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Population Status and Habitat Preferences of Critically Endangered Dipterocarpus littoralis (Bl.) Kurz. in West Nusakambangan Nature Reserve, Indonesia

2011Population status and habitat preferences of critically endangered Dipterocarpus littoralis (Bl.) Kurz. in West Nusakambangan Nature Reserve, Indonesia.ROBIANSYAH Iyan (Indonesia)iyan.robiansyah@gmail.com
Organisation: University of East Anglia, Norwich (UK) - West Nusakambangan Nature Reserve (Indonesia)Supervisor :
Summary: A targeted survey of the endemic tree Dipterocarpus littoralis was carried out in West Nusakambangan Nature Reserve to assess its population status and habitat preferences. A total of 676 individuals of D. littoralis was located at 52 different locations, with an extent of occurrence and area of occupancy of 3.66 km2 and 1.71 km2, respectively. Most of the trees were found to be clumped in groups of 1-10 individuals, although in the some other locations the clumps were composed of up to 49 trees. The population had clear inverse-J shape of DBH distribution with high number of individuals at 0-5 cm (62.6%) and 5-10 cm DBH class (20.71%), and gradual decrease in the middle and larger diameter classes. During the survey I located only 11 (1.6%) mature individuals (DBH=30). The occurrence of D. littoralis was associated with steep, low, southwest-facing sites and sites that had high litter cover and thickness. The study predicted that the density of D. littoralis was high at sites with tree coverage of 5-25%. I observed that illegal logging and fuel-wood chopping was the main threat to D. littoralis and its habitat. In addition, a potentially invasive Langkap (Arenga obtusifolia. Arecaceae) was widely distributed throughout the reserve. Because of its endemism, its narrow range and localised distribution, low total population size, its preference to particular environmental variables and high threat from anthropogenic activities and invasive species, this study suggested that D. littoralis should retain its conservation status of Critically Endangered.
Keywords: Dipterocarpus littoralis, population status, habitat preferences, critically, endangered species, conservation