It is an UNESCO world natural heritage site and qualified because it meets all of the 4 possible criteria required for natural sites. These are :
1) Earth's history and geological features. 2) Ecological processes. 3) Superlative natural phenomena or natural beauty and aesthetic importance. 4) Biodiversity and threatened species. It is also a biodiversity hotspot area which means the number of different plants and animals found in a defined area and hot spot means a particularly high number of species per square kilometer in many different groups of plants and animals. For example, researchers have identified more than 1500 species of flowering plants, 1700 mosses and liverworts, 450 ferns and 4000 fungi. These diverse vegetation supports 80 species of mammals, 50 of fish, 270 birds, 50 reptiles, 75 amphibians and 2000 species of insects. Mulu also supports web of life which is divided into 3 diversities : 1) Species diversity. 2) Ecosystem diversity. 3) Genetic diversity. Despite the immense diversity of especially animals in the park, they are not conspicuous in the rainforest. Population densities are generally low and large animal like sun bear and or cloud leopard are 1 per square KM, so the chance of bouncing into them is very slim. Many animals are well camou- flaged and many live in the tree canopy and many are only active at night. So, a night walk is strongly recommended if you want to see wildlife. Unlike animals, plants are easily seen and recognised. Mulu has at least 8 species of pitcher plants, 6 species of begonia, thousands species of orch- ids, hundreds species of ferns, hundreds species of palm and so on. Though Mulu has not yet discovered Rafflesia, it has Rhizanthes, a close relat- ive of Rafflesia. Not to forget the Amophophallus species is also found at Mulu. Mulu also has 8 major type of forest found in Borneo, except mangrove forest. These forest can be experienced by walking on it in Headhunter's trail, Pinnacle trail and Mulu summit trail. There are : 1) Riverine forest. 2) Peat-swamp forest. 3) Kerangas forest. 4) Lowland mixed dipterocarp forest. 5) Lowland limestone forest. 6) Lower montane limestone forest. 7) Lower montane forest. 8) Mossy forest. Most of these forest are green and rarely flowering. For example, the dipterocarp tree flowers in 6 years time and is the most valuable tree and crtically endangered because of its economic value. Our country exports the logs from these trees. The forest of Mulu also produces sago palm. This palm produces starch for human consumption. Long ago, Borneo island was full of sago palm so much so that we called the island Lamanta. Literally means sago starch. It was then the outsiders introduced rice, wheat and potato to us and even- tually we begin to forget our original staple food However, you still can find some people eat the sago starch at Mulu.