Population assessment of the endangered and valuable timber tree Torem (Manilkara kanosiensis) in Customary Forest of Lorulun, Yamdena Island, Indonesia

Abstract

Torem (Manilkara kanosiensis) is a timber tree species endemic to Yamdena Island in Indonesia and the Bismarck Archipelago in Papua New Guinea. Due to its high-quality timber, the trees are harvested from its natural populations. These logging activities have put the species into the endangered category according to IUCN Red List since more than 20 years ago. In the present study, the population assessment of Torem will be conducted in the customary forest of Lorulun, Yamdena Island, Indonesia. Distance sampling using line-transect was used to assess the distribution of Torem, identify population size and structure, estimate population density, and update the conservation status of the species. The results showed Torem trees were mostly located at relatively flat areas (4.5±0.2°), with the elevation range of 81-134 m above sea level. A total of 228 individuals of Torem was located during the survey, with more than half of them (56.68%) were within 0-10 cm dbh class. The density estimate of the species was 14.8±4.4 individuals/ha. The assessment of conservation status against IUCN Red List Category and Criteria revealed that Torem was qualified for the status of Endangered A2cd, B2ab (i, ii, iv, v), C2a(i), D.