Though not protected, the plush, lowland forests are considered an important area for biodiversity and have been used since 2002 as a release point for around 100 Sumatran rehabilitated orangutans -- some orphaned when their mothers were allegedly killed by workers on nearby palm oil plantations.
"It took scientists decades to discover how to successfully reintroduce critically endangered orangutans from captivity into the wild," said Peter Pratje of the Frankfurt Zoological Society. "It could take APP just months to destroy an important part of their new habitat."
Asia Pulp & Paper acknowledged that one of its suppliers had applied for a license in the area. It made no mention of the proposed plantation's impact on orangutans, but said it would be creating a buffer between the site and Bukit Tingapuluh National Park, and a corridor linking the park with Taman Raja Reserve located east of the park.
"Because of the business APP is in, and the fact that we operate in an environmentally sensitive part of the world, we understand that we may be an easy public relations target," the company said in a statement. "Despite that, we urge stakeholders to be responsible and considered in their approach to long term sustainable development in Indonesia."
The company said last month that the government had officially allocated the forest for plantation use and that it would follow all legal procedures -- including carrying out an independent, third party assessment about potential conservation threats.
There are an estimated 50,000 to 60,000 orangutans left in the wild, around 10 percent of them on Sumatra, and the rest on the nearby island of Borneo, which is divided largely between Indonesia and Malaysia. Their numbers have dropped dramatically as rain forests have been cleared and burned on both islands.
Logging drove much of the destruction in the last few decades and now palm oil plantations have emerged as the biggest threat. Indonesia is the world's top palm oil producer with some 15 million acres covered by plantations and is likely to grow amid an Indonesian policy that requires biofuels to account for 5 percent of the country's energy mix by 2025.
Along with biofuels, palm is used in everything from cosmetics to cooking oil.
The forests around Bukit Tigapuluh National Park are also home to 100 of the last 400 critically endangered Sumatran tigers left in the wild, said Dolly Priatna of Zoological Society of London, and roughly 50 endangered elephants.
The groups protesting the APP's plans -- which include WARSI and the Sumatran Tiger Conservation and Protection Foundation -- have written an official letter of complaint to the government.
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