- A total of 4.47 million hectares (11.05 million acres) of Brazil’s Atlantic Forest has regenerated naturally since 1985, but nearly a third of this area has been cleared again.
- These “ephemeral” forest patches last less than eight years on average, a new study shows, raising concerns about the durability of efforts to recover deforested swaths of the Atlantic Forest.
- Most of the regenerated forests that get cleared lie inside private properties, raising questions about how landowners can be persuaded not to cut this vegetation.
For conservationists working to save the Atlantic Forest in Brazil, a key challenge has been maintaining recovered areas that lie inside private properties. Yet for recovery efforts to be successful, it’s necessary to investigate how long naturally regenerated forests (those recovering without human interference) are surviving.
Scientists now have an answer to that question: less than eight years on average, according to a recent study by a team of Brazilian researchers.
For their analysis, they identified a combined area of 4.47 million hectares (11.05 million acres) of forest that had regenerated throughout Brazil’s Atlantic Forest between 1985 and 2019. They found that about two-thirds of this total, 3.1 million hectares (7.7 million acres), had survived as of 2019. The remaining 1.37 million hectares (3.39 million acres) of regenerated forest were cut by landowners after four to eight years. These patches of forest survived for an average of just 7.9 years — a relatively fleeting period that the researchers called “ephemeral forest regeneration.”
For the study authors, led by biologist Pedro Ribeiro Piffer from Columbia University in the U.S., the high prevalence of ephemeral regeneration is cause for concern, especially in light of the worsening climate crisis and ongoing dismantling of environmental safeguards in Brazil.
Previous studies, including one from 2020, showed encouraging potential for forest recovery through natural regeneration in the Atlantic Forest, Piffer told Mongabay. By analyzing satellite images from MapBiomas, a collaborative initiative between various universities, NGOs and tech companies, Piffer and his colleagues were able to zoom in on the nature of the regeneration taking place.
“We were able to map this regeneration at the pixel level, squares of 30 by 30 meters [100 by 100 feet], and see how long each pixel of forest survived or not in the biome as a whole,” Piffer said. “This is the first set of data to start analyzing these dynamics on a more local scale for the future.”
The study found that in areas of more intensive agriculture, natural regeneration is less likely, as would be expected. But when it does occur, the regenerated forest has a better chance of surviving longer.
“When you have a soybean or sugarcane plantation on the farm, the forest regenerates in an area along a river, stream, or bordering these plantations. These more marginal areas are abandoned, so they end up surviving,” Piffer said. In addition, these particular areas inside a rural property typically fall under the categorization of a permanent preservation area (APP), which landowners are prohibited under Brazil’s Forest Code from deforesting.
Piffer said longer-lived regenerated forests were also found in areas where agricultural yields are higher and where the local economy is doing better.
In areas of pasture or shifting agriculture — where land use changes over time, unlike in monocrop farms growing soy or sugarcane full-time — different dynamics play out, the study found. Although these areas are larger and have a greater potential for natural forest regeneration, Piffer said, “the restored stretches are probably cut down again so as not to impede land use” — such as maintaining or expanding open pasture for livestock.
Under Brazil’s Atlantic Forest Law, from 2006, areas of the biome restored 10 years or more ago may not be cut down. This may explain why naturally regenerating forests often last for less than a decade before being cut down, the study authors suggest.
“We don’t claim that the landowners are doing this, because we haven’t investigated the properties. But that is one of the most plausible explanations for our results,” Piffer said.
Why restored forests are being cut back
Anazélia Tedesco is searching for those very answers as she pursues her doctorate at the University of Queensland, Australia. She says she’s been “interviewing landowners to understand what incentives (economic or otherwise) could change their behavior to reconvert natural regeneration to conservation of these areas.”
Tedesco was not involved in the recent study, but is a member of the socioeconomic and diversity working groups of the Atlantic Forest Restoration Pact. This is a movement formed by more than 300 institutions that has already restored about 1 million hectares (2.5 million acres) of native vegetation in 13 years. Their goal by 2050 is to restore 15 million hectares (37 million acres) of the biome.
Tedesco welcomed the findings from the new study, saying its “central innovation is to investigate which biophysical and demographic factors are correlated to the conservation and reconversion of newly regenerated areas over the last three decades.”
She says this is important because other studies, including one published in 2021 and co-authored by Piffer, “had already shown that regenerated forests are often reconverted to other land uses, but until then it was unclear under which conditions natural regeneration was more or less likely to perpetuate over time.”
According to Tedesco, “the [new] study confirms that there is no magic solution to achieve the ambitious goals that Brazil has assumed.” Under the country’s commitments to the Paris Agreement, Brazil plans to restore 12 million hectares (30 million acres) of native forest by 2030, which coincides with the end of the United Nations’ Decade on Ecosystem Restoration. Tedesco cited the Reflorestar Program in Espírito Santo state, home to part of the Atlantic Forest, as one of the many initiatives aimed at achieving the larger goal.
Piffer, P. R., Rosa, M. R., Tambosi, L. R., Metzger, J. P., & Uriarte, M. (2022). Turnover rates of regenerated forests challenge restoration efforts in the Brazilian Atlantic forest. Environmental Research Letters, 17(4), 045009. doi:10.1088/1748-9326/ac5ae1
Crouzeilles, R., Beyer, H. L., Monteiro, L. M., Feltran-Barbieri, R., Pessôa, A. C., Barros, F. S., … Strassburg, B. B. (2020). Achieving cost‐effective landscape‐scale forest restoration through targeted natural regeneration. Conservation Letters, 13(3). doi:10.1111/conl.12709
Rosa, M. R., Brancalion, P. H., Crouzeilles, R., Tambosi, L. R., Piffer, P. R., Lenti, F. E., … Metzger, J. P. (2021). Hidden destruction of older forests threatens Brazil’s Atlantic Forest and challenges restoration programs. Science Advances, 7(4). doi:10.1126/sciadv.abc4547
Banner image by Andre Cherri/WRI Brasil.