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How scientists and a community are bringing a Bornean river corridor back to life

Community tree nursery

Community tree nursery manager Norsalleh Bin Abdul Malik collects local tree seeds and grows them to seedling stage for reforestation teams to plant. Image by Carolyn Cowan for Mongabay.

  • Decades of deforestation to make way for oil palm monoculture have transformed the Kinabatangan River floodplain in east Sabah, Malaysian Borneo, dividing wildlife populations and confining many of the region’s most iconic species to small fragments of forest that cling on along the river.
  • Local communities and conservation initiatives are working together to restore and reconnect pockets of remaining habitat along the river to preserve the vital wildlife corridor, but restoration in the unpredictable and often-waterlogged floodplain is notoriously difficult.
  • One such initiative, Regrow Borneo, is facing the challenge by leveraging the expertise of scientists and local knowledge of community members who have been planting forests along the Kinabatangan for decades.
  • They say that by focusing their approach on a model that benefits both people and wildlife, they hope their program inspires others to shift away from simply planting numbers of trees toward restoring forests where they’re most needed, including in areas that present challenging conditions.

SABAH, Malaysia — Although it’s early in the day, the sun is already beating down fiercely as we step off the boat onto the muddy banks of the Kinabatangan River in the Malaysian state of Sabah. Amaziasizamora Jumail strides ahead into a patch of degraded forest, weaving her way through a tangled web of spiky liana vines and jauntily angled tree stems. As we clamber deeper into the thicket, the sunlight sears through multiple canopy gaps. There’s no hope of the cool shade of a mature forest here. Not yet, anyway.

“We’re not just planting trees here, we’re restoring an entire ecosystem,” Jumail, field manager of the U.K.-based nonprofit Regrow Borneo, says as she stoops to inspect a dung beetle pitfall trap she set up previously in this scrubby yet-to-be-planted forest plot. “Dung beetles are good indicators of forest health, so this baseline data will help us measure ecosystem recovery,” she says.

The distant call of gibbons trails through the humid air, their whooping crescendo a reminder that pockets of intact forest still cling on within the wider sea of oil palm monoculture that dominates the expansive Kinabatangan floodplain.

Jumail’s dung beetle survey is part of Regrow Borneo’s efforts working alongside the local community to reconnect fragmented patches of rainforest along the river corridor. In the process, it’s studying the effects of restoration on biodiversity, carbon sequestration and ecosystem resilience. 

The initiative is a collaboration between the Danau Girang Field Centre (DGFC) — Cardiff University’s scientific research and training facility in Sabah — and KOPEL, a community-led cooperative that runs ecotourism operations and has been planting native trees around the four villages of Batu Puteh township for more than two decades.

Kinabatangan floodplain
An isolated fragment of forest sits on higher ground amid a sea of oil palm on the Kinabatangan floodplain. Batu Puteh township and a riparian reforestation site are in the foreground. Image by Carolyn Cowan for Mongabay.

Regrow Borneo’s initial targets are modest as it focuses on finding the most effective methods of long-term forest restoration. Ultimately, the team has its sights set on 2,600 hectares (6,400 acres) of forest in need of restoration in the Kinabatangan corridor. “While we are not yet able to operate at this scale, we are ambitious!” says its website.

Since it was launched in 2020, the partnership has replanted and monitored approximately 30 hectares (74 acres) of degraded forest at five separate sites in the vicinity of Batu Puteh. But working along a dynamic river system surrounded by intensive agriculture hasn’t been without its challenges. From unseasonable flooding and unruly neighbors, to disruptions due to the lockdowns imposed during the COVID-19 pandemic, the researchers and community have had to rely on each other’s experience and ingenuity to ensure the long-term survival of their nascent forests.

Biologists in Borneo
Amaziasizamora Jumail and field assistant Masnor Is bin Nasran process a dung beetle trap. The team will also monitor small mammals, birds, amphibians and carbon storage at each site. Image by Carolyn Cowan for Mongabay.

A vital wildlife corridor

Richly fertile rainforest once blanketed the 500,000-hectare (1.2-million-acre) Kinabatangan floodplain, providing a vast stomping ground for wildlife such as orangutans, proboscis monkeys, hornbills, clouded leopards, otters and Bornean elephants. But since the 1980s, roughly 90% of the floodplain has been converted to oil palm monoculture, dividing wildlife populations and leaving isolated fragments of forest scattered along the river.

The 41,100 hectares (101,560 acres) of forest that remains is mostly protected by the government, either as the Lower Kinabatangan Wildlife Sanctuary under the protection of the Sabah Wildlife Department, or as forest reserves managed by the Sabah Forest Department. Sabah’s riparian legislation also requires a 20-meter (66-foot) vegetation zone along the riverbanks of major watercourses.

Together, the protected forests and riparian zone form an incredibly important wildlife corridor hugging the shores of the Kinabatangan River. It’s particularly valuable for large animals that might otherwise be forced to pass though agricultural land or villages where the risk of conflict with people is high. However, many parts of the forest corridor have been degraded by past logging practices and more recent encroachment by plantations.

Oil palms encroach on the shores of the Kinabatangan River, despite regulations that stipulate a 20-meter riparian buffer zone should be maintained. Image by Carolyn Cowan for Mongabay.

“We really need to protect this habitat for wildlife because there’s so much endemic wildlife here,” Jumail says as we return to the boat, her dung beetle surveys completed. “This area is the only place along the whole Kinabatangan where you can see 10 species of primates. If the habitat is gone, the wildlife will be gone, and then the ecotourism will be gone, which is generating money for communities right the way up to the state government.”

Motoring back downriver to Jumail’s base at the DGFC, the steady erosion of the forest corridor and dominance of oil palm are plain to see. At several locations, plantations come so close to the river that the oil palms are tumbling down eroded riverbanks, their upended crowns awash with water. Meanwhile, a glance down each narrow tributary that flows into the main river reveals impenetrable waves of jagged, deep-green palm fronds stretching far into the distance.

As the remaining slivers of forest diminish, so do the Kinabatangan’s wildlife populations. For instance, the area lost nearly one-third of its population of orangutans (Pongo pygmaeus) between 2002 and 2017, and family groups of Bornean gibbons (Hylobates muelleri) have suffered up to a tenfold decline over the past three decades.

Map of Kinabatangan
The stretch of the Kinabatangan floodplain and five sites where Regrow Borneo are restoring forest to connect up patches of remaining habitat along the river corridor. The green outlined protected areas represent Forest Reserves and the Kinabatangan Wildlife Sanctuary.

Regrow Borneo is born

For DGFC director and Regrow Borneo co-chair Benoit Goossens, restoring connectivity to the river corridor through forest restoration was the logical next step for the research facility that’s been operating in the area since 2008.

“For the first 10 years, we looked at the impact of landscape changes on wildlife … and we realized that fragmentation was happening and that corridors were extremely important,” Goossens says. The DGFC data indicated, for example, that clouded leopards (Neofelis diardi) completely avoid oil palm plantations and so are confined to increasingly smaller and isolated forest patches. Likewise, groups of proboscis monkeys (Nasalis larvatus) with very small home ranges were trying to eke out a living in very narrow forest corridors between plantations and the river’s edge.

“It became obvious that we should look at other things,” Goossens says. “One was tackling poaching and trafficking … and the other was tackling fragmentation and trying to restore and increase corridors.”

And as luck would have it, the nearby community at Batu Puteh township, a roughly 20-minute boat ride upstream of the field center, has spent the past two decades doing just that.   

Small mammal trapping
Nazrul Mohammad Natsyir, DGFC boat skipper and field assistant, sets a small mammal trap at a forest restoration site in the Kinabatangan River corridor. Image by Carolyn Cowan for Mongabay.

A motivated community

In 1998, devastating forest fires swept through the Kinabatangan following one of the most intense El Niño-related droughts in recent decades, severely degrading what remained of the forest corridor at the time.

Witnessing the fragility of the surrounding landscape and recognizing that the forests were the intrinsic asset that drew tourists to the area, local residents operating through their recently founded ecotourism cooperative, KOPEL, began planting native trees around Batu Puteh in the hopes of restoring some of the green back to their charred surroundings.

“People want to come here because we have a forest and wildlife. If we don’t protect them, then why would people want come and visit? Do they want to come and see us, the villagers? I don’t think so,” says Saidal bin Udin, KOPEL’s general manager, who has been involved in the reforestation work since it began in the early 2000s. Since then, the community has planted more than 400,000 trees across roughly 350 hectares (865 acres) of degraded floodplain.

“You see all over that this NGO is managing this, or the government is managing that. But here we do things differently. The community themselves manage their own team in the community to do the conservation work,” Saidal tells Mongabay. “The community here really understand what they’re doing and why.”

Reforestation team
Memee bin Dairin (left) and Karseh bin Salamat (right), members of the KOPEL community reforestation team, plant seedlings at Regrow Borneo’s restoration sites. Image courtesy of Regrow Borneo.

Approximately 10% of the Batu Puteh community of approximately 2,000 people are involved either directly or indirectly in KOPEL’s ecotourism and conservation activities, Saidal says. When it comes to forest restoration, they’ve learned largely through trial and error, he says, documenting tree by tree which species grows well in which places, and gradually building up a picture of where their best hopes lie.

The early restoration efforts were largely funded by revenues generated by KOPEL’s local ecotourism ventures, such as homestays, wildlife hikes and riverboat cruises, enabling them to set up a community nursery and accrue expertise in local restoration techniques and selecting appropriate species for planting in the highly variable floodplain soils.

But in a fortunate twist of fate, by the time tourist numbers plummeted due to the lockdowns imposed during the COVID-19 pandemic, KOPEL had already embarked on its partnership with Regrow Borneo, which was able to help sustain the community’s conservation work through that period using funds raised via donations.

While carbon offsetting isn’t its main aim, the project was founded in part to offer researchers traveling to the DGFC a way to offset emissions associated with their travel. The team estimates that planting 1 hectare of healthy forest in the Kinabatangan costs roughly 15,000 pounds ($18,800), or about $7,600 per acre, with replanted plots so far storing up to 7 metric tons of carbon per hectare per year.   

Saidal bin Udin, KOPEL general manager, at the KOPEL HQ on the shores of the Kinabatangan River. Image by Bruno Gonzalez for Mongabay.
Ecotourism homestays
Ecotourism homestays in Batu Puteh accommodate visitors who take part in the community forest restoration initiative. Image by Carolyn Cowan for Mongabay.

With the support of Regrow Borneo, reforestation teams comprising fully employed local residents and visiting tourists are now focusing on planting a total of 20 tree species, mainly within the Pin Supu Forest Reserve through an agreement with the Sabah Forestry Department, and within areas set aside for conservation in nearby oil palm plantations. The teams also carry out the vital maintenance of reforestation plots, cutting back grass and climbers prior to planting and for at least three years after to ensure the saplings have enough sunlight to grow.

The proven track record and continuity of KOPEL’s conservation work has demonstrated to many local residents that forest restoration can be a sustainable long-term livelihood.

For Batu Puteh resident Mohamad Sharul Bin Abdullah, 27, working as part of the community reforestation team is a chance to learn skills that he expects will remain relevant well into the future, while allowing him to remain close to his friends and family. “This project is directly in my home community, so I can gain knowledge and skills right here,” he says.

Inspiring the next generation to sustain Batu Puteh’s conservation legacy into the future is vitally important, Saidal says. “Now I teach the new generation, who have a new point of view. It’s a business, a job opportunity. But I try to plant it in their soul: to do community-based tourism, the program must have a soul.”

Memee Bin Dairin, 44, who has been working with KOPEL for more than 10 years following years as a worker on an oil palm plantation, says that while reforestation work is hard and physical, it’s far more pleasant and healthier than the dust and chemicals of plantation labor. Still, Sharul is skeptical that simply providing better conditions than nearby plantations will be enough to attract young people to local conservation work and halt the prevailing trend of his peers migrating to urban areas in seek of more tempting opportunities. 

Reforestation team
Members of the community reforestation team prepare seedlings for planting at one of Regrow Borneo’s five restoration sites. Image courtesy of Regrow Borneo.

Strength in complementary skills

While the project has achieved tangible benefits for the local community and nature over a relatively short time, the Regrow Borneo efforts have also faced setbacks. By seeking strength in their complementary skills, the researchers and the Batu Puteh community have been able to overcome a slew of challenges.

For starters, establishing trees in waterlogged floodplain soil is notoriously difficult. Planting needs to be timed just right to give the young trees the best chance to form roots and grow above seasonal flood levels. However, Jumail says that rainfall patterns in the Kinabatangan area are becoming less predictable. “The last few years I couldn’t differentiate between the dry season or wet season anymore; it’s been rain all year round,” she says.

In 2020, abnormally heavy rain caused the river levels to swell for a prolonged period, submerging a low-lying restoration site that had recently been planted with hundreds of seedlings. Most of them perished, compelling the community nursery, which normally supplies around 12,000 saplings a year, to produce more to replant the site the following year.

Tree seedlings
Tree seedlings in the community-managed tree nursery in Batu Puteh. The main types planted locally are flood-tolerant Nauclea sp. and Mallotus muticus. Images by Bruno Gonzalez for Mongabay.

At another restoration site, the project ran into a dispute over encroachment by an adjacent oil palm estate. In 2020, the plantation uprooted and removed roughly 5% of the native tree seedlings that had been planted by the community in 2014, replacing them with commercial oil palms. Community reforestation teams attending to the maintenance of the site alerted DGFC staff to the encroachment, and Goossens was able to work with the Sabah Land and Survey Department to establish the boundary of the wildlife sanctuary and riparian reserve and reclaim the right to remove the oil palms and replant the area with native seedlings. 

While the authorities dealt with the issue when prompted, Goossens notes that if projects like Regrow Borneo were not out and about on the ground, many such cases of encroachment could well go unnoticed. “Further inland, there is so much encroachment around the wildlife sanctuary,” Goossens says. “No one is checking unless you do aerial surveys. Plantations just try to get a little bit more land.”

Regardless of the encroachment, Goossens says it’s been possible to build trust and good working relationships with local oil palm estates over the years, in part due to the DGFC’s legacy of reliable research and expertise in the area. Plantations are now asking Regrow Borneo to restore forests on their land. Once the project has established solid methods for restoring forest in the floodplain, it aims to expand these efforts to restore up to 800 hectares (1,980 acres) of land set aside for conservation in the Sawit Kinabalu plantation close to Batu Puteh.

Reforestation plot
A thin strip of restored riparian forest at a site first replanted in 2014 but suffered a land dispute with the neighboring plantation. Image by Carolyn Cowan for Mongabay.

Recovering habitat within every scrap of disused land in and around the oil palm landscape itself is an approach John Payne, executive director of the nonprofit Bringing Back Our Rare Animals (BORA) in Sabah, advocates.

“In the Kinabatangan, at least 95% of the oil palm land is owned by corporations … and in my view, they have an obligation — sadly it’s not a legal obligation — but they have an obligation to contribute towards nature conservation,” Payne says. “Even a little bit [of land set aside by plantations] would go a long way to conserving wildlife.”

Payne says that while reforesting a floodplain like the Kinabatangan is always going to be challenging, the dividends for nature are ultimately well worth the effort. “You need to have both the plant species that are ecologically or evolutionarily evolved to live in floodplains and you need to get the timing right. But even if you have those [factors in place], you always run a risk that you have a big flood … The only thing you can [do] is keep planting and take that risk.”

Regrow Borneo isn’t the only group seeking to restore connectivity to the Kinabatangan’s crucial wildlife corridor. Conservation organizations, including BORA, are seeking to bring life back to the degraded habitats using a variety of methods, such as boosting the carrying capacity for animals in unplanted areas of oil palm plantations by planting figs and other key food sources.

Meanwhile, restoration ambitions are just as high in other parts of Sabah. In Tabin, for instance, groups are trying to reconnect wildlife corridors by buying up and rewilding legally planted oil palm estates; and in Tawau, conservation programs are working with an oil palm company to bridge several forest reserves via a 14-km (9-mi) corridor. 

Restoration plot
Amaziasizamora Jumail describes the work it took to replant a flooded area after the majority of seedlings were killed by an unseasonal flood. Image by Carolyn Cowan for Mongabay.

Wildlife returns

In June 2023, staff from KOPEL spotted two wild adult orangutans playing in trees planted by the community reforestation team in 2014 at Ladang Kinabatangan. As one of the project’s riparian reserve sites, no bigger than 20 hectares (49 acres), the new strip of forest creates an exceedingly thin but precious strip of natural vegetation between the riverbank and an oil palm plantation.

For Goossens, the sight of the exuberant primates in the restored trees is confirmation that the project is on the right track. A once broken arboreal corridor is now flush with new growth, and one of the floodplain’s most threatened mammals is cavorting in it. “That makes me happy; I feel like something is improving,” he says.

“But the most important thing is that we’re restoring an ecosystem. It’s not about numbers of trees that we’re planting. It’s about hectares of functional forest that we’re restoring.”

Restoration plot
The restoration site at Laab Swamp is waterlogged for up to 6 months each year. The photographs show one of two restoration plots prior to planting in 2021 (top) and once seedlings had begun to develop in 2022 (below). Images courtesy of Regrow Borneo.

Carolyn Cowan is a staff writer for Mongabay. Follow her on 𝕏 @CarolynCowan11.

Banner image: Community tree nursery manager Norsalleh Bin Abdul Malik collects local tree seeds and grows them to seedling stage for reforestation teams to plant. Image by Carolyn Cowan for Mongabay.


Hearn, A. J., Ross, J., Bernard, H., Bakar, S. A., Goossens, B., Hunter, L. T., & Macdonald, D. W. (2017). Responses of Sunda clouded Leopard Neofelis diardi population density to anthropogenic disturbance: Refining estimates of its conservation status in Sabah. Oryx, 53(4), 643-653. doi:10.1017/s0030605317001065

Stark, D. J., Vaughan, I. P., Evans, L. J., Kler, H., & Goossens, B. (2017). Combining drones and satellite tracking as an effective tool for informing policy change in riparian habitats: A proboscis monkey case study. Remote Sensing in Ecology and Conservation, 4(1), 44-52. doi:10.1002/rse2.51

Related audio from Mongabay’s podcast: A discussion of numerous examples of reforestation projects around the world that prioritize communities as well as the environment, listen here:

Podcast: Reforestation done right, from Haiti to Honduras and Ho Chi Minh City


See related story:

Nursing oil palm plantations back to nature in Malaysian Borneo


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