Analisis Spasial Preferensi Habitat Orangutan Tapanuli (Pongo tapanuliensis) di Cagar Alam Dolok Sibual-Buali dan Cagar Alam Dolok Sipirok

Abstract

The Tapanuli orangutan (Pongo tapanuliensis) was the last species to be introduced after the Bornean orangutan (P. pygmaeus) and the Sumatran orangutan (P. abelii). However, pressure on existence of the Tapanuli orangutan has recently increased, both in terms of population and habitat. The remaining habitat of the Tapanuli orangutan has now been fragmented into two large sections, including several small populations in the Dolok Sibual-buali Nature Reserve (NR) and Dolok Sipirok NR. The size of the area and various considerations of the problems encountered make it very important to analyze the habitat preferences of orangutan in Dolok Sibuali-buali NR and Dolok Sipirok NR to do through a spatial model. This research was conducted to analyze the spatial preference distribution of the Tapanuli orangutan habitat in Dolok Sibuali-buali NR and Dolok Sipirok NR, in addition to knowing the composition of habitat vegetation and knowing the effect of land change on habitat preferences. Signs of orangutans existence directly or indirectly are used as the key to modeling habitat preferences. The logistic regression statistical approach was used to develop a preference model consisting of 8 factors or predictor variables, including vegetation index, humidity index, elevation, slope, distance from roads, distance from rivers, distance from settlements and distance from plantation. Vegetation composition identified by vegetation analysis using plotted line transect combined with observations of the orangutans existence sign. Analysis of land cover change effect on habitat preferences is known spatially using multi temporal (time series) satellite images data for the last three decades. The results showed that the area studied was dominated by high habitat preference area. The forest vegetation composition in the study area has moderate to high diversity, evenness and species richness. Changes in land cover and reduction in forest area over the last three decades in the study area have led to a decline in the quality of orangutan habitat preference.