Notícias
The trees of the Atlantic Forest are severely threatened
More than 80% of the tree species unique to this South American tropical forest are at risk of extinction mainly due to deforestation. Species extinction is one of the most extreme impacts humans have on nature. Extinction is forever and with every species lost, we lose millions of years of a unique evolutionary history and the opportunity to learn from that history. Thus, preventing the extinction of species is the greatest challenge to combat the current global crisis of biodiversity loss, which has a direct impact on our lives, including issues related to the risk of pandemics, bioeconomy, biomaterials, drug development, and several other ecosystem services. The first step to stop this process of species extinction is to know where they are and what is the degree of threat to each species, which allows the construction of the so-called Red Lists of Species. These lists help us make the decision of which species are the priority to invest time and resources in biodiversity conservation.
A study recently published in Science presents the Red List of almost 5000 tree species occurring in the Atlantic Forest, one of the most biodiverse and threatened forests in the world. "The overall picture is very worrying", says Renato Lima, professor at the University of São Paulo who led the study. "Most of the tree species in the Atlantic Forest have been classified in one of the threat categories of the International Union for Conservation of Nature (IUCN). This was expected because the Atlantic Forest lost most of its forests and with them its trees. Even so, we were frightened when we saw that 82% of the more than 2000 species unique to this global biodiversity hotspot are threatened", Lima adds.
Many emblematic species of the Atlantic Forest, such as the Brazilwood and Paraná Pine, were classified as endangered species. A total of 13 endemic species - species that occur only in the Atlantic Forest and nowhere else in the world - have been classified as possibly extinct, that is, they may have disappeared from the planet! On the other hand, five species previously thought to be extinct in the wild were rediscovered by the study. The study used more than 3 million herbarium records and forest inventories, as well as detailed information on the biology, ecology and uses of the tree, palm, and fern species included in the assessments.
The construction of the list of threatened species of the Atlantic Forest was based on different IUCN criteria. "And that was another critical aspect of the work", Lima adds. "If we had used fewer IUCN criteria in the conservation assessments, which is what has generally been done so far, we would have detected six times fewer threatened species. In particular, the use of criteria that incorporate deforestation drastically increases our understanding of the threat status of the Atlantic Forest, which is much greater than we previously thought", concludes Lima.
Most of the information needed for IUCN assessments using multiple criteria is hard to obtain or estimate from other sources. Consequently, most extinction risk assessments currently available at IUCN are based solely on the geographical distribution of species (the so-called criterion B). However, the decline in the number of adult trees caused by deforestation (criterion A, which investigates population reductions) is the main cause of species threat, especially in highly altered biodiversity hotspots such as the Atlantic Forest. In other words, the use of several IUCN criteria for the construction of red lists avoids a serious underestimation of the degree of species threat. To estimate the decline of populations, forest inventory data throughout the Atlantic Forest were gathered in a single database (TreeCo), allowing us to understand how the number of adult trees has been reduced by deforestation over time.
Hans ter Steege (Naturalis Biodiversity Center, Netherlands), co-author of the study, recalls that the study was not limited to assessing the threat of extinction only in the Atlantic Forest. "We made projections about what the magnitude of the impact of forest loss would be on tree species on a global scale." These projections included the world's major rainforest areas. "Projections suggest that between 35-50% of the planet's tree species could be threatened due to deforestation alone", concludes ter Steege. In addition to these projections, the study proposes a methodological flow and tools to implement it on a large scale, allowing the assessment of the degree of threat of thousands of species simultaneously. "This also makes it possible to apply the same approach to other regions of the world or even other forms of life, such as orchids or bromeliads, for example", says Gilles Dauby (IRD, France), also a co-author of the study.
According to Marinez Siqueira, a researcher at the Rio de Janeiro Botanical Garden (JBRJ) and current Director of the National School of Tropical Botany (ENBT), who also co-authored the study, the approach used is robust for assessing the degree of threat of species, and will be used systematically from 2024 to assess the approximately 12,000 plant species that occur only in Brazil and that have not yet had their degree of threat officially assessed. "This will be an unprecedented gain in scale for assessing Brazil's mega-diverse flora, in a timeframe that is much more compatible with the urgent need for public policies and action plans to protect them," says Marinez.
For Eduardo Fernandez, Project Coordinator of the Conservation Status Assessment Center (NuAC) of the National Center for Flora Conservation (CNCFlora/JBRJ) and a collaborator on this study, the innovative approach proposes to advance the use of population data on Atlantic Forest tree species, which have often been neglected during the extinction risk assessment process because they are not readily available in digital repositories or because they are scattered in different databases. "Finally, understanding where endangered species are located and which pressure vectors are increasing their risk of extinction will allow us to act to reverse this scenario," he concludes.
The scenario is very worrying because the study considered only past threats (deforestation) and not future threats, such as climate change, which can accelerate the risks of species extinction.
What can we do in the face of this scenario? In addition to the conservation of species in botanical gardens and germplasm banks, there are the so-called National Action Plans, instruments for promoting public policies aimed at the conservation and recovery of endangered species in Brazil, especially those at imminent risk of disappearing.
Another way to try to reverse the loss of tree species in the Atlantic Forest is forest restoration, as André de Gasper, a professor at FURB and co-author of the study, comments. "Restoration projects, in open lands or degraded forests, can select the most threatened regional species of the Atlantic Forest in their projects, aiming to stimulate the production of seeds and seedlings of these species and the recovery of their wild populations". We are amid the United Nations Decade on Ecosystem Restoration, which favors regional and global initiatives that use restoration to reverse this awful scenario faced by the tree species from the Atlantic Forest and other tropical forests across the world.