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High extinction risk of the endemic tree flora in a hyper-diverse region of the Amazon

Abstract:

Societal Impact Statement: The rapid global loss of biodiversity, especially in the Neotropics, underscores the need to understand how deforestation impacts endemic plant species' extinction risk and conservation status. Due to limited ranges and habitat specialization, endemics are particularly vulnerable. Our study reveals that around 14% and 47% of Ecuadorian Amazon endemic trees are Critically Endangered and Endangered, respectively, with 41% facing high extinction risk. Traits like life-form, fruit size, and height relate to extinction vulnerability. These findings highlight the factors driving Amazonian tree flora endangerment, providing crucial insights for conservation efforts of this fundamental component of Amazon hyper-diverse forests. Summary: Comprehensive analyses of the global conservation statuses of endemic tree species are scarce, especially for species-rich forests. Endemic trees arguably suffer a higher extinction risk than other plant species due to their restricted geographic range and habitat specialization. Here, we present an updated assessment of the conservation status and extinction risk estimates for the endemic tree flora of the Ecuadorian Amazon, a darkspot of biodiversity. We combined an extensively verified taxonomic database of Amazon tree species abundance and occurrence with the most updated data of deforestation for this region. We found that approximately one sixth of the Ecuadorian Amazon endemic tree flora is Critically Endangered. A few clades, including Myrtaceae, Elaeocarpaceae, Fabaceae s.l., and Lauraceae, harbor one third of the Critically Endangered endemic tree species. According to our analysis, the extinction risk for endemic trees is associated not only with extrinsic factors such as deforestation but also with their ecology. Life-form, fruit size, and maximum height are significantly related to extinction risk. Thus, endemic understory and canopy trees with small fruits are more prone to suffer extinction than emergent tree species. We argue that assessment programs should also include biological trait information in addition to geographic ranges and habitat specialization for the establishment of effective conservation strategies of this hyper-diverse region of the Amazon.