Rare forests and apes on the island of Borneo

November 8, 2013

Borneo, the third largest island in the world, is situated between Indonesia, Malaysia and Brunei. It was once covered with dense rainforests, but along with its tropical lowland and highland forests, there has been extensive deforestation in the past 60 years.

by Michal Brink / Forestry Solutions / michal@abtraining.biz / www.forestrysolutions.net

Two forest controllers in the tropcial forest. Note the red rock climbing helmet worn by the front controller. It is robust, VERY comfortable and light.

In the 1980s and 1990s, the forests of Borneo underwent a dramatic transition. They were burned, logged and cleared, and commonly replaced with agricultural land or palm oil plantations.

Half of the annual global tropical timber production currently comes from Borneo. Furthermore, palm oil plantations are rapidly encroaching on the last remnants of primary rainforest. Much of the forest clearance is illegal. 

The majority of Borneo’s landscape was once covered by the tropical lowland evergreen forest which is also called the mixed dipterocarp forest. The name comes from the dominating tree family found in these forests, the Dipterocarpaceae. Most of Sabah’s timber trees are dipterocarps, such as seraya, keruing and kapur. These forests, which once covered a large area of Sabah, occur from sea level up to 1 200m. 

Most of the biggest and tallest trees (called emergent) are found in this forest, protruding above the canopy of crowns and reaching heights of over 60 metres. Underneath the forest canopy one finds a profusion of trees of different sizes and kinds and in different stages of development, as well as other plant life such as bamboo. 

Bamboos are giant grasses – they are classified in the plant family of grasses – poaceae. There are more than 1 200 species of bamboo worldwide. Bamboos range from plants the size of field grass to giants up to 36m tall. All continents have native bamboos except Europe. In Malaysia, 80 species of bamboos are found, including those introduced from other countries. 

Bamboos grow very fast. The world record is the common Japanese madake bamboo (Phyllostachys bambusoides), which was recorded growing at 1.2m a day. In Sabah, bamboo was traditionally the most important raw material used by the natives of Sabah. It is used for house building, making bridges and rafts, fences and water pipes. Other uses of bamboo include making animal traps and cages, blowpipes, kites, musical instruments, household and kitchen utensils and ornaments.

After the diperocarps, the second most important natural forests are the peatswamp forests. These forests support a unique kind of vegetation different from that of the dry land, and which are specially adapted to grow under waterlogged conditions. 

Peat is an organic type of soil which is formed by undercomposed plant material. The peat is formed because the normal decomposition of plant material is slowed down by constant flooding by rainwater (as opposed to mangrove forests, which colonise the muddy shores of coasts and river estuaries).   Sabah also has mangrove forests along the coastline, which are all protected by law. 

The Bornean orang-utan, Pongo pygmaeus, is a species of orang-utan native to the island of Borneo. Together with the Sumatran orang-utan, it belongs to the only genus of great apes native to Asia. Like the other great apes, orang-utans are highly intelligent, displaying advanced tool use and distinct cultural patterns in the wild. Orang-utans share approximately 97% of their DNA with humans. The Borneo orang-utan is an endangered species, with deforestation, palm oil plantations and hunting posing a serious threat to its continued existence. An orang-utan male may stand up to 1.4 metres tall and can weigh up to 100kg. Their arms are almost twice as long as their legs, giving an enormous reach of up to 2.4 metres. The adult female is much smaller, weighing about 50kg.

Another unique primate found in Borneo is the proboscis monkey or long-nosed monkey, which  is a reddish-brown arboreal Old World monkey that is endemic to Borneo. The protruding nose of the proboscis monkey develops with age, with infants having more monkey-like noses and older mature males having larger and more bulbous ones.

Although scientists are still unsure as to exactly why the nose of the proboscis monkey grows so big, it is widely believed that it is used to attract a female mate as the noses of females are much smaller. Due to the fact that the proboscis monkey requires a good fresh water supply such as a swamp or river, they are excellent swimmers and are known to travel across very deep areas to find food or to escape approaching danger.

Oil palm – the agricultural crop that has led to the devastation of millions of hectares of tropical rain forests in Asia.
Proboscis monkeys. This species of monkey enjoys swimming and they have been found in the ocean by fishermen, more than a km from land.
Native bamboo species growing in the Bornean forests.
Typical dipterocarp forest that dominates the tropical forest landscape.


Published in August 2013

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