in the
Niah National Park, Sarawak The lowlands of Borneo are home to the richest
rainforest in the world. The climate provides an ideal growing environment for approximately 10,000 species of plant (more than in the whole continent of Africa). Among these are some 2,000 species of
orchids and 3,000 species of trees, including 267 species of dipterocarps (family
Dipterocarpaceae), of which 155 are endemic to Borneo. This makes the island the center of the world's diversity for dipterocarps. Mixed dipterocarp forests, including lowland and hill forests, are the predominant plant community. The forests have a closed canopy 24 to 36 meters high, with emergent trees up to 65 meters tall extending above the canopy. Dipterocarps are the most common emergents, comprising up to 80% of the emergent stratum. The dipterocarp genera
Dipterocarpus, Dryobalanops, and
Shorea are typically emergents, while the dipterocarp genera
Hopea and
Vatica are common canopy trees.
Koompassia excelsa (Fabaceae) is an emergent tree with a distinctive white trunk that can reach up to 85 meters high. Trees from the plant families
Burseraceae and
Sapotaceae are also common in the canopy. There is an understorey stratum under the canopy, composed of shade-tolerant trees draped with
lianas and
epiphytic orchids and ferns. Understorey trees are commonly of the plant families
Euphorbiaceae,
Rubiaceae,
Annonaceae,
Lauraceae, and
Myristicaceae.
Cauliflory – trees which bear flowers and fruits on their trunks – is common among understorey trees, including the forest durian (
Durio testudinarius).
Forest floor plants include five species of the strong-smelling parasite
Rafflesia, one of which,
Rafflesia arnoldii, has flowers over a metre wide, making it the world's largest flower. The limestone uplands of the
Sangkulirang Peninsula and Sarawak support their own particular plant communities, as do the Labi Hills on the Brunei-Sarawak border. ==Fauna==