The vegetation that grows according to physiography, temperature and amount of rainfall at different places is known as the natural vegetation of the place, the natural vegetation of India is mainly divided into the following types basing upon the variations in rainfall.
Evergreen forests are found on the western part of the Western Ghats at a height of 1370 meters, in the Tara Region of the foot-Himalayas, the hilly areas of the north-eastern India and the Andaman and Nicobar Islands as the annual average rainfall is more than 200 cms in those areas. These forests are dense owing to heavy rainfall and high temperature.
The trees of these forests don't shed their leaves in summer. So these are known as 'evergreen forests'. Valuable trees like ebony, mehogany, sandal, rubber etc. grow in these forests.
These forests grow in such regions where the rainfall is between 100 to 200 cms. The trees of these forests shed their leaves in summer owing to limited rainfall. So these are known as deciduous forests. They are not so dense as the evergreen forests. Valuable and useful trees like sal, piasal, asan, kurum, sishu, teak, bandhan, gambhari, kusum, kangada, khaira, mahua. Sandal etc. grow there. Besides, bamboo grows abundantly in these forests. These forests are found in the northeastern region of India, the eastern part of the Western Ghats, the Eastern Ghats, Chhotnagpur Plateau and the hilly areas of Orissa and Madhya Pradesh.
Tropical Thorn Forests:
This type of forest is found in Rajasthan, Punjab, Uttar Pradesh, Madhya Pradesh and at some places of south India. The areas under this type of forest where the rainfall is between 50 to 100 cms. Have grass-lands and trees like Shimili, Babul, Acasia etc. here and there.
Plants like Munja and Sabai grass also grow in this grassland. These are used in paper industry in making paper. Owing to demographic pressure (i.e. population pressure) in India, these forest lands are gradually being coverted to arable lands (agricultural lands). In north-western part of Punjab and Rajasthan where the annual average rainfall is less than 50 cms. Thorny bushes and cactus type of plants grow.
Tidal forests are seen in some low lands of the coastal belt of India and in the deltas of river-mouths as those areas are flooded by tidal waves with brined waters of the sea. Such type of forests on the marshy lands and deltaic low lands in the east coast are known as the mangrove forests or Hintal forests.
The Sundarbans in the Gang etic delta are the largest mangrove forests. It is named as the Sundarbans as the Sundari trees grow abundantly in this area. Besides this, mangroves for sets are also seen in the deltas of the Mahanadi, the Krishna and the Godavari rivers. Such types of for sets are not found in the west coast as it is narrow and the coastal sea is comparatively deep.
According to the distribution of altitude and temperature almost all types of forests are seen in the Himalayan ranges. Because of warm and wet climate evergreen forests are seen in the foot hills, pine type of coniferous forests in the cooler high altitudes and still higher up grasslands are also seen. The peaks of mountains remain covered with snow all the year round; so no vegetation is possible there. When ice melts in summer, mosses and lichens grow in the lower parts of the high peaks. The coniferous forests found between the altitudes of 2750 meters to 3600 meters of the Himalayas, are known as the Alpine forests. Trees like silver fir, juniper, birch etc. grow here.
The forest wealth of India is diminishing very fast causing various problems in the natural environment. So a forestation is being adopted in order to preserve our forests.