Sri Lanka is one of the smallest, but biologically diverse countries in Asia. Consequently it is recognized as a Biodiversity hotspot of global and national importance. Its varied climate and topographical conditions have given rise to this rich species diversity, believed to be the highest in Asia in terms of unit land area.
Much of the species are endemic, a reflection of the island’s separation from the Indian subcontinent since the late Mesozoic. This is especially relevant for mammals, amphibians, reptiles and flowering plants. These species are distributed in a wide range of ecosystems which can be broadly categorized into forest, grassland, aquatic, coastal, marine and cultivated. The diversity of ecosystems in the country has resulted in a host of habitats, which contain high genetic diversity.
Biodiversity includes species diversity, genetic diversity and ecosystem diversity.
Species diversity – fauna and flora
An interesting feature of the species diversity in Sri Lanka is its high degree of endemism, which is observed in several taxonomic groups. Even more interesting is distribution of endemics. A large proportion is found in the wet zone in the south western region of the island.
Flora – Twenty three percent of the flowering plants are endemic and most of them are confined to the wet evergreen and wet montane forests of the central and southwest part of the country.
Vegetational analysis has resulted in the identification of fifteen different floristic regions with the great majority being found in the wet and intermediate zones. The presence of many floristic regions within a relatively small area is a reflection of the high level of ecosystem diversity in the country.
Fauna – The fauna of Sri Lanka is as diverse as the flora. While sharing common features with the neighboring subcontinent, the fauna exhibits very high endemism among the less mobile groups. With taxonomical revisions and descriptions of new species the number of species in each group keeps changing.
For endemic species, the distribution patterns are similar to the flora: the wet zone has many more endemic species than the dry zone. In terms of mammals, birds and fishes, the three major groups that are well studies in Sri Lanka, each group has a different distribution pattern.
Genetic diversity is the component of biodiverstiy that this least documented. Almost all of the available information is confined to economically important agricultural crops. The Plant Genetic Resource Centre (PGRC) at Gannuoruwa, Peradeniya has collected and preserved propagative material of a large number of species from various agro-climatic zones of the country. For example PGRC has germoplasm materials of 3194 traditional varieties and cultivars, and 17 wild relatives of Rice (Oryza sativa).
For fauna, there have been some studies on elephants (Elephas maximus) and leopards (Panthera pardus), which indicate a decrease in genetic diversity as a consequence of natural isolation from Indian sub-continent.
There is a wide range of ecosystem diversity in the island. The major natural ecosystems in the country are forests, grasslands, inland wetlands, and coastal and marine ecosystems. It also includes agricultural ecosystems.
Forests varying from wet evergreen forests (both lowland and montane), dry mixed evergreen forests to dry thorn forests. Grasslands are found in montane and low country Inland wetlands include a complex network of rivers and freshwater bodies. Marine ecosystems include sea-grass beds, coral reefs, estuaries and lagoons and mangrove swamps.
Sri Lanka: One of 25 World’s Biodiversity Hot Spots
Sri Lanka has been identified by the environment activist group Conservation International (CI) as one of 25 biodiversity hot spots in the world.
These hot spots could have maximum benefit by preservation efforts, the magazine said in a cover story titled “Heroes for the Planet: Earth Angles”. The U.S.-based CI said that together with Western India, Sri Lanka, the island in the Indian ocean, accounts for 2,180 plant species that are unique to each hot spot. Sri Lanka’s tropical rain forest ecosystem is considered as an area which is disturbed by human activity, but still exceptionally rich in animal and plant species found nowhere else.
Environment Division, Ministry of Transport, Environment and Women’s Affairs (1994) Strategy for the preparation of a biodiversity action plan for Sri Lanka. Prepared by IUCN and Ministry of TEWA. Forest Sector Master Plan (1995) Forestry Planning Unit, Minsitry of Agriculture, Lands and Forestry.