We Have Broken Nature into More Than 990,000 Little Pieces

Habitat fragmentation is splintering undeveloped areas on Earth.

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A new global survey has revealed that areas on Earth with little human impact are becoming smaller and more isolated. Human activity is continually bisecting forests and grasslands into smaller and smaller slivers of undeveloped land.

Using satellite data, the new research suggests that 56% of the land on Earth—excluding areas covered in ice and snow—has relatively low human impacts.

But that area is being parsed into ever-shrinking segments. Land with low human impact exists in roughly 990,000 fragments larger than 1 square kilometer, a much higher number than what occurs with natural boundaries of water, rock, and ice. The same area would be broken into just 73,000 fragments naturally.

The latest survey could serve as a guide when shaping future international goals for biodiversity protection. Lead author of the study Andrew Jacobson, a professor at Catawba College in North Carolina, said in a press release that the findings are “good news for the planet” because they show there is still time to preserve land in low-impact areas.

“This paper shows that it’s late in the game, but not too late,” Jacobson said. “We can still greatly increase the extent of the world’s protected areas, but we must act quickly.”

The study identifies areas that may be ideal for land conservation in the future.

Splintered Land

Using publicly accessible satellite data, Jacobson and his team mapped areas that are not actively managed for human use.

They ruled out land with forest clearing, agriculture, light pollution, human population, and other marks of human activity. Notably, they left in some roads as well as areas with humans and livestock at levels that would not stress ecosystem health.

The study then computed fragmentation using an idealized globe with no human-caused fragmentation. They created a baseline map of natural habitat fragmentation from water, ice, and rock boundaries and counted the individual pieces. Comparing the baseline fragmentation with the observed fragmentation from the satellite data, they showed that humans have splinted nature into hundreds of thousands of segments, increasing the number by over 1,200%.

The result is a world with more boundaries and fewer areas far from development. Patches in their observations were 95% smaller on average than in a human-free world, and more land sat close to each fragment’s edge, particularly for temperate broadleaf forests. The median distance to an edge for a segment of broadleaf forest was 58 kilometers in the baseline map, compared to 1.4 kilometers in their observations.

Overall, patches of low-impact lands in temperate grasslands and tropical dry forests showed the largest deviation from the baseline, with an average size decrease of 99%.

Future Targets

Professor Nicholas Haddad at Michigan State University, who was not involved in the research, said that the study “sheds new light on the pervasiveness of habitat fragmentation” and the findings could be used to identify areas for future conservation.

The latest research confirms earlier results, according to Professor Erle Ellis at the University of Maryland, Baltimore County, who did not work on the study. Ellis said that future action must be taken to “connect isolated habitats together and conserve biodiversity.”

Past research is divided on how fragmenting habitats affects wildlife. Jacobson and his team wrote in their study, presented in Scientific Reports in October, that they would not comment on the impacts of fragmentation but presented their results as one way to “review the conservation status of different biomes.” The National Geographic Society provided funding for the work.

Humans are the leading cause of dwindling natural habitat that leads to biodiversity loss, and countries have signed on to global initiatives to save habitats from farming, grazing, and development, but economic pressures make conservation difficult.

The upcoming 2020 United Nations Biodiversity Conference will set future targets for global land preservation. Some have called for global land protection targets to shoot for 30% and 50% land conservation by 2030 and 2050, respectively. Currently, 15% of land on Earth is preserved.

But Jacobson said with so much relatively untouched land left, “it’s not too late to aim high.”

—Jenessa Duncombe (@jrdscience), News Writing and Production Fellow

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