The Leuser Ecosystem is an area of forest located in the provinces of

Aceh Aceh ( , ; , Jawi script, Jawoë: ; Van Ophuijsen Spelling System, Old Spelling: ''Atjeh'') is the westernmost Provinces of Indonesia, province of Indonesia. It is located on the northern end of Sumatra island, with Banda Aceh being its capit ...

and

North Sumatra North Sumatra () is a Provinces of Indonesia, province of Indonesia located in the northern part of the island of Sumatra. Its capital and largest city is Medan on the east coast of the island. It borders Aceh to the northwest, Riau to the sou ...

on the island of

Sumatra Sumatra () is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the list of islands by area, sixth-largest island in the world at 482,286.55 km2 (182,812 mi. ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

. Covering more than 2.6 million hectares it is one of the richest expanses of

tropical rain forest Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes (in the torrid zo ...

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

and is the last place on earth where the Sumatran elephant,

rhino A rhinoceros ( ; ; ; : rhinoceros or rhinoceroses), commonly abbreviated to rhino, is a member of any of the five extant taxon, extant species (or numerous extinct species) of odd-toed ungulates (perissodactyls) in the family (biology), famil ...

tiger The tiger (''Panthera tigris'') is a large Felidae, cat and a member of the genus ''Panthera'' native to Asia. It has a powerful, muscular body with a large head and paws, a long tail and orange fur with black, mostly vertical stripes. It is ...

and

orangutan Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genus ...

are found within one area. It has one of the world's richest yet least-known forest systems, and its vegetation is an important source of Earth's oxygen. Leuser also possesses more lowland rainforest than the rest of Sumatra combined and supports some of the last viable populations of tiger, rhino, orangutan and elephant. These, and many co-occurring species, are severely threatened by

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

and poaching.

Geography

The ecosystem stretches from the coast of the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

to the Malacca Straits. It encompasses two vast mountain ranges including Mount Leuser that reaches 3455m, two major volcanoes, three lakes and more than nine major river systems. As well as providing habitats for a number of endangered wildlife species, the ecosystem acts as a life support for approximately four million people who live around it by providing a steady supply of water, soil fertility, flood control, climate regulation and pest mitigation.

Ecology

The ecosystem is home to the largest remaining populations of the

Sumatran tiger The Sumatran tiger is a population of ''Panthera tigris sondaica'' on the Indonesian island of Sumatra. It is the only surviving tiger population in the Sunda Islands, where the Bali tiger, Bali and Javan tigers are extinct. DNA sequencing, Sequ ...

, Sumatran elephant, Sumatran rhino and the

Sumatran orangutan The Sumatran orangutan (''Pongo abelii'') is one of the three species of orangutans. Critically endangered, and found only in the north of the Indonesian island of Sumatra, it is rarer than the Bornean orangutan but more common than the recently ...

. There are at least 130 species of mammals within the

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

which means that one in 32 of the world's mammals are found there, or one quarter of Indonesia's mammals. Primates residing within the ecosystem include the white-handed gibbon, the

siamang The siamang (, ; ''Symphalangus syndactylus'') is an endangered arboreal, black-furred gibbon native to the forests of Indonesia, Malaysia, and Thailand. The largest of the gibbons, the siamang can be twice the size of other gibbons, reaching i ...

macaque The macaques () constitute a genus (''Macaca'') of gregarious Old World monkeys of the subfamily Cercopithecinae. The 23 species of macaques inhabit ranges throughout Asia, North Africa, and Europe (in Gibraltar). Macaques are principally f ...

s, the

loris Loris is the common name for the strepsirrhine mammals of the subfamily Lorinae (sometimes spelled Lorisinae) in the family Lorisidae. ''Loris'' is one genus in this subfamily and includes the slender lorises, ''Nycticebus'' is the genus cont ...

and the lutung. Leuser is home to as many as seven species of cats including the

clouded leopard The clouded leopard (''Neofelis nebulosa''), also called mainland clouded leopard, is a wild cat inhabiting dense forests from the foothills of the Himalayas through Northeast India and Bhutan to mainland Southeast Asia into South China. It w ...

, the

Asian golden cat The Asian golden cat (''Catopuma temminckii'') is a medium-sized wild cat native to the northeastern Indian subcontinent, Southeast Asia and China. It has been listed as Vulnerable on the IUCN Red List since 2025, and is threatened by poaching ...

, and the spotted linsang. The

sun bear The sun bear (''Helarctos malayanus'') is a bear species in the Family (biology), family Ursidae found in the tropical forests of Southeast Asia. It is the only species in the genus ''Helarctos'' and the smallest bear species, standing nearly ...

is quite common within the boundaries of the ecosystem. File:Tiger Melbourne.JPG,

File:Sumatra elephant Ragunan Zoo 3.JPG, Sumatran elephant File:Sumatran Rhino 2.jpg, Sumatran rhino File:SUMATRAN_ORANGUTAN.jpg,

The most common herbivores found in Leuser are the deer which include the sambar, the

muntjac Muntjacs ( ), also known as the barking deer or rib-faced deer, (URL is Google Books) are small deer of the genus ''Muntiacus'' native to South Asia and Southeast Asia. Muntjacs are thought to have begun appearing 15–35 million years ago, ...

and the mouse deer. Among the largest reptiles found in Leuser are the

turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

s and

tortoise Tortoises ( ) are reptiles of the family Testudinidae of the order Testudines (Latin for "tortoise"). Like other turtles, tortoises have a shell to protect from predation and other threats. The shell in tortoises is generally hard, and like o ...

s. The most venomous are the snakes which include the

king cobra The king cobra (''Ophiophagus hannah'') is a species complex of snakes Endemism, endemic to Asia. With an average of and a record length of , it is the world's longest venomous snake and among the heaviest. Under the genus ''Ophiophagus'', i ...

and pythons that can reach up to ten meters in length.

Monitor lizard Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and West African Nile monitor, one species is also found in south America as an invasive species. A ...

skink Skinks are a type of lizard belonging to the family (biology), family Scincidae, a family in the Taxonomic rank, infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one o ...

gecko Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates. They range from . Geckos are unique among lizards ...

s and a variety of frogs are also common. At least 325 species of birds have been recorded in the ecosystem with at least eight species endemic to Sumatra. This rich diversity of bird species includes:

bee-eater The bee-eaters are a group of birds in the family (biology), family Meropidae, containing three genera and thirty-one species. Most species are found in Africa and Asia, with a few in southern Europe, Australia, and New Guinea. They are characte ...

s, flycatchers, flowerpeckers,

honeyguide Honeyguides (family (biology), family Indicatoridae) are a family of birds in the order Piciformes. They are also known as indicator birds, or honey birds, although the latter term is also used more narrowly to refer to species of the genus ''Pro ...

kingfisher Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly coloured birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species living in the tropical regions of Africa, Asia, and Oceania, ...

s, spiderhunters,

woodpecker Woodpeckers are part of the bird family (biology), family Picidae, which also includes the piculets, wrynecks and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar and the extreme ...

s, barbets, babblers, broadbills,

bulbul The bulbuls are members of a family, Pycnonotidae, of medium-sized passerine songbirds, which also includes greenbuls, brownbuls, leafloves, and bristlebills. The family is distributed across most of Africa and into the Middle East, tropic ...

, drongos,

hornbill Hornbills are birds found in tropical and subtropical Africa, Asia and Melanesia of the family Bucerotidae. They are characterized by a long, down-curved bill which is frequently brightly coloured and sometimes has a horny casque on the upper ...

magpie Magpies are birds of various species of the family Corvidae. Like other members of their family, they are widely considered to be intelligent creatures. The Eurasian magpie, for instance, is thought to rank among the world's most intelligent c ...

s, minvets,

myna The mynas (; also spelled mynah) are a group of birds in the starling family (Sturnidae). This is a group of passerine birds which are native to Iran and Southern Asia, especially Afghanistan, India, Pakistan, Bangladesh, Nepal and Sri Lan ...

, orioles, robins, shamas,

shrike Shrikes () are passerine birds of the family Laniidae. The family is composed of 34 species in two genera. The family name, and that of the larger genus, '' Lanius'', is derived from the Latin word for "butcher", and some shrikes are also known ...

swallow The swallows, martins, and saw-wings, or Hirundinidae are a family of passerine songbirds found around the world on all continents, including occasionally in Antarctica. Highly adapted to aerial feeding, they have a distinctive appearance. The ...

swift Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIF ...

s, thrushes, treepies, trogons,

warbler Various Passeriformes (perching birds) are commonly referred to as warblers. They are not necessarily closely related to one another, but share some characteristics, such as being fairly small, vocal, and insectivorous. Sylvioid warblers T ...

weavers Weaver or Weavers may refer to: Activities * A person who engages in weaving fabric Animals * Various birds of the family Ploceidae * Crevice weaver spider family * Orb-weaver spider family * Weever (or weever-fish) Arts and entertainment ...

whistlers Whistler may refer to: * Someone who whistles Places Canada * Whistler, British Columbia, a resort town ** Whistler railway station ** Whistler Secondary School * Whistler Blackcomb, a ski resort in British Columbia * Whistler Mountain, Bri ...

, white-eyes, leafbirds,

sunbirds Sunbirds and spiderhunters make up the family (biology), family Nectariniidae of passerine birds. They are small, slender passerines from the Old World, usually with downward-curved bills. Many are brightly coloured, often with iridescent feathe ...

, tailorbirds,

fantail Fantails are small insectivorous songbirds of the genus ''Rhipidura'' in the family Rhipiduridae, native to Australasia, Southeast Asia and the Indian subcontinent. Most of the species are about long, specialist aerial feeders, and named as "f ...

, forktails, needletails, wagtails,

doves Columbidae is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with small heads, relatively short necks and slender bills that in some species feature fleshy ceres. ...

pigeons Columbidae is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with small heads, relatively short necks and slender bills that in some species feature fleshy ceres. ...

, quails,

partridges A partridge is a medium-sized galliform bird in any of several genera, with a wide native distribution throughout parts of Europe, Asia and Africa. Several species have been introduced to the Americas. They are sometimes grouped in the Perdic ...

pheasants Pheasants ( ) are birds of several genera within the family Phasianidae in the order Galliformes. Although they can be found all over the world in introduced (and captive) populations, the pheasant genera's native range is restricted to Euras ...

, cuckoos, parakeets,

parrots Parrots (Psittaciformes), also known as psittacines (), are birds with a strong curved beak, upright stance, and clawed feet. They are classified in four families that contain roughly 410 species in 101 genus (biology), genera, found mostly in ...

, bitterns,

herons Herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 75 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genus '' Botaurus'' are referred to as ...

, finfoots,

ducks Duck is the common name for numerous species of waterfowl in the family (biology), family Anatidae. Ducks are generally smaller and shorter-necked than swans and goose, geese, which are members of the same family. Divided among several subfam ...

snipe A snipe is any of about 26 wading bird species in three genera in the family Scolopacidae. They are characterized by a very long, slender bill, eyes placed high on the head, and cryptic/ camouflaging plumage. ''Gallinago'' snipe have a nearly ...

s, sandpipers,

wader 245px, A flock of Red_knot.html" ;"title="Dunlins and Red knot">Dunlins and Red knots Waders or shorebirds are birds of the order Charadriiformes commonly found wikt:wade#Etymology 1, wading along shorelines and mudflats in order to foraging, ...

falcon Falcons () are birds of prey in the genus ''Falco'', which includes about 40 species. Some small species of falcons with long, narrow wings are called hobbies, and some that hover while hunting are called kestrels. Falcons are widely distrib ...

hawks Hawks are bird of prey, birds of prey of the family Accipitridae. They are very widely distributed and are found on all continents, except Antarctica. The subfamily Accipitrinae includes goshawks, sparrowhawks, sharp-shinned hawks, and othe ...

nightjars Nightjars are medium-sized nocturnal or crepuscular birds in the family Caprimulgidae and order Caprimulgiformes, characterised by long wings, short legs, and very short bills. They are sometimes called bugeaters, their primary source of food b ...

owls Owls are birds from the Order (biology), order Strigiformes (), which includes over 200 species of mostly Solitary animal, solitary and Nocturnal animal, nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vis ...

, serpent

eagle Eagle is the common name for the golden eagle, bald eagle, and other birds of prey in the family of the Accipitridae. Eagles belong to several groups of Genus, genera, some of which are closely related. True eagles comprise the genus ''Aquila ( ...

s, hawk eagles, fish eagles, sea eagles, and many more.Griffiths, M. (1992)"Leuser". World Wide Fund for Nature The Leuser Ecosystem comprises one of the remaining examples of Indo-Malayan (Malesian) vegetation communities, with an estimated 45% of the approximately 10,000 recorded plant species. In general the ecosystem can be characterised as a montane rainforest community. However, the typical vegetation type up to an altitude of 600 metres is moist tropical lowland forest characterised by multi-layered stories with emergent trees reaching between 45 and 60 metres in height and high densities of fruit tree species. The large variety of tree species found in Leuser represent virtually all life-strategies of trees, from root flowering and trunk flowering to common twig flowering types. Among the most important and impressive trees are the several species of strangling fig. The largest flower on earth; the parasitic

Rafflesia ''Rafflesia'' (), or stinking corpse lily, is a genus of Parasitic plants, parasitic flowering plants in the family Rafflesiaceae. The species have enormous flowers, the buds rising from the ground or directly from the lower stems of their host p ...

is a relatively common in the ecosystem.

Recent history

As a result of the peace agreement between the

Free Aceh Movement The Free Aceh Movement (, GAM; ) was a separatism, separatist group seeking independence for the Aceh region of Sumatra, Indonesia. GAM fought against Indonesian government forces in the Insurgency in Aceh, Aceh insurgency from 1976 to 2005. E ...

(GAM) and the central government of Indonesia, Aceh was awarded a significant level of autonomy over its natural resources, including the right to govern the Leuser Ecosystem. Irwandi Yusuf, the current Governor of Aceh, established Badan Pengelola Kawasan Ekosistem Leuser (BPKEL) to govern the Leuser Ecosystem and coordinate wildlife management in Aceh.(2009) "Challenges of Forest Governance in Aceh". Eye on Aceh. The local Aceh government has introduced a land development plan that would open up an estimated 1.2 million hectares of the forest reserve’s 2.6 million hectares to mining, logging, and agriculture. A group of Aceh citizens has decided to sue the Home Ministry.

Leuser As a National Strategic Area

Act No.26/2007 on Spatial Planning has designated important conservation and areas of high biodiversity as National Strategic Areas. One such area is the Gunung Leuser National Park and the broader Leuser Ecosystem. The area provides water to nearly 4 million people living in Aceh and it is of global importance to the conservation of biodiversity, as well as an important status symbol of Aceh. Conservationist applauds the national governments tough stance on criminal activities in the National Strategic Areas such as Leuser; Act No.26/2007 allow criminal charges to be brought against not only those who carry out illegal activities in the area, but also to those who give permission allowing criminal activities to take place. This is an important milestone, and stand to deter corrupt officials from ‘selling’ permits to conduct activities could damage this sensitive ecosystem. National Spatial Planning Law ruled maximum sentence of 5 years imprisonment and Rp 500 million fine. The Aceh administration did not mention the KEL’s status as a national strategic area in its land use plan issued through Qanun (Islamic bylaw) No. 19/2013.

Threats

Roads

One of the biggest threats to the Leuser Ecosystem is the building of road networks through the forest. The expansion of roads and settlements into this area lead to increased

deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...

and allows

illegal logging Illegal logging is the harvest, transportation, purchase, or sale of timber in violation of laws. The harvesting procedure itself may be illegal, including using corrupt means to gain access to forests; extraction without permission, or from a p ...

and

poaching Poaching is the illegal hunting or capturing of wild animals, usually associated with land use rights. Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set against the huntin ...

to be undertaken with greater ease. A proposed road network known as "Ladia Galaska" that would connect the east and west coasts of Aceh and cut through the Leuser Ecosystem in at least nine places would have a devastating effect on the area's animals, many species of which do not cross roads. The plans for the proposed road comprise of main road plus more than of minor roads, the majority of which would lie within the boundaries of the Leuser Ecosystem.

Palm oil plantations

Also a major threat are

palm oil Palm oil is an edible vegetable oil derived from the mesocarp (reddish pulp) of the fruit of oil palms. The oil is used in food manufacturing, in beauty products, and as biofuel. Palm oil accounted for about 36% of global oils produced from o ...

plantations, particularly in an area on the west coast of Aceh known as Tripa. Palm oil plantations in this area are primarily located on

peat Peat is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. ''Sphagnum'' moss, also called peat moss, is one of the most ...

swamps up to three metres deep. Between 50 and 100 million tonnes of

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

is stored in the peat swamps, and is released into the atmosphere as carbon dioxide when the peat is burned. Palm oil plantations clear primary forest and burn the peat swamps in order to construct large canals to facilitate the planting of palm oil. The

land degradation Land degradation is a process where land becomes less healthy and productive due to a combination of Human impact on the environment, human activities or natural conditions. The causes for land degradation are numerous and complex. Human activitie ...

caused by palm oil plantations in Tripa compromises the welfare of local communities and destroys the habitats of a number of charismatic animal species, including the highest density of orangutans found anywhere in the world. Despite a two-year moratorium on forest clearance, Governor Irwardi Yusuf issued an official permit to oil palm corporation PT Kallista Alam to cut-and-burn the Tripa peat swamp forest, endangering many rare species. These actions have spurred an international movement to save Tripa. Conservation groups have aligned together in an international campaign that has resulted in historic cancellation of palm oil plantation permits. This sets a legal precedent for saving critically endangered orangutan habitat."Pencabutan Izin Kalista Pertama Sepanjang Sejarah Aceh"

References

{{coord missing, Aceh, North Sumatra Forests of Indonesia Geography of Aceh Geography of North Sumatra Ecosystems by region