversity informatics, Extinction, global, natural history collections, species distribution models, species migrations, warming
Tropical forests are threatened by many human disturbances - two of the most important of which are deforestation and climate change. In order to mitigate the impacts of these disturbances, it is important to understand their potential effects on the distributions of species. In the tropics, such understanding has been hindered by poor knowledge of the current distributions and range limits of most species. Here we use herbarium collection records to model the current and future distributions of ca 3000 Amazonian plant species. We project these distributions into the future under a range of different scenarios related to the magnitude and extent of disturbance as well as the response of species to changes in temperature, precipitation and atmospheric concentrations of CO2. We find that the future of Amazonian diversity will be dependant primarily on the ability of species to tolerate or adapt to rising temperatures. If the thermal niches of tropical plants are fixed and incapable of expanding under rapid warming, then the negative effects of climate change will overshadow the effects of deforestation, greatly reducing the area of suitable habitat available to most species and potentially leading to massive losses of biodiversity throughout the Amazon. If tropical species are generally capable of tolerating warmer temperatures, rates of habitat loss will be greatly reduced but many parts of Amazonia may still experience rapid losses of diversity, with the effects of enhanced seasonal water stress being similar in magnitude to the effects of deforestation.