This ecoregion consists of tropical mountain cloud forest and laurel forest above 1000 meters elevation in the mountains in the centre of Borneo. It covers portions of all three countries – Brunei, Malaysia, and Indonesia – which divide Borneo. These cooler and moister slopes rise above the carpet of thick rainforest that covers the warmer lowlands below, and as well as additional rainfall also derive moisture from low clouds. Soils are poorer and more acidic than the lowlands.[1]
Flora
The isolated higher and cooler forests of the island are home to a rich and distinctive set of plants of both Asian and Australasian origin. There are especially large numbers of Nepenthes pitcher plants (>15 species), rhododendrons, and orchids.
Montane forests typically have a closed canopy with single stratum, and the canopy height generally decreases with elevation. Typical trees include species of the plant families Fagaceae and Lauraceae, with conifers increasingly abundant at higher elevations. The lower montane forests have a high diversity of orchid and fern species. Carnivorous plants, including species of Nepenthes, Drosera, and Utricularia, are most abundant in areas with high rainfall and a stunted, open tree canopy. The montane forests are interspersed with areas of graminoid scrub, generally associated with hypermagnesic cambisol soils.[4]
This ecoregion also contains important areas of forest on limestone upland, especially Mount Api which has clear elevational zones of differing vegetation. Long Pasia in the Meligan Range and the Usun Apau Plateau have important areas of high-elevation wetland.[1]
The ultramafic rocks which make up portions of the Crocker Range and Mount Kinabalu create soils rich in certain metallic elements (nickel, cobalt, chromium, and manganese), high cation imbalances (high Mg:Ca molar quotients), and deficiencies of some nutrients including potassium and phosphorus. These soil conditions affect the plant life, and plant communities on ultramafic soils show lower stature and lower biomass, higher levels of endemism, and a distinct species composition compared to typical montane plant communities at similar elevations.[4]
Fauna
The montane rain forests are home to a distinct fauna, including large numbers of mammals such as civets (such as the rare Hose's civetDiplogale hosei, endemic to these montane forests), tree shrews, squirrels, and rats and primates such as orangutan (Pongo pygmaeus), gibbons, and langurs. Although most of these primates prefer lower elevations there are especially good numbers of the large macaque monkeys and as the forests are less-disturbed at higher elevations larger animals such as orangutans and Sumatran rhinoceros (Dicerorhinus sumatrensis) have retreated here from the lowlands.[1]
The higher elevations of Borneo are relatively inaccessible, and subject to less logging and conversion to agriculture than the lowland rain forests. The montane forests were less affected by the forest fires of 1997-8 that damaged so much of Borneo's lowland forest.[1] Approximately three-quarters of the montane forests are still relatively intact.[6] 23.11% of the ecoregion is in protected areas.[3] Protected areas include a very large block in Kayan Mentarang National Park, which is home to communities of indigenous people but is threatened by commercial logging and road building. This park and others such as Betung Kerihun National Park are important refuges for wildlife as lowland habitats are being systematically removed.[1] Protected areas include:[3]
^Eric Dinerstein, David Olson, et al. (2017). An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm, BioScience, Volume 67, Issue 6, June 2017, Pages 534–545; Supplemental material 2 table S1b. [1]
^ abvan der Ent, A., Erskine, P., Mulligan, D., Repin, R., & Karim, R. (2016). Vegetation on ultramafic edaphic “islands” in Kinabalu Park (Sabah, Malaysia) in relation to soil chemistry and elevation. Plant and Soil, 403(1/2), 77–101. http://www.jstor.org/stable/43872634
