Forest Types in India
Vegetations are the immediate expression of climate of a region. There are various types of forests found in the Indian subcontinent. Basically, there are 6 major groups (or 5 major groups if both - Moist Tropical and Dry Tropical types are considered as one major group) namely, Moist Tropical, Dry Tropical, Montane Subtropical, Montane Temperate, Sub Alpine, and Alpine, further subdivided into 16 major types of forests. Evidently, India has a diverse range of forests: from the rainforest of Kerala in the south to the alpine pastures of Ladakh in the north, from the deserts of Rajasthan in the west to the evergreen forests in the northeast.Champion and Seth (1968) recognized sixteen types of forest which are listed below.
|The most prominent among them in order of their area are:
|I. Moist tropical
||II. Dry tropical|
|1||Wet evergreen: Dense Tall forests, entirely evergreen or nearly so||5||Dry evergreen: Hard leaved evergreen trees predominates with some deciduous emergent often dense but usually under 20 m high|
|2||Semi-evergreen: Domants includes deciduous species but evergreens predominants||6||Dry deciduous: Entirely deciduous or nearly so top canopy uneven rarely over 25 m high
|3||Moist deciduous: Dominants mainly deciduous but sub-dominants and lower story largely evergreen top canopy even and dense but 25m high||7||Thorn: Deciduous with low thorny trees and xerophytes predominant top canopy more or less broken, less than 10 m high|
|4||Littoral and swamp: Mainly evergreens of varying density and height but always associated predominantly with wetness|
|III. Montane subtropical
||IV. Montane temperate forests|
|8||Broad leaved: Broad-leaved largely evergreen high forests
||11||Wet: Evergreen without coniferous species|
|9||Pine: Pine associated predominates
||12||Moist: Evergreen forests mainly sclerophyllous oak and coniferous species|
|10||Dry evergreen: Low xerophytic forest and scrubs
||13||Dry: Coniferous forests with sparse xerophytic undergrowth|
|V. Alpine||VI. Subalpine
|14||Moist: Low but often dense scrub of evergreen species||16||Subalpine: Stunted deciduous or evergreen forests, usually close formation with or without confers
|15||Dry: Xerophytic scrub in open formation mostly of deciduous in nature|
In the 1980s, space satellites were deployed for remote sensing of real forest cover. The first satellite recorded forest coverage data for India became available in 1987. India thereafter switched to digital image and advanced satellites with 23 metres resolution and software processing of images to get more refined data on forest quantity and forest quality. India now assesses its forest distribution data biennially.
Standards were introduced to classify India's forests into the following categories:
Classification based on Predominant Vegetation and Climatic Regions
(This classification is given in the NCERT book, so it is important from the exam point of view.)
On the basis of certain common features such as predominant vegetation type and climatic regions, Indian forests can be divided into the following groups:
- Tropical Evergreen and Semi Evergreen forests
- Tropical Deciduous forests
- Tropical Thorn forests
- Montane forests
- Littoral and Swamp forests
Tropical Evergreen and Semi Evergreen Forests
Tropical evergreen forests are well stratified, with layers closer to the ground and are covered with shrubs and creepers, with short structured trees followed by tall variety of trees. In these forests, trees reach great heights up to 60 m or above. There is no definite time for trees to shed their leaves, flowering and fruition. As such these forests appear green all the year round.
These forests are found in the western slope of the Western Ghats, hills of the northeastern region and the Andaman and Nicobar Islands. They are found in warm and humid areas with an annual precipitation of over 200 cm and mean annual temperature above 22oC.
- Dominant Species:
Species found in these forests include rosewood, mahogany, aini, ebony, etc.
Semi Evergreen Forests
Such forests have a mixture of evergreen and moist deciduous trees. The undergrowing climbers provide an evergreen character to these forests.
The semi evergreen forests are found in the less rainy parts of these regions.
- Dominant Species:
Main species are white cedar, hollock and kail.
The British were aware of the economic value of the forests in India, hence, large scale exploitation of these forests was started. The structure of forests was also changed. The oak forests in Garhwal and Kumaon were replaced by pine (chirs) which was needed to lay railway lines. Forests were also cleared for introducing plantations of tea, rubber and coffee. The British also used timber for construction activities as it acts as an insulator of heat. The protectional use of forests was, thus, replaced by commercial use.
Tropical Deciduous Forests
They are also called the monsoon forests. These are the most widespread forests in India. 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.
Moist Deciduous Forests
The dominant species in these forests are mainly deciduous. The sub-dominants and lower story are largely evergreen having top canopy even and dense generally 25m high.
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 Himalayas, eastern slopes of the Western Ghats and Odisha.
- Dominant Species:
Teak, sal, shisham, hurra, mahua, amla, semul, kusum, and sandalwood etc. are the main species of these forests.
Dry Deciduous Forest
On the wetter margins, it has a transition to the moist deciduous, while on the drier margins to thorn forests.
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. In the western and southern part of Rajasthan, vegetation cover is very scanty due to low rainfall and overgrazing.
These forests cover vast areas of the country, where rainfall ranges between 70 -100 cm. These forests are found in rainier areas of the Peninsula and the plains of Uttar Pradesh and Bihar.
- Dominant Species:
Tendu, palas, amaltas, bel, khair, axlewood, etc. are the common trees of these forests.
Tropical Thorn Forests
In these forests, plants remain leafless for most part of the year and give an expression of scrub vegetation. These consist of a variety of grasses and shrubs.
Tropical thorn forests occur in the areas which receive rainfall less than 50 cm. It includes semi-arid areas of south west Punjab, Haryana, Rajasthan, Gujarat, Madhya Pradesh and Uttar Pradesh.
- Dominant Species:
Important species found are babool, ber, and wild date palm, khair, neem, khejri, palas, etc. Tussocky grass grows upto a height of 2 m as the undergrowth.
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.
Northern Mountain Forests
The Himalayan ranges show a succession of vegetation from the tropical to the tundra, which change in with the altitude. A brief survey of these attitudinal variation in the vegetation is given below.
- Altitude of 1,000-2,000 m: 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.
- Altitude of 1,500-1,750 m: 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.
- Altitude of 2,225-3,048 m: 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.
- Altitude of 3,000-4,000 m: 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.
Southern Mountain Forests
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. The temperate forests are called Sholas in the Nilgiris, Anaimalai and Palani hills.
These forests are found in three distinct areas of Peninsular India viz; the Western Ghats, the Vindhyas and the Nilgiris. In the Western Ghats, they are found especially in Kerala, Tamil Nadu and Karnataka. Such forests are also found in the Satpura and the Maikal ranges.
- Dominant Species:
Some of the trees of economic significance include, magnolia, laurel, cinchona and wattle.
Littoral and Swamp Forests
The littoral zone is the part of a sea, lake or river that is close to the shore. The types of forest developed in these areas are called littoral forests. These forests develop in the moderate temperature in the areas near lakes, beaches, etc.
Littoral and Swamp forests are also called wetland forests. They can be classified into the following types:
- Beach forests: Beach forests are ecosystems that can be found adjacent to beaches.
- Tidal forests: Popularly known as the Mangrove forests, these forests grow along the coastal region in the salt marshes, tidal creeks and estuaries. In India, the mangrove forests spread over 6,740 sq. km which is 7 percent of the world’s mangrove forests. They are highly developed in the Andaman and Nicobar Islands and the Sundarbans 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.
- Freshwater swamp forests: Also called as the flooded forests, these are the forests which are inundated with freshwater, either permanently or seasonally. They normally occur along the lower reaches of rivers and around freshwater lakes.
India has a rich variety of wetland habitats. About 70 percent of this comprises areas under paddy cultivation. The total area of wetland is 3.9 million hectares. Two sites — Chilika Lake (Odisha) and Keoladeo National Park (Bharatpur) are
protected as waterfowl habitats under the Convention of Wetlands of International Importance (Ramsar Convention).
The country’s wetlands have been grouped into eight categories depending on their regional presence (Scott, 1989):
- the reservoirs of the Deccan Plateau in the south together with the lagoons and other wetlands of the southern west coast;
- the vast saline expanses of Rajasthan, Gujarat and the Gulf of Kachchh;
- freshwater lakes and reservoirs from Gujarat eastwards through Rajasthan (Keoladeo National Park) and Madhya Pradesh;
- the delta wetlands and lagoons of India’s east coast (Chilika Lake);
- the freshwater marshes of the Gangetic Plain;
- the floodplains of the Brahmaputra; the marshes and swamps in the hills of northeast India and the Himalayan foothills;
- the lakes and rivers of the montane region of Kashmir and Ladakh; and
- 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, mud flats 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.
Most of the wetlands in India are directly or indirectly linked with major river systems such as the Ganges, Cauvery, Krishna, Godavari and Tapti. In India, out of an estimated 4.1 mha (excluding irrigated agricultural lands, rivers and streams) of wetlands, 1.5 mha are natural, while 2.6 mha are man-made. Wetlands in southern peninsular India are mostly man-made and are known as yeris (tanks). They are constructed in every village and provide water for various human needs, besides serving as nesting, feeding and breeding sites for a large variety of bird species.