As in any other part of the world, natural vegetation of India is also determined by climate, physiographic and soil factors. Based on factors of temperature, rainfall and topographic conditions, India has diverse vegetation patterns. Dense natural vegetation is found in North-Eastern region, Western Ghats and Andaman Nicobar. The Northern plain and North-Western Region supports very scanty vegetation and is under cultivation. The Deccan region is full of scrubs and mixed deciduous forests.
Natural vegetation of India can broadly be divided into the following groups:
- Tropical Evergreen Forests
- Tropical Deciduous Forests
- Thorn Forests
- Tidal Forests
- Himalayan Forests
1. Tropical Evergreen Forests
Trees in these forests remain green all the year round as the climate of the region is warm and wet throughout the year. The leaves of these trees do not fall in any particular season. Hence, they are evergreen. These forests are found in the areas having more than 200 cm of rainfall with a short dry season. The trees reach a height up to 60 meters or even more.
It has a dense and mixed vegetation of all kinds including trees, shrubs, climbers, creepers, epiphytes and ferns giving it a multilayered structure. Hence, their economic exploitation is not viable. The number of species of trees is very large in a small area. Rosewood, ebony, mahogany, rubber, jack wood and bamboo are the important species of trees found in Tropical Evergreen Forests.
In India, this type of vegetation is found in the areas of heavy rainfall in Western Ghats, upper parts of Assam and islands of Lakshadweep, Andaman and Nicobar. Hardwood from these forests is used for furniture, handicraft, etc. They prevent landslides and soil erosion.
2. Tropical Deciduous Forests
Trees in these forests shed their leaves once in a year. That is why they are called tropical deciduous forests. These are most widespread forests of India. These forests are found in the areas receiving annual rainfall between 75 to 200 cm. These forests are found in the entire country excluding some parts of Deccan Plateau, North-Eastern Region, Western Ghats and Eastern coast.
These forests have been subject to extensive clearance by man for the purpose of cultivation. Still some patches of natural vegetation are found along the foothills of Himalayas, hilly regions of peninsular and central part of the country. On the basis of the availability of rainfall these forests are further divided into moist deciduous and dry deciduous.
(a) The moist deciduous forests are found in the areas of rainfall between 100 to 200 cm. These are distributed mainly in the eastern parts of the country, North-eastern states along the foothills of Himalayas, Jharkhand, Odisha and Chhattisgarh, and eastern slopes of Western Ghats. Teak, Bamboo, Sal, Shisham, Sandalwood, Khair, Kusum, Arjun, Mahua, Jamun and Mulberry are the important species of trees found in these forests.
(b) The dry deciduous forests are spread in the areas receiving annual rainfall between 75 to 100 cm annually. These forests are found in the interior parts of the Peninsular plateau and the plains of Uttar Pradesh, Madhya Pradesh and Bihar. Tree species of these forest are Teak, Sal, Peepal, and Neem.
3. Thorn Forests
The areas with less than 75 cm of annual rainfall are characterised by the natural vegetation of thorny trees and bushes. Climate of this part is mainly dry with occasional wet period, so it does not support dense vegetation. They are mainly found in North-Western India, interior parts of the Peninsular India including semi arid areas of Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Uttar Pradesh, Haryana, Karnataka, Andhra Pradesh and Maharashtra.
Vegetation of these forests is widely distributed in the form of small trees and bushes with deep roots. The stems are succulent to conserve water. Leaves are mostly thick and small to minimise evaporation. Acacia, euphorbias, babul, cacti, khair, date and palms are common variety of trees in this type of vegetation.
4. Tidal Forests
These forests are found in tidal creeks and swamps influenced by the tides and wetland topography. These areas are characterised by mud, silt and water accumulated on the surface. Roots and branches of the trees are submerged under water for specific period of time. They are also called mangrove forests.
Mangroves are practically evergreen with thick leathery leaves. Such types of forests are found in the deltas of Sundarbans, Mahanadi, the Godavari, Krishna, Kaveri rivers and in the Andaman and Nicobar Islands. Mangrove or Sundari is the common tree in sunderbans while palm, coconut, keora, and agar are other important species of tidal forest.
These forests are located along the coasts. They provide protection against cyclones.
5. Himalayan Forest
These forests are mainly found in the mountainous region of the Himalayas. The decreasing in temperature and increasing in altitude lead to varied types of vegetation depending upon the factors like slope of the mountain and sun rays receiving side. The ecosystem is highly fragile. Himalayan forests have been exploited in many ways in recent decades.
Areas with relatively low altitude up to 1000 meters, warm climate and good amount of rainfall are characterised by dense vegetation cover. These areas look like tropical forest. Sal and Bamboo are main species in these areas. Between the elevation of 1000 to 2000 meters evergreen broad leave Oak and Chestnut are the common species found in these forests.
In eastern Himalayas the same elevation is occupied by sub tropical Pine forests. Chir is common species found in this part. Moist temperate forest in Himalayas are found between the elevation 1500 to 3500 meters which receives annual rainfall in the range of 100 to 250 cm. Oak, laurel, chestnut, cedar, Silver, Fir, spruce rhododendron and deodar are the main species found in this part of Himalayas. They have been widely exploited for their timber.
Alpine forest found in Himalayas at the height of between 3000 to 3800 m with large and extensive highland grassland and sparsely distributed pine, birch, sliver, fir and rhododendron trees.