When someone in Rogdog falls ill, Wolter knows where to go. The 73-year-old sikerei (traditional healer and spiritual guide) of Uma Samalelet walks into the forest, where decades of experience have taught him which leaves can ease a persistent fever, which roots are used when a woman struggles during childbirth, and which plants are needed in a ritual to call a wandering soul back to the body.  

He gathers only what is needed for the person he is treating, rather than collecting plants in advance or keeping a stock at home. Knowing where to find them, when to pick them and how to use them has taken years of learning, much of it acquired from older healers and through experience in the forest.  

For Wolter, being a sikerei involves much more than knowing the uses of different plants. It requires an understanding of the beliefs, rituals and customary rules that have shaped the relationship between the Mentawai people and their natural surroundings for generations.

Wolter lives in Rogdog, a hamlet of Madobag village in South Siberut, the largest island of the Mentawai archipelago of West Sumatra. The forest is part of almost every aspect of life here, providing sago, the community's staple food, timber for houses and dugout canoes, rattan and game for traditional ceremonies. Its springs and rivers supply water to nearby settlements, while its plants are used by traditional healers and sought by people from neighbouring islands.  

This relationship with nature is rooted in Arat Sabulungan, the ancestral teachings of the Mentawai people, which holds that every tree, river, and animal has a soul. People are considered part of this spiritual world and are expected to respect the beings around them, following customs that have been passed down through generations.

These beliefs also shape how land is owned and managed. In Mentawai, ancestral territories traditionally belong to an uma, a clan whose members share a communal longhouse and the surrounding land. Each hill, river bend and sago grove falls within the territory of an uma, with boundaries remembered through natural landmarks such as ridges and streams, or trees planted by forefathers.  

“Trees often have marks on them. One cannot simply cut it down, even if it is on their land.” Says Walter. “If they do, they will be fined.”

The rules of living with nature

The relationship between the Mentawai people and their forests is guided by customs that determine how natural resources can be used. Before cutting down the tree, people leave an offering for the ancestral spirits believed to inhabit the land. It may be a piece of cloth, some tobacco, or a few coins. Ancestors will take the spirits of the offering, and the physical forms will stay where it was left. Opening a new field also requires a ritual before the land can be cleared.

Hunting comes with its own obligations. When an animal is killed, the Sikerei explains, its spirit rises and speaks to the hunter, asking which of them will bear the consequences of breaking the taboo.  

“Which of us is bound by the taboo?” the spirit asks. “If it is me, my whole family will perish. But if it is you, it is your whole family that will perish.”

After a successful hunt, the hunter's household observes keikei, a set of restrictions lasting several days. Certain foods are avoided, and husbands and wives sleep separately. These practices reflect the customary rules governing how people interact with the forest and the animals they hunt.  

To outsiders, some of these traditions may seem unfamiliar. Within Mentawai communities, however, they are part of a system that sets limits on how land and natural resources can be used. For Wolter, these customs are also part of his work as a sikerei, which requires an understanding of both the natural and spiritual worlds described in Arat Sabulungan.  

The forest as classroom  

The sikerei are also teachers. In the interior of Siberut, they lead the sekolah adat, schools on customs and traditions where the forest is the classroom and the sikerei are the master teachers. There are no walls and no timetable. Lessons happen on guided walks into the leleu, the forested hills, and at gatherings inside the uma.

The sekolah adat curriculum is both spiritual and practical. Young people learn to find and prepare medicinal plants, the bakkat alu. They learn to dance the turuk laggai, whose steps mimic the movements of forest animals, and to chant the sacred uliat. They learn to read nature's signs, keep the keikei and honour the guardian spirits of the forests and rivers, and to understand titi, the tattoos that mark identity, status and maturity. Not every student will become a sikerei. But each one leaves with a deeper bond with the forest and pride in the heritage it holds.

When the forest thins, the medicines thin with it, and so does the knowledge of which plant heals what. A healer without a forest has nothing to teach.

The healer and the forest

No one depends on the forest more closely than the sikerei.  

When someone falls ill, a sikerei may see that the person’s simagere. Under Arat Sabulungan, a prolonged illness may be understood as a sign that the person's simagere, or soul, has wandered away from the body, perhaps into the forest or towards the resting place of deceased relatives. To bring it back, the healer rings a small bell called a jejeneng, calling the soul home before proceeding with the healing ritual.  

The healers of Rogdog work almost like a specialist doctors. They have specialised responsibilities determining the treatments and ceremonies they perform. A healer called to conduct a soul-retrieval ritual, for example, will devote that day to the ceremony, leaving other treatments to another day or another healer.  

Their work also requires strict personal discipline. After gathering plants in the forest, the sikerei bathes there, alone and without clothes, so that no spirit disturbs him on his journey home. Whilst treating a patient, the sikerei must also observe personal taboos, avoiding certain foods such as sour dishes, ferns, and eels. “The eel taboo goes back to the very first sikerei in our line,” says Wolter.  

Becoming a sikerei takes years of learning, ceremonies and strict observance of customary taboos. Much of this knowledge is passed down through practice, as younger healers learn from their elders to recognise plants, perform rituals and understand the responsibilities that come with their role.

But the continuation of this tradition is not guaranteed. Wolter has six children, yet none has chosen to follow in his footsteps.

“If they do not want to, we do not force them,” he says.  

Recognizing customary rights

For generations, the uma have managed their ancestral territories through customary rules governing how the land is used and protected. However, these customary rights also need formal recognition under Indonesian law to provide communities with greater certainty over their forests.

About 82 percent of the islands is designated as state forest area. Over the decades forest management has been shaped by national policies and development priorities, while customary communities have continued to care for the ancestral territories on which their livelihoods and traditions depend.

Recognising these territories as customary forests provides legal certainty for communities to manage and protect their ancestral lands according to their customary institutions and rules, within the national legal framework. Through a formal decree, the government acknowledges their customary rights over these forests.  

For communities such as Uma Samalelet, this recognition is important because their relationship with the forest extends beyond the resources they use every day. Their customary territories are also where traditional practices are maintained, where elders share their knowledge and where younger generations learn about their community's history and traditions.

In October 2026, an integrated team led by the Directorate of Tenurial Conflict Management and Customary Forests at Indonesia's Ministry of Forestry, together with local governments, universities, community organisations and other partners, travelled to Mentawai to begin verifying 13 customary forest proposals across Siberut and Sipora islands.  

The team reviewed documents, walked through customary boundaries and verified the communities' customary institutions, while ensuring that the proposed areas were consistent with official spatial plans. This process helps establish the boundaries and customary arrangements of each community before the government makes a decision on formal recognition.

The work in Mentawai is part of a wider national effort. Indonesia has committed to recognising 1.4 million hectares of customary forests by 2029. As of June 2026, the government had issued 174 customary forest decrees, covering more than 360,000 hectares and benefiting approximately 92,000 families. Meeting the national target will require accelerating the verification and recognition process for communities across the country.

With support from Norway's International Climate and Forest Initiative (NICFI), UNDP works closely with the Ministry of Forestry and its Customary Forest Task Force to accelerate this process. The partnership supports a national acceleration roadmap, stronger field verification capacity and a consolidated customary forest database.  

Keeping the knowledge alive  

At 73, Wolter continues to practise what he has learned from generations of healers before him. Whether any of his six children will choose to become sikerei remains uncertain, and Wolter does not intend to force them. What matters is that the opportunity to learn remains open to those who wish to follow this path.

For that to happen, the forest must remain part of community life. It is where healers learn to identify plants, where customary practices are observed and where the relationship between people and nature continues to be taught through everyday experience.

Recognising customary forests gives communities like Wolter's greater legal certainty to continue looking after their ancestral territories and maintaining the traditions associated with them. It is also an investment in the generations to come, ensuring that young Mentawai people can still learn from their elders and from the forests that have shaped their communities for centuries. (*)