Only 3% of Land on Earth Remains Ecologically Intact

A small fraction of Earth’s landmass remains functionally intact, but through the targeted reintroduction of key species to their native habitats, scientists believe that could rise to as much as 20%.

Amazon rainforest canopy. (Credit: Vitek Jirinec, LSU)

(CN) — Humans have done a bang-up job branching out across the Earth’s surface in recent centuries, so much so that few lands remain untouched. Even fewer can be considered functionally intact — regions whose plant and animal life remain mostly as they were 500 years ago.

When one sees a wilderness area in a national park, it’s usually somewhat of a misnomer — merely the closest approximation available. A truly intact wilderness area would include all its original plant and animal species in their proper numbers, at least those dating back to the year 1500, according to the authors of a new study.

Researchers from the Key Biodiversity Areas Secretariat at Cambridge looked at undeveloped land around the world to determine what exactly qualifies as “intact habitat,” and tried to figure out how much is left. They published their results Wednesday in the journal Frontiers in Forests and Global Change.

“We know intact habitat is increasingly being lost and the values of intact habitat have been demonstrated for both biodiversity and people,” said Andrew Plumptre, lead author of the study, in a related statement. “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.”

The authors distinguished between three types of intactness that together make up ecological integrity. Habitat intactness, meaning there’s no sign of human disturbance nearby. Faunal intactness occurs when an area retains all the original animal species known to reside there after a certain date. Finally, functional intactness, the gold standard, is achieved when animal numbers in a region remain high enough to support a healthy functioning ecosystem.

“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 authors explained in their study.

In other words, Earth’s last remaining functionally intact ecosystems are synonyms for some of the most remote outposts on the planet.

Past studies claimed as much as 40% of land remained free from human development, however Plumptre and his team approached the question a different way. Instead, they looked at overall ecological integrity, rather than human impact alone, since many crucial species in those regions had long since gone extinct or fled. Remove a major predator, a key plant, or even a helpful insect from an ecosystem and you no longer have balance, you have a house of cards.

The authors believe conservation efforts should focus on the few areas of the planet that remain ecologically intact, or close to it, and attempt to preserve and expand them while it’s still possible. The authors pieced together a series of datasets examining species loss at various sites to determine the number and ecological importance of the missing species.

Based on the data they collected, less than 3% of lands studied remain in the same condition with the same animal species that were found there 500 years ago. Because animals, especially large mammals, are the key piece missing from large swaths of otherwise intact land, they claim those lands could be increased substantially through conservation efforts focused on reintroducing native species that are not yet extinct.

“The results show that it might be possible to increase the area with ecological intactness back to up to 20% 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 fulfil their functional role,” Plumptre said in a related statement.

Among other threats to their survival, hunting has taken a heavy toll on important species dating back centuries. The impact caused by hunters can be hard to quantify because they can reach deep into untouched habitat, spending days or weeks moving around between camps, and they’re impossible to track remotely with satellites and sensors. Previous research found that mammal populations have lost 29% of their natural habitats as a result of overhunting by humans.

“Human footprint indices can play an essential role in identifying areas with potential for ecological restoration through reintroduction of extirpated species, as there will typically be fewer barriers to successful restoration in areas with low human footprint,” explained the authors in their study. “As the world develops the next goals and targets for the Convention on Biological Diversity under the post 2020 global biodiversity framework, ‘intact habitat’ has been recognized as an important target.”

%d bloggers like this: