Habitat destruction and hunting reduce mammal diversity in the world’s largest tropical dry forest
Rapid deforestation and the expansion of hunting are threatening mammal diversity in the world’s largest dry forest, according to an international group of researchers from Bolivia, Spain, and Germany.
The research, led by scientists at Humboldt-Universität zu Berlin, and published in the journal Global Change Biology, found that different aspects of the diversity of mammals – species numbers, evolutionary diversity, and the range of ecological roles – had decreased in the forest over the last three decades.
The Gran Chaco forest where the research took place is the world’s largest tropical dry forest, spanning parts of Argentina, Bolivia, and Paraguay. It covers 1.1 million square kilometers, or three times the size of Germany, and is home to iconic mammals such as jaguars, tapirs, and capybaras. In the past few decades, the Chaco has become one of the most rapidly deforested places on Earth, as the trees are cleared to make way for cattle ranches and soy plantations.
“It’s not just species that are being lost but also the diversity of their evolutionary history, and their important roles within the Gran Chaco ecosystem,” said lead author Alfredo Romero-Muñoz from Humboldt-Universität zu Berlin. “Mammals are vital to keeping the forest ecosystem in balance through their roles in dispersing seeds, grazing plants, and predating other animals. This decline in diversity is a worrying trend that could have serious impacts for the forest and the people who directly or indirectly depend on it.”
Co-author Guillermo Fandos, from University of Potsdam, added: “In this area there is a huge diversity of mammals, spanning many branches of the evolutionary tree of life. Some species are found nowhere else on earth, such as the Chacoan peccary – a type of wild pig – and the southern threebanded armadillo. Losing mammal diversity here means cutting branches from that tree of life – destroying millions of years of evolution.”
The study found that, unsurprisingly, habitat destruction was the main force of the decline in biodiversity. However, even in remote forests with little deforestation, hunting pressure had a major impact. “These results highlight the importance of looking beyond of just the deforestation to understand human impacts on nature”, said coauthor Ana Benítez-López from Doñana Biological Station in Spain. “Knowing where these different threats are important can help to guide conservation actions.”
All the countries encompassing the Chaco forest have committed to international plans to conserve 17% of their country’s land area for nature. The researchers found that to conserve the top 17% of land for each aspect of diversity – number of species, diversity of evolutionary history, and diversity of ecological roles 23% of the Gran Chaco would have to be protected.
„We urge policymakers to safeguard the most important areas for nature in the Chaco“, said Tobias Kuemmerle from Humboldt-Universität zu Berlin, and senior author of the study. „Our maps show where protected areas should be implemented to protect imperiled Chacoan mammals before it is too late „, he continued.
Alfredo Romero-Muñoz, Geography Department, Humboldt-Universität zu Berlin,
Romero-Muñoz A, Fandos G, Benítez-López A, Kuemmerle T. Habitat destruction and overexploitation drive widespread declines in all facets of mammalian diversity in the Gran Chaco. Glob Change Biol. 2020;00:1–13. DOI: 10.1111/gcb.15418