* Sri Lanka can be divided into 5 major climatic zones based on temperature and annual rainfall.
1. _Water Zone
2. _Kandara Zone_
3. Intermediate zone_
4. _Dry zones
5. _The Arid Zone_
*Forest*
About 23% of Sri Lanka's land area is currently covered by forest. 18% of these are in the dry zone, 2.1% in the low-lying wet zone and 1.1% in the hilly region. There are four main types of forests in Sri Lanka.
1. Tropical rain forest
2. Mountain forests
3. Dry mixed evergreen forests
4. Thorns and scrub
* Tropical Rainforest *
Annual rainfall in these areas is 2500 - 5000mm.
- Temperature 27'C.
- Biodiversity is high.
- There are very tall stems.
- The base of the stems is wide. That is, the chiropractic feature is prominent.
- There are evergreen plants.
- The leaves are broad.
- Plant shows a stratification. That is,
- Naked layers
- Sub-canopy layer
- Shrub Layer
- There is a ground layer.
- The canopy layer is continuous so the forest gets less light.
Therefore, the ground layer is weakly increased.
- Mass flux is prominent. That is, the stems are flowering.
- A prominent feature is the sheathing of the leaf terminal.
- Ascending plants abound.
- Epilogues abound.
- The soil is acidic.
- Mineral nutrients in the soil are low. That is, the soil is less fertile.
Most of the mineral nutrients are in the biomass
The soil becomes nutrient-deficient because of the excess of the soil.
* Leading plants in the nil layer *
- Thief - Dipterocarpus zeylanicus
- Given - Shorea congestiflora
- Leading plants of the canopy layer
- Na - Mesua
- Malaboda - Mysristica dactyloids
- Leading plants of the sub-canopy layer
- Land - Dillenia retusa
- Badulla - Semecarpns
- Leading plants in the shrub layer
- Reed - Ochlandra
- Meincylon
- Ascending plants
- Cane - Calamus rotang
- Venivale - Cascinium fenestratum
* Rain Forest Spreads *
_Singharaja Forest_
_ Kanneliya, Dediyagala, Nakiyadeniya Complex_
_Eratta_
_Ginīmalē_
* Is a tropical mountain forest
Spread over 1200m in the southwestern part of the central highlands.
Rainfall from the southwest and northeast monsoons results in scattered rainfall throughout the year.
In the morning and evening the fog is high and the light is reduced.
There are no trees that are as tall as tropical rain forests. Trees up to 10 m tall.
The center of the leaves of the trees is flat. There are no stems.
The forest is dark because there is a canopy layer. Because of this the undergrowth is not very good. There are many species of oak tree ferns here.
Moss and lichens abound on trees. These absorb network vapors from the air.
* Canopy Tree Plant *
- Kina - Callophyllum
- Dumb - Syzygium
- Usnea babata lichen is common here.
Mountainous areas
_Samanala Mountain_
_Pidurutalagala_ _Agrabopattalawa_
_Kikiḷiyāmāna_
_Haggala_
* Tropical dry mixed evergreen forests *
- Spread over a large area of Sri Lanka's land area.
- Spread in the North and East of Sri Lanka.
- Annual rainfall is between 1250 - 1900mm. Scattered throughout the year
- No rainfall. There is a drought period between May and September.
- Most of the rain comes in November - January. North
It receives rain from long monsoons.
- Average temperature is around 30'C.
- There are evergreen and deciduous plants in the forest.
- During the drought some leaves fall off.
- There are no very tall trees as lowland wet forests.
- The bark of the trees is very rough.
- The leaves of the trees are small and rough.
- The trunk is not straight. It has knots. There is no obvious femininity. There are small trees and shrubs beneath the canopy of tall trees.
Aspiration plants are common.
* Leading Plants *
1.Paloo - Manilkara
2.Wire - Drypetes
3.Colombo - Diospyros ebenum
4.Milla - Vitex
5.Halmilla - Berrya
