Natural Vegetation is that part of plant life which grows in wild without direct or indirect help of man, and which easily adapts to the constraints of natural environment in size, structure and requirements.
Classification of Vegetation Types
Depending upon the climate soil, relief and structure, Indian forests can be classified into following categories.
- Tropical Evergreen Forests
- Tropical Deciduous or Monsoon Forests
- Tropical Dry Forests
- Arid Forests
- Delta Forests
- Mountainous Forests
1. Tropical Evergreen Forests
These forests are found in hot and humid areas of India. The average annual rainfall in these areas is above 200 cms and the relative humidity is more than 70%. The average temperature is in the vicinity of 24’C. These areas are characterised by tall trees whose height varies from 45 to 60 metres and dense forests due to high heat and high humidity. Different trees germinate, grow and wither at different times enabling the entire vegetation look as evergreen forests. The important trees of these forests are rubber, mahogany, ebony, coconut, canes, palms, bamboos, lianas, ferns, iron-wood. Due to thick growth, the sun’s rays do not reach the surface of the earth and there is darkness below the trees. Under these circumstances, the trees rise high competing with one another for sun-light. These forests are spread over 4.6 million hectares in Andaman Nicobar Islands, Assam, Meghalaya, Nagaland, Manipur, Mizoram, Tripura, West Bengal and on the western slopes of the Western Ghats. They are hard wood forests and are not very important economically.
2. Tropical Deciduous or Monsoon Forests
These forests are found in areas receiving 100 to 200 cms of annual rainfall. Monsoon forests grow over the Sahyadris (Western Ghats) the north-eastern parts of the Peninsula, middle and lower Ganga valley, and along the foothills of the Himalayas in the Shiwaliks, the bhabar and the tarai. Sal, teak, shisham, sandalwood, khair, etc. are important trees. These trees provide useful wood and are economically very important. They shed their leaves in the beginning of summer season in the face of water shortage and are called deciduous forests. They are 30 to 45 metres tall and cover about 20% of our forest area.
3. Tropical Dry Forests
Areas receiving 50 cms to 100 cms of annual rainfall are covered by tropical dry forests. These areas cover large parts of Maharashtra, Andhra Pradesh, Telangana Karnataka, Punjab, Haryana and Tamil Nadu, northern and western parts of Madhya Pradesh, eastern part of Rajasthan and southern part of Uttar Pradesh. Neem, shisham, babul, pipal, mango are the main trees of these forests. These trees shed their leaves with the advance of summer season. They are less dense an d small in size than the trees of monsoon forests. Their normal height is 6 to 9 metres. Their roots are thick and long so that they can use the underground water in the best possible manner. They have thick bark to avoid undue evaporation. Most of these forests have been cleared for cultivation. Presently they cover just 5.2 million hectares of land.
4. Arid Forest
These forests are found in areas receiving less than 50 cms of annual rainfall. These areas include Rajasthan and adjoining parts of south-west Punjab, south-west Haryana and some parts of Gujarat. This vegetation includes small size kikar, babul and some thorny bushes and shrubs. They have small leaves, thick bark and long, thick roots which enable them to face the dry climatic conditions. Their wood is generally used as fuel.
5. Delta or Tidal Forests
Tidal areas and the delta region abound in a special type of vegetation known as the forest. Sundari tree is abundantly grown there. Hence, they have assumed the name Sundari forests. Mangrove is another famous species of trees of the tidal forests. Sundar Vana of the Ganga delta, deltas of the Mahanadi, the Godavari, the Krishna and the Cauvery and the Andaman and Nicobar Islands are areas where tidal forests are largely grown.
6. Mountainous Forests
As their name indicates, these forests are found in the mountain areas of India. Geographically they can be divided into northern, i.e., Himalayan forests and southern, i.e., Peninsular forests.
(a) Northern or Himalayan Forests
These forests are found on the southern slopes of the Himalayan ranges. In their altitude, the Himalayan ranges show a succession of vegetation from the tropical to the Alpine.
The following brief account justifies it:
At the foothills, are belts of deciduous types. The wet temperate type is a belt of high and dense forests to the east of 88’E longitude between 1,000 metre to 2,000 metre altitude. They cover mostly the hill ranges of north-east India and the Himalayan parts of West Bengal, Bihar and Uttarakhand. The main trees are oaks, chestnuts and sal. Pine forests are well-developed between 1,500 metres to 1,750 metres. Higher parts of this zone are covered with temperate grasslands in the main ranges as well as in the Shillong (Meghalaya) Plateau.
Between 2,000 metres to 3,000 metres elevation, the southern slopes of the Himalayas are covered with moist temperate forests. Broad-leaved evergreen trees of oak, laurels and chestnuts are in plenty. Upper parts of this zone are Similarly, the chinar and the walnut are important trees of the Kashmir Valley. At many places, there are temperate grasslands.
Above 3,000 metres elevation, there is transition to Alpine forests and pastures. Fairly dense forests of silver fires, junipers, pines, birches and rhodendrons are found between 3,000 meters 4,000 meters altitude. But they get progressively stunted and gnarled as they approach them snowline. Alpine pastures, with stunted conifers below and snow-fields above, occur at altitudes between 2,250 and 2,750 m.’these covering the higher slopes almost below the permanent snow cover in ranges like the Pir Panjal. There is no vegetation above the snowline.
(b) Vegetation of Peninsular Hills
The vegetation of the Peninsular hills is characterised by rolling downs interspersed with stunted rain forests, shrubs, masses and ferns. Eucalyptus now-a-days covers large slopes of hills of the Peninsula. is type of vegetation covers the Nilgiris, the Annamalai and Palani hills, the Western Ghats, the Satpura, the Maikal and the Abu hills.