Population structure and composition of a tropical Island forest containing the narrow endemic and critically endangered tree <i>Hopea bancana</i> on Mursala island

Long-term data from permanent monitoring plots are essential for understanding ecological succession, detecting changes in forest structure, assessing community stability, examining species interactions, and tracking population trends of species of conservation concern. In this study, we established a permanent plot to monitor the regeneration and population dynamics of Hopea bancana (Boerl.) Slooten—a critically endangered tree species restricted to Mursala Island in western coast of North Sumatera Province, Indonesia. A 0.25-hectare plot (50 × 50 meters) was set up to collect baseline information on both H. bancana and the surrounding tree community. All trees with a Diameter at Breast Height (DBH) greater than 5 cm were measured and identified. In total, 318 trees were recorded, representing 49 species, 41 genera, and 27 plant families. Among them were nine H. bancana individuals—one mature tree with a DBH of 66.4 cm and eight younger trees with DBHs ranging from 7 to 34 cm. Given the high intensity of anthropogenic threats on Mursala Island, including illegal logging and forest conversion, conservation measures should prioritize protecting remaining forest cover, controlling illegal logging, monitoring invasive species, and preventing further forest conversion to ensure the long-term persistence of H. bancana and other threatened Dipterocarpaceae species. This dataset offers valuable baseline information for future monitoring and conservation efforts targeting H. bancana. Additionally, the study provides a replicable framework for conserving other narrowly distributed and threatened plant species in Indonesia’s tropical forests.