Humans Have Impacted Most of the World’s Ecosystems

By Kylie Wolfe

The Earth and its mix of species look different than they did hundreds of years ago. Some animals and plants have gone extinct, others are threatened. The land they once called home has either been cleared or polluted, a result of an overwhelming presence of people. Whether direct or indirect, our existence has influenced ecosystems around the world.

A new study published in Frontiers in Forests and Global Change found that only three percent of our globe has remained unchanged, what its authors refer to as an intact ecosystem. These results are making scientists take a closer look at the way human activity affects other species.

Finding Balance

The team, led by Andrew Plumptre, a conservation biologist at the University of Cambridge, assessed 7,500 animal species and combined multiple data points to reach their conclusion. Surveying Earth’s land-based ecosystems, they considered places where habitats and species had decreased or disappeared.

For the purposes of their study, an intact ecosystem was defined as an area presently consisting of the same species in the same amounts as it did in the year 1500. Of the three percent of ecosystem found intact, only eleven percent are within protected lands.

Some of these lands, like the Amazon Rainforest, remain biodiverse. Others, like the tundra of Greenland, are more limited. According to the study, these areas still thrive with the same levels and mix of species they’ve always had. A balance of predator and prey keeps the ecosystem in check.

Important Considerations

In many cases, human intervention challenges an ecosystem’s natural balance, but in some, it’s proven the opposite. Just over 25 years ago, wolves were reintroduced to Yellowstone National Park. This helped strengthen other animal populations, including elk. While successful, this may not be the solution for every ecosystem.

As reported in Science News for Students, Jedediah Brodie, a conservation ecologist at the University of Montana in Missoula, thought the study authors put too confining of parameters in place for their survey. His analysis clarifies that the loss of a few species might not always throw an ecosystem out of balance.

“Many ecosystems around the world have lost one or two species but are still vibrant, diverse communities,” said Brodie.

With a greater understanding of the issues at hand, scientists are left with an opportunity to protect and restore natural ecosystems, no small task.