Module 55. Soils, Forests and Natural Vegetation of India

India, a land of vast geographical diversity, possesses a remarkable variety of soils, forests, and natural vegetation shaped by its climate, relief, and geological formations. The interplay of monsoons, topography, and human activity has produced distinct ecological zones across the subcontinent. Understanding these natural resources is vital for environmental management, agriculture, and biodiversity conservation.

Major Soil Types in India

India’s soils exhibit immense diversity due to differences in parent material, climatic conditions, and relief features. The Indian Council of Agricultural Research (ICAR) classifies soils into eight major types.

1. Alluvial Soils: Found in the Indo-Gangetic-Brahmaputra plains and coastal areas, alluvial soils are among the most fertile. Formed by the deposition of silt and sediments brought by rivers, they are rich in potash and lime but often deficient in nitrogen and humus. Crops like rice, wheat, sugarcane, and pulses thrive here.
2. Black Soils (Regur Soils): Predominantly found in the Deccan Trap region covering Maharashtra, Madhya Pradesh, Gujarat, and parts of Andhra Pradesh, black soils originate from basaltic rocks. They contain high amounts of iron, lime, aluminium, and magnesium carbonates. Their capacity to retain moisture makes them ideal for cotton cultivation, earning them the name black cotton soils.
3. Red and Yellow Soils: These soils develop in areas of low rainfall on crystalline igneous rocks, notably in Tamil Nadu, Karnataka, Odisha, and Jharkhand. Their reddish colour results from the presence of iron oxides. They are less fertile but can support millets, pulses, and groundnuts with appropriate irrigation and fertilisation.
4. Laterite Soils: Found in areas of high temperature and heavy rainfall such as Kerala, Karnataka, and Meghalaya, laterite soils are rich in iron and aluminium but poor in nitrogen and organic matter. These soils are suitable for crops like tea, coffee, cashew, and rubber under proper management.
5. Arid or Desert Soils: Present in Rajasthan and parts of Gujarat, arid soils are sandy, saline, and alkaline, with poor humus content. With irrigation facilities such as the Indira Gandhi Canal, these soils have been rendered productive for growing wheat and mustard.
6. Mountain Soils: Developed on the slopes of the Himalayas, mountain soils vary with altitude and climate. They are rich in humus and support horticultural crops like apples, plums, and apricots.
7. Saline and Alkaline Soils: Occurring mainly in arid and semi-arid regions, these soils contain excessive salts of sodium, potassium, and magnesium, which hinder plant growth. Reclamation through gypsum treatment and improved drainage is often necessary.
8. Peaty and Marshy Soils: Found in humid regions such as parts of Kerala, West Bengal, and Tamil Nadu, these soils are rich in organic matter but acidic in nature. They are suitable for rice and jute cultivation.

Forest Types and Distribution

India’s forests, covering about 21.7% of its total geographical area (as per the Forest Survey of India, 2023), are classified on the basis of temperature, rainfall, and altitude.

1. Tropical Evergreen Forests: Found in regions of heavy rainfall exceeding 200 cm, such as the Western Ghats, North-Eastern states, and the Andaman and Nicobar Islands. These forests remain green throughout the year and contain valuable timber species like mahogany, ebony, and rosewood.
2. Tropical Deciduous Forests: Also known as monsoon forests, they are the most widespread in India. Divided into moist and dry deciduous types, they are found in states such as Madhya Pradesh, Odisha, and Jharkhand. Teak, sal, and sandalwood are the dominant species.
3. Tropical Thorn Forests and Scrubs: Occurring in arid areas of Rajasthan, Haryana, and Gujarat where rainfall is less than 75 cm, these forests contain xerophytic vegetation such as acacia, babool, and cactus.
4. Montane Forests: Found in the Himalayan ranges, these forests vary by altitude. The lower slopes have tropical deciduous forests, the middle zones contain temperate forests with oak and pine, while higher altitudes have alpine vegetation such as fir and juniper.
5. Mangrove Forests: Occurring in coastal deltas and estuaries such as the Sunderbans, Mahanadi, and Godavari, mangrove forests are adapted to saline conditions. Rhizophora and Avicennia are common species, and the Sunderbans are noted for the Royal Bengal Tiger.

Natural Vegetation and Its Relation to Climate

Natural vegetation in India corresponds closely to climatic zones. The diversity ranges from tropical evergreen forests in the south to alpine vegetation in the north.

• Tropical Region: Characterised by dense, evergreen vegetation due to heavy rainfall and high humidity.
• Subtropical Region: Features deciduous and mixed forests adapting to seasonal rainfall.
• Temperate Region: Contains coniferous trees such as pine and deodar, reflecting cooler temperatures.
• Alpine Zone: Composed of mosses and lichens, found near snowlines at high altitudes.

Rainfall is the key determinant of vegetation type. Areas with over 200 cm of rainfall support evergreen forests, while those receiving less than 50 cm sustain thorny shrubs and grasses.

Significance and Conservation

Soils, forests, and natural vegetation form the ecological foundation of India’s economy and biodiversity. Forests regulate climate, prevent soil erosion, and sustain wildlife. Soils determine agricultural productivity and food security.
However, deforestation, soil erosion, overgrazing, and urban expansion have degraded these natural resources. The Government of India has implemented several measures such as the National Forest Policy (1988), National Afforestation Programme, and the Soil Health Card Scheme to promote conservation and sustainable use.
Afforestation, controlled grazing, terrace farming, and adoption of organic farming are crucial for maintaining soil fertility. The expansion of protected areas like national parks, wildlife sanctuaries, and biosphere reserves ensures biodiversity conservation and ecological balance.