The Sumatran lowland rain forests

ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of ...

(WWF ID: IM0158) covers the lowland forests running the length of the island of Sumatra in

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

. The region is one of exceptionally high biodiversity, similar to

Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and ea ...

and

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

islands. Many endangered mammals species (including the Sumatran rhinoceros and the Lar gibbon) are present, and over 450 species of birds have been found in the region. In recent years,

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 corruption, corrupt means to gain access to forests; extraction without permission, o ...

and human encroachment have put great strain on this ecoregion.

Location and description

The ecoregion runs for 1,600 km down the northeast and southwest sides of the

Barisan Mountains The Bukit Barisan or the Barisan Mountains are a mountain range on the western side of Sumatra, Indonesia, covering nearly 1,700 km (1,050 mi) from the north to the south of the island. The Bukit Barisan range consists primarily of volca ...

on the island of Sumatra. The ecoregion thus surrounds the higher elevation Sumatran ''montane'' rain forests ecoregion. The lowlands rainforest is at an average elevation of , and a maximum of . Also in this region are the islands of

Simeulue Simeulue is an island of Indonesia, off the west coast of Sumatra. It covers an area of 1754 square kilometres (677 square miles), including minor offshore islands. It had a population of 80,674 at the 2010 census and 92,865 at the 2020 census ...

Nias Nias ( id, Pulau Nias, Nias language: ''Tanö Niha'') (sometimes called Little Sumatra in English) is an island located off the western coast of Sumatra, Indonesia. Nias is also the name of the archipelago () of which the island is the centre, ...

(both about 150 km off the west coast), and

Bangka Island Bangka is an island lying east of Sumatra, Indonesia. It is administered under the province of the Bangka Belitung Islands, being one of its namesakes alongside the smaller island of Belitung across the Gaspar Strait. The 9th largest island in ...

off the east coast.

Climate

This ecoregion has a

tropical rainforest climate A tropical rainforest climate, humid tropical climate or equatorial climate is a tropical climate sub-type usually found within 10 to 15 degrees latitude of the equator. There are some other areas at higher latitudes, such as the coast of southea ...

(

Köppen Köppen is a German surname. Notable people with the surname include: * Bernd Köppen (born 1951), German pianist and composer * Carl Köppen (1833-1907), German military advisor in Meiji era Japan * Edlef Köppen (1893–1939), German author and ...

: ''Af''). This climate is characterized as hot, humid, and having at least 60 mm of precipitation every month. The lowland rain forests on the west side of the Barisan Mountains are wetter (6,000 mm/year) than those on the east side (2,500+ mm/year).

Flora and fauna

The characteristics trees in the lowland rain forest are those of family '' Dipterocarpaceae '' (Greek: di = two, pteron = wing and karpos = fruit). On Sumatra, 111 species of these trees have been recorded, six of which are endemic. These trees in the canopy can reach 90 meters in height. The dipterocarps in the understory are joined by smaller trees of the 'peacock flower' family ''( Caesalpinioideae)''. Other trees include Torchwood trees ''(

Burseraceae The Burseraceae are a moderate-sized family of 17-19 genera and about 540 species of flowering plants. The actual numbers differ according to the time period in which a given source is written describing this family. The Burseraceae are also kno ...

)'', evergreens of the family ''

Sapotaceae 240px, '' Madhuca longifolia'' var. ''latifolia'' in Narsapur, Medak district, India The Sapotaceae are a family (biology), family of flowering plants belonging to the order (biology), order Ericales. The family includes about 800 species of ev ...

'', member of the Coffee tree family ''(

Rubiaceae The Rubiaceae are a family of flowering plants, commonly known as the coffee, madder, or bedstraw family. It consists of terrestrial trees, shrubs, lianas, or herbs that are recognizable by simple, opposite leaves with interpetiolar stipules a ...

)'', members of the Soursop family ''(

Annonaceae The Annonaceae are a family of flowering plants consisting of trees, shrubs, or rarely lianas commonly known as the custard apple family or soursop family. With 108 accepted genera and about 2400 known species, it is the largest family in the Ma ...

)'', Laurels ''( Lauraceae)'', and ''(

Myristicaceae The Myristicaceae are a Family (biology), family of flowering plants native to Africa, Asia, Pacific islands, and the Americas and has been recognized by most taxonomists. It is sometimes called the "nutmeg family", after its most famous member, ...

)''. Trees of the Mulberry family ''(

Moraceae The Moraceae — often called the mulberry family or fig family — are a family of flowering plants comprising about 38 genera and over 1100 species. Most are widespread in tropical and subtropical regions, less so in temperate climates; however ...

)'' are also common, with over 100 species. Epiphiytes (plants that grow on the surface of others and gather moisture from the atmosphere or surroundings) are common. There is little ground vegetation, mostly saplings of canopy trees. The soils are commonly

Podzol In soil science, podzols are the typical soils of coniferous or boreal forests and also the typical soils of eucalypt forests and heathlands in southern Australia. In Western Europe, podzols develop on heathland, which is often a construct of ...

s in the lowland rain forest. Animals and birds are very diverse, with species similar to

and the Malaysian Peninsula as all three landmasses were connected in the last ice age. Mammals of conservation interest include the endangered Asian elephant ''(

Elephas maximus ''Elephas'' is one of two surviving genera in the family of elephants, Elephantidae, with one surviving species, the Asian elephant, ''Elephas maximus''. Several extinct species have been identified as belonging to the genus, extending back t ...

)'', the endangered Lar gibbon ''(

Hylobates lar The lar gibbon (''Hylobates lar''), also known as the white-handed gibbon, is an endangered primate in the gibbon family, Hylobatidae. It is one of the better-known gibbons and is often kept in captivity. Taxonomy There are five subspecies of ...

)'' (the Sumatran rain forests contain many species of primates), the endangered Malayan tapir ''( Tapirus indicus)'', and the critically endangered Sumatran rhinoceros ''(

Dicerorhinus sumatrensis The Sumatran rhinoceros (''Dicerorhinus sumatrensis''), also known as the Sumatran rhino, hairy rhinoceros or Asian two-horned rhinoceros, is a rare member of the family Rhinocerotidae and one of five extant species of rhinoceros. It is the o ...

)''. Over 450 species of birds have been recorded. Many endemic species are found in the biodiversity hotspot around

Lake Toba Lake Toba ( id, Danau Toba) ( Toba Batak: ᯖᯀᯬ ᯖᯬᯅ; romanized: ''Tao Toba'') is a large natural lake in North Sumatra, Indonesia, occupying the caldera of a supervolcano. The lake is located in the middle of the northern part of the i ...

, located in the caldera of a supervolcano.

Protected areas

About 7% of the ecoregion is under some form of official protection. The protected areas include: * Mount Leuser National Park * Bukit Barisan Selatan National Park *

Kerinci Seblat National Park Kerinci Seblat National Park is the largest national park on the island of Sumatra, Indonesia. It has a total area of 13,791 km2, and spans four provinces: West Sumatra, Jambi, Bengkulu, and South Sumatra. Geography It is located between 1 ...

Bukit Tigapuluh National Park Bukit Tigapuluh National Park (also called ''Bukit Tiga Puluh'' and ''Bukit Tigapulah'') - ''The Thirty Hills'' - is a 143,223 hectare National Park in eastern Sumatra, consisting primarily of tropical lowland forest, largely in Riau province, wit ...

* Tesso Nilo National Park * Bukit Duabelas National Park

References

{{reflist Indomalayan ecoregions Ecoregions of Indonesia