With Earth’s human population spreading into previously unpopulated areas, more of the planet’s territory will need to be shared between animals and the human race in the future, putting thousands of species at risk, scientists have found.
Competition for forests and agricultural land
A study by a team at the US University of Michigan, predicts that over half of Earth’s land will see a greater overlap between humans and other species and forested areas will be particularly in demand. Places where the need to share will drop, such as Europe, only constitute a small proportion of the available territory.
“We found that the overlap between populations of humans and wildlife will increase across about 57% of the global lands, but it will decrease across only about 12% of the global lands. We also found that agricultural and forest areas will experience substantial increases of overlap in the future,” said Deqiang Ma, lead author of the study and a postdoctoral research fellow at the Institute for Global Change Biology in the Michigan’s School for Environment and Sustainability.
It will be population growth and the subsequent increase in dense settlements in areas formerly uninhabited by people driving the shift, rather than climate change, according to the findings, causing more people to interact with wildlife in ways that Neil Carter, the study’s lead and associate professor of environment and sustainability called both “good and bad”.
China, India, South America and Africa
The calculations compared 2015 data with projections for 2070 and were made by integrating estimates of human population density with distributions of 22,374 species of terrestrial amphibians, birds, mammals, and reptiles. They also took into account factors such as species richness, mean annual temperature (MAT), and gross domestic product (GDP) by country, as well as looking at different types of territory including cropland, grassland, urban, and forested space.
China and India, where human population figures are already high and are set to grow further will see the greatest increase in overlap, as well as forests in Africa and South America, which is “concerning” the researchers say, “because those areas have very high biodiversity that would experience greater pressure in the future.”
Amphibians, reptiles and birds at risk
Potential “richness” losses of amphibians, reptiles and birds will be worst in South American forests, reaching medians of 45.4%, 40% and 36.8% respectively. Bird population richness will also drop by 26.1% in African forests.
The study highlights that action to preserve biodiversity while reducing the overlap between humans and animals can be beneficial on both sides, by keeping a helpful balance between pests and their predators, maintaining sanitary conditions thanks to animals that scavenge and cleanse environments, and reducing the spread of diseases caused by human-animal contact such as Covid-19.
