Mulu's vegetation zones and curiosities
Mulu's unique mosaic of landscapes on limestone, sandstone and alluvium, coupled with altitudes ranging from 60m to 2300m and the tropical climate have produced an area of extremely high biodiversity. The remarkable diversity of plants is related to changes in climate with altitude and soil differences linked to rock types.
Numerous plant and animal species have been observed and studied. Many of them are endemic (ie found nowhere else in the world). It's known that there are over 3500 plant species in Mulu (with about 2000 flowering plants) as well as 8000 fungi. The diversity is such that new discoveries are still being made.
Plant distribution depends on the type of land and soil, and the altitude and climate. Since the 1960's research has been carried out to map Mulu's vegetation zones. To date fifteen different vegetation formations had been recognized.
Visitors most often first discover the vegetation of the Melinau river valley which is the main entry point to Mulu. This is the realm of lowland alluvial forests with magnificent buttressed trees some several meters in girth and Borneo's ironwood tree the belian. Lianas and epiphytes are abundant in this zone.
On several of the forest trails visitors can approach the limestone cliffs where Mulu's famous caves open. The limestone cliffs, rocks and the thin discontinuous soils they support are home to a specific type of vegetation. This includes a number of remarkable endemic species. One of these is the curious one-leaved plant Monophyllaea which can be seen clinging to stalactites at the entrance of Clearwater cave (see photo in our Gallery).
High up on trails, like the one leading to the Pinnacles for example, visitors can enjoy the sights of the lower and upper montane limestone forests. In these forests the trees are smaller and often twisted and bent. The upper zones are the realm of the pandan palms.
One fascinating plant group is the Pitcher plant Nepenthes, of which several speices can be found in Mulu. These vase shaped plants are carnivorous: they have evolved to trap and digest insects for nutrition - an example of adaptation to nutrient poor soils (see photo in our Gallery).
On sandstones above 1200m, visitors fit enough to climb to Gunung Mulu summit will pass through the mossy montane forest, with its characteristic stunted trees, mosses, lichens, conifers and rhododendrons which thrive on the cloudy moist atmosphere of the upper reaches of the mountain.
Mulu's forest trails
There are a large number of trails in the forest, from well established paths for visitors to the rough wild trails used by the indigenous Berawan and Penan to get about in the forest (and generally invisible to the untrained eye!).
In order of increasing difficulty, there are:
concrete paths with lighting
wooden plank walks
trails improved with gravels in wettest spots
wild trails
To view life in the tree tops there is also the extraordinary Canopy Skywalk. This suspended trail takes visitors right up into the heights of the forest canopy and, with its 480m length, is the world's longest tree based canopy walk.