Kerangas forest
Encyclopedia
Sundaland heath forest, 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.
. Heath forest
s 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. 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.
s in species composition, structure, texture, and color. The heath forests have a low, uniform canopy, with thick underbrush and rich growth of moss and epiphyte
s.
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. Myrmecophyte
s, including Myrmecodia
spp. and Hydnophytum
spp., are tree species that develop symbiotic associations with ants to get their nutrients. Other plants, including pitcher plant
s (Nepenthes
spp.), sundew
s (Drosera ssp.), and bladderwort
(Utricularia ssp.), are carnivorous, trapping and digesting insects.
The heath forests are characterized by many plants of Australasian
origin, including trees of families families Myrtaceae
and Casuarinaceae
and the southern hemisphere conifers Agathis
, Podocarpus
, and Dacrydium
.
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
, is a type of tropical moist forest
Tropical and subtropical moist broadleaf forests
Tropical and subtropical moist broadleaf forests , also known as tropical moist forests, are a tropical and subtropical forest biome....
found on the island of Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
, which is divided between Brunei
Brunei
Brunei , officially the State of Brunei Darussalam or the Nation of Brunei, the Abode of Peace , is a sovereign state located on the north coast of the island of Borneo, in Southeast Asia...
, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, and Malaysia, as well as on the Indonesian islands of Belitung
Belitung
Belitung, , is an island on the east coast of Sumatra, Indonesia in the Java Sea. The island is known for its pepper and for its tin. It was in the possession of the British from 1812 until the British ceded control of the island to the Dutch in the Anglo-Dutch Treaty of 1824...
and Bangka
Bangka Island
Bangka is an island lying east of Sumatra, Indonesia. Population 626,955. Area: c.4,600 sq mi .There is an additional small island named Pulau Bangka in northern Sulawesi, Indonesia.-Geography:...
, which lie to the west of Borneo.
Setting
The word Kerangas, which means "land which cannot grow rice", came from the Iban languageIban language
The Iban language is spoken by the Iban, a branch of the Dayak ethnic group formerly known as "Sea Dayak" who live in Sarawak, the Indonesian province of Kalimantan Barat and in Brunei. It belongs to the Malayo-Polynesian branch of the Austronesian language family, and is related to Malay, more...
. Heath forest
Heath forest
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.-External links:**...
s 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. The sandy soil of the heath forest are often lacking in nutrients; it is generally considered that nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
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
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
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.
Flora
The Sundaland heath forests are distinct from the surrounding Borneo lowland rain forestBorneo lowland rain forest
Borneo lowland rain forest is an ecoregion, within the Tropical and subtropical moist broadleaf forests Biome, of the large island of Borneo in Southeast Asia. It supports approximately 10,000 plant species, 380 bird species and several mammal species...
s in species composition, structure, texture, and color. The heath forests have a low, uniform canopy, with thick underbrush and rich growth of moss and epiphyte
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
s.
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
Rhizobia
Rhizobia are soil bacteria that fix nitrogen after becoming established inside root nodules of legumes . Rhizobia require a plant host; they cannot independently fix nitrogen...
(nitrogen fixing bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
) in their root nodules. Myrmecophyte
Myrmecophyte
Myrmecophyte is a plant that lives in a mutualistic association with a colony of ants. There are over 100 different genera of myrmecophytes. These plants possess structural adaptations that provide ants with food and/or shelter. These specialized structures include domatia, food bodies, and...
s, including Myrmecodia
Myrmecodia
Myrmecodia is a genus of epiphytic myrmecophytes native to Southeast Asia and large islands extending south to Queensland in Australia. Myrmecodia plants grow in tree branches and on trunks. In nature, Myrmecodia tubers often grow hanging downward on bare branches without significant amounts of...
spp. and Hydnophytum
Hydnophytum
Hydnophytum is a genus of epiphytic myrmecophytes native to Southeast Asia, the Pacific region and also extending into Queensland in northern Australia. The name is derived from the Ancient Greek hydnon "tuber", and phyton "plant", after their appearance with their swollen succulent stems. The...
spp., are tree species that develop symbiotic associations with ants to get their nutrients. Other plants, including pitcher plant
Pitcher plant
Pitcher plants are carnivorous plants whose prey-trapping mechanism features a deep cavity filled with liquid known as a pitfall trap. It has been widely assumed that the various sorts of pitfall trap evolved from rolled leaves, with selection pressure favouring more deeply cupped leaves over...
s (Nepenthes
Nepenthes
The Nepenthes , popularly known as tropical pitcher plants or monkey cups, are a genus of carnivorous plants in the monotypic family Nepenthaceae. The genus comprises roughly 130 species, numerous natural and many cultivated hybrids...
spp.), sundew
Sundew
Drosera, commonly known as the sundews, comprise one of the largest genera of carnivorous plants, with at least 194 species. These members of the family Droseraceae lure, capture, and digest insects using stalked mucilaginous glands covering their leaf surface. The insects are used to supplement...
s (Drosera ssp.), and bladderwort
Bladderwort
Utricularia, commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species . They occur in fresh water and wet soil as terrestrial or aquatic species across every continent except Antarctica...
(Utricularia ssp.), are carnivorous, trapping and digesting insects.
The heath forests are characterized by many plants of Australasian
Australasia ecozone
The Australasian zone is an ecological region that is coincident, but not synonymous , with the geographic region of Australasia...
origin, including trees of families families Myrtaceae
Myrtaceae
The Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. Myrtle, clove, guava, feijoa, allspice, and eucalyptus belong here. All species are woody, with essential oils, and flower parts in multiples of four or five...
and Casuarinaceae
Casuarinaceae
Casuarinaceae is a family of dicotyledonous flowering plants placed in the order Fagales, consisting of 3 or 4 genera and approximately 70 species of trees and shrubs native to the Old World tropics , Australia, and the Pacific Islands...
and the southern hemisphere conifers Agathis
Agathis
The genus Agathis, commonly known as kauri or dammar, is a relatively small genus of 21 species of evergreen tree. The genus is part of the ancient Araucariaceae family of conifers, a group once widespread during the Jurassic period, but now largely restricted to the Southern Hemisphere except for...
, Podocarpus
Podocarpus
Podocarpus is a genus of conifers, the most numerous and widely distributed of the podocarp family Podocarpaceae. The 105 species of Podocarpus are evergreen shrubs or trees from 1-25 m in height...
, and Dacrydium
Dacrydium
Dacrydium is a genus of conifers belonging to the podocarp family Podocarpaceae. Sixteen species of evergreen dioecious trees and shrubs are presently recognized. The genus was first described by Solander in 1786, and formerly included many more species, which were divided into sections A, B, and C...
.