Analisis Jangkauan Historis dan Daya Dukung Habitat Orangutan Tapanuli di Pesisir Barat Tapanuli Tengah

Abstract

The distribution of Tapanuli orangutans is currently only recorded in the Batang Toru landscape, at an altitude of 300 metres above sea level (masl) to the mountainous region at around 1,300 masl. Based on surveys conducted in 2000- 2001 and 2021-2024, Tapanuli orangutans were found in Pesisir Lumut and Kampung Sawah, Pesisir Barat, Tapanuli Tengah Regency. This study used thermal drones to monitor and identify the presence of Tapanuli orangutans and other animals. The use of thermal drones successfully identified three male individuals and a pair of Tapanuli orangutan parents and their offspring. The optimal flying height for drones is below 120 AGL (above ground level), with the best flying time being in the morning between 06:00 and 08:00 WIB (Western Indonesian Time). Land cover change analysis was conducted on an area of 155,000 ha using Landsat imagery from 1989, 2007, and 2025 to detect the connectivity of the Batang Toru and Lumut landscapes. The analysis results show that in the first 18-year period (1989–2007), there was a change in forest cover area from 113,472.18 hectares to only 89,122.41 hectares in 2007 (-24,349.77 hectares/21.46%). This decline in forest area has resulted in the formation of forest pockets that are increasingly distant from one another. In 1989, the distance between forest pockets was approximately 1,314 m, then 4,237 m in 2007, and 6,092 m in 2025. Predictions regarding land cover changes over the next 15 years (by 2040) indicate insignificant changes in area, amounting to 537.57 ha. Modelling the carrying capacity of population pockets using Maxent shows that the Pesisir Lumut and Kampung Sawah forests are no longer able to provide habitat for Tapanuli orangutans, as only 2,230 hectares of the 24,558 hectares of observation area remain (9%).