A stream flowing through the greenery at Sinharaja Forest, the Best Biodiversity Hotspot of Sri Lanka
Sinharaja Forest, the Best Biodiversity Hotspot of Sri Lanka

There is a variety of life on Earth, and there are many interactions among all these forms of life. This biodiversity is what provides vital ecosystem functions. However, this beautiful island of Sri Lanka is on top amongst lands with rich biodiversity. It exhibits a wide range of ecosystems, from marine to wetlands, forest and grassland environments. Besides, the variety of climate zones in the country has favored the presence of many different types of ecosystems. Therefore, Sri Lanka has a good recognition as a biodiversity hotspot.

The geologic isolation from the continental landmass, climate, and unique location has shaped the biodiversity of Sri Lanka. It is home to a wide variety of exotic fauna and flora. This rich biodiversity contributes considerably to the economy of the country through sectors such as tourism, agriculture, and the fisheries industry. Therefore, the preservation of a high level of biodiversity in Sri Lanka is important not only environmentally, but also economically.

Anyway, there is a lot to know regarding the biodiversity of Sri Lanka. Continue reading to know about them!

Why is Sri Lanka Considered a Biodiversity Hotspot?

Simply, this island has the highest biodiversity per unit area of land amongst Asian countries. To be specific, Sri Lanka’s wet zone rainforests are home to numerous woody endemic plants and about 75% of endemic animals. Its genetic diversity is also quite remarkable. In fact, the percentage of endemic species out of different types of animals is as follows.

  • Mammals – 5%
  • Reptiles – 52%
  • Amphibians – 65%
  • Fish – 41%
  • Birds – 10%
  • Freshwater crabs – 100%
  • Land Snails – 80%
  • Flowering plants 28%

Besides, the varying landscapes it holds, along with the significant climatic variations have offered this country the required factors to house rich biodiversity. So, owing to all these reasons, Sri Lanka is famous as a biodiversity hotspot. 

Knowing why Sri Lanka is called a biodiversity hotspot, let us now have an idea about the ecosystems, wildlife fauna, and flora that makes Sri Lanka a place rich in biodiversity.

Ecosystems in Sri Lanka

Of course, there is a wide range of ecosystems in Sri Lanka. The following list includes the types of ecosystems under each category and the land area occupied by each ecosystem.

Forest and Related Ecosystems         

  • Tropical wet lowland evergreen forest – 124340.8 ha
  • Tropical sub-montane forest – 65792.3 ha
  • Tropical montane forest – 3099.5 ha
  • Tropical moist monsoon forest – 221977 ha
  • Tropical dry monsoon (mixed evergreen) forest – 1027544.1 ha
  • Tropical thorn forest (Arid Zone)
  • Riverine dry forest – 18352.1 ha
  • Grasslands (wet pathana, dry pathana, savannah) –  >75,000.0 ha

Inland Wetland Ecosystems  

  • Flood plains
  • Swamps

Lentic Waters (Tanks/Reservoirs and Ponds)

  • River basins – 5924500 ha
  • Wet villu grasslands – 12500 ha

Coastal and Marine Ecosystems      

  • Mangroves – 6080 ha
  • Salt marshes – 23819 ha
  • Sand dunes and beaches – 19394 ha
  • Mudflats – 9754 ha
  • Seagrass beds 
  • Lagoons and estuaries – 129075 ha
  • Coral reefs – 68000 ha

Agricultural Ecosystems      

  • Paddy lands – 977561 ha
  • Fruit cultivations – 85066 ha
  • Small crop holdings or other field crops – 130297 ha
  • Vegetables

Crop Plantations (Major Export Crops)

  • Minor export crops – 119862 ha
  • Home gardens (cultivated) – 76483.2 ha
  • Chena lands

Let us now have a detailed look at the forest and related ecosystems, Inland wetland ecosystems, and coastal and marine ecosystems in detail!

Forest and Related Ecosystems

The inland forest ecosystem of Sri Lanka mainly consists of the following.

  1. Tropical lowland wet evergreen forests
  2. Lower montane forests
  3. Montane forests
  4. Tropical moist evergreen forests
  5. Dry mixed evergreen forests
  6. Thorny shrub forests

Rainforests are present in the wet zones while thorn shrubs are present in the dry zone. Continue reading to know more about these forest types.

1. Tropical Lowland Wet Evergreen Forests

Lowland wet evergreen forests are mainly available in the southwestern part of the island. At present they are highly fragmented.

You can find below some of the lowland wet evergreen forests that you can find in Sri Lanka.

  • Sinharaja
  • Kanneliya
  • Dediyagala-Nakiyadeniya

These forests are dominated by the plant species like  Dipterocarpaceae, Clusiaceae, Sapotaceae, Myrtaceae, and Bombacaceae. Besides, the Mesua ferrea and Shorea trapezifolia dominate the lower canopy of these forests.

Further, around 60 – 75 % of the tree species present in these forests are endemic to Sri Lanka. Also, most of the tree species are soft and medium hardwoods. Moreover, they have the most diverse and richest endemic biota among terrestrial ecosystems.

Besides, Sinharaja forest has the largest number of birds reported per flock. Many of them are endemic and threatened species. Further, the fauna found in these forests includes small mammals, avifauna, reptiles, fishes, amphibians, butterflies, spiders, ants, freshwater crabs, and land snails.

2. The Lower Montane Forests

These forests are mainly available in areas with middle elevations like the Peak Wilderness, Knuckles, Namunukula, and the Rakwana-Deniyaya ranges. Their canopies are about 20–25 m high. 

The plants of families Dipterocarpaceae, Clusiaceae, and Myrtaceae cover these forests. However, soft and medium hardwood species like Shorea gardneri, Calophyllum spp, Cryptocarya wightiana, Myristica dactyloides, and Syzygium spp are also dominant.

Further, the proportion of endemic tree species in these forests is about 50%. However, the Knuckles mountain range shows much heterogeneity in its vegetation distribution.

3. The Montane Forests

The montane forests are mainly available in the uppermost elevations of the country, above 1500m high, to be specific. Plant species like Clusiaceae, Myrtaceae, Lauraceae, Symplocaceae, and Rubiaceae dominate these forests. Besides, the most common tree species in these forests are as follows.

  • Calophyllum walkeri
  • C. trapezifolium
  • S. rotundifolium
  • S. umbrosum
  • Symplocos cochinsinensis
  • Syzygium revolutum
  • Neolitsea fuscata
  • Cinnamomum ovalifolium
  • Litsea ovalifoli

The characteristic features of these forests are short-statured trees, gnarled twisted branches, an abundance of epiphytes and mosses, leafy liverworts, ferns, orchids, colorful foliage, small, thick, leathery leaves, and the absence of drip tips.

However, the lower montane and montane ecosystems have the highest amount of bryophyte flora. Besides, endemic species of amphibians, freshwater crabs, and land snails are present. Moreover, there are localized distributions of Ceratophora spp. , the direct-developing shrub frogs, Philautus spp. , freshwater shrimp, and freshwater crabs.

4. Tropical Moist Evergreen Forests

These forests represent the transition between forests in the aseasonal and seasonal climates. They consist of features and wildlife of both the tropical lowland wet evergreen forests and the tropical dry mixed evergreen forests. 

Examples of tropical moist evergreen forests are Barigoda near Kurunegala, Daragoda near Monaragala, and some areas in Randenigala and Samanalawewa. The dominant species here are as follows.

  • Mangifera zeylanica
  • Canarium zeylanicum
  • Filicium decipiens
  • Dimorcarpus longan
  • Nothopegia beddomei
  • Gironniera parvifolia

Further, Lianas can be seen abundantly in this forest type. Moreover, about 17 % of the tree species in these forests are endemic to Sri Lanka. Also, Hopea brevipetiolaris is one of these endemics.

5. Tropical Dry Mixed Evergreen Forests 

These forests occupy 54 % of Sri Lanka’s natural forest cover and 16 % of the total land area. Moreover, tropical dry mixed evergreen forests are seen in the North, Eastern, North Central, North Western, and Southern Provinces.

They consist of a mixture of evergreen and deciduous canopy species. These canopy species shed their leaves during the late dry period, allowing light to filter to the forest floor. Besides, the appearance of these forests differs seasonally. Moreover, these forests are characterized by the small compound leaves of plant species, without drip tips, and tree trunks that branch lower down with no buttresses. Further, Epiphytes and lianas are scattered in this forest type.

 Kahalla, Ritigala, Maduru Oya Reserve, Polonnaruwa, Wasgamuwa, the Irrigation area of the Lower Walawe Basin, and Wilpattu are some of the tropical dry mixed evergreen forest ecosystems.

6. Thorn Scrub Forests 

These ecosystems are found in the arid zone; in Yala in the southeast of the island and Mannar region in the Northern Province. Thorny species are abundant in these forests and they reach about 5 m in height.

The dominant species in these forests are as follows.

  • Salvadora persica
  • Acacia planifrons
  • Dichrostachys cinerea
  • Bauhinia racemosa
  • Eugenia bracteata
  • Phyllanthus polyphyllus
  • Zizyphus oenoplia

Also, there are not many known endemic plant species in these forests.

Yala and Bundala together with its neighboring grasslands and water bodies, give habitat to large mammals like leopards, elephants, spotted deer, sambhur, and wild pigs. Many bird species, including migrant birds, reptiles, amphibians, and a diversity of invertebrate species can be found here.

Coastal and Marine Ecosystems

Since Sri Lanka is an island, coastal and marine ecosystems are available all around the country. They include salt marshes, mangroves, and seashores.

1. The Salt Marshes

They are mainly available in the intertidal flats frequently flooded with salt water in the northwestern and southeastern arid zones of Sri Lanka. It covers an estimated area of 34,000 ha. Halophytic plants like Halosarcia indicum, Salicornia brachiata, Sueda maritima, and S. monoica dominate these areas. Marshes also provide habitats for waterfowl and milkfish.

2. The Mangroves

Mangroves are influenced by tidal amplitude and they are scattered, and restricted to coastal lagoons and estuaries. Besides, mangroves are best seen near Jaffna, Batticaloa, Kalpitiya, Rekawa, and Trincomalee. Plant families like Rhizophoraceae, Acanthaceae, and Avicenniaceae are abundant in these ecosystems.

Moreover, the plant species found here are as follows.

  • Rhizophora apiculata
  • Rhizophora mucronata
  • Ceriops tagel
  • Bruguiera gymnorhiza
  • Acanthus illicifolius
  • Lumnitzera racemosa
  • Avicennia officinalis
  • Avicennia marina

Further, mangroves give habitat to rich migrant and resident animal species including finfish, shellfish, clams, crabs, oysters, and shrimp. They also provide nursery grounds for marine organisms and roosting sites for birds. 

3. The Sea-shore

Seashore vegetation is seen above the high-water mark on sandy and gently sloping beaches. The vegetation includes short-statured creeping form near the seafront, herbaceous erect shrubs, and tall littoral woodland. Further, Ipomea pescaprae are dominant in the wet zone of the country and the grass Spinifex littoreus is dominant in the drier parts.

The special adaptations of plants in this ecosystem are, the ability to root in unconsolidated sandy soil and to withstand strong winds laden with salt spray and saline soil-moisture conditions. Their seeds also have adaptations to wind or water dispersal.

They provide habitats for nesting turtles of species as follows.

  • Caretta caretta (Loggerhead turtle)
  • Lepidochelys olivacea (Olive Ridley turtle)
  • Eretmochelys imbricata (Hawksbill turtle)
  • Chelonia mydas (Green turtle)
  • Dermochelys coriacea (Leatherback turtle)

Moreover, the common herbaceous species found in these areas include Vernonia, Hedyotis, Phyllanthus, and Crotalaria.

Inland Wetland Ecosystems

Natural inland wetlands include rivers and streams, riverine floodplains, small isolated freshwater bodies, freshwater springs, seasonal ponds, and freshwater marshes. Besides, coastal wetlands include estuaries and lagoons with associated mangrove swamps, saline marshes, mudflats, and coastal seagrass. Further, paddy fields, irrigation tanks, large reservoirs, canals, and aquaculture ponds are man-made wetlands.

However, Sri Lanka has been fortunate to have103 rivers flowing from the central highlands. The rivers, associated streams, and waterfalls provide special habitats for plant species in the riverine and aquatic ecosystems. Besides, endemic species like Cryptocoryne, Laginandra, and Mapania immersa are present in these areas. Riverine floodplains contain Villus that become flooded with overflow from rivers during the rainy seasons and they get dried during drought conditions.

Sri Lanka does not have natural lakes. Still, there are around 12,000 reservoirs that are useful for agricultural purposes.  However, the inland water bodies are important for zooplankton and invertebrates. In fact, inland wetlands offer food, water, and cover to a rich diversity of birds including many migratory species. Also, the rivers and streams of the wet zone are the main habitats for indigenous freshwater fish.

Many of the wetland sites in Sri Lanka are important regionally as well as globally. Further, among the important inland wetlands in Sri Lanka, Bundala is well-known as a Ramsar site.

Loss of Biodiversity in Sri Lanka

Human-wildlife encounters have increased rapidly in recent years. In fact, competition has grown over the shared space between humans and wildlife. Of course, this has put humans and animals in conflict over land, water, and resources. Thus, there is a huge risk of the loss of biodiversity in Sri Lanka.

Some of the main threats against the biodiversity of this island are as follows.

  • The loss of habitat
  • Fragmentation, and alteration of habitat
  • Climate change
  • Spread of invasive species
  • Mismanagement of waste
  • Agrochemical pollution of streams and waterways

Apart from that, there are many other reasons why different ecosystems in Sri Lanka are being harmed.

Threats for Mangrove Forests

Mangrove forests and seagrass beds store carbon and protect coastlines from storms and tsunamis. Still, exploitation and pollution have affected these ecosystems. Some of the threats to the mangrove forests are as follows.

  • Land reclamation
  • Urbanization
  • Pond aquaculture
  • Extraction of firewood and timber
  • Inflow of sediments and pollutants
  • Desalination due to inland irrigation projects
  • Harvesting polychaetes for brood-stock feed
  • Drag-net operations during fishing
  • Chemicals used in agriculture
  • Industrial waste disposal in waterways

Likewise, there are many threats to different types of ecosystems in the world.

Threats for Coastal Ecosystems

Degradation of coastal ecosystems happens due to natural processes, as well as human actions. However, some of the most common threats to coastal ecosystems are as follows.

  • Wave action
  • Sea level rise
  • Tsunamis
  • Mining of beach and river sand
  • Destruction of coral deposits
  • Construction of groynes, harbors, jetties, improperly cited coastal buildings
  • Removal of coastal vegetation

So, owing to various reasons as such, it is not a secret that the biodiversity of Sri Lanka has been under great threat in the recent past. Therefore, it is essential to take immediate steps to conserve this biodiversity hotspot.

Conservation of Biodiversity in Sri Lanka

So, let us now discuss some steps that would be important in preserving the biodiversity of Sri Lanka.

  • Strong motivation and commitment towards conservation among the citizens of the country through increased awareness of the conservation value through conservation education and awareness programs.
  • Coming up with a legal framework that is capable of recognizing the protective measures to save species threatened with extinction and implementing recovery plans for any of these.

After all, there are many factors that continue to threaten the country’s prime position as a biodiversity hotspot in the world. Therefore, it is important to take different measures to conserve biodiversity in the country.

However, there are more important strategies that can be followed with regard to this conservation. Some of them are as follows.

1. Ex-situ Conservation

It is the process of protecting an endangered species or variety or breed of plant or animal outside its natural habitat.  Removing part of the population from a threatened habitat and placing it in a new location or an artificial environment that is similar to the natural habitat of the respective animal is done. Zoological parks and wildlife safaris are examples for this process.

For ex-situ conservation, the authorities can establish more botanical gardens, and mandate them to undertake ex-situ conservation of biodiversity in all bio-climatic regions. Further, it is important that the authorities develop capacity in the National Zoological Gardens to engage in ex situ conservation programs.

2. Conservation through Traditional Knowledge and Cultural Diversity

Identifying traditional ecological sites, locations, and geographical positions and requiring the associated knowledge for preservation is important with regard. For that, professionals should study and conduct further research about these specific fields. 

Also, the promotion of traditional medicine and related medical practices is also important. Accordingly, we can mobilize and develop cultural practices and traditional wisdom related to biodiversity.

3. Minimize Underlying Causes that Affect Biodiversity

With regard to this strategy, the authorities can assess the impacts of urban greening projects, climate change, agrochemicals, and pollutants on biodiversity and then propose recommendations, to develop a database of available information with respect to the impact of the above on biodiversity in Sri Lanka. Also, establishing and regulating a list of freshwater organisms that may be imported alive would be important with regard. These steps would be helpful in minimizing underlying causes that affect biodiversity. 

4. Sustainable Use of the Environment

The following practices would promote sustainable use of the environment.

  • Minimizing extraction of firewood from areas with high biodiversity levels. 
  • Encouraging sustainable harvesting from state-owned plantation forests to maintain low-cost sawn wood, and then offering a disincentive to the illegal logging of natural forests.
  • Providing incentives for animals scheduled as threatened and held in captivity, to be bred and to develop a sustainable population within a regulatory framework for humane treatment.
  • Regularising and monitoring turtle hatcheries while providing incentives for in situ conservation.

The Bottom Line

After all, it is a blessing that Sri Lanka has got this much biodiversity with distribution in a wide array of landscapes and waterscapes. But at present, the biodiversity of Sri Lanka is under threat. So, it is the duty of the authorities and the general public to take immediate steps to conserve this beautiful land with this prestigious wealth of rich biodiversity. If so, Sri Lanka would remain as a biodiversity hotspot in the future too.

However, if you are a nature lover, the biodiversity of Sri Lanka is simply a must-experience. So, while you are in Sri Lanka, make sure you visit the best biodiversity hotspots in Sri Lanka, in order to witness the best. Happy and safe traveling!