Tradition Beyond the Hotspot: Biocultural Conservation and Medicinal Plant Diversity in the Ilha Grande National Park, Brazil

The Ilha Grande National Park region (Brazil) holds one of the most diverse traditional knowledge repositories among Atlantic Forest conservation areas. This study describes the current composition of the medicinal plant knowledge, its taxonomic breadth, and its relevance for conservation. In 2026, this inventory documented 47 species from 33 botanical families cited across a sample of 4 remaining traditional healers. About 27.7% of these specimens are wild/native to nature and 72.3% are cultivated, reflecting both historic management and the residents’ long tradition in household plant acclimatization. The collection includes 25 species of herbs and 11 species of trees, as well as 9 shrubs and 2 climbers. Quantitative analysis at the category level revealed that gastrointestinal disorders had the highest consensus index (ICF = 0.375) after interviews, taxonomic revision, data grouping, and standardizing nomenclature based on the British National Formulary. The results reveal a severe risk of information erosion and a limited representation of younger generations among practitioners, underscoring the need for targeted safeguarding. Strengthening national partnerships, developing cooperative cultivation networks, and improving scientific validation records are proposed as key strategies to enhance the biocultural preservation value of this traditional heritage. Overall, the Ilha Grande healer knowledge serves as an important scientific, educational, and pharmacological resource and plays a central role in advancing the preservation of Brazil’s medicinal plant diversity.