The Sri Lanka lowland rain forests represents

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

Tropical rainforest 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 ...

s below in elevation in the southwestern part of the island. The year-around warm, wet climate together with thousands years of isolation from mainland India have resulted in the evolution of numerous plants and animal species that can only be found in

rain forests Rainforests are forests characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropical rainforests o ...

in Sri Lanka. The thick forest canopy is made up of over 150 species of trees, some of the emergent layer reaching as high as . The lowland rain forests accounts for 2.14 percent of Sri Lanka's land area. This ecoregion is the home of the jungle shrew, a small

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

mammal of Sri Lanka. Sri Lanka has the highest

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...

species worldwide. Many of these, including 250 species of

tree frog A tree frog (or treefrog) is any species of frog that spends a major portion of its lifespan in trees, known as an arboreal state. Several lineages of frogs among the Neobatrachia suborder have given rise to treefrogs, although they are not clos ...

s, live in these

rain forest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...

Forest cover

The lowland rain forests cover in total and accounts for 2.14 percent of Sri Lanka's land area. Wet monsoon forests receive of annual rainfall and are situated belove of altitude. Kanneliya, Viharakele, Nakiyadeniya, and Sinharaja, which is a

World Heritage Site World Heritage Sites are landmarks and areas with legal protection under an treaty, international treaty administered by UNESCO for having cultural, historical, or scientific significance. The sites are judged to contain "cultural and natural ...

, are the forests that represent this ecoregion. Bambarabotuwa, Morapitiya Runakanda, Gilimale and Eratne are some of the other forest reserves. Even rainfall throughout the year, and invariable temperature resulted in rich

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

. These forests also act as an important catchment area for rivers.

Geological history

Sri Lanka is a continental island, separated from the

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

n continent only by shallow Palk Strait. Sri Lanka was once a part of Gondwanaland, until the

Cretaceous Period The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 77.1 million years, it is the ninth and longest geologi ...

. Then as a part of the

Indian Plate The Indian plate (or India plate) is or was a minor tectonic plate straddling the equator in the Eastern Hemisphere. Originally a part of the ancient continent of Gondwana, the Indian plate broke away from the other fragments of Gondwana an ...

, it detached and drifted northward. The Indian Plate collided with the Asian mainland about 55 million years later. Therefore, there are many ancient Gondwana taxonomic groups present in Sri Lanka. Sri Lanka first became separated from the mainland Indian subcontinent during the late

Miocene Epoch The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

. Due to climatic changes, an intermittent drier region emerged between the moist forests in southwest Sri Lanka and the Western Ghats in India, the closest other moist forests. Although the island has been connected with the mainland repeatedly by land bridges since the initial separation, Sri Lanka's moist forests and its wet forest-adapted biota have been identified as being ecologically isolated.

Features

The ecoregion partially encircles the Central Massif, which reach above and detached Knuckles Mountain Range. These mountains are represented by their own ecoregion, Sri Lanka montane rain forests. The type of the soil of the ecoregion is red-yellow podzolic soil. The extended Southwestern monsoon in May to September brings more than of rainfall to the ecoregion. The temperature remains constantly between throughout the year. Due to the proximity to 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), ...

daily temperatures are relieved by the ocean breezes.

Relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

ranges between 75%-85%.

Flora

The vegetation of the region is determined primarily by climate, with

topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the landforms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sci ...

and edaphic conditions contributing secondarily. Two floral communities dominate in the Sri Lankan lowland rain forests - the ''

Dipterocarpus '' D. retusus'' in Köhler ''Dipterocarpus'' is a genus of flowering plants and the type genus of family Dipterocarpaceae. ''Dipterocarpus'' is the third-largest and most diverse genus among the Dipterocarpaceae. The species are well known for ...

''-dominated ( Sinhalese "''Hora''") community and the '' Mesua- Doona'' community (Sinhalese "''Na-Doona''"). The ''Dipterocarpus'' community comprises '' Dipterocarpus zeylanicus'', '' Dipterocarpus hispidus'', '' Vitex altissima'', '' Chaetocarpus castanicarpus'', '' Dillenia retusa'', '' Dillenia triquetra'', '' Myristica dactyloides'', and '' Semecarpus gardneri''. The ''Mesua-Doona'' community comprises '' Anisophyllea cinnamomoides'', '' Cullenia rosayroana'', ''

Mesua ferrea ''Mesua ferrea'', the Ceylon ironwood, or cobra saffron, is a species in the family Calophyllaceae native to the Indomalayan realm. This slow-growing tree is named after the heaviness and hardness of its timber. It is widely cultivated as an o ...

'' (the national tree of Sri Lanka), ''Myristica dactyloides'', '' Palaquium petiolare'', '' Doona affinis'', '' Doona congestiflora'', '' Doona disticha'', '' Doona macrophylla, Doona trapezifolia'', '' Doona venulosa'', '' Syzygium rubicundum'', and a sub canopy of ''Chaetocarpus castanicarpus'', '' Garcinia hermonii'', '' Syzygium neesianum'', and '' Xylopia championii''. Virgin forests of this ecoregion have four strata, a main canopy at , a sub-canopy at , a

understory In forestry and ecology, understory (American English), or understorey (English in the Commonwealth of Nations, Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the Canopy (biology), forest ca ...

, and a sparse shrub layer. Trees of the emergent layer reach above the main canopy to . Freshwater swamp forests situated closer to the coastlines are a distinct plant community within the ecoregion. ''

Avicennia ''Avicennia'' is a genus of flowering plants currently placed in the bear's breeches family, Acanthaceae. It contains mangrove trees, which occur in the intertidal zones of estuarine areas and are characterized by its "pencil roots", which ar ...

- Rhizophora- Sonneratia'' dominated

mangrove A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...

s fringe the coastlines.

Biodiversity

Almost all the

flora Flora (: floras or florae) is all the plant life present in a particular region or time, generally the naturally occurring (indigenous (ecology), indigenous) native plant, native plants. The corresponding term for animals is ''fauna'', and for f ...

and

fauna Fauna (: faunae or faunas) is all of the animal life present in a particular region or time. The corresponding terms for plants and fungi are ''flora'' and '' funga'', respectively. Flora, fauna, funga and other forms of life are collectively ...

of Sri Lanka are confined to the southwestern rain forests. Due to the warm and moist climate and long physical isolation, wet forest adopted species have promoted a high degree of endemism and specialization. More than 60 percent of 306 endemic tree species of Sri Lanka are restricted to this ecoregion. A further 61 species are shared with the montane rain forests and

dry forests The tropical and subtropical dry broadleaf forest is a habitat type defined by the World Wide Fund for Nature and is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive ...

. The dominant tree family in Asian rain forests, the family

Dipterocarpaceae Dipterocarpaceae is a family (biology), family of flowering plants with 22 genera and about 695 known species of mainly lowland tropical forest trees. Their distribution is pantropical, from northern South America to Africa, the Seychelles, India ...

shows a special endemicity. All but one species of the 58 species of the family

can only be found in these rain forests, including two endemic genera, '' Doona'' and '' Stemonoporus''. ''Anoectochilus setaceus'' or ''Wanaraja'' (Sinhalese for "King of forest"), an endemic orchid, is only found in undisturbed forests of this ecoregion. Several plant species show highly localized distribution. The lowland and sub montane forests are the floristically richest in Sri Lanka and of all

South Asia South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...

Fauna

Mammals

Sri Lanka lacks the land area to support large animals. Although fossil records of ancestral forms of

rhinoceros 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 ...

es,

hippopotamus The hippopotamus (''Hippopotamus amphibius;'' ; : hippopotamuses), often shortened to hippo (: hippos), further qualified as the common hippopotamus, Nile hippopotamus and river hippopotamus, is a large semiaquatic mammal native to sub-Sahar ...

es, and

lion The lion (''Panthera leo'') is a large Felidae, cat of the genus ''Panthera'', native to Sub-Saharan Africa and India. It has a muscular, broad-chested body (biology), body; a short, rounded head; round ears; and a dark, hairy tuft at the ...

s have been found. Despite the small number of species, this ecoregion is home to several near-endemic mammals, including one strict endemic species, the jungle shrew. The two endemic shrews, the Asian highland shrew and the jungle shrew are listed as vulnerable and endangered respectively. The Sri Lanka leopard, the largest carnivore of the island, is identified as threatened.

Asian elephant The Asian elephant (''Elephas maximus''), also known as the Asiatic elephant, is the only living ''Elephas'' species. It is the largest living land animal in Asia and the second largest living Elephantidae, elephantid in the world. It is char ...

s live in small numbers in these rain forests and are listed as endangered. Unlike in dry-zone forests, where they live in large numbers, this ecoregion's elephant population is faced with

habitat loss 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 fragmentation. The Indian hare, fishing cat and rusty-spotted cat are some of the other mammals who dwell in this ecoregion. The near-endemic and strict endemic mammals live in the areas listed below. Strict endemic species are marked with an asterisk. * Asian highland shrew * Jungle shrew* * Thailand roundleaf bat * Purple-faced langur * Golden palm civet * Layard's palm squirrel * Travancore flying squirrel * Ceylon spiny mouse * Nolthenius's long-tailed climbing mouse

Birds

This ecoregion is completely contained within the Endemic bird area of Sri Lanka. Out of sixteen bird species categorized as near-endemic, two species, the green-billed coucal and the white-throated flowerpecker are indigenous. The green-billed coucal and the Sri Lanka whistling-thrush are listed as threatened. The ashy-headed laughingthrush, red-faced malkoha and scaly thrush are the other threatened species. The near-endemic and strict endemic birds live in the areas listed below. Strict endemic species are marked with an asterisk. * Sri Lanka wood pigeon *

Sri Lanka grey hornbill The Sri Lanka grey hornbill (''Ocyceros gingalensis'') is a bird in the hornbill family and a widespread and common endemic resident breeder in Sri Lanka. Hornbills are a family of tropical near-passerine birds found in the Old World. Habitat ...

* Red-faced malkoha *

Green-billed coucal The green-billed coucal (''Centropus chlororhynchos'') is a member of the cuckoos. It is endemic to Sri Lanka's wet zone and listed as Vulnerable on the IUCN Red List, as the small population declined due to forest destruction and fragmentation ...

* * Sri Lanka spurfowl * Sri Lanka junglefowl *

Sri Lanka blue magpie The Sri Lanka blue magpie or Ceylon magpie (''Urocissa ornata'') is a brightly coloured member of the family Corvidae, found exclusively in Sri Lanka. This species is adapted to hunting in the dense canopy, where it is highly active and nimble. I ...

* Spot-winged thrush * White-faced starling * Sri Lanka myna * Kashmir flycatcher * Brown-capped babbler * Orange-billed babbler * White-throated flowerpecker* * Yellow-fronted barbet * Sri Lanka hanging parrot * Layard's parakeet * Chestnut-backed owlet

Reptiles, fishes and amphibians

Sri Lanka's reptile fauna includes 204 species with 114 endemic species. A further 17 taxa are endemic at subspecies level. The mugger crocodile and the spineless forest lizard are listed as endangered along with eight

freshwater fish Freshwater fish are fish species that spend some or all of their lives in bodies of fresh water such as rivers, lakes, ponds and inland wetlands, where the salinity is less than 1.05%. These environments differ from marine habitats in many wa ...

species. Sri Lanka has the highest

species worldwide (3.9 species per ). These include 250 species of

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

s belonging to the family Rhacophoridae. Many of these species have only limited range distributions, often less than . These species are also faced with habitat fragmentation and loss.

Threats and conservation

Most of the Sri Lanka's rain forests were cleared for plantations, originally for

coffee Coffee is a beverage brewed from roasted, ground coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content, but decaffeinated coffee is also commercially a ...

and

cinchona ''Cinchona'' (pronounced or ) is a genus of flowering plants in the family Rubiaceae containing at least 23 species of trees and shrubs. All are native to the Tropical Andes, tropical Andean forests of western South America. A few species are ...

and then

tea Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of '' Camellia sinensis'', an evergreen shrub native to East Asia which probably originated in the borderlands of south-western China and nor ...

and

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Types of polyisoprene ...

. The remaining forests cover only 4.6 percent of the wet zone. Between 1990 and 2005, Sri Lanka has had one of the highest deforestation rates of primary forests in the world. A survey carried out in 2005 found that 17 of Sri Lanka's frogs have become extinct in the past decade and another 11 species face imminent threat of extinction unless their habitat is secured. These remaining forests exist as highly fragmented patches. Most of them are less than in extent. Poaching and the extraction of forest products (timber, firewood, medicinal plants) are a problem in almost all forest reserves. Nevertheless, if the existing forests are preserved the condition can be improved, as many of the species of this ecoregion have small habitat needs. There are several protected areas that overlap with the ecoregion. The two most notable are the world heritage site the Sinharaja Forest Reserve and the Peak Wilderness Sanctuary. Altogether, protected areas of this ecoregion accounts for only . Protected areas that overlap with the ecoregion:

References

{{Geography of Sri Lanka Ecoregions of Sri Lanka Forests of Sri Lanka Indomalayan ecoregions Tropical and subtropical moist broadleaf forests