The Leuser Ecosystem is one of the largest rainforests in South East Asia, it is also the last place on Earth where critically endangered orangutans, rhinos, elephants and tigers coexist in the wild. There are an estimated 10,000 species fo plants, more than 200 mammal species and approximately 580 bird species of which 465 are residents and 21 are endemic.

Illegal activities such as poaching, illegal logging, forest conversion for agriculture and plantation, irresponsible infrastructure development such as settlement, roads, geothermal and hydropower dams continue to threaten the integrity of the Leuser Ecosystem.