Kelvin Davies, Founder of the Rainforest Rangers program, reports on his recent trip to North Sumatra, Indonesia, and the Gunung Leuser Ecosystem—the only place on Earth where orangutans, tigers, rhinos, and elephants coexist in one habitat.
A return with purpose
We have a responsibility to our donors to ensure that funds are well spent and that outcomes are meaningful and long-lasting. For this reason it was time for me to revisit Sumatra. On my first visit in over a decade I had two clear purposes: to assess the success of previous restoration efforts—particularly trees planted with Australian donor support—and to identify opportunities for future impactful projects.
Sumatran Orangutan
Gunung Leuser: A Critical Biodiversity Hotspot
The Gunung Leuser Ecosystem spans 7,927 km² of tropical rainforest across Aceh and North Sumatra provinces. This national park is a biodiversity hotspot, home to an estimated 10,000 plant species, nearly 600 bird species, 200 mammals, and close to 100 species of amphibians and reptiles. It is one of only two remaining habitats for the critically endangered Sumatran orangutan. Other unique species include the Sumatran tiger, Sumatran rhinoceros, and Sumatran elephant.
However, when the park was established in 1980, its boundaries were poorly defined and enforced. Since then, illegal clearing—by both corporations and individual farmers—has taken a heavy toll. Thousands of hectares of the national park were cleared illegally by oil palm companies with further encroachment by small scale farmers. Today, more than four million people live within or near the park, many depending on small- to medium-scale rubber and palm oil plantations.
One of the 500,000 trees planted in 2008.
Orangutan Information Centre
I first visited Sumatra in 2008 when I began supporting the Orangutan Information Centre (OIC), a non-government organisation founded and led by local Indonesians. They have now planted over 3 million trees. You can read more about this project here.
When I arrived at Medan's Kualanamu International Airport in March 2025, I was met by Panut Hadisiswoyo, OIC's founder. We headed straight to a site we had first visited in 2008—an area where 500 hectares of rainforest had been illegally cleared in the 1990s for oil palm plantations.
Reversing Destruction: 500,000 Trees Planted
Thanks to OIC's work, those 500 hectares have since been rehabilitated with over 500,000 trees planted (1,000 trees per hectare). The restoration project required the removal of the oil palms using chainsaws, the planting of the trees and several years of maintenance to ensure they survived. The four “pondok” (temporary buildings used for staff accommodation and nurseries) that once supported planting activities have now been removed, their purpose fulfilled. Their presence also served to deter illegal logging, poaching, and encroachment during critical restoration phases.
The replanted rainforest is already being used by wildlife and camera traps have recorded the presence of tigers, and orangutans and while walking in the rainforest we saw elephant footprints. Remarkably, the proximity to a remnant rainforest in the national park has enabled wildlife such as primates, bats and birds to assist in seed dispersal, accelerating natural regeneration.
Millions of tree seedlings have germinated naturally.
A World First in Restoration
This is the world’s first documented success in converting an industrial oil palm plantation back into functioning rainforest. With Panut, botanist Rio, and the restoration team, we inspected the site and observed firsthand how well the trees had grown.
Drone footage confirmed the full restoration of the 500-hectare site. On the ground, pioneer species like Macaranga had formed a new canopy, creating ideal conditions for slower-growing rainforest species to establish.
Using a drone to see the 500 hectares of replanted rainforest
Wildlife Returning
Camera trap images, orangutan sightings, and elephant footprints offer compelling evidence that wildlife is returning to the area. This is a living, functioning rainforest once again.
Camera trap have recorded orangutans and elephants.
Community Transformation
The OIC's success is rooted in its commitment to community empowerment. Many locals once relied on income from illegal palm oil operations. OIC provided a pathway to a new economy centered around restoration and conservation.
Employment opportunities have been created for locals who now:
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Grow, plant, and maintain rainforest trees
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Patrol forests to prevent logging and poaching
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Operate wildlife rehabilitation centers for rescued orangutans, gibbons, and sun bears
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Manage eco-tourism facilities
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Establish agroforestry systems with fruit trees
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Work at a local school with 10 teachers and over 50 students
This model ensures long-term protection of restored areas and transforms lives.
During this visit, I was also able to visit Aal, the current Director of OIC, at their Medan office.
Seeing tree growth with botanist Rio
International Knowledge Exchange
The relationship between Australian supporters and the OIC has been a two-way exchange of skills and culture. OIC staff have visited restoration projects in Far North Queensland and northern NSW. Likewise, Australian rainforest regenerators and volunteers have contributed their expertise in Sumatra. Tours have also been organised for donors to visit the sites and witness the impact of their support firsthand.
3 Million Trees and Counting
Since planting their first tree in 2008, OIC has now planted over 3 million rainforest trees. The restoration knowledge, tools, and support provided by Australian donors and experts have played a significant role in this success.
This is, without question, one of the world’s most successful rainforest restoration programs.
Growing trees in the nursery creates employment.
A Cost-Effective Investment in Nature
Planting one tree through OIC costs just $2.00, including community engagement and follow-up care to ensure long-term survival. That’s a small investment for such a profound impact on biodiversity and climate.
Thank You
Thank you to our Australian and international donors who continue to support Gondwana Rainforest Trust. In 2020/21, your generosity enabled the planting of 64,000 trees. To fully understand the scale of this impact, there is nothing more powerful than standing among trees that were once seedlings and now form a thriving rainforest.
Kelvin's trip to Sumatra was made possible thanks to an anonymous donor who funded the visit to assess and confirm the effectiveness of the project.