Restoring forests speeds up their ability to capture carbon that humans added to atmosphere by over 50%: Study
Forest areas that underwent active restoration recovered faster, from 2.9 to 4.4 tons of aboveground carbon per hectare per year
Stored in living leaves and woody tissues, tropical forests contain more than half of the planet’s aboveground forest carbon, the degradation of which poses a direct threat to global climate regulation. However, due to increasing forest loss and degradation, these important reservoirs are declining and becoming less able to help mitigate rising levels of atmospheric carbon dioxide. Scientists have found that active restoration and management of tropical forests accelerates their ability to absorb and store carbon compared to processes by which forests naturally regenerate. According to them, restoration practices can improve carbon storage recovery by more than 50% compared to natural regeneration.
According to study author Professor Mark Cutler, School of Social Sciences, University of Dundee, UK, the findings emphasize that the protection of existing forests, even those that have been degraded or previously exploited, is paramount for retaining aboveground carbon density, as well as for maintaining biodiversity and other critical ecosystem services. “The protection of existing forests, even those that have been degraded or previously exploited, is paramount from the point of view of retaining aboveground carbon density, as well as maintaining biodiversity and other critical ecosystem services. The implementation of even relatively low-cost active restoration measures can lead to a significant increase in aboveground carbon density in forests that have been previously disturbed,” Cutler told MEA WorldWide (MEAWW).
“Not long ago, we treated degraded tropical forests as lost causes. Our new findings, combined with those of other researchers around the world, strongly suggest that restoring tropical forests is a viable and highly scalable solution to regaining lost carbon stocks on land,” explains Greg Asner, director of the Arizona State University Center for Global Discovery and Conservation Science (GDCS). He adds, “Restoring degraded tropical forest works to mitigate climate change, and it saves biodiversity along the way.”
Deforestation removes aboveground carbon in the form of trees, reducing the size of global carbon stocks in the process. Once forests are degraded, they are often perceived to have little ecological value, despite evidence of their ability to continue to provide important ecosystem services and to store significant amounts of carbon. According to the authors, this misconception has marked degraded forests as prime candidates for full conversion to agricultural plantations. However, the current study challenges this idea and offers a promising alternative: Forest restoration is a more sustainable solution capable of both replenishing carbon storage and preserving biodiversity.
In their analysis, published in the journal, Science, the international team of scientists from 13 institutions provided a long-term comparison of aboveground carbon recovery rates between naturally regenerating and actively restored forests in Southeast Asia.
The researchers studied an area of tropical forest in Malaysian Borneo, where agricultural activities have caused soaring deforestation rates for years. The study site was heavily logged in the 1980s and subsequently protected from further logging or conversion to plantation agriculture. To assess forest recovery, the investigators mapped the area using their Global Airborne Observatory, equipped with powerful lasers and spectrometers, in 2016. The resulting maps revealed the location and amount of carbon stored above ground across thousands of hectares of forest.
The analysis reveals that restoring degraded tropical forests can generate big carbon gains. Areas left to regenerate naturally recovered by as much as 2.9 tons of aboveground carbon per hectare of forest each year, highlighting the ability of degraded forests to recover if protected from full agricultural conversion. But most importantly, the team found that forest areas that underwent active restoration recovered 51.7% faster, from 2.9 to 4.4 tons of aboveground carbon per hectare per year.
Restoration methods included planting native tree species, removing tree-climbing vines, and thinning vegetation around saplings to improve their chances of survival. “The findings of the three-decade study show that active restoration enhanced the decadal aboveground carbon density (ACD). Thus, the impacts of active restoration to forests enhance their potential contribution to mitigating climate change. Full ACD recovery in a naturally regenerating logged forest would take around 60 years, while recovery for an actively restored forest takes just 40 years,” the findings state.
While the costs of forest restoration are higher than leaving them to regrow on their own, the findings suggest that such efforts are economically feasible and could become more attractive as global carbon costs rise, suggest the authors. “Science has laid out a clear pathway for land managers. We now must turn to the economics of the problem to generate the support to pursue these solutions,” recommends Asner.