Belum-Temenggor is believed to have been in existence for over 130 million years, making it one of the world's oldest rainforests, older than both the Amazon and the Congo.

[1] In the heart of the forest lies the manmade lake of Tasik Temenggor, covering 15,200 hectares which is dotted with hundreds of islands.

Environmental organizations such as Malaysian Nature Society and the World Wildlife Fund have been lobbying both the state and the federal government to gazette the area as a park.

As of 2019, due to poaching and the depletion of prey, the number of tigers in Belum-Temengor Forest Reserve has declined about 60 percent over a period of 7-8 years, from approximately 60 to 23.

The Brown marmorated stink bug is native to parts of East Asia and has now become an invasive species in Europe and North America.