Sundaland heath forests | |
---|---|
Ecology | |
Realm | Indomalayan |
Biome | tropical and subtropical moist broadleaf forests |
Borders | |
Geography | |
Area | 76,130 km2 (29,390 sq mi) |
Countries | |
Conservation | |
Conservation status | critical/endangered |
Protected | 6,436 km2 (8%) [1] |
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.
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. [2] Open-canopied woodlands are known as padang. [3] 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. [2]
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. [4] [5]
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. [2] In contrast, padang woodland is relatively open, with shrubs and trees up 5 metres tall, and a ground layer of sparse grasses and sedges. [3]
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. [3] 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. [2]
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 Cinnamomum cassia , Durio zibethinus , Garcinia mangostana , Artocarpus heterophyllus , Ficus benghalensis , Gnetum gnemon , Mangifera indica , Toona ciliata , Toona sinensis , Cocos nucifera , Tetrameles nudiflora , Ginkgo biloba , Shorea robusta , Prunus serrulata , Camphora officinarum , Tsuga dumosa , Ulmus lanceifolia , Tectona grandis , Terminalia elliptica , Terminalia bellirica , Quercus acutissima , Agathis borneensis, Cotylelobium burckii, Dipterocarpus borneensis, Madhuca curtisii, Hopea vaccinifolia, 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 . [2]
The heath forests generally have less wildlife and species diversity than the surrounding lowland rain forests, with little or no endemic species. [2]
9.695% of the ecoregion is in protected areas. These include: [6]
Heath forest is a type of tropical moist forest found in areas with acidic, sandy soils that are extremely nutrient-poor. Notable examples are the Rio Negro campinarana of the Amazon Basin in South America, and the Sundaland heath forests of Borneo and neighboring islands.
The Tropical Rainforest Heritage of Sumatra site was inscribed as a UNESCO World Heritage Site in 2004. It comprises three Indonesian national parks on the island of Sumatra: Gunung Leuser National Park, Kerinci Seblat National Park and the Bukit Barisan Selatan National Park. The site is listed under Criteria vii - outstanding scenic beauty; ix- an outstanding example representing significant on-going ecological and biological processes; and x- contains the most important and significant natural habitats for in-situ conservation. The Tropical Rainforest Heritage of Sumatra has been placed on the Danger List since 2011 to help overcome threats posed by poaching, illegal logging, agricultural encroachment, and plans to build roads through the site.
The Borneo peat swamp forests ecoregion, within the tropical and subtropical moist broadleaf forests biome, are on the island of Borneo, which is divided between Brunei, Indonesia and Malaysia.
The Peninsular Malaysian peat swamp forests is an ecoregion on Malay Peninsula, which includes portions of Malaysia. It is in the tropical and subtropical moist broadleaf forests biome.
The Taiwan subtropical evergreen forests is an ecoregion that covers most of the island of Taiwan, with the exception of the southern tip of the island, which constitutes the South Taiwan monsoon rain forests ecoregion. The island's concentrated steep mountains host a range of forest types, from subtropical forests in the lowlands to temperate and alpine or montane forests.
The Northern Indochina subtropical forests are a subtropical moist broadleaf forest ecoregion of northern Indochina, covering portions of Vietnam, Laos, Thailand, Myanmar, and China's Yunnan Province.
The Lambir Hills National Park is a national park in Miri Division, Sarawak, Malaysia, on the island of Borneo. It is a small park, at 6,952 hectares, and is composed largely of mixed dipterocarp forest, with some small areas of 'kerangas'. The park is 150–465 m (492–1,526 ft) above sea level.
Shorea pachyphylla is a species of tree in the family Dipterocarpaceae. It is endemic to Borneo and threatened by habitat loss. It grows in peat swamp forests and heath forests.
Shorea revoluta is a species of plant in the family Dipterocarpaceae. It is a tree endemic to Borneo.
The Mizoram–Manipur–Kachin rain forests is a subtropical moist broadleaf forest ecoregion which occupies the lower hillsides of the mountainous border region joining Bangladesh, China's Yunnan Province, India, and Myanmar. The ecoregion covers an area of 135,600 square kilometres (52,400 sq mi). Located where the biotas of the Indian Subcontinent and the Indochinese Peninsula meet, and in the transition between subtropical and tropical regions of Asia, the Mizoram–Manipur–Kachin rain forests are home to great biodiversity. The WWF rates the ecoregion as "Globally Outstanding" in biological distinctiveness.
The Borneo lowland rain forests is an ecoregion, within the tropical and subtropical moist broadleaf forests biome, of the large island of Borneo in Southeast Asia. It supports approximately 15,000 plant species, 380 bird species and several mammal species. The Borneo lowland rain forests is diminishing due to logging, hunting and conversion to commercial land use.
The Borneo montane rain forests is an ecoregion on the island of Borneo in Southeast Asia. It includes montane tropical and subtropical moist broadleaf forests, also known as a cloud forests. The ecoregion is partly in East Malaysia and Indonesia (Kalimantan).
The Sunda Shelf mangroves ecoregion, in the mangrove biome, are on the coasts of the islands of Borneo and eastern Sumatra in Malaysia and Indonesia. They are home to the proboscis monkey.
The Tenasserim–South Thailand semi-evergreen rain forests is a tropical moist broadleaf forest ecoregion on Mainland Southeast Asia. The ecoregion extends north–south along the Kra Isthmus. It includes lowland forests along the coasts, and montane forests on the Tenasserim Hills and Bilauktaung range, which form the mountainous spine of the isthmus.
The Peninsular Malaysian rain forests is an ecoregion on the Malay Peninsula and adjacent islands. It is in the tropical and subtropical moist broadleaf forests biome.
The Sulawesi montane rain forests is a tropical moist forest ecoregion in Indonesia. It includes the highlands of Sulawesi.
The Vogelkop–Aru lowland rain forests is a tropical moist forest ecoregion in Indonesia. The ecoregion covers the peninsular lowlands of western New Guinea, along with the Aru Islands and other nearby islands.
The Northern Vietnam lowland rain forests ecoregion covers the central-eastern coast of Vietnam from the Red River delta in the north to Tam Kỳ in the center of the country and neighboring adjacent parts of Laos. The region is one of the wet evergreen forests, with rain over 50 mm in every month. The forests have been highly degraded by human use, and the high levels of biodiversity have been pushed back into relatively small protected areas like Pu Mat National Park.
The Sumatran lowland rain forests ecoregion covers the lowland forests running the length of the island of Sumatra in Indonesia. The region is one of exceptionally high biodiversity, similar to Borneo and New Guinea islands. Many endangered mammals species are present, and over 450 species of birds have been found in the region. In recent years, illegal logging and human encroachment have put great strain on this ecoregion.
Gymnostoma nobile is a species of tree endemic to northern Borneo.