Study shows natural regrowth of tropical forests has immense potential to address environmental concerns

Published: Oct 30, 2024

By: Sarah Hansen, M.S. '15

A new study in Nature finds that up to 215 million hectares of land (an area larger than Mexico) in humid tropical regions around the world has the potential to naturally regrow. That much forest could store 23.4 gigatons of carbon over 30 years and also significantly help enhance biodiversity and water quality. The study showed that more than half of the area with strong potential for regrowth was in five countries: Brazil, Mexico, Indonesia, China, and Colombia.

"Tree planting in degraded landscapes can be costly. By leveraging natural regeneration techniques, nations can meet their restoration goals cost effectively," says the study's co-lead author, Brooke Williams, a researcher at the Queensland University of Technology, Australia, and the Institute for Capacity Exchange in Environmental Decisions. "Our model can guide where these savings can best be taken advantage of," she says.

A culmination of decades of work

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In that work, "We used satellite images to identify millions of small areas where tree cover increased over time. We then excluded the areas planted by humans with machine learning, focusing on natural regrowth," Fagan says. The study tracked regrowth between 2000 and 2012, and then checked if the regrowth was maintained through 2015. "Those natural patches were the input data for this novel study," he says, "the first to predict where future forest regrowth will occur, given observed past regrowth."

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The study found that the factors most strongly associated with high regrowth potential were a patch's proximity to existing forest, the density of nearby forest, and the content of carbon in the soil. Those factors in particular "seem to do a really good job explaining the patterns of regrowth we see across the world," Fagan says. Being close to existing forest, for example, is key to supplying a variety of seeds to the area to support diverse regrowth, Fagan explains.

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