Notes on Natural Vegetation of India; Minerals and Rocks

Natural Vegetation of India

“Natural Vegetation refers to a plant community that has been left undisturbed for a long time”

Tropical Evergreen and Semi Evergreen Forests

Tropical Evergreen

These forests are found in warm and humid areas of western slopes of Western Ghats, hills of North-Eastern region and Andaman & Nicobar Islands.
Annual precipitation – Over 200cm
Mean annual temperature – Above 220C
Species found – Rosewood, Mahogany, Aini, Ebony etc.
These forests are well stratified with short trees followed by tall trees.
There is no definite time for trees to shed their leaves, hence these forests appear green all the year round.

Semi Evergreen

These forests are found in less rainy of above-mentioned regions
They contain mixture of evergreen and moist deciduous trees.
Main species – White Cedar, Hollock and Kail

Tropical Deciduous Forests

These are also known as Monsoon forests and are the most widespread forests in India.
Annual rainfall – 70 to 200 cm
Mean annual temperature – 270C to 300C
On the basis of availability of water, these are divided into moist deciduous and dry deciduous forests

Moist Deciduous

Found in North-Eastern states along the foothills of Himalayas, Eastern slopes of Western Ghats and Odisha
Annual rainfall – 100 to 200cm
Mean annual temperature – 270C
Main species – Teak, Sal, Shisham, Mahua, Amla, Kusum and Sandalwood

Dry Deciduous

Found in wet areas of peninsula and plains of UP and Bihar
Annual rainfall – 70 to 100cm
Mean annual temperature – 300C
Main species – Tendu, Palas, Amaltas, Bel, Khair, Axlewood etc.
In western and southern part of Rajasthan, vegetation cover is minimal due to less rainfall.

Tropical Thorn Forests

Found in semi-arid areas of South-West Punjab, Haryana, Rajasthan, Gujarat, MP and UP
Annual rainfall – Less than 50cm
Mean annual temperature – 250C to 300C
These forests consist of variety of grasses and shrubs
Plants remain leafless for most part of year
Main species – Babool, Ber, Khair, Neem, Khejri etc

Montane Forests

In mountainous areas, decrease in temperature with increasing altitude leads to corresponding change in natural vegetation
Mountain forests are classified into Northern Mountain forests and Southern Mountain forests

Wet Temperate Forests

Found between a height of 1000 and 2000m along higher hills of Kerala and Tamil Nadu and Eastern region
Annual rainfall – 150 to 300 cm
Mean annual temperature – 110C to 140C
Main species – Indian chestnut, Oak, Hemlock etc.

Temperate forests

Found between a height of 1500 and 3000 m along southern slopes of Himalayas.
Annual rainfall – 150 to 250c
Mean annual temperature – 100C
Main species – Pine, Silver Fir, Spruce, Cedar etc.

Alpine forests

Found at high altitudes of more than 3600m above the sea level.
Annual rainfall below 100cm
Mean annual temperature – 50C to 100C
Main species – Silver firs, Pines, Junipers, Birches etc.
These forests are used for grazing by nomadic tribes like Gujjars and Bakarwals

Note – At higher altitudes, Lichens and Mosses are also found.

Littoral and Swamp Forests (Mangroves)

In India, Mangrove forests are spread over 6740km2 of area which is 7% of world’s mangrove forests
Found in Andaman and Nicobar Islands, Sunderbans of West Bengal, Deltas of Mahanadi, Krishna, Kaveri and Godavari
Annual rainfall – 100 to 150cm
Mean annual temperature – 220C
Main species – Palm, Coconut, Keora, Agar etc.

Forest Cover in India

As per National Forest Policy of India, 33% of the total geographical area should be covered under forests and trees.

As per 16th edition India State of Forests Report 2019, released by Forest Survey of India –

Total forest and tree cover is 24.56% of the total geographical area of the country
Total forest cover – 21.67% of the total geographical area of the country
Largest forest cover (Area Wise) – Madhya Pradesh
Largest forest cover (Percentage Wise) – Mizoram
Mangrove cover – 0.15% of the total geographical area (West Bengal has the highest percentage)
Forest cover in hilly districts – 40.30%
Forest cover in tribal districts – 37.54%
Maximum trees – Karnataka
Maximum shrubs – Arunachal Pradesh
Maximum herbs – Jammu and Kashmir
Gujarat has the largest area of wetlands

Forest Conservation

It is the practice of planting and maintaining forested areas for the benefit and sustainability of future generations.

Government of India came up with National Forest Policy of India in 1988 which emphasizes on sustainable forest management. The policy aimed –

To monitor forest cover and changes therein at the National, State and District levels.
To generate information on forest cover in different density classes and changes the rein.
To produce forest cover and other thematic maps derived from it for the whole country.
To provide a primary base layer for assessment of different parameters including growing stock, forest carbon etc.
To provide information for international reporting

Steps to Conserve Forests

National Mission for Green India – Aims at protecting, restoring and enhancing India’s diminishing forest cover.
CAMPA funds – To compensate the loss of forest area and to maintain the sustainability
National Afforestation Program – For ecological restoration of degraded forests
Forest conservation act 1980 – Deals with any matter related to conservation of forests

Social Forestry

It is defined as the management and protection of forests and afforestation of barren lands with the purpose of environmental, social and rural development. Three types of social forestry are –

Farm Forestry – Process under which farmers grow trees for commercial and non -commercial purposes on their farm lands.
Urban Forestry – It pertains to the raising and management of trees on public and privately owned lands in urban centres.
Rural Forestry – It lays emphasis on promotion of agro-forestry and community- forestry

Agro-Forestry – Raising of trees and agricultural crops on the same land.
Community Forestry – Raising of trees on public and community land such as roadside, schools, colleges etc.

Minerals and Rocks

The Earth is composed of various types of elements which are found in solid form in outer layer and molten form in the interior of the Earth.

About 98% of the total Earth’s crust is composed of 8 elements viz; oxygen, silicon, aluminium, iron, calcium, sodium, potassium and magnesium and the rest is constituted by hydrogen, phosphorus, titanium etc.

Source of Minerals

The basic source of all minerals is the hot magma in the interior of the earth.
When magma cools, crystals of minerals appear and solidify to form rocks.
Minerals such as coal, petroleum and natural gas are organic substances found in solid, liquid and gaseous form respectively.

Mineral composition of Earth

Mineral – Percentage

Oxygen – 47%
Silicon – 28%
Aluminium – 8%
Iron – 5%
Magnesium – 4%
Calcium – 2%
Potassium – 2%
Calcium – 2%
Others – 2%

Minerals in India

Petroleum [Assam, Gujarat and Maharashtra]

Digboi in Assam is the oldest oil region in India
Vasudhara was the first oil well in Ankleshwar

Coal [Jharkhand, Chhattisgarh, Odisha, Assam, Meghalaya, J&K and Nagaland]

Anthracite is the best quality of coal
Coal is also called “Black Gold”
Lignite is called “Brown Gold”

Iron ore [Odisha, Jharkhand, Andhra Pradesh, Chhattisgarh, Tamil Nadu and Karnataka] – India has the largest reserves of iron-ore in the world

Manganese [Odisha, Maharashtra, Karnataka, Andhra Pradesh, Jharkhand and Rajasthan] – India has the second largest reserves of manganese ore after Zimbabwe

Copper [Jharkhand, Rajasthan, Maharashtra, Karnataka, MP and Andhra Pradesh] – Copper is also extracted from Zinc in Rajasthan

Gold [Karnataka, Andhra Pradesh, Telangana and Tamil Nadu] – 99% of total gold production in India comes from Karnataka

Diamond [Madhya Pradesh] – The Kohinoor diamond was extracted from Golconda mines in Andhra Pradesh

Zinc [Rajasthan, Odisha and J&K] – Zawar mines in Rajasthan is top zinc producing mine

Uranium[Jharkhand] – Most important uranium mine of India is Jadugora mine

Tungsten [Rajasthan, Tamil Nadu and Karnataka] – Major tungsten reserve is in Degana, Rajasthan

Lead [Jharkhand and Rajasthan] – Largest lead reserves are found in Rajasthan

Tin [Chhattisgarh] – Bastar district of Chhattisgarh

Rocks

A rock is composed of one or more minerals. Rocks do not have definite composition of mineral constituents. Feldspar and quartz are the most common minerals found in rocks.

On the basis their mode of formation, rocks are categorized into 3 types –

Igneous rocks

These are formed out of magma and lava from the interior of the earth. Hence, they are known as primary rocks.
These are formed when magma cools and solidifies.
This process of cooling and solidification may happen either in the earth’s crust (known as intrusive rocks) or on the surface of earth (known as extrusive rocks)
Fossils are not found in igneous rocks.
These rocks are classified based on texture which depends on size and arrangement of grains of materials –
Very large grains – When molten material is cooled slowly at great depths
Small and smooth grains – When cooling occurs suddenly
Intermediate grains – When there are intermediate conditions of cooling
Examples – granite, gabbro, pegmatite, basalt, breccia, tuff etc.

Sedimentary Rocks

These are formed by the deposition, sedimentation and lithification of sediments over a long period of time.
Depending upon the mode of formation, these are classified into –
Mechanically formed – sandstone, limestone, conglomerate, shale etc.
Organically formed – geyserite, chalk, limestone, coal
Chemically formed – halite, potash etc.

Metamorphic Rocks

These rocks are formed from igneous and sedimentary rocks under the action of pressure, volume and temperature changes.
Metamorphism is a process by which already consolidated rocks undergo recyrstallisation and reorganization of materials within the rocks.
Examples – Marbles, quartzite, diamond, slate etc.
In the process of metamorphism, minerals are arranged in layers in some rocks. Such an arrangement is called foliation or lineation.
Sometime minerals are arranged into alternating thin to thick layers appearing in light and dark shades. Such a structure in metamorphic rocks is called banding and the rocks displaying banding are called banded rocks.