Sierra Madre Biodiversity Corridor
The Sierra Madre mountain range contains the largest remaining tract of old-growth tropical rainforest in the Philippines. The longest mountain range in the country (known as the “backbone” of the northern island of Luzon), the Sierra Madre contains 1.4 million hectares of forest, representing 40% of the country’s forest cover. The biological importance of the corridor is not only due to the remaining intact forest in the central part of the mountain range, but also to its high plant diversity. The Sierra Madre forests are also home to hundreds of wildlife species, many of which are unique to the Philippines, including the Philippine eagle and golden crowned flying fox.

The Sierra Madre mountain range is also one of the major drivers of the Philippine economy, as its watersheds provide services that support major infrastructure, including dams that irrigate thousands of hectares of farm lands in Central Luzon and the Cagayan Valley region (the “rice bowl” of the Philippines), and water utilities and power plants that supply Manila, the capital and industrial center of the Philippines. 

Although protected on paper, much of the Sierra Madre is still under threat from human encroachment and associated timber poaching, mining, conversion of forests for agriculture, and migration. These threats have resulted in forest loss and degraded watersheds, including siltation and sedimentation of the Cagayan River and ecosystems at the river’s mouth such as estuaries, reefs, mangroves, and wetlands. Development — particularly road construction that will improve access and subsequent potential for exploitation of the area — is also a serious threat. The ecological interdependence of the Sierra Madre’s terrestrial, coastal, and marine ecosystems hangs in a fragile balance.

Currently, CI’s work in the Sierra Madre focuses on three key biodiversity areas: Peñablanca Protected Landscape and Seascape, Quirino Protected Landscape, and Northern Sierra Madre National Park. CI’s research work helped provide the scientific basis for establishing the Peñablanca and Quirino sites as protected areas under the Philippines’ National Integrated Protected Areas System, and ongoing projects within these protected areas seek to reduce threats and promote forest restoration activities, in partnership with local communities.