Forest frontline: The Kabulnan Watershed

The heat generated by the urban jungle — a forest of concrete buildings filled with the cacophony of churning machines and shrouded in a haze of pollutants — can make us forget the sounds, scents, and sensations of a lush, green forest. It is a jarring juxtaposition of two places, two different and contesting worlds.

The Philippines is acknowledged as one of the world’s megadiversity hotspots, home to an unparalleled abundance of flora and fauna and unique ecosystems. As urban sprawl continues to grow and the ideals of modern lifestyle and consumption dominate, only around 248 protected areas in the country remain. These areas preserve our vital biodiversity corridors. While there are other areas that are environmentally critical, they do not enjoy the necessary protection to sustain life.

We put our spotlight on the lesser known Kabulnan River Watershed, a 116,451.83-hectare forest area covering the municipalities of Esperanza, Isulan, Bagumbayan, Senator Ninoy Aquino, Kalamansig, and Palembang in Sultan Kudarat; Ampatuan in Maguindanao; and Lake Sebu in South Cotabato — a contested lifescape where nature and the anthropogenic often collide.

FOILAGE. Inside the forest in Barangay Ned, Lake Sebu, South Cotabato. Photo from LRC

A watershed

The Kabulnan River is the major river body that courses through and gives life to the watershed area, with its uppermost headwaters emanating from Lake Sebu and Palembang, and its tributaries eventually merging and draining towards the Magonoy River in Maguindanao. These are places that evoke myths but are as real and integral as the life-giving force they provide the peoples in their environs.

In 2000, Kabulnan Watershed was established as a protected watershed forest reserve through Presidential Proclamation No. 241 s. 2000 with the intent of improving the water yield and restraining disruptive land and forest use. Its waters are “Class A” pristine, exhibiting low levels of pollution and categorized for public consumption. Imagine water you can drink, filtered by the earth herself and coursing through natural sediments.

The watershed sustains and nourishes an estimated half a million people across the eight municipalities with potable water, and irrigates at least 20,000 hectares of agricultural lands. Its forests also safeguard the entire area from hazards linked to climate extremes, especially landslides and floods. 

Overlay map of the Kabulnan Watershed and its interconnected Key Biodiversity Areas. Based on map images retrieved from Mallonga et al. (2020) and Critical Ecosystem Partnership Fund (n.d.)

Key biodiversity area

Kabulnan Watershed is also interconnected with 245,318 hectares of declared and candidate key biodiversity areas, namely the Mt. Daguma and Mt. Busa-Kiamba KBAs and the Kalamansig-Palimbang Candidate KBA. While KBAs are scientifically assessed as highly biodiverse, they do not have a protected status.

A study in a select site of the watershed found high floral and faunal biodiversity richness especially within the closed canopy forests of the watershed. There were at least 531 plant and animal species found in the sampling sites, of which 38 are listed as at risk ranging from near-threatened to critically endangered, and 170 are endemic. A similar biodiversity profile is established
in another part of the watershed, where at least 111 species of forest and open-habitat fauna were discovered, of which 52% are endemic and 34% are at risk (Ibanez, 2010).         

The identified species, which range from near-threatened to critically endangered, all play critical ecological roles in the forest landscape. Critically endangered hardwood dipterocarps such as Gisok-Gisok and Yakal, described as skyscrapers of the forest, are keystone species that feed, shelter, and generally support various life forms, and conserve soil and regulate water.

The vulnerable Philippine Hawk Eagle and the critically endangered Philippine Eagle are likewise keystone species that regulate prey populations and excellent bio-indicators of forest health as they require a large area for their habitat and territory. Similarly, the endangered Large Flying Fox also serves as an indicator of healthy forest areas, as they are highly selective in choosing roosting sites and play a crucial role in pollen dispersal and nutrient transfer.

CRITICALLY ENDANGERED. The Philippine Eagle (Pithecophaga jefferyi). Photo from Animalia/Shankar S.

There are also the vibrant Mindanao Bleeding-heart, Visayan Hornbill, Rufous Hornbill, Blue-headed Racquet-tail, and Mindanao Lorikeet — ranging from near-threatened to endangered — act as “forest farmers.” They disperse seeds and pollen across vast forest areas and regulate pest populations through hunting, fostering natural landscape regeneration.

‘FOREST FARMER.’A Rufous Hornbill (Buceros hydrocorax) rests on a tree. Photo by Ranieljosecastaneda via Wikimedia Commons.

Fragmentation

In spite of its protected status, the Kabulnan Watershed is beset by longstanding forest denudation, with satellite data estimating at least 54,100 hectares of tree cover lost between 2001 and 2023 in the three provinces that bound the area. 

A comparison of vegetation cover data between a report in 2007 and in 2020 in select areas within the watershed demonstrates the percentage share of closed canopy vegetation decreased by more than half of the total. Closed canopy forests are dense forests in which the entire land surface is covered by tree crowns. 

The observed trend indicates the fragmentation of the forests, their reduction into smaller, isolated patches, constricting species and ecosystem biodiversity. This fragmentation is expected to worsen the impacts of climate-linked disasters. Last year, more than 290,000 people in the watershed area were affected by El Niño-amplified droughts and flooding.

Forest frontline 

Various threats encroach into the Kabulnan Watershed and contribute to its degradation. Right at the headwaters in Barangay Ned, Lake Sebu, three coal mines affiliated with the San Miguel Global Power have rapidly commenced extractive operations over more than 17,000 hectares of land since last year, clearing huge swathes of vegetation and excavating lands despite opposition from affected indigenous people and farmers. 

Downstream towards the tri-boundary of Sultan Kudarat, Maguindanao, and South Cotabato, a 29,000-hectare Integrated Forest Management Agreement (IFMA) continues to operate legalized logging and agroforest plantations. Indigenous communities observed that native plants and wildlife are being displaced by monocropping and agrochemical use. 

The Kabulnan Watershed is one of the remaining but dwindling forest territories and may well be one of the last lines of defense our communities have in the face of a climate-changed world.

According to the 2022 Philippine Forestry Statistics, the country’s forest cover now spans 7.22 million hectares, accounting for only 24.07% of its total land area — a stark contrast to the 17.8 million hectares of lush forests that once thrived in 1934. In less than a hundred years, we’ve cut down and laid to ruin what nature has taken millennia to grow. This dwindling expanse speaks not just of loss, but of the layered histories of extraction, neglect, and the fragile threads of ecological survival that remain. It forces us to face the challenge of navigating life amidst economic and environmental collapse. Because if not, the fragmentation and collapse of forests will be our own as well. – Rappler.com

Atty. E.M. Taqueban is the executive director of the Legal Rights and Natural Resources Center – Friends of the Earth Philippines (LRC-FoE PH). She is an associate professor at the Department of Anthropology at the University of the Philippines Diliman.