Classification of Vegetation –
Based on climatic conditions, forests are divided into categories. They are:
Tropical Evergreen Forests –
Tropical evergreen forests are found in the regions that receive annual precipitation of over 200 cm and mean annual temperature above 220C.
Tropical evergreen forests are found in the western slope of the Western Ghats, hills of the northeastern region, and the Andaman and Nicobar Islands.
In tropical evergreen forests, trees reach great heights, i.e., up to 60 m or even above. And, largely these trees do not have fixed time to shed their leaves.
Major examples of evergreen forests are rosewood, mahogany, aini, ebony, etc. Semi-evergreen Forests. Semi-evergreen forests are a mixture of evergreen and moist deciduous trees, found in the regions that receive less precipitation than the evergreen forests. Main species of semi-evergreen forests are white cedar, hillock, and kail.
Tropical Deciduous Forests –
Tropical Deciduous Forests are the most widespread forests of India and are popularly as Monsoon Forests. Tropical deciduous forests are found in the regions, which receive rainfall between 70 and 200 cm.
The moist deciduous forests are found in the regions, which record rainfall between 100 and 200 cm. The moist deciduous forests are found 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 the moist deciduous forests.
Dry deciduous forests are found in the regions that receive precipitation between 70 and 100 cm.
Tropical Thorn Forests –
Tropical thorn forests are found in the areas, which receive rainfall less than 50 cm.
Tropical thorn forests are found in the areas of south west Punjab, Haryana, Rajasthan, Gujarat, Madhya Pradesh, and Uttar Pradesh.
Babool, ber, and wild date palm, khair, neem, khejri, palas, etc. are the important species of tropical thorn forests.
Mountain Forests –
Mountain forests in India are normally classified into two types, i.e. the northern mountain forests and the southern mountain forests.
Deciduous forests are found in the foothills of the Himalayas. Temperate forests found between an altitude of 1,000 and 2,000 m.
In the higher hill ranges of northeastern India; for example, hilly areas of West Bengal and Uttaranchal, evergreen broad leaf trees such as oak and chestnut are predominant.
Chir, deodar, pine, etc. are the important species of temperate forests.
Between 3,000 and 4,000 m, Silver firs, junipers, pines, birch, and rhododendrons, etc. are found. However, at higher altitude, the tundra vegetation is found and major species are mosses and lichens. At a higher altitude, the southern mountain forests largely belong to the temperate type, which are locally known as ‘Sholas’ in the Nilgiris, Anaimalai,and Palani hills. Some of the trees of economic significance include magnolia, laurel, cinchona, and wattle.
Littoral and Swamp Forests.
India is rich in Littoral and Swamp Forests.
Chilika Lake (in Odisha) and Keoladeo National Park (in Bharatpur, Rajasthan) are protected as water- fowl habitats under the Convention of Wetlands of International Importance (i.e. Ramsar Convention). Mangrove grows along the coasts in the salt marshes, tidal creeks, mud flats, and estuaries; and, it has a number of salt-tolerant species of plants.
In India, the mangrove forests spread over 6,740 sq. km, which is 7% of the world’s mangrove forests. Mangroves are largely found in the Andaman and Nicobar Islands and the Sunderbans of West Bengal.
Soil Horizon is classified into three categories — Horizon A, Horizon B, and Horizon C; collectively known as Soil Profile (i.e. the arrangement of soil layers).
On the basis of genesis, color, composition, and location, the soils of India have been classified as:
Alluvial Soils –
Alluvial soils are widespread in the northern plains and the river valleys and cover about 40% of total area of India.
Alluvial soils are depositional soils, as transported and deposited by the rivers streams. Alluvial soils are normally rich in potash, but poor in phosphorous.
In the Upper and Middle Ganga plain, two different types of alluvial soils are found i.e. Khadar (it is the new alluvium and is deposited by floods annually) and Bhangar (it is a system of older alluvium, deposited away from the flood plains).
Black Soils –
Also popular as Regur Soil or the Black Cotton Soil, Black soil covers most of the Deccan Plateau; for example, black soil is found in parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, and Tamil Nadu.
Black soil is usually clayey, deep, and impermeable; therefore, it can retain the moisture for a very long time (very useful for the crops especially cotton). Black soil is rich in lime, iron, magnesia, alumina, and also potash. The color of the black soil varies from deep black to grey.
Red u0026amp; Yellow Soils –
Red soil develops on crystalline igneous rocks in the areas of low rainfall,especially, in the eastern and southern parts of the Deccan Plateau.
Red soil develops a reddish color because of a wide diffusion of iron in crystalline and metamorphic rocks. On the other hand, it develops yellow color when it occurs in a hydrated form.
Laterite Soils –
The laterite soils develop in areas of high temperature and high rainfall.
The laterite soils are commonly found in Karnataka, Kerala, Tamil Nadu, Madhya Pradesh, and the hilly areas of Odisha and Assam.
Laterite soils are the result of intense leaching due to tropical rains; because of rain, lime and silica are leached away, and soils become rich in iron oxide and aluminum.
Laterite soils however are poor in organic matter, nitrogen, phosphate, and calcium, but rich in iron oxide and potash.
Arid Soils –
Lower horizons of the arid soils are occupied by ‘kankar’ layers because of the increasing calcium content downwards.
Arid soils have poor content of humus and organic matter. Arid soils are typically developed in western Rajasthan.
Saline Soils –
Saline soils contain a larger proportion of sodium, potassium, and magnesium, and thus, they are infertile, and do not support vegetation. Because of the dry climate and poor drainage system, saline soil contains more salt.
Saline soils are normally found in arid and semi-arid regions, as well as in waterlogged and swampy areas. Deficient in nitrogen and calcium, saline soils are found in western Gujarat, deltas of the eastern coast, and in Sunderban areas of West Bengal.
Peaty Soils –
In the areas of heavy rainfall and high humidity, large quantity of dead organic matter accumulates and enrich humus and organic content that forms the peaty soils.
Peaty soils are normally heavy and black in color and widely found in the northern part of Bihar, southern part of Uttaranchal, and the coastal areas of West Bengal, Odisha, and Tamil Nadu.
Decline in soil fertility because of any reason (either natural or human induced) is known as soil degradation.
Land use record is maintained by the Land Revenue Department. The Survey of India is accountable for measuring geographical area of administrative units in India.
There is difference between the actual forest area and the forest area defined by the Government.
Land under settlements (i.e. rural and urban), infrastructure (i.e. roads, canals, industries, shops, etc.) are kept under the category of Non-Agricultural Land.
Barren hilly terrains, desert lands, ravines, etc. normally are not suitable for cultivation, hence, they are known as Barren and Wastelands.
The land owned by the village panchayat comes under ‘Common Property Resources’.
Any land, which is left fallow (uncultivated) for more than five years is categorized as Cultivable land. The land, which is left without cultivation for one or less than one agricultural year is known as Current Fallow. The physical extent of the land on which crops are sown and harvested is known as Net Sown Area.