In the Amazon, there are significant numbers of indigenous and non-indigenous populations who depend on natural resources for their subsistence. The objective of this study was to conduct an ethnobotanical inventory in three communities (Comunidade do Caju-Úna; Povoado do Céu; and Vila do Pesqueiro) within the Soure Marine Extractive Reserve, located in the Archipelago of Marajó, in the state of Pará, Brazil. Data were collected through semi-structured interviews and participant observation. We performed the sampling using non- probabilistic methods and feature selection. In a quantitative analysis, we evaluated the following indices: total species diversity; informant diversity of a species; use value of a species; consensus use value of a species; and use equitability value of a species. Of the 215 ethnobotanical species listed for the Soure Marine Extractive Reserve, 79 were cited as useful by respondents. We identified nine use categories, of which medicinal use was the most often cited. The indices calculated showed that the level of species diversity is high in the Soure Marine Extractive Reserve. Many of the species in the area are of great utility and cultural value to the local population
