The largest of the Mentawai archipelago district, Siberut Biosphere Reserve lies approximately 150 km off the western coast of Sumatra, within the West Sumatra Province. The Siberut Island is one of Indonesia`s most unique cultural and ecological assets, as recognized in the Indonesian Government`s decision to designate Siberut as a Biosphere Reserve in 1981 and approved by the International Coordinating Council of UNESCO the same year.
Siberut Island has been isolated from the mainland for approximately 500.000 years and has due to its `splendid isolation` undergone an own evolutionary process with minor influences from the mainland, allowing it to develop a specific and endemic environment. In 1993, the western part of the island was designated as a National Park, covering an area of 190,500 ha. The population on Siberut is estimated between 30,000 and 35,000, representing a population density of about 7,5/ km˛. An estimated 10% of the population of Siberut is of non-native origin. The Mentawai people are of austronesian descendent, having arrived on the Mentawai Islands at least thousands of years ago. The prevailing social organization on Siberut is a relic of the Neolithic socio-political structure. Mentawaians are organized into autonomous political units called the uma, a landowning patrilineal family group. The uma represents an egalitarian structure without any strict forms of political hierarchy or organized leadership. Due to a fast changing socio-economic environment during the last decades, the concept of the uma has undergone a process of socio-cultural hybridization and transition.
The Mentawaian communities, living within the Siberut Biosphere Reserve, are one of the few remaining communities, whose way of life is still primarily dependent on the traditional use of resources. Many parts of Siberut still feature a semi-subsistence economy, in which the forest serves as a storehouse providing food, medicines and other material inputs. The local communities` customary environmental management systems ensure economic continuity and contribute to the protection of the island`s biological diversity. Nonetheless, facing a rapidly changing world, local communities are forced to shift their economic strategies and adopt more extractive and less sustainable practices, generating negative environmental impacts.