TROPICAL EVERGREEN FORESTS

TROPICAL EVERGREEN FORESTS

Types of vegetation

The following major types of vegetation may be identified in our country (Figure 5.3).

Figure 5.3: Natural Vegetation

       i)  Tropical Evergreen Forests

      ii)  Tropical Deciduous Forests

     iii)  Tropical Thorn Forests and Scrubs

     iv)   Montane Forests

      v)   Mangrove Forests

Tropical Evergreen Forests

These forests are restricted to heavy rainfall areas of the Western Ghats and the island groups of Lakshadweep, Andaman and Nicobar, upper parts of Assam and Tamil Nadu coast. They are at their best in areas having more than 200 cm of rainfall with a short dry season. The trees reach great heights up to 60 metres or even above. Since the 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. There is no definite time for trees to shed their leaves. As such, these forests appear green all the year round.

Figure 5.2: Tropical Evergreen Forest

Some of the commercially important trees of this forest are ebony, mahogany, rosewood, rubber and cinchona.

The common animals found in these forests are elephant, monkey, lemur and deer. One- horned rhinoceroses 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.

Activity :

Study the given map for the forest cover and try to find the reasons as to why certain states have more forest area as compared to others?

Source: This topic is taken from NCERT TEXTBOOK

TROPICAL DECIDUOUS FORESTS

TROPICAL DECIDUOUS FORESTS

These are the most widespread forests of India. They are 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. The former is found in areas receiving rainfall between 200 and 100 cm. These forests exist, therefore, mostly in the eastern part of the country — northeastern states, along the foothills of the Himalayas, Jharkhand, West Odisha 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 and mulberry are other commercially important species.

Figure 5.4: Tropical Deciduous Forest

The dry deciduous forests are found in areas having rainfall between 100 cm and 70 cm. 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 neem grow. A large part of this region has been cleared for cultivation and some parts are used for grazing.

In these forests, the common animals found are lion, tiger, pig, deer and elephant. A huge variety of birds, lizards, snakes and tortoises are also found here.

Source: This topic is taken from NCERT TEXTBOOK

THE THORN FORESTS AND SCRUBS

THE THORN FORESTS AND SCRUBS

In regions with less than 70 cm of rainfall, the natural vegetation consists of thorny trees and bushes. This type of vegetation is 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 minimise evaporation. These forests give way to thorn forests and scrubs in arid areas.

In these forests, the common animals are rats, mice, rabbits, fox, wolf, tiger, lion, wild ass, horses and camels.

Figure 5.5: Thorn Forests and Scrubs

Source: This topic is taken from NCERT TEXTBOOK

MONTANE FORESTS

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. These forests 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 the 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. However, they get progressively stunted as they approach the snow-line. Ultimately, through shrubs and scrubs, they merge into the Alpine grasslands. These are used extensively for grazing by nomadic tribes, like the Gujjars and the Bakarwals. At higher altitudes, mosses and lichens form part of tundra vegetation.

The 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.

Figure 5.6: Montane Forests

Source: This topic is taken from NCERT TEXTBOOK

MANGROVE FORESTS

MANGROVE FORESTS

The mangrove tidal forests are found in the areas of coasts influenced by tides. Mud and silt get accumutated on such coasts. Dense mangroves are the common varieties with roots of the plants submerged underwater. The deltas of the Ganga, the Mahanadi, the Krishna, the Godavari and the Kaveri are covered by such vegetation. In the Ganga- Brahmaputra delta, sundari trees are found, which provide durable hard timber. Palm, coconut, keora, agar, etc., 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.

Figure 5.7: Mangrove Forests

Medicinal plants

India is known for its herbs and spices from ancient times. Some 2,000 plants have been described in Ayurveda and at least 500 are in regular use. The World Conservation Union’s Red List has named 352 medicinal plants of which 52 are critically threatened and 49 endangered. The commonly used plants in India are:

Sarpagandha: Used to treat blood pressure; it is found only in India.

Jamun: The juice from ripe fruit is used to prepare vinegar, which is carminative and diuretic, and has digestive properties. The powder of the seed is used for controlling diabetes.

Arjun: The fresh juice of leaves is a cure for earache. It is also used to regulate blood pressure.

Babool: Leaves are used as a cure for eyesores. Its gum is used as a tonic.

Neem: Has high antibiotic and antibacterial properties.

Tulsi: Is used to cure cough and cold.

Kachnar: Is used to cure asthma and ulcers. The buds and roots are good for digestive problems.

Activity :

Can you identify the type of forest shown in this picture? Identify some trees in it. What type of similarity/ dissimilarity you notice in this type of vegetation from the one found in your region?

Let’s find out

1.  What will happen if plants and animals disappear from the earth’s surface?

2.  Can human beings survive under such a situation?

3.  Why is biodiversity necessary and why should it be conserved?

4.  Do the following two statements mean the same? Justify your answer.

Source: This topic is taken from NCERT TEXTBOOK