Thousands of hectares of forests in Mount Leuser National Park in North Sumatra and Aceh are reported to have been illegally encroached upon and converted into widespread plantations of oil palms, rubber trees, cacao trees and coffee plants.

To restore the natural functions of the protected forests, the park management office is planning to curb the rampant spread of the illegal plantations.

A joint team of the park’s officials and security apparatus had reconverted some 75 hectares of plantation in Sei Lepan district, Langkat regency, North Sumatra last month, cutting down the commercial vegetation and replanting indigenous flora. In the near future, the same measure would also be taken on another 80 hectares that had been turned into plantations in Southeast Aceh regency, said Joko Iswanto, the spokesman of the Mount Leuser National Park office.

The reconversions are aimed at restoring the natural functions of the whole area within the national park where the officials would clear the plantations and replant them with forests trees.

Joko expressed regret that the conversions had been going on in the area for years, but so far no measures had been taken to restore its function as a protected forest. More than 2,000 hectares within the National Park had been converted into plantations, which were mostly spread throughout Langkat, North Sumatra and Southeast Aceh.

The forest conversions were mostly committed by local people who were supported by payments from outside investors.

“Most of the investors come from Medan,” Joko said.

(Read also: Protection sought for Leuser ecosystem, Sumatran orangutans)

Joko also said that the national park had been intensively conducting preventive measures using persuasion to stop local people from destroying the protected forests. Thanks to the measures, 18 encroachers had voluntarily handed over their illegal plantations to be restored back into protected forest.

He said various kinds of vegetation had been replanted in the area after hundreds of two- to five-year-old palm trees were all cut down.

Very recently, seven non-governmental organizations grouped under the Mount Leuser National Park rescue coalition asked President Joko “Jokowi” Widodo to save the park from rampant encroachments.

Panut Hadisiswoyo of the coalition said the encroachments were massive in the national park, illegally converting the forests into plantations and housing for local people.

He said the total area of the park was 838,872 hectares, but it continued to decrease because of the encroachments, especially in Langkat regency, North Sumatra.

“The area in Langkat is the worst encroached,” Panut said.

The most massive conversions occurred in the Barak Induk area in Sei Lepan and in Lapangan Tembak in Besitang district in Langkat. He claimed that some oil palm plantations in these areas were under the control of some companies.

“Some palm oil companies have been operating in the national park area for years. Surprisingly, no one has the guts to get rid of them,” he said.

The park had been listed in UNESCO’s World Heritage in Danger list in 2011 following rampant encroachments along with two other national parks in Sumatra: Kerinci Seblat National Park in West Sumatra, Jambi, Bengkulu and South Sumatra, and Bukit Barisan Selatan National Park in Lampung and Bengkulu provinces. The three national parks were declared by UNESCO to be World Heritage Sites in 2004.

According to UNESCO, Sumatran tropical rainforests are home to 10,000 plant, 201 mammal and 580 bird species. They also serve as a habitat for mammals that needed a large range for roaming, such as Sumatran tigers, orangutans, elephants and rhinos.

Punut said that if by 2018 the encroachments could not be settled, the Mount Leuser National Park most likely could be excluded from UNESCO’s list of world’s heritage sites.

“If that is the case it will be a bad record for Indonesia as it is not capable of preserving the area already declared as a part of the world’s heritage,” he added.