Lower Montane Oak-Chestnut Forest
Above about 1,200 meters (4,000 feet) the lowland trees peter out as conifers and oaks become more dominant. The trees are smaller, the canopy reaching 25 to 30 meters (80 to 100 feet) at most. Because of the cooler climate, peat begins to develop and mosses become common. More light reaches the ground so there is both a thicker ground cover and thicker development of epiphytes, especially orchids.
Other trees that are particularly common in this montane forest are members of the eucalyptus and tea families as well as conifers such as Dacrydium, Podocarpus, Dacrycarpus, Agathis and Phyllocladus which have no flowers.
Co-dominant with the conifers are the oaks. Borneo is at the hub of the Malesian oak kingdom, with over 100 species in the oak family Fagaceae recorded on the island. Twelve chestnuts and almost 50 oaks occur on Kinabalu, their fruit ranging from shiny little pixie caps sitting in a dainty cup, to stony kernels almost covered by the thick, massive coat, except for a hole at the top, as big as a child's fist. Fallen acorns and spiny chestnut cases are common along the trails.
Oaks and chestnuts are also an important source of food, not only for animals such as squirrels who can gnaw through even the hardest kernel, but also for wild pigs. In the past, when large tracts of forest still covered Borneo, pigs formed large herds migrating up to the oak-chestnut forest in the fruiting season. Here they could also build 'nests' in which to give birth, taking advantage of the abundant food.
Lowland Dipterocarp Forest
Lowland dipterocarp forest occurs mainly to the north and east, covering about 35% of the park. The forest canopy can reach as high as 50 meters (160 feet). It is dark and dim and there is little ground cover. Trees in the family Dipterocarpaceae are dominant.
These lowland dipterocarp forests support the highest concentrations of animal life because the stature of the trees provides a much greater variety of habitats and food. Dipterocarps themselves are not a main source of food.
They fruit rarely but when they do, they fruit "en masse". At these times, whole hillside is covered in drifts of cream, yellow or pink with flowers or young fruits, making you realise just how dominant the dipterocarps are in what little remains of Borneo's undisturbed lowland forest.
The lowland forests are also rich in a variety of fruit trees such as durian, rambutan and Tarap, as well as figs. Figs have been proven to be one of the most important sources of food, especially for monkeys and civets and for larger birds such as Hornbills, Barbets and Pigeons. For birdwatchers it is always worthwhile spending some time beneath a large fruiting fig, since large mixed species feeding parties are often attracted to its abundant fruits. While other fruits can be very seasonal, there is always a fig fruiting somewhere.
Subalpine Meadow Zone
Subalpine meadow zone by about 3,300 meters (11,000 feet), a subalpine zone has developed. The trees are gnarled and stunted, forming a shrub community with conifers and rhododendrons dominant. The scarlet, thimble-sized flowers of the Heath Rhododendrons (R. ericoides) grow in thickets here together with the larger red-flowered Box-leaved Rhododendron (R. buxifolium) which can be spectacular when in full bloom around March and April. In open soggy patches, grassy meadow-like associations develop, consisting buttercups, potentillas, eyebright and gentians, more familiar from temperate meadows. Shrubs raspberries are common - a favourite food for the Mountain Blackbird.
In cracks and crevices in the rocks, tough little mountain orchids find a root-hold, looking like drifts of snow when in full bloom. The tree-line here is determined not by altitude but by the soil, or rather, by the lack of it. The fierce winds and torrential rains make it impossible for most plants to survive higher than about 3,700 meters (12,000 feet). In sheltered places and in rock crevices, a few dwarves, twisted bonsai-like shrubs struggle for life while sparse tough grasses barely survive in sheltered shallow hollows filled with sand scoured from the surrounding granite rocks.
Upper Montane/Cloud Forest
Cloud forest Above about 2,200 meters (7,200 feet), where swirling mist blanket the forest for much of the day, lies the moss or cloud forest. Here the trees are thickly cloaked and shield with mosses and liverworts dripping with moisture. Orchids are abundant, both in the ground cover and as epiphytes, and members of rhododendron family, as well as conifers, become particularly common at these altitudes.
It was in these forests that Sir Hugh Low found one of his most spectacular plants - the magnificent Low's Rhododendron, its huge golden heads almost glowing in the misty forest. The rhododendrons are some of Kinabalu's loveliest flowers and while Kinabalu cannot lay claim to the vast numbers of rhododendrons as grow in the forests of China and Nepal, 24 out of the 50 described for Borneo grow on the mountain and five are found nowhere else.
The underlying rock also has a strong influence on vegetation zones. In areas where ultramafic rocks occur, the vegetation changes abruptly. Ultramafic forests cover about 16% of the park. Here the soils are low in phosphates and high in iron, silica and metals poisonous to many plants. The high toxic content of these soils prevents many species from growing in these areas, so distinct communities containing rare and unusual species and many endemics have developed. The pitcher plants Nepenthes villosa and N. rajah and the slipper orchids, Paphiopedilum rothschildianum and Paphiopedilum dayanum are found only on ultramafic soils in the Kinabalu Park.