Alarming number of tree species threatened in the Atlantic Rainforest 

A new study by Brazilian researchers has revealed startling details about the Atlantic Rainforest biome. The experts found that 82 percent of the rainforest’s endemic trees, totaling over 2,000 distinct species, face varying degrees of extinction risk. 

Unprecedented assessment 

The scope of the research is unprecedented. The team assessed all 4,950 tree species within the Atlantic Rainforest using the criteria of the International Union for Conservation of Nature (IUCN). The study revealed that 65 percent of the total species are vulnerable, endangered, or critically endangered.

“The number (82% of endemic species threatened) came as a shock. 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,” said study co-author Professor Renato Lima from the University of São Paulo Luiz de Queiroz College of Agriculture.

Innovative approach 

The research team conducted an automated conservation assessment of the tree species, incorporating over 800,000 herbarium records and 1.3 million tree counts from forest inventories. 

The experts also analyzed data on the species’ life histories, commercial uses, and habitat loss over time. The forest inventory data came from TreeCo, a repository managed by Lima.

Critical insights

A key finding of the study was that less than 30 percent of the endemic species have experienced a population decline in the last three generations. 

This threshold is critical as species with a 30 to 50 percent decline are classified as vulnerable by the IUCN, the lowest level of threat. A decline above 50 percent places species in the endangered or critically endangered categories.

Threatened species 

Among the threatened species, 75 percent were categorized as endangered. Notably, the brazilwood (Paubrasilia echinata) is now considered critically endangered after an estimated 84 percent reduction in its population size over recent generations. 

Other familiar species like the Paraná pine (Araucaria angustifolia), Jussara palm (Euterpe edulis), and Yerba mate (Ilex paraguariensis) have lost over half of their populations, earning them the endangered status.

The study also highlights the plight of species unique to the Atlantic Rainforest, such as Brazilian sassafras (Ocotea odorifera) and Brazilian walnut (Ocotea porosa), which have experienced population declines between 53 and 89 percent.

Future assessments 

The IUCN’s categorization system, which includes criteria A (population decline), B (geographic range), C (small and declining population), and D (very small population), was fully utilized in this study. 

The research demonstrated that incorporating more of these criteria results in a higher number of species identified as threatened. When fewer criteria were used, as was common in previous studies, the number of threatened species was six times less.

The study’s methodology is set to drastically improve future assessments, with plans already underway to apply it to approximately 12,000 plant species endemic to Brazil. This research will be conducted by the National Center for Conservation of Flora at the Rio de Janeiro Botanical Garden.

Study implications 

In a simulation based on data for other tropical forests, the researchers found that 30 to 35 percent of the planet’s tree species may be threatened by deforestation alone.

“Information of this kind is critically important to the formulation of public policies for conservation and reforestation,” said Professor 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.”

On a positive note, the study led to the rediscovery of five species previously thought to be extinct in the wild. However, the team also concluded that 13 species endemic to the Atlantic Rainforest may already be extinct.

The study is published in the journal Science.

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