Exotic and native medicinal plants used by Quilombola Communities in the Atlantic Forest: Popularity, versatility and exclusivity as proxies for medicinal keystone species

Abstract

Native species used in the traditional medicine of Indigenous Peoples and Local Communities undeniably require conservation efforts. Some theoretical models suggest that exotic species may reduce the pressure on native species by sharing their functions and increasing redundancy within medicinal plant use. As a result, native species would no longer be exclusive. Exclusivity in use, along with versatility and popularity, are indicators of more frequent use, potentially leading to overexploitation. These characteristics are also used to define cultural keystone species. Our study investigated these three attributes in medicinal plants used by three afro-descendants quilombola communities within the Atlantic Forest to identify the local importance of exotic and native species and to determine possible keystone species in the local medical system, in parallel with the cultural keystone species model. We conducted semi-structured interviews with local specialists and guided tours for data collection. We compared the values of popularity, exclusivity, and versatility between exotic and native species, and further identified the species with the highest values for each attribute, using as cutoff the probability of citation occurrence of each plant under a null scenario. We found no significant differences between exotic and native species in the tested attributes, suggesting that species from both origins share similar use pressures. However, when setting a threshold for the most critical attributes, we observed that, in the resulting list, most species appearing in at least two attribute lists are native. We highlight the need for conservation actions for the species present in all three lists compiled in this study and propose that these attributes be incorporated into the classification of species that form the structural core of a local medical system.