Karakteristik Pohon Tempat Bersarang Orangutan Sumatera (Pongo abelii Lesson, 1827) di Kawasan Hutan Batang Toru, Kabupaten Tapanuli Utara – Sumatera Utara
Abstract
The decline of natural habitat of Sumatran Orangutan (Pongo abelii Lesson, 1827) and persecution causing it's population decline. Batang Toru Forest has an important value as a habitat of Sumatran Orangutan which is separated from it's main habitat in Leuser Ecosystem (Aceh). Orangutan is rare species and it has preferention of choosing the nest location and the species of nesting tree with spesific characteristics. The objective of this research is to discover the characteristics of Sumatran Orangutan's nesting tree in Batang Toru Forest. The research conducted at October 23th until December 22th 2008 in Research Station Yayasan Ekosistem Lestari – Sumatran Orangutan Conservation Program (YELSOCP) in the 12,75 km2 area of West Block of Batang Toru Forest, in North Tapanuli of North Sumatera. Equipment that used are girth measuring tape, 30 m measuring tape, 20 m rope, machete, compas, flagging tape, digital camera, camera trap, thermo-hygrometer, watch, and stationary. Primary data are vegetation structure and composition, temperature and humidity, water availability, and profil of nesting tree (species of tree, total height, diameter, crown width, and crown shape), nest height, nest position, and the existence of other animals. This primary data are colected by nest survey method and vegetation analysis. Secondary data are general condition of research site and bio-ecology of Sumatran Orangutan. During the research found 154 nesting trees, it’s content 20 tree species. 33,74% (52 trees) of it is Hoting (Lithocarpus spp.). The tree height of nesting tree is about 16-20 m (34%) with average tree height from all trees is 20,35 m and average nest height in 17,24 m. In such as low nest and tree height the Orangutan's nest is covered by the taller crown of other trees from rain and wind. Orangutan tend to build their nest at tree with diameter 10-19 cm and average diameter from all the trees is 23,71 cm. The crown width less than 11 m2 with average from all the trees 15,64 m2. Orangutan's nest near the river indicated that nest location preferention caused by the location near the river is lower (the slope area). In the research location, potential competitor animal are Siamang (Symphalangus syndactilus), Gibbon (Hylobates agilis ungko), Pig-tailed monkey (Macaca nemestrina), Binturong (Arctictis binturong), squirrel (Callosciurus notatus) and Hornbill. The concultion of nesting tree characteristics are total height 16-20 m, diameter 10- 19 cm, crown width less then 11 m2, and ball shape crown. Hoting (Lithocarpus spp.) is tree species that qualify with that tree characteristics, for that reason Orangutan in Batang Toru Forest prefer to use this tree species than other tree. The location preferention is location which is covered from rain and wind.