The Malaysian Rainforest

Major forest types in Malaysia are lowland dipterocarp forest, hill dipterocarp forest, upper hill dipterocarp forest, oak-laurel forest, montane ericaceous forest, peat swamp forest and mangrove forest. In addition, there also smaller areas of freshwater swamp forest, heath forest, forest on limestone and forest on quartz ridges.

The forests in Malaysia are mostly dominated by trees from the Dipterocarpaceaefamily, hence the term ‘dipterocarp forests’. The dipterocarp forest occurs on dry land just above sea level to an altitude of about 900 metres.

The term ‘dipterocarp’ specifically refers to the fact that most of the largest trees in this forest belong to one plant family known as Dipterocarpaceae. It was so called because their fruits have seeds with two wings (di = two; ptero = wing; carp = seed).

This type of forest can be classified according to altitude into lowland dipterocarp forest (LDF), up to 300m above sea level, and hill dipterocarp forest (HDF) found in elevation of between 300m and 750m above sea level, and the upper dipterocarp forests, from 750m to 1,200m above sea level. However in Sarawak both the lowland and hill dipterocap forests are known as mixed-dipterocarp forest (MDF).

HDF, normally found in areas 500-700m above sea level, contains less undergrowth. It is a little poorer in wildlife compared to the LDF, but is the preferred habitat of birds and small mammals that are tree "specialists" such as the squirrels. The Rafflesia species, which have the largest flowers in the world, can be found in these forests. At present, LDF is a threatened habitat. There are very few areas of this forest type left outside of protected areas such as parks and wildlife reserves. While most of the country was covered with lowland forest in the past, today the majority has been cleared for other land uses. The few remaining pockets are under threat.

There are some pockets of lowland forests near urban centres such as the Sungai Buloh Reserve, Kanching Forest Reserve (part of which is the popular Templer's Park) and Ampang Forest Reserve outside Kuala Lumpur. These areas, however, are under intense pressure from development and these islands of natural lowland forests are shrinking rapidly.

Beautiful and relatively undisturbed LDF can be found at Taman Negara in Peninsular Malaysia, Lambir Hills National Park in Sarawak and at the Maliau Basin, Sepilok Forest Reserve and Danum Valley in Sabah. But there is a real need to conserve the remaining areas of LDF in other parts of the country.

Most of the dipterocarp forest left in Malaysia is HDF because HDF terrain is usually hilly and rugged – making it unsuitable for agriculture or large-scale settlements, as well as being difficult to access and clear. Timber extraction from these areas is also more difficult, but improving technology may change this situation.

In Peninsular Malaysia, for example, most of the highland areas are covered with this type of habitat, which is important not only in its biological richness but more for its other ecological functions. The Main Range or Banjaran Titiwangsa is an important water catchment area for the whole of Peninsular Malaysia. Many of these areas are now being developed for hydroelectric dam projects, roads and highways, and resorts. Steep slopes are sensitive areas prone to soil erosion. Disturbances in the hinterland will most certainly affect areas downstream as well.

There is a real need to put more effort in saving and protecting this precious habitat type. Fortunately, some state governments have halted land clearing for agriculture. It is vital that all remaining forest areas are protected. In this way, this valuable natural habitat can be managed on a sustainable basis.

The Main Range

The Main Range, or Banjaran Titiwangsa, is the largest remaining continuous forest tract in Peninsular Malaysia. Running along the backbone of the peninsular, the Main Range stretches for 500km southwards from the border of Thailand.

It supplies most of the peninsula's water needs. Rivers that originate from highland forests supply fresh water to meet almost 90% of the water needs of the domestic, agricultural and industrial sectors. Acting as natural water reservoirs, they help ensure that this water is clean and free from silt and sediment.

These forests are important water catchment areas. They are the source of many important rivers that supply fresh water to the states of Kelantan, Perak, Pahang, Selangor and Negeri Sembilan. And it is up to us to preserve the quality of our water sources for the sake of our own health and well-being. The tremendous economic value of clean water will quickly become clear if we need to pay for the high costs of cleaning a polluted water supply.

The slopes of highland forests also act to prevent landslides. Highland forests slow down the flow of rainwater down slopes and help retain some of this water. Take away this natural "sponge" and you'll have torrents of muddy water eroding the soil, bringing with them landslides and flash floods. Rivers become choked with silt and water quality everywhere suffers.

The catastrophic consequences of landslides can cause devastation for people and the environment. Examples include the June 1995 landslide in a Genting Highlands slip road, which resulted in at least 21 deaths and 22 injuries; the January 1996 landslide at Gua Tempurung and the January 2000 Kampung Raja, Cameron Highlands landslide which resulted in six deaths. The Tanah Rata–Brinchang road tragedy also cut off links for more than 15,000 people living on the Blue Valley Estate and Kampung Raja.

Highlands are also rich in biodiversity. The mountain peacock-pheasant and the Malayan whistling thrush, both endemic to the Main Range, are among the 600 or so species found in Peninsular Malaysia. It is home to over 25% of all plants species found in Malaysia. Of the 850 orchid species found in the peninsula, more than 400 are found in the highland forests within this Main Range. Studies have shown that there are still many undiscovered plants that possess medicinal value – which provide potential cures for many diseases.

However, the Main Range is not as cool as it once was. Reports have shown increasing temperatures in Cameron Highlands and Genting Highlands due to massive forest clearing. If this trend continues, the effects of a warmer climate would be severe and widespread.

Cloud formation would decrease, reducing water supply for many cities throughout Malaysia. Many plant and animal species could be threatened with extinction. The number of tourists could decrease, resulting in significant losses of national revenue. Finally, a temperature rise could devastate temperate agriculture such as tea, vegetables, fruits, cut flowers and ornamental plants.