Ecosystems

Ecosystems​

Sri Lanka has a spatially varied climate and topography and this variation has contributed to rich biodiversity, distributed within a range of ecosystems. There are two categories of ecosystems, aquatic and terrestrial. Some are natural and others human made. Examples of natural aquatic ecosystems are marshes, streams, rivers, estuaries, lagoons, coastal seas, seagrass beds and mudflats, mangroves and salt marshes, coral reefs, sandstone reefs and villus. Human-made aquatic ecosystems are tanks, reservoirs, canals, ponds and lakes. Examples of natural terrestrial ecosystems are tropical wet evergreen forests, tropical sub montane and montane forests, mixed evergreen forests, grasslands, scrub forest, Savannah, Sand dunes and beaches. Some of these pristine ecosystems have both beauty and diversity and have been identified as global biodiversity hotspots.

Human-made terrestrial ecosystems are home gardens, agriculture fields, botanical gardens, monocultures and mixed plantations, The ecosystems of Sri Lanka are under threat from logging, land use change, urbanization, and intensification of use. The population density is high and this corrupt practices and inability of policy makers to fully account for social and environmental costs results in untoward destruction of ecosystems and habitats.

Natural Aquatic Ecosystems

Aquatic Ecosystems can be divided into Coastal & Marine and Inland Ecosystems. When we look at the Coastal and Marine ecosystems its significance is due to the fact that 24% of the land in Sri Lanka lies in this vicinity as well as 34% of the country’s total population. The said ecosystem also houses the country’s capital Colombo as well as six of the twelve largest municipal councils and nineteen of the thirty nine urban councils. It has as it’s major industries fishing which produces 97% of the total fish production and sand, surf, beaches as one of the main tourist attractions of the country as well as significant productions of coconut and cinnamon plantations. . It also hold immense importance as coral reefs, estuaries, lagoons, mangroves and salt marshes are essential as rich reservoirs of genetic resources. These ecosystems also provide rich sources of minerals such as Ilmenite, Silica, Miocene, Limestone, Kaolin, China clay, Copper magnetite and Peat. These ecosystems provide sanctuary to many bird species as well as harbour hundreds of aquatic species amongst these Large Pelagics such as Tuna, Shark, Seerfish, Small Pelagics such as Sardines, Crustaceans such as Lobster, Prawns and ornamental fish. Furthermore these systems preserve and grow many plant habitats which include seagrass beds, Rhizophora, Bruguiera, Avicennia etc..

The main threats that faces these unique eco habitats are coastal erosion which diminishes beaches and this is aggravated by sand and coral mining, removal of vegetation and poorly sited buildings and harbours. Further over exploitation of resources together with coastal pollution have also made it severely harmful for biotic and abiotic environments in these surroundings. There have been efforts by the Ministry of Fisheries and Aquatic Resources, NAtional Aquatic Resources agency and Central Environment Authority in mitigating damage however with industrialization and pollution there is a need for action at macro levels in conservation.
Inland Aquatic Ecosystems comprise mainly of rivers, streams and wetlands. These function primarily as water storages and conveyances where water is made available for habitat and growth. These systems further given space for unique riverine species of fish and other aquatic animals. Fishing has also been an industry based on these areas. Several factors cause alarm in the preservation of these natural habitats foremost among these would be be pollution from from agriculture and development, floods, development of buildings on wetlands. Considering the importance of water in livelihoods, habitat growth, storage and industry the protection of these sensitive ecosystems is a vital need for the country.

Natural Terrestrial ecosystems

In precolonial times these ecosystems provided the populations with much of all their daily needs. These systems while providing all these needs have also been the main component of maintaining a rich biodiversity, proper functioning of the water cycle and soil conservation. Over the past century due to several reasons these have diminished at alarming rates. The present need is to manage the remaining of these ecosystems while establishing new cover which needs political will and strong nationwide consensus. While there was a scenario that the entire island was covered with forests, wet southwestern regions and central highlands have the most luxuriant plant cover in modern times. The lowland area, upto an elevation of 900 meters has a climax of tropical rain forests while dominant trees forming canopy at 25-30m. Wet evergreen montane forests are at 900 -1350m and hold a thicker undergrowth. The major part of the dry zone has a tropical dry mixed evergreen forests while most of this area where long periods of dry weather is sustained are covered with low trees and undergrowth of thorny shrubs. Especially in these areas felling of trees for chena cultivation has intensified the degradation of forests. There are also plantation forests with pines, eucalyptus, teak and also natural grasslands called ‘villu’ and ‘patana’. While all these covers are unique in association and conservation it also faces unique issues in survival.

Forests provide an integral role in the functioning of the climate with its contribution to the water cycle. It also provides habitat for numerous species of plants and animals. The forests prevent soil erosion and adds to natural beauty. Natural forests also provide berries, fruits, nuts and game as well as medicinal products, horticultural and flower plants. 90% of endemic flowering plants and endemic fauna is found in the forests cover. The British sharply increased shifting cultivation content and forest exploitation for timber supply. However from the colonial times to the modern day 95% of forest cover has been state owned and no substantial efforts have been taken into consideration by either government in rule to rectify the situation that has continued to decline. The forest department has been able to reserve forty biospheres for reserved and proposed reserve forests. The International Union for Conservation of Nature and the UNESCO’s human and biosphere programmes have had contributions in the process of reservation.

Timber yields from these forests and especially from the dry zone has continued from the 1800’s. Much of these are of prime species and have been exported mainly to Britain. With rapid demands even the untouched species were over exploited. Illicit felling has also been rampant and this has led to the intertwining of politics in the equation as well. Apart from these there is a continued need of wood for industrial purposes which is also on the rise. There has been several objections for the commercial planting of monoculture trees as this has reduced biodiversity and soil quality. However as demands soar this has been in practice which compromises on the habitats. Fuelwood has also been a concern in the recent times but it has been overtaken with forest clearance for development needs. Over the past four decades deforestation has slashed natural forests by 50%. While reforestation and forest management has been in place the results of such measures will need to be analyzed and evaluated as the country with growing needs and increasing populations face a multitude of demands from its terrestrial environment.

Biosphere and hydrological presence in Sri Lanka
Biosphere and hydrological presence in Sri Lanka

Wildlife of Sri Lanka

Sri Lanka is a biodiversity and wildlife hotspot with high species richness and endemicity. The identification of an area as a biodiversity hotspot should increase the likelihood of conservation investment. Within the Asian region Sri Lanka has the highest species density for flowering plants, amphibians, reptiles and mammals. It has the highest density of Asiatic elephants and leopards.There are 4000 species of flowering plants, 107 species of freshwater fish, 59 species of amphibians, 174 species of reptiles, 435 species of birds, 140 species of mammals and several thousand invertebrates. The country has 22 national parks under Department of Wildlife Conservation, forest reserves,wilderness areas and four forests recognized as Natural world heritage sites(WHS) yet the wildlife is under threat and urgent conservation action is needed, especially in augmenting the protected area network. There is a need for scientific and research advances and for these to be brought to play assist in the protection of wildlife.

Diversity of wildlife in Sri Lanka

At the micro level, genetic material in domesticated crop plants, trees, livestock, aquatic animals and small organisms constitutes essential biological diversity. It has been the basis of breeding programmes for continued improvement in yields, nutritional quality, flavour , durability and pest resistance Other plant and animal products gathered from wild or in cultivation or domestication such as medicinal plants, fruits and nuts, vegetables, fibre, leather, spices rattan and bamboo meet the daily need of many islanders as well as support village based industries. However only a fraction of the country’s plants and animals have been mobilized to support human survival. Around the world areas, natural area, zoological gardens, botanic gardens and other monuments to biological diversity have become increasingly important for recreation and relaxation as urban areas expand and grow, the variety of species provide rich scenic and recreational experiences that have become increasingly appreciated as the world becomes crowded. Wildlife as important as the environments that preserve these species play important roles such as providing diversity of food types and other useful products to humans, maintenance of the ecological processes such as nutrient recycling and forest regeneration.

With the dry floodplains being irrigated and lowlands subject to extensive deforestation combined with the loss of forest cover has led to to risk of this rich diversity being jeopardized. With the arrival of plantation crops and use of large areas for timber the situation has worsened. Other critical habitats such as coral reefs and wetlands are also threatened due to coastal erosion and effects of fishing. In addition to habitat destruction biological diversity suffers from selective exploitation of species, particularly plants. Many species once plentiful are now found in smaller numbers and some are considered to be threatened. Without quick action to conserve their habitats they will become seriously endangered, their genetic variety reduced, and their long term survival in doubt.

Marine Life

Being an island and blessed with thundering water falls and more than 100 rivers, the Aquatic Life in Sri Lanka is a real beholders pleasure. The amphibians and the reptiles account for the highest number of endemic species. Of the 107 species of fish found in the island, most have found a safe haven in the marshes and the rivers. With sea mining and coastal degradation with pollution threatens these volatile eco systems.

Coral reef presence in Sri Lanka
Coral reef presence in Sri Lanka

References:

  1. Abeywickrema B. A. et al., (1991.) Natural Resources of Sri Lanka: Conditions and Trends, Energy and Science Authority of Sri Lanka, Colombo, Sri Lanka.
  2. Department of Wildlife Conservation. (2018) retrieved from http://www.dwc.gov.lk/
  3. Rainforest Rescue International (2018) retrieved from http://www.rainforestrescuesrilanka.org/forests/
  4. Sri Lankan Ecosystems (2018). retrieved from
    http://www.terrestrial-biozones.net/Paleotropic_Ecosystems/Sri_Lanka_Ecosystems.html
  5. Biodiversity Clearing House Mechanism. (2018). http://lk.chm-cbd.net/