By Guilherme Salgado Grittz, 3rd September 2025
It is easy to marvel at the diversity of tree species in the Atlantic Forest. Yet, this once-vast domain has been reduced to fragments, with barely a quarter of its original cover remaining. In our recent study published in Oryx, we assessed the extinction risk of tree species in Santa Catarina, a southern Brazilian state lying entirely within the Atlantic Forest. What we discovered was alarming: almost all the tree species we evaluated face some degree of extinction threat.
Cloud forests. Photo: Anderson Kassner Filho.
The Atlantic Forest is a biodiversity hotspot where decades of deforestation, illegal logging and habitat fragmentation have pushed its flora to the brink. Given the multitude of threats, tree species often face endangerment for multiple reasons.
While Lima et al.’s (2024) assessment revealed that 80% of all endemic Atlantic Forest species are threatened, we conducted this regional evaluation for several key reasons. First, Santa Catarina’s official species list (2014) has not been updated in over a decade and lacked objective criteria like those of the IUCN, even though the FlorestaSC has made sufficient data available through its systematic forest surveys. Second, the scale of human impacts varies locally: a species thriving in Bahia, northeastern Brazil, could be declining in Santa Catarina due to distinct environmental pressures. Finally, conservation action depends on regional support, typically driven by state or national policies.
The Alto Paraná forests, situated in higher elevations. Photo: Anderson Kassner Filho.
For our assessments, we strictly followed IUCN guidelines, evaluating criteria A, B, C and D, which relate to population and geographic threats. At every stage, we referred back to IUCN standards to ensure our approach was rigorous and actionable for conservation. By integrating data from forest surveys and herbarium collections, we applied the IUCN Red List criteria to evaluate over 500 tree species. The results were staggering: 98% of assessed species are threatened, with many experiencing population declines of over 50% in the past few generations.
Alluvial portion of Serra do Mar coastal forests. Photo: Anderson Kassner Filho.
Our findings underscore the urgent need for conservation measures. Protecting remaining forest patches, restoring degraded lands and establishing wildlife corridors are essential to save these forests. As the next step, we plan to submit our list to local authorities to inform their evaluation and update Santa Catarina’s threatened tree species list.
The emblematic “pinheiro-do-paraná” (Araucaria angustifólia), showing its landscape dominance. Photo: Anderson Kassner Filho.
The Article ‘Assessing the extinction risk of tree species in the subtropical Atlantic Forest using multiple IUCN criteria’ is available open access in Oryx—The International Journal of Conservation.
