Gunung Kentawan

Gunung Kentawan Nature Reserve (Cagar Alam Gunung Kentawan) is a small strict nature reserve of about 2.6 square kilometers (approximately 258 hectares) in Loksado District, Hulu Sungai Selatan Regency, South Kalimantan, Indonesia, located in the hill country within the broader Meratus mountain region. ^[1] Established in May 1999 through Ministry of Forestry Decree No. 336/Kpts-II/1999 and managed by the South Kalimantan Natural Resources Conservation Agency (BKSDA Kalsel) under the Ministry of Environment and Forestry, the reserve protects an upland forest ecosystem associated with three peaks — Kentawan Laki, Kentawan Bini, and Kentawan Anak — reaching approximately 400 meters in elevation. ^[2] As a cagar alam, it carries strict protection status aimed at conserving its forest ecosystem and biodiversity, including a significant population of proboscis monkeys.

Despite its small size, the reserve harbors a notable and growing population of proboscis monkeys (Nasalis larvatus), Borneo's endemic flagship primate, which have adapted to its mountainous karst dipterocarp forest — an unusual habitat for this species that more typically occupies riverine and mangrove zones. ^[1] The population grew from 46 individuals in 2013 to 102 individuals across eight groups by 2026. Other mammals include gibbons (Hylobates muelleri), mouse deer (kancil), pangolins, wild cats, and various squirrels and civets. The reserve also supports 53 bird species including hornbills and kingfishers, plus reptiles, amphibians, and forest insects associated with moist upland habitats. ^[2]

The reserve protects upland tropical forest growing on steep karst and hilly terrain, with a canopy of native Bornean hardwoods including bangkirai, dammar, ulin, and surian, and an understory of palms, ferns, shrubs, and climbing plants. ^[1] At least 93 plant species have been documented in the reserve, including 28 species of wild orchids and eight bamboo species. Vegetation reflects the moist forest conditions of the Meratus foothills, where diverse tree species and epiphytes thrive. Because surrounding lands have been extensively cleared, the reserve's forest holds local significance as a remnant of the native plant communities once widespread across the province's hill country.

Gunung Kentawan rises within the hill country bordering the Meratus Mountains, a range that forms the geological backbone of southeastern Kalimantan, and is characterized as a karst ecosystem with hydrological and orological functions. ^[1] The terrain is rugged with steep slopes, ranging from rolling to extremely steep, shaped by uplift and erosion of older sedimentary and metamorphic rocks. Three forested peaks — Kentawan Laki, Kentawan Bini, and Kentawan Anak — dominate the reserve, with soils derived from the weathering of the underlying rocks. The hilly relief and forest cover help regulate water flow and protect against erosion in the surrounding catchment.

The reserve experiences a humid tropical climate with high rainfall and warm temperatures throughout the year, moderated somewhat by its upland setting. The wet season generally falls between November and April under monsoon influence, while the months around mid-year are relatively drier. Mist and frequent rain keep the forest moist, and temperatures are typically a little cooler than in the surrounding lowlands, contributing to the reserve's value as upland forest habitat.

The Hulu Sungai region of South Kalimantan, including the area around Kandangan (the regency seat approximately 20 kilometers from the reserve), has long been inhabited by Banjar communities and others whose livelihoods depend on rice farming, river trade, and use of forest resources from the nearby Meratus hills. Loksado District, where the reserve lies, also has a tradition of Dayak settlement in the Meratus foothills. Over time, much of the surrounding land was cleared for agriculture and settlement. The reserve's establishment reflects efforts to retain a sample of the region's native hill forest amid this history of human use and landscape change.

Gunung Kentawan was designated a strict nature reserve (cagar alam) on May 24, 1999, through Ministry of Forestry Decree No. 336/Kpts-II/1999, securing protection for a small but ecologically significant tract of South Kalimantan's upland forest. ^[1] It is administered by BKSDA South Kalimantan's Conservation Section I (Pelaihari), with on-site management delegated to the Banua Anam Resort. Its cagar alam status limits permitted activities to research, monitoring, and conservation, in keeping with the goal of preserving the reserve's natural forest ecosystem.

As a strict nature reserve, Gunung Kentawan is not developed for tourism, and access is restricted to authorized research and conservation work. Its principal value lies in its protected hill forest and the wildlife it shelters, especially its growing population of proboscis monkeys and its diverse orchid flora. The forested slopes and three peaks of this small mountain offer a glimpse of native upland Bornean karst-forest ecosystems for those granted permission to enter, though the reserve is primarily a conservation rather than recreation site.

The reserve lies in Loksado District, roughly 20 kilometers from Kandangan in the interior of South Kalimantan, and is reached by road and forest tracks through the surrounding countryside. There are no tourist facilities, consistent with its strict protection status. Visitors with legitimate research or conservation purposes must obtain permits and coordinate with the South Kalimantan BKSDA office via the Banua Anam Resort, and local guidance is recommended given the rugged, forested terrain.

Conservation of Gunung Kentawan focuses on preserving a small remnant of upland karst forest and its role in protecting watersheds and biodiversity in a heavily cultivated region. The reserve's growing proboscis monkey population, which rose from 46 to 102 individuals between 2013 and 2026, is an encouraging conservation indicator. ^[1] As a small reserve surrounded by farmland and settlement, it faces pressures including encroachment, illegal logging, and isolation from larger forest blocks. BKSDA South Kalimantan, in partnership with Pertamina EP Tanjung Field, works to monitor and protect the area.