More than 80% of endemic tree species in the Atlantic rainforest are at risk of extinction, study finds

A study carried out by Brazilian researchers and reported in an article published on January 11 in the journal Science shows that 82% of the more than 2,000 tree species found only in the Atlantic Rainforest biome are threatened with extinction to some extent, while 65% of the 4,950 tree species found in the biome including including non-endemic species, are endangered.

This is the first time that the degree of threat to all populations of all tree species in Brazil’s Atlantic Rainforest biome has been assessed using the International Union for Conservation of Nature criteria. nature (IUCN), of which the Red List of Threatened Species is considered a critical indicator. of the health of global biodiversity.

“The number (82% of endangered endemic species) was a shock. We took into account the forest availability for each species, whether it is a healthy forest or not for example. Not all species are not able to survive in degraded fragments, so the current situation could be even more alarming,” said Renato Lima, corresponding author of the article.

Lima is a professor at the Luiz de Queiroz College of Agriculture (ESALQ-USP) at the University of São Paulo in Piracicaba, São Paulo State, Brazil. His postdoctoral research at the Institute of Biosciences (IB-USP) included part of the study.

The authors conducted an automated conservation assessment of some 5,000 species using more than 800,000 herbarium records and 1.3 million trees from forest inventories, as well as information on the species’ life history, their commercial uses and long time series of habitat loss. Forest inventory data was obtained from TreeCo, a repository administered by Lima.

Another troubling finding is that population decline over the past three generations was less than 30% for only 7% of endemic species. Species showing a decline of 30 to 50 percent in ten years or three generations are classified as vulnerable, the IUCN’s lowest threat level. Above this level, they are endangered or critically endangered.

Of the threatened species, 75% were in the Endangered category. Brazil’s iconic wood, Paubrasilia echinata, has been deemed critically endangered due to an estimated 84% decline in its population size over the past three generations.

Once common species, such as Araucaria angustifolia (Paraná pine), Euterpe edulis (Jussara palm), and Ilex paraguariensis (Yerba mate), have lost at least 50% of their populations and are classified as endangered. of disappearance.

Species endemic to the Atlantic rainforest, such as the Brazilian sassafras (Ocotea odorifera) and the Brazilian walnut (Ocotea porosa), have lost 53 to 89 percent and are listed as endangered or critically endangered.

First assessment of this type

The IUCN categorizes the risks of extinction of animal and plant species according to several criteria, divided into A, B, C and D. In this study, the researchers found that the more data they used, the greater the degree of threat.

Simply put, population decline over the past three generations is criterion A, geographic range (the area occupied by the species) is criterion B, and a small and declining population or a very small population (less than 10,000 adults) is C and D.

“When we included few IUCN criteria in the assessments, which most researchers had done before, we got six times fewer threatened species. Using criteria that took into account the impact of “Deforestation has significantly affected our assessments of the degree of threat to Atlantic rainforest species, which is much worse than we previously thought,” Lima said.

To illustrate the difference, the researchers separated a set of species for which data was available on all four criteria and assessed the degree of threat. For all species in the subgroup, 91.4% were threatened according to criterion A. For endemic species, the proportion was 90.3%.

Under criterion B, the only one of four used in most assessments of this type, only 10.7% of all species and 16.6% of endemic species were threatened. According to C and D, the proportions were 2.5% for all species and 3.2% for endemics.

The innovative methodology will now be used to estimate the degree of threat facing some 12,000 plant species endemic to Brazil and not yet included in such an assessment. The research is being carried out by the National Center for Flora Conservation at the Rio de Janeiro Botanical Garden, where two of the paper’s co-authors work.

The authors advocate for global use of the methodology. In a simulation based on data from other tropical forests, they found that 30 to 35 percent of the planet’s tree species could be threatened by deforestation alone.

“Information of this type is of crucial importance for the formulation of public conservation and reforestation policies. The most degraded areas and threatened species can be prioritized without neglecting areas where forests are found that might not be viable in the long term if nothing is done now,” Lima said.

The good news is that the authors of the paper have rediscovered five species thought to be extinct in the wild. In contrast, they determined that 13 species endemic to the Atlantic rainforest may be extinct.