Just 3 percent of terrestrial habitat is 'ecologically intact'

More recently, scientists and policy makers have called for more concrete definitions of "wilderness." In its efforts to combat climate change and preserve biodiversity, the United Nations has highlighted the importance of ecosystem integrity.

As new research proves, intact habitat doesn't guarantee ecosystem integrity. In fact, the new analysis -- published Thursday in the journal Frontiers in Forests and Global Change -- suggests an overwhelming majority of the planet's terrestrial ecosystems are compromised.

"We know intact habitat is increasingly being lost, and the values of intact habitat have been demonstrated for both biodiversity and people," lead study author Andrew Plumptre, biodiversity expert at the University of Cambridge's Conservation Research Institute, said in a news release. "But this study found that much of what we consider as intact habitat is missing species that have been hunted by people, or lost because of invasive species or disease."

Numerous studies have highlighted the problem of ecosystem fragmentation, but few have quantified the issue. In Africa, there is a surprising amount of usable habitat, but due to poaching threats, elephants only utilize a small percentage. Even the planet's protected wilderness is highly fragmented.

Previous efforts to quantify and map ecosystem integrity have focused exclusively on the influence of human activity -- including the incursion of human settlements, roads and light and noise pollution -- on terrestrial acreage all over the world. Estimates suggest between 20 and 40 percent of terrestrial habitat is free from human influence.

For the new study, scientists added another level of analysis. Plumptre and his research partners compared current plant and animal diversity levels in intact habitat with historical biodiversity benchmarks.

They determined only between 2 and 3 percent of habitat identified as intact still hosts a full slate of animal and plant diversity and remains mostly free of invasive species.

Many of the regions identified as ecologically intact are places managed by Indigenous communities.

"Areas identified as functionally intact included east Siberia and northern Canada for boreal and tundra biomes, parts of the Amazon and Congo basin tropical forests and the Sahara Desert," the study's authors wrote.

According to the new study, there is hope for recovery. Scientists determined as much as 20 percent of Earth's terrestrial habitat could be restored to faunal intactness.

"The results show that it might be possible to increase the area with ecological intactness back to up to 20 percent through the targeted reintroductions of species that have been lost in areas where human impact is still low, provided the threats to their survival can be addressed and numbers rebuilt to a level where they fulfill their functional role," Plumptre said.

Numerous studies have highlighted the importance of ecosystem integrity and biodiversity for maintaining vital ecosystems services, curbing climate change and promoting human health. Scientists hope their latest research will help conservationists and policy makers improve protection and restoration plans.