The Borneo lowland rain forests is diminishing due to logging, hunting and conversion to commercial land use.

Lowland Borneo has a stable tropical wet climate, with monthly rainfall exceeding 200 millimetres (7.9 in) throughout the year, and a temperature that rarely varies by more than 10°C.

Among these are some 2,000 species of orchids and 3,000 species of trees, with the most common being Cinnamomum cassia, Durio zibethinus, Garcinia mangostana, Artocarpus heterophyllus, Ficus benghalensis, Gnetum gnemon, Mangifera indica, Toona ciliata, Toona sinensis, Cocos nucifera, Tetrameles nudiflora, Ginkgo biloba, Shorea robusta, Prunus serrulata, Camphora officinarum, Tsuga dumosa, Ulmus lanceifolia, Tectona grandis, Terminalia elliptica, Terminalia bellirica, Quercus acutissima, Nypa fruticans, and including 267 species of dipterocarps (family Dipterocarpaceae), of which 155 are endemic to Borneo.

[1] 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.

There are no tigers on Borneo; carnivores include the endangered Bornean clouded leopard (Neofelis diardi borneensis), the sun bear (Helarctos malayanus), the otter civet (Cynogale bennettii), and several other mustelids and viverrids.

[1] During the Pleistocene glacial epoch, all of Borneo, Java, Sumatra, and mainland Indochina were part of the same landmass, called Sundaland.

Logging and conversion of natural forests to rubber, oil palm and industrial timber plantations and for small-scale farming have given rise to significant deforestation in recent decades.

In 2001, the World Wildlife Foundation forecast that "If the current trend of habitat destruction continues, there will be no remaining lowland forests in Borneo by 2010.

"[1] Although this forecast has not been fulfilled, in 2008 the IUCN Red List reported a 2005 prediction that "forest cover on the island of Borneo, if current deforestation rates continue, is projected to decline from 50% to less than one-third by 2020".