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Lowland
rain forests in Sri Lanka
The
southwest portion of the island, low and mid country wet
zone, where the influence of the moisture-bearing
southwest monsoon is strongest, is home to the Sri Lanka
lowland rain forests. These forests are called tropical
rain forests or wet evergreen forests and rich in
biodiversity. The best example for rainforests in Sri
Lanka is the Sinharaja rain forest and
Kanneliya-Dediyagala-Nakiyadeniya (KDN). At higher
elevations they make the transition to the Sri Lanka
montane rain forests. Both these tropical moist forest
ecoregions bear strong affinities to those of India's
Western Ghats.
Two floral communities dominate in the Sri Lanka lowland
rain forests; The Dipterocarpus-dominated
(Sinhalese "Hora") community and the
Mesua-Shorea community (Sinhalese "Na-Doona").
The Dipterocarpus community comprises several
species; Dipterocarpus zeylanicus,
Dipterocarpus hispidus, Vitex altissima,
Chaetocarpus castanocarpus, Dillenia retusa,
Dillenia triquetra, Myristica dactyloides,
Semecarpus gardneri.
The Mesua-Shorea community, comprises
Anisophyllea cinnamomoides, Cullenia rosayroana,
Mesua ferrea (The national tree of Sri Lanka),
Mesua nagassarium, Myristica dactyloides,
Palaquium petiolare, Shorea affinis,
Shorea congestiflora, Shorea disticha,
Shorea megistophylla, Shorea trapezifolia, Shorea
worthingtoni, Syzygium rubicundum, and a sub
canopy of Chaetocarpus castanocarpus, Garcinia
hermonii, Syzygium neesianum, Xylopia
championi.
Virgin forests of this ecoregion have four strata, a
main canopy at 30-40 m, a sub-canopy at 15-30 m, a 5-15
m understory, and a sparse shrub layer (Wickramanayake
and Gunatilake, 2001). Trees of Emergent layer reach
above the main canopy to 45 m.
Hundreds of endemic flora and fauna of Sri Lanka are
confined to the southwestern rain forests
(Wickramanayake and Gunatilake, 2001) due to warm and
moist climate and long physical isolation wet forest.
More than 60 percent of 306 endemic tree species of Sri
Lanka are reported in this ecoregion. Further 61 species
are shared with montane rain forests and dry forests.
However, the dominant tree family in Asian rain forests,
the family Dipterocarpaceae shows a special endemicity.
All but one species of the 58 species of the family
Dipterocarpaceae only be found in these rain forests,
including two endemic genera, Shorea and Stemonoporus.
Anoectochilus setaceus or Wanaraja
(Sinhalese for "King of forest") an endemic orchid is
only found in undisturbed forests of this ecoregion. The
lowland and sub montane forests are considered as the
floristically richest in Sri Lanka and of all South
Asia.
Despite small number of species, this ecoregion is home
to several near-endemic mammals, including one strict
endemic species, Jungle Shrew (Wickramanayake and
Gunatilake, 2001). The two endemic shrews, Asian
Highland Shrew, Jungle Shrew listed as vulnerable and
endangered respectively. Sri Lanka Leopard, the largest
carnivore of the island is identified as threatened.
Asian elephants live in small numbers in these rain
forests and listed as endangered. Unlike in dry-zone
forests, where they live in large numbers this
ecoregion's elephant population faced with habitat loss
and fragmentation. Indian Hare, Fishing Cat and
Rusty-spotted Cat are some of the other mammals dwell in
this ecoregion.
This ecoregion completely contain within the Endemic
bird area Sri Lanka. Out of sixteen bird species
categorized as near-endemic, while two species two,
Green-billed Coucal and White-throated Flowerpecker are
indigenous. Green-billed Coucal and Sri Lanka
Whistling-thrush are listed threatened. Ashy-headed
Laughingthrush, Red-faced malkoha and Scaly thrush are
the other threatened species.
Sri Lanka's reptile fauna includes 204 species with 114
endemic species. A further 17 taxa are endemic at
subspecies level. Mugger Crocodile and Spineless Forest
Lizard are listed as endangered along with eight
freshwater fish species. Sri Lanka has the highest
density of amphibian species worldwide (3.9 species per
1000 square kilometers). Many of these include 250
species of frogs belongs Rhacophoridae family.
Threats
Forest clearance for plantation agriculture
Poaching and the extraction of forest products
Encroachment
Read
on Sinharaja-The giant forest
Montane rain
forests
Dry zone
evergreen forests and other vegetations
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