NATURAL VEGETATION OF INDIA
- Natural vegetation refers to a plant in the community that has been left undisturbed over a long time, so as to allow its individual species to adjust themselves to climate and soil conditions as fully as possible.
- Natural vegetation is the primaeval plant cover unaffected by man either directly or indirectly.
- India is a land of a great variety of natural vegetation. Himalayan heights are marked with temperate vegetation; the Western Ghats and the Andaman Nicobar Islands have tropical rain forests, the deltaic regions have tropical forests and mangroves; the desert and semi-desert areas of Rajasthan are known for cactii, a wide variety of bushes and thorny vegetation.
- Depending upon the variations in the climate and the soil, the vegetation of India changes from one region to another.
Factors Affecting Vegetation
- The geographical factors which influence natural vegetation include Climate, Soil, Topogrphy.
- The main climatic factors are rainfall and temperature.
- Generally speaking, rainfall is more important than temperature except for the Himalayas.
- On the basis of certain common features such as predominant vegetation type and climatic regions, Indian forests can be divided into the following groups:
- TYPES OF FORESTS
Moist Tropical Forests
- 1. Tropical Wet Evergreen
- 2. Tropical Semi-Evergreen forests
- 3. Tropical moist Deciduous
- 4. Littoral and Swamp
Dry Tropical Forest
- 5. Tropical Dry Evergreen
- 6. Tropical Dry Deciduous
- 7. Tropical Thorn
Montane subTropical Forest
- 8. Sub tropical broad-leaved hill
- 9. Subtropical moist hill
- 10. Subtropical dry evergreen
Montane Temperate Forests
- 11. Montane We Temperate
- 12. Himalayan Moist Temperate
- 13. Himalayan Dry Temperate
Alpine Forests
- 14. Sub Alpine
- 15Moist Alpine
- Dry Alpine Scrub
Moist Tropical Forests
- 1. Tropical Wet Evergreen
- 2. Tropical Semi-Evergreen forests
- 3. Tropical moist Deciduous
- 4. Littoral and Swamp
1. Tropical Wet Evergreen
- These are typical rain forest which grows in those areas where the annual rainfall exceeds 250cm.
- The annual temperature is about 25-27 degree celsius.
- The average annual humidity exceeds 77 per cent and the dry season is distinctly short.
- Due to the high heat and high humidity, the tree of these forests does not shed their leaves annually.
- These are lofty, very dense multilayered forest with mesophytic evergreen.
- The tree often reaches 45 metres in height, individual trees exceed 60 metres.
- The entire morphology looks like a green carpet when viewed from above, the sunlight cannot reach the ground and owe to deep shade, the undergrowth is formed mainly of the tangled mass of canes, bamboos, ferns, climber,
- True evergreen forest is found along the western side of the Western Ghat (between 500-1370 metres above sea level) south of the Mumbai, in the strip running from northeast to southwest direction across Arunachal Pradesh, upper Assam, Nagaland, Manipur, Mizoram and Tripura up to a height of 1070 metres and in the Andaman and Nicobar Island.
2. Tropical Semi-Evergreen forests
- Bordering area of the tropical wet evergreen forest, are comparatively drier areas of the tropical semi-evergreen forest
- The annual rainfall is 200-250 cm, the mean annual temperature varies from 24- 27 degree celsius and relative humidity is about 75 per cent.
- These forces are found on the Western coast, Assam, lower slopes of the Eastern Himalayas, Orissa and Andamans.
- These forests represent a transition from wet evergreen to deciduous forest.
- Species: Aini, Semul, Gutel, Rosewood, Mesua.
3. Tropical moist Deciduous
- These forests are found in areas of moderate rainfall of 100 to 200 cm per annum, mean annual temperature of about 27-degree Celsius and the average annual relative humidity of 60 to 75 per cent.
- The area includes a belt running along the western Ghats surrounding the belt of evergreen forests both on the western and eastern slopes, a strip along with the shiwalik range including terai and bhabar from 77degree east and to 88 degrees East, Manipur, Mizoram, hills of eastern Madhya Pradesh and Chhattisgarh, Chota Nagpur plateau, Most of Orrisa part of West Bengal and in the Andaman Nicobar island.
- The important species found in these forests are teak, sal, padauk, laurel, rosewood, bamboo.
- It is comparatively easy to exploit these forest due to their high degree of gregariousness.
- Littoral and Swamp Forests
- These forests occur in and around the delts, estuaries and creeks prone to tidal influences and such are also known as delta or tidal forests.
Tropical Deciduous Forests
- These are the most widespread forests in India. They are also called the monsoon forests. They spread over regions which receive rainfall between 70-200 cm. On the basis of the availability of water, these forests are further divided into moist and dry deciduous.
- The moist deciduous forests are more pronounced in the regions which record rainfall between 100-200 cm.
- These forests are found in the northeastern states along the foothills of the Himalayas, eastern slopes of the Western Ghats and Odisha. Teak, sal, shisham, hurra, mahua, amla, semul, kusum, and sandalwood etc. are the main species of these forests.
- Dry deciduous forest covers vast areas of the country, where rainfall ranges between 70 -100 cm. On the wetter margins, it has a transition to the moist deciduous, while on the drier margins to thorn forests.
- These forests are found in rainier areas of the Peninsula and the plains of Uttar Pradesh and Bihar. In the higher rainfall regions of the Peninsular plateau and the northern Indian plain, these forests have a parkland landscape with open stretches in which teak and other trees interspersed with patches of grass are common. As the dry season begins, the trees shed their leaves completely and the forest appears like a vast grassland with naked trees all around.
- Tendu, palas, amaltas, bel, khair, axlewood, etc. are the common trees of these forests. In the western and southern part of Rajasthan, vegetation cover is very scanty due to low rainfall and overgrazing.
Tropical Thorn Forests
- Tropical thorn forests occur in the areas which receive rainfall less than 50 cm.
- These consist of a variety of grasses and shrubs.
- It includes semi-arid areas of south-west Punjab, Haryana, Rajasthan, Gujarat, Madhya Pradesh and Uttar Pradesh. In these forests, plants remain leafless for the most part of the year and give an expression of scrub vegetation.
- Important species found are babool, ber, and wild date palm, khair, neem, khejri, palas, etc. Tussocky grass grows up to a height of 2 m as the undergrowth.
Montane Forests
- In mountainous areas, the decrease in temperature with increasing altitude leads to a corresponding change in natural vegetation. Mountain forests can be classified into two types, the northern mountain forests and the southern mountain forests.
- The Himalayan ranges show a succession of vegetation from the tropical to the tundra, which changes in with the altitude.
- Deciduous forests are found in the foothills of the Himalayas.
- It is succeeded by the wet temperate type of forests between an altitude of 1,000-2,000 m.
- In the higher hill ranges of northeastern India, hilly areas of West Bengal and Uttaranchal, evergreen broadleaf trees such as oak and chestnut are predominant.
- Between 1,500-1,750 m, pine forests are also well-developed in this zone, with Chir Pine as a very useful commercial tree.
- Deodar, a highly valued endemic species grows mainly in the western part of the Himalayan range. Deodar is a durable wood mainly used in construction activity.
- Similarly, the chinar and the walnut, which sustain the famous Kashmir handicrafts, belong to this zone. Blue pine and spruce appear at altitudes of 2,225-3,048 m. At many places in this zone, temperate grasslands are also found. But in the higher reaches, there is a transition to Alpine forests and pastures. Silver firs, junipers, pines, birch and rhododendrons, etc. occur between 3,000-4,000 m. However, these pastures are used extensively for transhumance by tribes like the Gujjars, the Bakarwals, the Bhotiyas and the Gaddis.
- The southern slopes of the Himalayas carry a thicker vegetation cover because of relatively higher precipitation than the drier north-facing slopes. At higher altitudes, mosses and lichens form part of the tundra vegetation.
- The southern mountain forests include the forests found in three distinct areas of Peninsular India viz; the Western Ghats, the Vindhyas and the Nilgiris. As they are closer to the tropics, and only 1,500 m above the sea level, vegetation is temperate in the higher regions, and subtropical on the lower regions of the Western Ghats, especially in Kerala, Tamil Nadu and Karnataka. The temperate forests are called Sholas in the Nilgiris, Anaimalai and Palani hills. Some of the other trees of this forest of economic significance include magnolia, laurel, cinchona and wattle. Such forests are also found in the Satpura and the Maikal ranges.
Littoral and Swamp Forests
- India has a rich variety of wetland habitats. About 70 per cent of this comprises areas under paddy cultivation. The total area of wetland is 3.9 million hectares. Two sites — Chilika Lake (Odisha), Loktak Lake (Manipur) and Keoladeo National Park (Bharatpur) are protected as water-fowl habitats under the Convention of Wetlands of International Importance (Ramsar Convention).
- The country’s wetlands have been grouped into eight categories, viz.
- (i) the reservoirs of the Deccan Plateau in the south together with the lagoons and other wetlands of the south-west coast.
- (ii) the vast saline expanses of Rajasthan, Gujarat and the Gulf of Kachchh.
- (iii) freshwater lakes and reservoirs from Gujarat eastwards through Rajasthan (Keoladeo National Park) and Madhya Pradesh.
- (iv) the delta wetlands and lagoons of India’s east coast (Chilika Lake).
- (v) the freshwater marshes of the Gangetic Plain.
- (vi) the floodplains of the Brahmaputra; the marshes and swamps in the hills of northeast India and the Himalayan foothills.
- (vii) the lakes and rivers of the montane region of Kashmir and Ladakh.
- (viii) the mangrove forest and other wetlands of the island arcs of the Andaman and Nicobar Islands.
- Mangroves grow along the coasts in the salt marshes, tidal creeks, mudflats and estuaries. They consist of a number of salt-tolerant species of plants.
- Crisscrossed by creeks of stagnant water and tidal flows, these forests give shelter to a wide variety of birds.
- In India, the mangrove forests spread over 6,740 sq. km which is 7 per cent of the world’s mangrove forests.
- They are highly developed in the Andaman and Nicobar Islands and the Sunderbans of West Bengal. Other areas of significance are the Mahanadi, the Godavari and the Krishna deltas. These forests too, are being encroached upon, and hence, need conservation.
