With its vast, unspoilt expanse of rainforests and rugged peaks, the Indonesian park of Gunung Leuser represents a treasure trove of biodiversity. A place where many species still unknown to science are concentrated, but above all it represents the last strip of land where Sumatran orangutans and elephants, bears and rhinoceroses live side by side.

American actor Leonardo DiCaprio, present at Cop 21 in Paris, posted a photo on his Instagram profile to promote support for the Rainforest Action Network (Ran) campaign The last place on Earth for the protection of Leuser.

Despite being formally protected by Indonesian legislation, this delicate ecosystem is seriously threatened by the rapid industrial expansion of the palm oil, paper and mining sectors.

"The Leuser ecosystem is an extremely precious area for the high animal and plant biodiversity that characterises it. The Sumatran orangutan (Pongo abelii), which lives here, is the rarer of the two existing orangutan species. If deforestation were not halted, the survival of the species would be put at risk. It is our duty to protect areas such as this, which represent true sanctuaries for our planet," declared Gustavo Gandini, lecturer in conservation genetics at the Faculty of Veterinary Medicine in Milan and former vice-president of Wwf Italia. It would not only be biodiversity that suffers. Millions of people, in fact, call the Leuser territory "home" and their survival depends on it.

In November 2014, Ran began negotiations — still ongoing — to promote the organisation of a more sustainable production process with the three main palm oil producers (Wilmar International, Musim Mas Group and Golden Agri-Resources Ltd). Although progress has been made, the risk remains high.