Sierra de Bohol

Sierra de Bohol
Name	Sierra de Bohol
Country	Philippines
Region	Central Visayas
Province	Bohol
Highest	Mt. Maya Peak
Elevation m	870
Coordinates	9°50′N 124°10′E

Sierra de Bohol is a mountain range on the island of Bohol in the Philippines that forms a central spine across the island, linking lowland plains to upland plateaus. The range includes a series of karst hills, limestone cliffs, and volcanic remnants that influence regional transport corridors such as the road between Tagbilaran and Ubay, and shape watersheds feeding the Cebu Strait and inland rivers. The Sierra has been a focal point for naturalists from institutions such as the Philippine Biodiversity Conservation Foundation and researchers affiliated with University of the Philippines and Ateneo de Manila University.

Geography

The Sierra spans multiple municipalities including Dauis, Sierra Bullones, Ubay, and Bilar, forming an orographic barrier that separates the coastal plains near Tagbilaran from the eastern shorelines adjacent to Cebu Island waters. Prominent nearby features include the Chocolate Hills to the northwest, the Anda peninsula, and the lowlands around Carmen. Major settlements connected by passes through the Sierra include Loay, Dimiao, and Loon. The range’s ridgelines orient broadly north–south and intersect provincial boundaries with nearby islands serviced by ports at Tagbilaran Port and Ubay Port.

Geology and Topography

Geologically, the Sierra comprises Miocene to Pleistocene limestone, with patches of andesitic and basaltic volcanics linked to the Philippine archipelago arc, echoing regional geology found on Negros Island and Leyte. Topographic highs such as Mt. Maya Peak and adjacent tors rise to approximately 800–870 m and exhibit cuesta and karstic morphology similar to the Chocolate Hills karst fields. Geological mapping by teams from Philippine Institute of Volcanology and Seismology has identified fault traces related to the Philippine Fault Zone and stratigraphic contacts comparable to exposures on Samar. Quarrying and past mining near Carmen, Bohol have exposed limestone benches and fossiliferous horizons studied by paleontologists from National Museum of the Philippines.

Climate and Hydrology

The Sierra lies within the tropical monsoon climate belt affecting Central Visayas, with seasonal rainfall controlled by the Northeast Monsoon and Southwest Monsoon. Orographic lift generates higher precipitation on windward slopes facing the Bohol Sea, sustaining headwaters for rivers such as the Inabanga River tributaries and springs feeding the Abatan River basin. Karst aquifers within the limestone produce cave systems and resurgence springs comparable to those in Palawan and influence municipal water supplies for Tagbilaran and Cortes. Tropical cyclones crossing the Philippine Sea periodically cause intense rainfall and landslides documented by the National Disaster Risk Reduction and Management Council.

Biodiversity and Ecology

The Sierra supports tropical lowland and montane forest remnants harboring endemic and endangered species reported by researchers from Conservation International and BirdLife International. Fauna includes populations of the Philippine tarsier, fruit bats of the family Pteropodidae, and amphibians akin to taxa described from Mindanao and Leyte. Avifauna records list species shared with the Visayan Islands assemblage, and herpetofauna surveys by Haribon Foundation and university teams have documented new localities for endemic frogs and skinks. Vegetation gradients include limestone forest, dipterocarp assemblages, and mossy cloud forest pockets hosting orchids and ferns also found in protected areas like Rajah Sikatuna National Park.

Human History and Cultural Significance

Indigenous communities and migrants from Cebu City and Tagbilaran have used the Sierra as a source of materials and spiritual sites, with oral histories recorded by the National Historical Commission of the Philippines referencing upland rituals and pathways used during the Revolution and World War II guerrilla campaigns. Cultural landscapes include ancestral estates, terraced farms, and ancestral domain claims pursued through the National Commission on Indigenous Peoples. Local festivals in municipalities such as Bilar and Garcia Hernandez celebrate upland crop cycles and commemorate resistance leaders linked to provincial narratives preserved at the Bohol Provincial Museum.

Economy and Land Use

Land use in the Sierra combines smallholder agriculture—rice, coconut, abaca—and agroforestry integrating cash crops promoted by the Department of Agriculture and development projects by Asian Development Bank and USAID. Quarrying for limestone supplies cement plants in Cebu City and aggregates for infrastructure linked to the Philippine Highway Network, while sustainable livelihood initiatives from World Wildlife Fund seek to balance forest protection with eco-tourism ventures connecting sites like cave systems and ridge trails to markets in Tagbilaran. Hydropower potential has been evaluated by the National Grid Corporation of the Philippines for micro-hydro projects serving remote barangays.

Conservation and Protected Areas

Portions of the Sierra overlap with designated protected areas and watershed reserves administered by the Department of Environment and Natural Resources, with conservation partners including Conservation International, Haribon Foundation, and local NGOs. Proposed expansions to buffer zones draw on models from Rajah Sikatuna National Park and Sierra Madre conservation strategies to protect endemic species and karst aquifers. Community-based forest management agreements and reforestation projects implemented under the Forest Carbon Partnership Facility aim to mitigate erosion, secure water supplies, and sustain biodiversity while engaging municipalities such as Bilar and Sierra Bullones in participatory governance.

Category:Landforms of Bohol