The montane and sub-montane forests of Malaysia differ according to elevation in their appearance, structure and floral and faunal composition. Forests below 1,200 metres elevation are composed primarily of lowland and hill dipterocarp forest. At approximately 1,200 to 1,500 metres elevation, lower montane forest gradually begins to replace hill dipterocarp forest. At around 1,800 metres elevation, lower montane forest gives way to upper montane forest and mossy forest. Subalpine vegetation can be found at around 2,900 metres and alpine vegetation, beyond the 3,500 metres mark.
Eight mountain ranges are present in Peninsular Malaysia, namely the Nakawan, Kedah-Singgora, Bintang, Keledang, Titiwangsa, Benum, Tahan and Timur Ranges. Collectively, these highlands make up close to 20% of the land area of Peninsular Malaysia. The general alignment of the mountain ranges is in a north-south direction. The Main Range, also known as the Banjaran Titiwangsa, is the largest, most prominent and continuous mountain range in Peninsular Malaysia. It stretches approximately 500 km from the border of Malaysia with Thailand in the north to Negeri Sembilan where its height decreases and merges into the State of Malacca’s coastal plain.
In Sabah, at least 12 different vegetation types are found throughout the State based on elevation and soil type. Since the overall topography of Sabah is mountainous, mountain biodiversity is very vast and important. The iconic Mt. Kinabalu which stands at 4,095 metres is comparatively well studied and has recorded plant species richness to be over 5,000 species (2.5 % of world flora) in an area less than 1,200 km2
The State of Sarawak can be classified topographically into three principal terrain groups: the alluvial coastal plain, the mountainous interior and the central belt of generally undulating country between the coastal plain and the interior. Sarawak’s mountain ranges rises to over 1,500 metres and thereby forms the divide between Sarawak and Kalimantan (Indonesia).
The highest peaks in Sarawak are Murud at 2,424 metres and Mulu at 2,371 metres. Around 37% of the state is over 300 metres in elevation. The highlands form the headwaters of most of the major rivers that flow within Sarawak. The Kelabit Highlands are the headwaters for the important Limbang and Baram rivers in Sarawak. The mountains located in the east side of the State receive the highest rainfall in Malaysia, at times exceeding 4,000 mm in a year.
There are outstanding geological and geomorphological features of the Sarawak highlands such as the Mulu Caves which is a UNESCO World Heritage site, the volcanic tablelands of the Usun Apau and Linau- Balui, as well as the spectacular peaks of Mount Murud and Batu Lawi that are formed by massive sandstone of the Meligan Formation.
In relation to land use patterns, the Sarawak highlands is characterised by large expanse of forested areas, with scattered settlements along river valleys. Small-hold agriculture is situated at close by settlements, on gentler slopes and river basins. National Parks and other Totally Protected Areas are mostly concentrated on the northern region, and these include the Gunung Mulu National Park, Pulong Tau National Park, Lanjak Entimau Wildlife Sanctuary and the Batang Ai National Park. The major threat to montane flora and fauna is habitat destruction. The development of various types of infrastructures impact the conservation of natural montane flora and fauna communities.
By assigning an Environmentally Sensitive Area (ESA) rank of 1 to all land areas above the elevation of 1,000m, the National Physical Plan (NPP) addresses the conservation of highland biodiversity by managing development and habitat loss in sub-montane and montane ecosystems in Peninsular Malaysia. Multiple protected area approaches are used to protect mountainous areas across Sabah and Sarawak as well.
