29 January 2024

Atlantic Forest, Brazil, 82% of tree species could disappear


In the forest area spanning the southeastern region of Brazil, two-thirds of all species and more than four-fifths of endemic ones are threatened with extinction

by Matteo Cavallito


In Brazil, four out of five endemic tree species found in the Atlantic Forest would now be at risk of extinction. This is the most striking figure to emerge from research published in recent weeks in the journal Science.

The figure “came as a shock,” explained Renato Lima, a professor at the University of São Paulo and co-author of the research in a statement released by FAPESP – Foundation for Research Support, a public organization active in the Brazilian state itself. “We took forest availability into account for each species, whether or not it was healthy forest, for example. Not all species are able to survive in degraded fragments, so the actual situation may be even more alarming.”

More variables examined means greater risk detected

The study carried out in Brazil is based on parameters provided by the largest biodiversity indicator available: the Red List of Threatened Species. This list is produced by the International Union for Conservation. The authors, the research explains, “used an automated, quantitative method to assess species based on the Red List criteria and applied it to nearly 5000 tree species from the Atlantic Forest, a relatively data-rich biodiversity hotspot in South America.”

The indicator ranks the risk of extinction of animal and plant species based on multiple criteria namely population decline over the last three generations, area occupied by the species, small and very small population size (below 10,000 adult specimens).

“When we included few IUCN criteria in the assessments, which is what most researchers had done before, we obtained six times fewer threatened species,” Lima explained. “The use of criteria that took the impact of deforestation into account drastically affected our assessments of the degree of threat to Atlantic Rainforest species, which was much worse than we previously thought.” The problem, in this sense, could also occur on a global scale: “We suggest that the conservation status of tropical forests worldwide is worse than previously reported,” they point out in the study.

Four-fifths of the species are at risk

The study, as mentioned, focused on the Atlantic forest. The area stretches along Brazil’s east coast from the state of Rio Grande do Norte to Paraguay and Argentina. Using IUCN criteria, the researchers produced “automated conservation assessments” for all detectable tree species in the territory (nearly 5,000). These includes about 1,100 species that were never examined before.

The result: “About 65% of all species and 82% of endemic species are classified as threatened,” the authors explain. Moreover they found “five species classified as Extinct on the IUCN Red List and 13 endemics as possibly extinct.”

And there’s more. “Another troubling discovery was that population decline in the last three generations was less than 30% for only 7% of the endemics“, the study says. “Species with a decline of 30%-50% in ten years or three generations are classified as Vulnerable, IUCN’s lowest level of threat. Above this level, they are Endangered or Critically Endangered.”

A threat not just for Brazil

Besides reviving once again the issue of biodiversity loss in the country, the study paves the way for further investigations based on the same method. This method, for example, could be used to estimate the overall level of risk that characterizes the approximately 12,000 varieties of trees that are typical of Brazil and have never been assessed.

Similarly, the same methodology could be used for a worldwide assessment. In a simulation based on data from other tropical forests, moreover, the researchers found that about a third of the Planet’s tree species could be threatened by deforestation alone.

“Information of this kind is critically important to the formulation of public policies for conservation and reforestation,” says Lima. “The most degraded areas and threatened species can be prioritized without overlooking areas where there are forests that may not be viable in the long run if nothing is done now.”