Natural forests in Sri Lanka
Sri Lanka exhibits a remarkable biological diversity[1] and is considered to be the richest country in Asia in terms of species concentration.
[2] Sri Lanka continental separated from the south eastern tip of peninsular India by the more than 20 m deep Palk Strait.
Notwithstanding these intermittent land connections with India, when exchange of species undoubtedly would have taken place between the island and mainland, Sri Lanka fauna and flora, especially those in the south western quarter, show remarkably high diversity and extraordinary endemism.
It is the only area of seasonal lowland climate between western Malaysia (Sumathra, Malay Peninsula, Borneo and Philippines) and eastern coastal Madagascar.
By the dawn of the 19th century, Sri Lanka's forest cover was estimated at up to 70% of the total land area.
Based on a global yardstick of concentrations of exceptional terrestrial biodiversity under threat, Sri Lanka and Western Ghats of southwestern India have been grouped together as one of the 34 global hotspots of biodiversity, implying that biologically they are among the richest and at the same time the most endangered terrestrial biogeographic region in earth.
Therefore it experiences a climate with high rainfall and temperature which permits the county to be broadly classified into groups as follows.
The tropical wet lowland rainforests are found below 900 m elevation in the south western quarter of the country.
A diverse population of epiphytic lichens, mosses, liverworts ferns, orchids are found while many fungi inhabit decaying woods and soil.
(Sinharaja, Nakiyadeniya and Kanneliya are some examples for wet lowlands rainforest) These forests are disturbed due to expansion of tea cultivation, agriculture, industrial and residential development.
There are trees with umbrella-shaped rounded crowns and twisted branches having leathery small leaves to accommodate the strong winds that prevail in the montane zone.
[11] Montane forests are distributed in the Central Highlands including Knuckles range, Pidurutalagala, Hakgala.
These forests have a mean annual temperature of about 29 °C and rainfall around 1,000 mm- 1,500 mm most of which falls during the northeast monsoon periods.
Some plant species naturally found in these forests are[12] Some of the canopy trees are deciduous during the dry spell of the year.
[10] These are called "scrubs" than "forests" as large trees are sparse and the vegetation is mainly consists of thorny shrubs.
They are distributed near Hambantota, Yala, Mannar, Puttalam areas and disturbed due to various development pressures.
[12] The following plant species are commonly found; Savannas have a thick grass cover and few scattered trees.
[12] Wetlands are simply habitats with permanent or temporary accumulation of water with associated plant and animals.
Plants that have adapted to grow in shallow stagnant water such as Colocassi spp., Aponogeton spp., species are abundant in inland marshlands.
It is a place where forest vegetation is inundated for a short period of time in the year as seen in Waturana swamp at Bulathsinhala located in the 'Kalu Ganga' river basin.
The most extensive coral reefs occur off the north west and east coast up to and around the Jaffna Peninsula.
The greatest extent of true corals in Sri Lanka lie in patchy reefs from Vakalai to the Kalpitiya peninsula.
Patchy coral reefs are also found on the western and eastern seaboards at a distance of about 15–20 km from the shore, at an average depth of 20m.
[15] There are no natural lakes in Sri Lanka, but there are numerous ancient irrigation tanks mainly scattered in the low land dry zone.
Examples for these plants are,[19] The vegetation gradually become stable a distance away from the tide mark, with the stabilization of the soil.
[2] Large scale agricultural and settlement schemes without the recognition given for wild animal habitats and their migration patterns have been a major driver of deforestation and degradation, particularly in the dry zone, during the last century.
Planted crops, such as sugar cane, banana, maize and paddy, in an unplanned manner, have led to ever-increasing human-elephant conflicts.
