Thursday, 18 February 2016

NATURAL VEGETATION


 NATURAL VEGETATION 
• It refers to a plant community which has grown naturally without human aid and has been left undisturbed by humans for a long time termed as a virgin vegetation. 
• cultivated crops and fruits, orchards form part of vegetation
but not natural vegetation. 
• The
virgin vegetation, which are purely Indian are known as endemic or indigenous species but those which have come from outside India are termed as exotic plants. 
• The term
flora is used to denote plants of a particular region or period. 
• the species of animals are referred to as
fauna. 
• The sandy soils of the desert support cactus and thorny bushes while wet, marshy, deltaic soils support mangroves and deltaic vegetation.
• Why are the southern slopes in Himalayan region covered with thick vegetation cover as compared to northern slopes of the same hills? 
• Answer-The growth of vegetation depends upon the amount of sunlight and rainfall received.
• The southern slopes of the Himalaya receives more rain due to south west monsoon winds which travel west along the southern slops.
•The northern slopes do not receive any such rainfall. 
• All the plants and animals in an area are interdependent and interrelated to each other in their physical environment forming an ecosystem.

 TYPES OF VEGETATION 

• The following major types of vegetation may be identified in our country 
• Tropical Ever green Forests 
• Tropical Deciduous Forests 
• Tropical Thorn Forests and Scrubs 
• Montane Forests 
• Mangrove Forests

Tropical Evergreen Forests

• restricted to heavy rainfall 
• best in areas having more than
200 cm of rainfall with a short dry season. 
• trees reach great heights up to
60 metres or even above. 
• region
is warm and wet throughout the year.
• It has a luxuriant vegetation of all kinds – trees, shrubs, and creepers giving it a multilayered structure.
no definite time for trees to shed their leaves. 
• appear
green all the year round.
•Some of the commercially important trees of this forest are ebony, mahogany, rosewood, rubber and cinchona.
• common animals found in these forests are elephants, monkey, lemur and deer. 
• The one horned rhinoceros are found in the jungles of Assam and West Bengal. 
• Besides these animals plenty of birds, bats, sloth, scorpions and snails are also found in these jungles.

Tropical Deciduous Forests:


• most widespread forests of India. 
• also called the
monsoon forests and spread over the region receiving rainfall between 200 cm and 70 cm. 
• Trees of this forest-type
shed their leaves for about six to eight weeks in dry summer. 
• On the basis of the availability of water, these forests are further divided into moist and dry deciduous.

moist deciduous:

• It found in areas receiving rainfall between 200 and 100 cm. 
• Exist mostly in the
eastern part of the country – northeastern states, along the foothills of the Himalayas, Jharkhand, W est Orissa and Chhattisgarh, and on the eastern slopes of the Western Ghats. 
Teak is the most dominant species of this forest. Bamboos, sal, shisham, sandalwood, khair , kusum, arjun, mulberry are other commercially important species. 

dry deciduous:

• The dry deciduous forests are found in areas having rainfall between 100 cm and 70cm. 
• These forests are found in the rainier parts of the
peninsular plateau and the plains of Bihar and Uttar Pradesh. 
• There are open stretches in which
Teak, Sal, Peepal, and Neemgrow. 
• A large part of this region has been cleared for cultivation and some parts are used for grazing. 
• common animals found are
lion, tiger , pig, deer and elephant. 
• variety of birds, lizards, snakes, and tortoises are also found here.


The Thorn Forests and Scrubs :

• In regions with less than 70 cm of rainfall, the natural vegetation consists of thorny trees and bushes. 
• found in the north-western part of the country including
semi-arid areas of Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Uttar Pradesh and Haryana.
Acacias, palms, euphorbias and cacti are the main plant species. 
• Trees are
scattered and have long roots penetrating deep into the soil in order to get moisture. 
• The stems are
succulent to conserve water. 
• Leaves are
mostly thick and small to minimize evaporation. 
• give way to thorn forests and scrubs in arid areas. 
• common animals are
rats, mice, rabbits, fox, wolf, tiger, lion, wild ass, horses and camels.

Montane Forests :

• In mountainous areas, the decrease in temperature with increasing altitude leads to the corresponding change in natural vegetation. 
• As such, there is a succession of natural vegetation belts in the same order as we see from the tropical to the tundra region. 
• The wet
temperate type of forests are found between a height of 1000 and 2000 metres. 
• Evergreen broad-leaf trees such as oaks and chestnuts predominate. 
• Between
1500 and 3000 metres, temperate forests containing coniferous trees like pine, deodar, silver fir, spruce and cedar, are found. 
• cover mostly the
southern slopes of the Himalayas, places having high altitude in southern and north-east India. 
• At
higher elevations, temperate grasslands are common. 
• At high altitudes, generally
more than 3,600 metres above sea-level, temperate forests and grasslands give way to the Alpine vegetation. 
Silver fir, junipers, pines and birches are the common trees of these forests. 
• get progressively stunted as they approach the snow-line. 
• used extensively for grazing by nomadic tribes like the Gujjars and the Bakarwals. 
• At higher altitudes, mosses and lichens form part of tundra vegetation. 
• common animals found in these forests are Kashmir stag, spotted dear , wild sheep, jack rabbit, Tibetan antelope, yak, snow leopard, squirrels, Shaggy horn wild ibex, bear and rare red panda, sheep and goats with thick hair.







Mangrove Forests

• found in the areas of coasts influenced by tides. 
• Mud and silt get accumulated on such coasts. 
• Dense mangroves are the common varieties with roots of the plants submerged under water . 
• The deltas of
the Ganga, the Mahanadi, the Krishana, the Godavari and the Kaveri are covered by such vegetation. 
• In the Ganga Brahamaputra delta, sundari trees are found, which provide durable hard timber. 
• Palm, coconut, keora, agar, also grow in some parts of the delta. 
Royal Bengal Tiger is the famous animal in these forests. 
• Turtles, crocodiles, gharials and snakes are also found in these forests.












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