Ethnobotanical knowledge of Tharu people living nearby Koshi River and Koshi Tappu Wildlife Reserve (KTWR), eastern Nepal

BACKGROUND: Many indigenous and ethnic communities have been displaced from their ancestral homelands and disconnected from their traditional dependencies on forests and rivers as a result of protected area management of Nepal. Ongoing changes in land use, socio-economy and culture pose additional threats to their livelihoods and knowledge systems. This study aims to document the traditional knowledge and ethnobotanical practices of the Tharu ethnic group living in and around the Koshi River and Koshi Tappu Wildlife Reserve (KTWR) in order to assess whether their culture has been influenced by the recent changes, including interventions associated with KTWR management. METHOD: Data were collected from 119 Tharu participants residing in the Jhapa, Morang, and Sunsari districts of Koshi Province. Quantitative ethnobotanical indices were computed to assess the significance and consensus of plant use within the community. Interactions of the Tharu with rivers, forests, and protected areas were also examined. RESULTS: A total of 2,426 use reports were recorded, documenting 113 useful plant species across 13 use categories. Ficus religiosa emerged as the most frequently cited species with 180 use reports, followed by Ficus benghalensis (156), Piper betle (130), Ocimum sanctum (119), and Mangifera indica (95). All these species were terrestrial and primarily agroforestry-based. Geographically, the highest number of use reports per person (33.16) was recorded in Jhapa district, which is located farthest from both the Koshi River and KTWR. CONCLUSION: The findings of this study not only document the rich ethnobotanical heritage of the Tharu people but also reveal the vulnerability of this knowledge system to modern pressure and protected area management. The concentration of knowledge among elder healers, the reduced species utilization near KTWR, and the pressures of modernization urge an immediate need for deliberate revitalization of ethnobotanical knowledge. Viable strategies include systematic documentation and intergenerational transmission, community-based biodiversity conservation, and strengthening and restoring traditional cultural practices.