Abstract
Global biodiversity is under high and rising anthropogenic pressure. Yet, how the taxonomic, phylogenetic, and functional facets of biodiversity are affected by different threats over time is unclear. This is particularly true for the two main drivers of the current biodiversity crisis: habitat destruction and overexploitation. We provide the first long-term assessment of multifaceted biodiversity changes caused by these threats for any tropical region. Focussing on larger mammals in South America's 1.1millionkm2 Gran Chaco region, we assessed changes in multiple biodiversity facets between 1985 and 2015, determined which threats drive those changes, and identified remaining key areas for all biodiversity facets. Using habitat and threat maps, we found, first, that between 1985 and 2015 taxonomic (TD), phylogenetic (PD) and functional (FD) diversity all declined drastically across over half of the area assessed. FD declined about 50% faster than TD and PD, and these declines were mainly driven by species loss, rather than species turnover. Second, habitat destruction, hunting, and both threats together contributed ~57%, ~37%, and ~6% to overall facet declines, respectively. However, hunting pressure increased where TD and PD declined most strongly, whereas habitat destruction disproportionally contributed to FD declines. Third, just 23% of the Chaco would have to be protected to safeguard the top 17% of all three facets. Our findings uncover a widespread impoverishment of mammal species richness, evolutionary history, and ecological functions across broad areas of the Chaco due to increasing habitat destruction and hunting. Moreover, our results pinpoint key areas that should be preserved and managed to maintain all facets of mammalian diversity across the Chaco. More generally, our work highlights how long-term changes in biodiversity facets can be assessed and attributed to specific threats, to better understand human impacts on biodiversity and to guide conservation planning to mitigate them.
Highlights
We considered the change from core area in 1985 to ‘poor habitat’ in 2015 as ‘habitat destruction’ and from core to ‘hunting pressure’ as increasing hunting pressure, because such increasing threats can be solely attributed to anthropogenic impacts during this period
We provide the first multi-decadal, broadscale assessment of changes in all three biodiversity facets caused by specific threats
This is to our knowledge the first assessment of changes in multiple biodiversity facets for mammals and in the tropics
Summary
Alfredo Romero-Muñoz1,2 | Guillermo Fandos1,3 | Ana Benítez-López4 | Tobias Kuemmerle. Assessing how different threats contribute to long-term changes in all three biodiversity facets, taxonomic (TD), phylogenetic (PD), and functional (FD) diversity, is crucial for a more comprehensive understanding of human impacts on nature. Likewise, this understanding is vital to develop conservation strategies that better account for all biodiversity facets. Habitat destruction and overexploitation are the leading drivers of global biodiversity decline (IPBES, 2019; Maxwell et al, 2016) Both threats are rapidly expanding into previously natural areas across the tropics due to the increasing human demand for agricultural products, such as beef, soy (predominantly used as livestock feed), and palm oil (Kehoe et al, 2017; Laurance et al, 2009). Where are the priority areas for conserving each facet of mammalian diversity in the Chaco and where do they overlap?
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