New study suggests that regenerating tropical forests may have short lifespans
The threatened Brazilian Atlantic Forest is one of the most biodiverse places on Earth. It is home to approximately 2,200 species of mammals, birds, reptiles and amphibians, many of which are endemic to the region, such as this green-headed tanager.Photo: Pedro Pifer
Preventing re-clearing of secondary forests is a major challenge for restoration efforts in the tropics, according to a study. new research Led by researchers from Columbia University, the University of São Paulo, and the Federal University of ABC in Brazil. The study found that one-third of the regeneration area in Brazil’s Atlantic Forest was logged again, most of it after four to eight years of regeneration.
Natural forest regeneration is considered a cost-effective strategy for countries to achieve their ecological restoration and carbon sequestration goals.Despite upbeat reports on forest restoration in the tropics, Recent research by study authors and others The proposed restoration has a high probability of being cleared within a few years.
The new study, published in Environmental Research Letters, quantifies forest regeneration in Brazil’s Atlantic Forest and identifies factors that influence how long regenerated forests survive.
The Brazilian Atlantic Forest is a rich natural area that originally covered 150 million hectares along the Atlantic coast. Only about 32 million hectares remain today. Highly fragmented and threatened ecosystems are now considered regeneration hotspots.
The authors used detailed land-use cover data from 1985 to 2019 to map and track the fate of more than 4.5 million hectares of regenerated forest in Brazil’s Atlantic Forest. They found that only 3.1 million hectares of land continued into 2019.
“While the continued presence of two-thirds of the regenerated forest in the region holds positive prospects for the conservation of the biome, the short lifespan of the regenerated forest presents a new challenge for restoration efforts in the region,” said Dr. Pedro Ribeiro Piffer of Columbia University. candidate and lead author of the study.
The ephemeral nature of these regenerated forests limits the Biodiversity and carbon storage benefits regeneration, he said.
“Given the increase in forest cover in many tropical regions in the early 2000s, carbon sequestration through tropical reforestation and natural regeneration could make an important contribution to climate change mitigation,” said senior author María Uriarte, a professor at the Columbia Earth Institute who Study tropical forest dynamics. “However, the size of this carbon sink will depend on how permanent and protected these forests are and will not be re-logged.”
Persistent and short-lived areas of native forest regeneration across the Brazilian Atlantic Forest. The area is shown in hectares of forest per 250 square kilometers of hexagons. (Click to enlarge the map and view the hexagons.) Image credit: Piffer et al., Environmental Research Letters 2022
in a previous papersPiffer and Uriarte found that without these reforestation reversals, forests in Brazil’s Atlantic Forest region could have already sequestered 1.75 billion tons of carbon — more than three times the estimated actual sequestration of 520 million tons.
“Our findings underscore the dual challenge of forest conservation in the tropics, where we need to not only restore degraded areas, but also ensure the persistence of these young, regenerated forests,” said Jean-Paul Metzger, professor of ecology at the university. . University of São Paulo and co-authors of the new study.
Ensuring the durability of tropical forest regeneration is critical for countries to meet their restoration and carbon sequestration commitments under the Paris Agreement, the researchers noted.
They also identified factors that may help protect regenerated forests. They found that regenerated forests were more likely to survive on steeper slopes, near rivers and existing forests, and near permanent agriculture. Forests are unlikely to persist in more rural areas. Furthermore, while regeneration occurs primarily in pastures and areas of agricultural transfer, it is also less likely to persist in these dynamic landscapes.
“Regenerating forests can take decades to regain their pre-disturbance levels of species richness and biomass, so identifying conditions that allow for greater persistence of these young forests is essential for developing effective public policies aimed at increasing forest cover in Brazil’s Atlantic Forest. Crucial,” Pifer said.
