University of São Paulo: One third of Atlantic Forest regeneration areas are deforested again up to eight years later

The Atlantic Forest has only 25.8% of its forest cover preserved, according to MapBiomas estimates , and natural regeneration is one of the main strategies for its restoration. But one study found that a third of the biome’s regenerating areas are cut again, with most of these cuts only occurring between the fourth and eighth year of growth.

This result is part of an article published in March in the journal Environmental Research Letters carried out by researchers from USP and the Federal University of ABC (UFABC) in partnership with Columbia University, in the United States.

Entitled Turnover rates of regenerated forests challenge restoration efforts in the Brazilian Atlantic forest , the study sought to characterize the regeneration areas of the Atlantic Forest.

Natural regeneration , also known as passive restoration, is the practice of purposefully abandoning an area so that vegetation naturally grows without human interference. In addition to being efficient, this technique is also low cost and it is important for Brazil to achieve forest restoration goals, such as the voluntary commitment made by the country in the Paris Agreement to restore 12 million hectares of native vegetation by 2030.

“Since natural regeneration is the most economical way to restore the Atlantic Forest, it is necessary to understand the environmental and socioeconomic conditions under which this regeneration occurs in order to promote public policies that can leverage this process”, Jean Paul Metzger tells Jornal da USP , professor of Ecology at the Institute of Biosciences (IB) at USP and one of the authors of the research.

Data and analysis
To collect data on areas that are undergoing natural growth, the researchers used the MapBiomas platform as a reference , which produces an annual mapping of the land cover and use of the Brazilian territory. Information collected from 1985 to 2019 was analyzed. “These are currently the best data that combine spatial and temporal information on land use in Brazil”, says Metzger.

“With this information, it is possible to identify where and when deforestation occurs. And also when an area of ​​use is abandoned, allowing the development of native vegetation until the formation of new forests”, he explains.

In this way, the study analyzed deforestation and regeneration events year by year and related them to environmental characteristics, such as different types of relief and soil, and socioeconomic characteristics, such as population density and per capita income . This association makes it possible to know which conditions favor or not the regeneration process.

The combination of information makes the study innovative, as there is a joint analysis of data that is usually done in isolation. “Until today, we only had information on the occurrence of deforestation and regeneration of the Atlantic Forest, but no information on the age and permanence of these forests, in particular, those that have regenerated in the last 30 years”, explains Jean Metzger.

The ephemerality of young forests
The main finding of the study, according to the professor, is that a third of the regeneration areas are deforested again, and these cuts occur in the initial stages of regeneration, when the forest is only four to eight years old. “Thus, the benefits that these areas could supply are wasted, such as climate regulation, reduction of surface water runoff, soil stabilization, or services of direct interest to some agricultural crops, such as pollination and pest control.”

The research also revealed that restoration predominates on sloping terrain and in areas with greater forest cover in the surroundings. In landscapes of pastures or agropastoral mosaics, there are more cases of deforestation of vegetation that was resuming growth.

With these results, it becomes easier to guide environmental public policies. The steeper areas and adjacent to rivers, considered permanent preservation areas , provide this regeneration and, therefore, can be considered important areas to stimulate restoration efforts. At the same time, knowing that the growth of forests lasts for a shorter period in municipalities with low GDP and pasture land, it is possible to create financial incentives for environmental services in order to encourage the permanence of forests.

The researcher emphasizes how these results were surprising and show that Brazil’s efforts are still insufficient: “We did not expect such a high turnover of the regenerated forest. This indicates that Brazil needs not only to promote policies to stimulate regeneration, but also policies aimed at the permanence of these young forests.”

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