Mount Pueh, Sarawak, Malaysia has been nominated as one of the proposed sites for the first Biosphere Reserve in Sarawak under the UNESCO Man and the Biosphere (MAB) Programme. The nomination is based on Mount Pueh’s high biogeographic representativeness, ecological diversity, and the presence of numerous endemic and IUCN/CITES-listed species. A 6-hectare plot was established on Mount Pueh as the proposed arboretum site, in line with one of the key functions of the MAB Programme — the conservation and protection of biodiversity, ecosystems, and landscapes. The assessment recorded a total of 2,543 trees with a diameter of 10 cm and above, representing a total basal area of 116.45 m² and encompassing 72 plant families. The mean diameter and height of the trees were 20.63 cm and 15.08 m, respectively. Non-Dipterocarpaceae dominated 88.9% of the plot areas, compared to Dipterocarpaceae, which had 283 trees. In addition to trees, the totally protected species Rafflesia tuan-mudae — listed under the Sarawak Wildlife Protection Ordinance, 1998 — was also recorded within the arboretum plot, providing further justification for the establishment of the Pueh Arboretum. The preliminary results of the tree assessment will serve as a reference for the establishment and management planning of the arboretum within the proposed MAB area.

Keywords: Pueh Arboretum, tree assessment, Man and Biosphere (MAB) Reserve, UNESCO