Kerangas

The Sundaland heath forests, also known as ''Kerangas'' forest, is a type of tropical moist forest found on the island of Borneo, which is divided between Brunei, Indonesia, and Malaysia, as well as on the Indonesian islands of Belitung and Bangka, which lie to the west of Borneo.

Setting

The word ''Kerangas'', which means "land which cannot grow rice", comes from the Iban language. Heath forests occur on acidic sandy soils that are the result of the area's siliceous parent rocks. Permanently waterlogged heath forests are known as ''kerapah'' forests.Wikramanayake, Eric; Eric Dinerstein; Colby J. Loucks; et al. (2002). ''Terrestrial Ecoregions of the Indo-Pacific: a Conservation Assessment.'' Island Press; Washington, DC. Open-canopied woodlands are known as ''padang''.Hazimah Din, Faizah Metali, Rahayu Sukmaria Sukri, "Tree Diversity and Community Composition of the Tutong White Sands, Brunei Darussalam: A Rare Tropical Heath Forest Ecosystem", ''International Journal of Ecology'', vol. 2015, Article ID 807876, 10 pages, 2015. https://doi.org/10.1155/2015/807876 The sandy soil of the heath forest are often lacking in nutrients; it is generally considered that nitrogen is the nutrient which is most lacking for plant growth in these forests. This is in contrast to many other lowland rain forests where phosphorus is considered to be lacking.

A more recent hypothesis, proposed by Proctor (1999), is that these forests are growing on soils which are highly acidic, such that hydrogen ion toxicity prevents the growth of non-adapted species. Moreover, heath forests' low soil pH hampers organic matter decomposition thus further slowing nutrient cycling.

Flora

The Sundaland heath forests are distinct from the surrounding Borneo lowland rain forests in species composition, structure, texture, and color. The heath forests typically have a low, uniform canopy approximately 20 metres high, with thick underbrush and rich growth of moss and epiphytes. Trees often have closely-spaced trunks. In contrast, ''padang'' woodland is relatively open, with shrubs and trees up 5 metres tall, and a ground layer of sparse grasses and sedges.

Leaf sizes are generally smaller than other lowland rain forest trees. As an adaptation to the nutrient-poor conditions, some heath forest species have small, hard, thick sclerophyll leaves which are low in nitrogen. Many tree and plant species in the nutrient-deprived heath forests have developed unconventional ways to get their nutrients. Some tree species ('' Gymnostoma nobile'', for example) utilise rhizobia ( nitrogen fixing bacteria) in their root nodules. Myrmecophytes, including ''Myrmecodia'' spp. and '' Hydnophytum'' spp., are tree species that develop symbiotic associations with ants to get their nutrients. Other plants, including pitcher plants ''(Nepenthes'' spp.), sundews ''(Drosera'' spp.), and bladderwort ''(Utricularia'' spp.), are carnivorous, trapping and digesting insects.

Dipterocarps, including species of ''Shorea'' and '' Hopea'', are common canopy trees on less barren soils, along with palms. Native trees include both heath forest endemics, typical lowland forest species like ''Cocos nucifera'', ''Quercus acutissima'', '' Agathis borneensis, Cotylelobium burckii, Dipterocarpus borneensis, Madhuca curtisii, Hopea vacciniifolia, Koompassia malaccensis, Shorea ovata, Shorea scabrida, Richetia faguetiana'', and species shared with peat swamp forests like '' Shorea albida, Shorea pachyphylla'', '' Shorea scabrida'', and ''Nypa fruticans''. Heath forests are also characterized by many plants of Australasian origin, including trees of families Myrtaceae and Casuarinaceae and the southern hemisphere conifers '' Agathis'', ''Podocarpus'', and ''Dacrydium''.
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Fauna

The heath forests generally have less wildlife and species diversity than the surrounding lowland rain forests, with little or no endemic species.

Protected areas

9.695% of the ecoregion is in protected areas. These include:Sundaland heath forests
DOPA Explorer. Accessed 1 April 2023.
* Sungai Serudong Forest Reserve
* Bukit Soeharto Grand Forest Park
* Gunung Lalang Grand Forest Park
* Gunung Menumbing Grand Forest Park
* Gunung Mangkol Grand Forest Park
* Kutai National Park
* Tanjung Puting National Park
* Betung Kerihun National Park
* Danau Sentarum National Park
* Sebangau National Park
* Meratus National Park
* Gunung Maras National Park
* Dered Krian National Park
* Jering Menduyung Nature Recreation Park
* Bukit Tangkiling Nature Recreation Park
* Bukit Tangkiling Nature Reserve
* Padang Luway Nature Reserve
* Muara Kaman Sedulang Nature Reserve
* Teluk Kelumpang, Selat Laut dan Selat Sebuku Nature Reserve

References

External links

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{{Borneo

Borneo
Ecoregions of Asia
Ecoregions of Indonesia
Ecoregions of Malaysia
Ecoregions of Malesia
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Indomalayan ecoregions
Tropical and subtropical moist broadleaf forests
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Sclerophyll forests