Layal Liverpool, 19 April 2021
As early as 12,000 years ago, nearly three-quarters of land on Earth was inhabited and shaped by human societies, suggesting global biodiversity loss in recent years may have been driven primarily by an intensification of land use rather than by the destruction of previously untouched nature.
“It’s not the process of using land itself [that causes biodiversity loss], it’s the way that land is used,” says Erle Ellis at the University of Maryland, Baltimore County. “You can have traditional land use and still have biodiversity.”
Ellis and his colleagues analysed the most recent reconstruction of global land use by humans over the past 12,000 years and compared this with contemporary global patterns of biodiversity and conservation. They found that most – 72.5 per cent – of Earth’s land has been shaped by human societies since as far back as 10,000 BC, including more than 95 per cent of temperate and 90 per cent of tropical woodlands.
“Our work confirms that untouched nature was almost as rare 12,000 years ago as it is today,” says Ellis. He and his team found that lands now considered natural, intact or wild generally exhibit long histories of use, as do protected areas and lands inhabited only by relatively small numbers of Indigenous peoples.
The extent of historical human land use may previously have been underestimated because prior analyses didn’t fully account for the influence that hunter-gatherer populations had on landscapes, says Ellis. “Even hunter-gatherer populations that are moving around are still interacting with the land, but maybe in what we would see as a more sustainable way,” he says.
The researchers also found that in regions now characterised as natural, current global patterns of vertebrate species richness and overall biodiversity are more strongly linked to past patterns of land use than they are with present ones. Ellis says this indicates the current biodiversity crisis can’t be explained by the loss of uninhabited wild lands alone. Instead, this points to a more significant role for recent appropriation, colonisation and intensification of land use, he says.
“The concept of wilderness as a place without people is a myth,” says Yadvinder Malhi at the University of Oxford. “Where we do find large biomes without people living in them and using them – as in North American national parks, Amazonian forests or African game parks – it is because of a history of people being removed from these lands through disease or by force.”
“[This study] shows that high biodiversity is compatible with, and in some cases a result of, people living in these landscapes,” says Malhi. “Working with local and traditional communities, and learning from them, is essential if we are to try to protect biodiversity.”
“With ambitious calls to expand global terrestrial protected areas to cover 30 per cent or even half of the Earth, this [study] brings into focus that protection necessarily cannot mean the exclusion of people and anthropogenic land uses,” says Jason Riggio at the University of California, Davis. The “30 by 30” pledge, being championed by a coalition of more than 50 countries, aims to expand protected areas to cover at least 30 per cent of land and sea by 2030.
Joice Ferreira at Embrapa Amazônia Oriental in Brazil says that there are important roles for both protected areas and sustainable land use in preserving biodiversity. “The combination of deforestation, degradation […] and climate change make protected areas paramount,” she says, adding: “if Indigenous custodianship was important in the past, it is much more so nowadays, in the face of new and more intense threats.”
Journal reference: PNAS, DOI: 10.1073/pnas.2023483118