Establishing permanent monitoring plots of narrow endemic and threatened plants of Indonesia: a case study on Dipterocarpus cinereus Slooten (Dipterocarpaceae)

Abstract

Permanent plots are commonly employed to record and monitor temporal changes in plant communities. In this study, we established a permanent plot to monitor the future population dynamics and regeneration of Dipterocarpus cinereus Slooten (Dipterocarpaceae), or Lagan bras, a critically endangered and narrowly endemic tree confined to the Mursala Island in Sumatera Utara Province, Indonesia. Using a quarter-hectare (50 × 50 m2) plot, we collected initial data on the population structure of D. cinereus and the floristic composition of the tree community within the plot. Tree inventories were conducted by measuring all individual trees with a Diameter at Breast Height (DBH) of more than 5 cm. In the 0.25-hectare plot established, we recorded 261 trees, representing 76 species, 49 genera, and 32 families of flowering plants. There were seven individuals of D. cinereus in the plot, of which six were in mature stages with a DBH range of 79.5–38.8 cm. The results of our study can serve as baseline data for future monitoring programs of D. cinereus and the accompanying tree community. Furthermore, these results can support the implementation of existing long-term conservation strategies and action plans for the species.