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Cleared tropical forests can regain ground surprisingly fast

Cleared tropical forests can regain ground surprisingly fast

Abandoned agricultural lands can recover by nearly 80 percent on average in just 20 years

A young tropical forest regrows on abandoned pasture in Brazil. Such forests can recover surprisingly fast, new research suggests.


Tropical forests are disappearing at an alarming clip across the globe. As lush land is cleared for agriculture, climate-warming carbon gets released and biodiversity declines. But when farmland is left alone, nature can make a surprisingly quick comeback. After just 20 years, forests can recover by nearly 80 percent in certain key areas, including biodiversity and soil health, researchers report in the Dec. 10 Science. Keeping existing forests intact is crucial for curbing climate change and stemming species loss (SN: 7/13/21), says ecologist Lourens Poorter of Wageningen University in the Netherlands. But this research shows “there’s tremendous [climate] mitigation potential” in letting forests regenerate.

Land cleared of tropical forests often is abandoned after a few years of low-intensity agricultural use, Poorter says, allowing nature to creep back in. To see how such areas recover, he and colleagues studied 77 sites across the Americas and West Africa that are regrowing forests that vary in age. Using 51 old-growth sites, those that show no signs of human use in at least 100 years, as a baseline, the

researchers investigated 12 forest attributes related to soil health, ecosystem functioning, forest structure and plant biodiversity, analyzing how quickly those things recovered.

Tropical forests can re-establish themselves on abandoned agricultural lands faster than expected, recovering by nearly 80 percent on average in just 20 years, new research suggests. But different forest attributes, related to soil (red), diversity (orange) and structure (blue), recover at different rates. Soil carbon and nitrogen levels rapidly recovered, reaching levels close to those found in old-growth forests in about 20 years. Plant species richness, or the number of species, in regrowing forests takes longer to come close to old-growth levels — about 40 years — while species composition, or the relative abundances of those species, takes more than a century. Likewise, total aboveground biomass will take 120 years to approach old-growth levels, the scientists estimate.