82% of endemic trees in the Atlantic Forest are threatened – 01/11/2024 – Environment

A study led by Brazilian researchers and published this Thursday (11) in the journal Science shows that 82% of the more than 2 thousand species of trees exclusive to the Atlantic Forest suffer some degree of threat of extinction. Of the total of 4,950 tree species present in the biome (including those that also occur in other areas), 65% have their populations threatened.

It is the first time that all populations of almost 5 thousand tree species in the Atlantic Forest have their degree of threat assessed according to the criteria of the International Union for Conservation of Nature (IUCN), the largest global reference on threatened species.

“The number [de 82% de espécies endêmicas ameaçadas] It was a shock for us, because we used a conservative approach,” says Renato Lima, professor at the Luiz de Queiroz School of Agriculture at the University of São Paulo (Esalq-USP), in Piracicaba, and coordinator of the study.

“We take into account whether or not the species had available forest, regardless of whether or not it was a healthy forest, for example. But not all species are able to maintain themselves in degraded fragments. It is possible, therefore, that the reality is even more worrying” .

Part of the work is the result of the researcher’s postdoctoral studies at the USP Biosciences Institute, financed with a scholarship from Fapesp.

The survey was carried out on more than 3 million herbarium records and forest inventories. The researchers also added as much information as possible, such as commercial uses of the species and time series of habitat losses, among others. Forest inventory data was stored in the TreeCo repository, managed by Lima.

Another worrying fact found is that only 7% of endemic species had a population decline of less than 30% in the last three generations. The IUCN considers that, above this level, the species can already be considered “Vulnerable”, the first category of threat of extinction. Above that are “Endangered” and “Critically Endangered.”

Among those threatened, 75% are in the “Endangered” category. The emblematic Brazilwood (Paubrasilia echinata) has been listed as “Critically Endangered”, given the estimated 84% reduction in its wild populations.

Previously common trees, such as the araucaria (Araucaria angustifolia), the juçara palm heart (Euterpe edulis) and yerba mate (Ilex paraguariensis), had declines of at least 50% and were therefore classified as “Endangered”.

Species exclusive to the Atlantic Forest, including cinnamon (species such as Ocotea odorifera It is O. porosa), suffered reductions of 53% to 89%, being classified as “Endangered” or “Critically Endangered”.

Unprecedented survey

The IUCN has a series of criteria to define the degree of threat of a species, whether animal or plant, divided between A, B, C and D. In the current study, the researchers observed that, the more data was entered, the degree threat increased.

In general terms, criterion A assesses population decline over the last three generations; criterion B, the size of the area occupied by the species; and criteria C and D, if the population is small and declining or very small, with less than 10 thousand adult individuals.

“When we meet fewer IUCN criteria in assessments, which has generally been done so far, we have six times fewer threatened species. Using criteria that incorporate the impacts of deforestation dramatically increases our understanding of the degree of threat to forest species Atlantic, which is much larger than we previously thought”, explains Lima.

To illustrate the difference, the group separated a set of species that had data for all criteria and assessed the degree of threat. Taking into account all the species in this subgroup, if only criteria A were considered, 91.4% of the total species would be threatened and 90.3% of those exclusive to the Atlantic forest.

When using only criterion B, often the only one used in surveys of this type, only 10.7% of species or 16.6% of endemic species would be threatened. Taking criteria C and D as a reference, then 3.2% of endemic species would be considered threatened and, at most, 2.5% of the total.

The innovative method will be used from 2024 to assess the degree of threat of the approximately 12 thousand plant species present exclusively in Brazil and which have not yet undergone this type of assessment. The work is carried out by the National Center for Flora Conservation, at the Rio de Janeiro Botanical Garden, where some of the study’s co-authors work.

The authors also propose that the method can be used on a global scale. In a simulation using data from other tropical forests, researchers found that 30% to 35% of the planet’s tree species may be threatened by deforestation alone.

“Information of this type is essential for creating public conservation and reforestation policies. More degraded areas and more threatened species can be prioritized, without forgetting to consider places where there are forests that may no longer be viable in the long term if something fails. is done now”, comments the researcher.

The good news is that five species considered extinct in the wild were rediscovered in the study. On the other hand, 13 tree species exclusive to the Atlantic Forest were reclassified as possibly extinct.