Natural Vegetation – Introduction
Natural vegetation are gifts of nature. They grow naturally. They follow the climatic variables. Due to a variety of climates, a wide range of natural vegetation grows in India. Types of natural vegetation vary according to climate, soil and altitude. A study of the distribution of the forests in India reveals that there is a marked relation between the rainfall zones and their belts of natural vegetation.
Types of Natural Vegetation
The following are the principal types of natural vegetation in India: (1) Tropical Evergreen Rain Forests, (2) Deciduous or Monsoon Type of Forests, (3) Dry Deciduous Forests and Scrubs, (4) Semi Desert and Desert Vegetation, (5) Tidal or Mangrove Forests and (6) Mountain Forests.
1. Tropical Evergreen Rain Forests: These forests grow in areas where rainfall is more than 200 cm. They are mainly found on the slopes of the Western Ghats and the north-eastern regions of Arunachal Pradesh, Meghalaya, Assam, Nagaland, the Tarai areas of the Himalayas and the Andaman groups of Islands. The trees in these forests never shed their leaves all at a time in any part of the year. Under humid tropical condition, sub-soil water never dries up completely. So that during the dry-season, trees in these forests do not shed their leaves due to lack of sub-soil water supply. The trees in these belts have dense growth. Important varieties of trees are sisthu, chaplash, rosewood, mahogany, bamboos, garjan and sandal wood.
2. Deciduous or Monsoon type of Forests: These forests are found in areas where the rainfall is between 100 cm and 200 cm. These forests grow on the lower slope of the Himalayas, Assam, West Bengal, Bihar, Jharkhand, Orissa, Madhya Pradesh, Chhattishgarh, Maharashtra, Karnataka and the adjoining regions. The trees of these forests shed their leaves during dry-winter and dry-summer. The main trees are teak, sal, sandal wood, deodar, bluegum, ebony, sisam, jack-fruit, mahua, palash, arjun, khair and bamboo. Teak and sal are valuable trees. These forests supply valuable timber.
3. Dry Deciduous Forests and Scrubs: These forests grow in areas where the rainfall is between 50 cm and 100 cm. These are found in areas of central Deccan plateau, south-east of Rajasthan, Punjab, Haryana and parts of Uttar Pradesh and Madhya Pradesh. Dwarf deciduous trees and long-grasses grow in these regions. Most of these areas are used for agriculture.
4. Semi-deserts and Deserts vegetation: These types of vegetation grow in areas where rainfall is less than 50 cm mostly thorny bushes, acacia, babul and sand binding grasses (graminoids) are found in this vegetation zone. The Indian wild date, known as “Khejur” is common in these deserts. These plants grow far apart from each other. They have long roots and thick fleshy stems in which they store water to survive during the long drought. These vegetation are found in Rajasthan and parts of Gujarat, Punjab and Karnataka. The leaves of short trees, shrubs, herbs and grass that are found in Thar desert have got high nutritional values.
5. Tidal or Mangrove Forests: These forests grow along the coast and on the edges of the deltas, e.g. the deltas of the Ganga, Mahanadi, Godavari, Krishna and Kaveri. Tides plays an important role in formation of mud and silt along these coastal mangrove forests. They are called ‘Tidal Forests’ because their dense growth depends upon tidal water which submerges the deltaic lands during high tides. They are also known as Littoral Forests. In West Bengal these forests are known as ‘Sundarbans.’
The ‘sundri’ is most significant tree in these forests. The other notable trees of these forests are hogla, garan, gewa, golpata, pasur, etc. These forests supply timber and fire wood. Palm and coconut trees adorn the coastal strip.
6. Mountain Forests: Mountain forests vary considerably according to altitude with varying rainfall and temperature along the slopes of mountain:
- On the foothills of the Himalayas up to a height of 1500 meters, evergreen trees, such as, sal, teak, bamboo and cane grow abundantly.
- On higher slope between 1,500 meters to 3,500 meters, temperate conifer trees, such as, pine, fir, oak, maple, deodar, laurel, spruce and ceder grow.
At the higher altitude of the Himalayas, rhododendrons and junipers are found. Beyond these vegetation-belts, alpine grasslands appear up to snowfield.