Natural vegetation of Sri Lanka

The trees, plants and creepers that grow in any place without the intervention of man is called Natural vegetation. The climatic differences bring about a diverse variety of plant and animal life. Natural vegetation is helpful to man and other living things. It depends mainly on topography, soil and climate.

              Tropical wet forests 

• Distributed in the low country and mid country wetzones.
• Present coverage of this forest is only 8% which is the   Sinharaja forest considered as a world Heritage forest.
• Bio-diversity is a special feature of these forests.
• Trees are of varying heights.
• There are layers of other plants below the tall trees.
• Trees of economic value are found such as Hora, Keena, Badidel, Godapara, Nadun are a few examples.
• The average rainfall is over 2000 mm.

 

Sinharaja forest 

            Dry mixed ever green forests

• Distributed extensively in the dry zone. 
• As the leaves drop from some trees it is called dry mixed.
• Average annual rainfall is between 1250mm- 2000mm .
• There is a long drought period from May- August and there is excessive evaporation and less rainfall.
•  The average height of a tree is between 15-20 metres, there is no under growth, bushes grow to height of 2-3 metres.
• Trees of economic value are- Satin wood, Halmilla, Hulanhik, Palu and Milla.
• The animals found here are elephants, wild boar, deer,etc.

Moist montane forest                                                                                                       

• Found in areas of over 1200 metres in elevation.
• Average annual rainfall is over 2000mm.
• Temperature is about 20°c - 24°c
• Found in the regions such as Knuckles and Pidurutalagala ranges, Adam's peak and Horton plains.
• As these forests are being cleared for tea and potato cultivation the land extent has gradually reduced.
• The height of trees is about 8-10 metres.
• Trees of economic value are Keena, Dhamba, Walsapu 
• Plenty of orchids, moss and lichens are found on trees.

                  Grasslands

• Patana grassland can be classified into two according to the elevation and locations
• Montane dry zone patanas are found is Uva basin, Knuckles range. Average rainfall is about 1250_1900mm. Mana variety is found in plenty.
• Wet zone patanas are found in areas above 1400 metres of elevation. Mainly found in Horton plains, Moon plains, Seethaeliya, Ambewela and Kandapola.
• Illuk grasslands are found in plenty in Bibile, Lunugala and Ampara regions. Trees such as Aralu, Villu, Nelli grow here.
• Low rainfall, availability of a thin layer of soil and the exposure to winds are factors which contribute to the growth of grasslands.

 Horton plains

                                                     

               Semi- Arid wood lands

• Found in the north - western and south- eastern regions.
• Average annual rainfall is 1000mm-1250 mm, and average temperature of 27°c 
• Receives rainfall from the North-East monsoon.
• Plants are adapted to resist long drought periods of about 6 months. Leaves are needle-leafed and scanty.
• Trees such as plau, weera and Plants such as eraminiya, cactus, Karamba are found in plenty.

                 Mangroves

• Found in plenty in places such as Jaffna, Mullaitivu, Trincomalee, Negombo, Batticaloa and Puttalam.
• Specially adapted to the coastal areas.
• Spread its roots above the water-prop roots, stilt roots and pneumataphores.
• Trees such as Kirilla, Kaduru, Kadol are found in plenty.
• Trees are useful for the survival of human beings. But due to human activities the vegetation has been destroyed.

Reasons for the destruction of forests in Sri Lanka

• Destruction by insects and pests
• Storms and cyclones
• Unlimited felling of trees for construction activities
• Illicit felling of trees
• Setting fire for chena cultivation, hunting