20BSCY201 Environmental Science and Engineering

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20BSCY201
ENVIRONMENTAL SCIENCE AND ENGINEERING
UNIT No: III NATURAL RESOURCES
3.1 Forest Resources

(Study material)
Version: 1.00
20BSCY20
Unit -III NATURAL RESOURCES
INTRODUCTION
A resource is a source or supply from which a benefit is produced and that has some utility. Resources can
broadly be classified upon their availability — they are classified into renewable and non-renewable
resources. An item becomes a resource with time and developing technology.
Natural resources are materials from the Earth that are used to support life and meet people's needs. Any
natural substance that humans use can be considered a natural resource. Oil, coal, natural gas, metals, stone
and sand are natural resources.
Natural resources can be classified as potential, actual, reserve, or stock resources based on their stage of
development. Natural resources are either renewable or non-renewable depending on whether or not they
replenish naturally.
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3.1 Forest resources
3.1.1 Introduction to forest resources

Forests are renewable natural resources capable of providing several major and minor forest products and
contribute substantially to economic development.
Forest cover: Includes all lands having trees more than one hectare in an area with tree canopy density of
more than 10%, irrespective of ownership, legal status of the land and species composition of trees.
Forest canopy cover, also known as canopy coverage or crown cover, is defined as the proportion of the
forest covered by the vertical projection of the tree crowns.
There are broadly five categories of forests in India. They are named as Tropical evergreen forests, Tropical
deciduous forests, Tropical thorn forests, Montane (mountain) forests, and Swamp (mangrove) forests.
TYPES OF FORESTS IN INDIA
Very Dense Forest: All lands with tree canopy density of 70% and above. The relative composition of forest
cover under this category is 3.02%
Moderately Dense Forest: All lands with tree canopy density of 40% and more but less than 70%. Forest
cover under this category is 9.39%
Open Forest: All lands with tree canopy density of 10% and more but less than 40 %. Forest cover of 9.26%
falls under this category.
Scrub Forest: Lands with canopy density less than 10%. Geographical area under this category is 1.41%.
Non-forest: Lands not included in any of the above classes (includes water). Geographical area under the
non-forest category is 76.92%.
3.1.2 Uses of Forests
Commercial uses:
❖ Man depends heavily on a larger number of plant and animal products from
forests for his daily needs.
❖ The chief product that forests supply is wood, which is used as fuel, raw material
for various industries as pulp, paper, newsprint, board, timber for furniture items,
other uses as in packing articles, matches, sports goods etc.
❖ Indian forests also supply minor products like gums, resins, dyes, tannins, fibers,
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etc.
❖ Many of the plants are utilized in preparing medicines and drugs; Total worth of
which is estimated to be more than $300 billion per year.
❖ Many forest lands are used for mining, agriculture, grazing, and recreation
and for development of dams.
Ecological uses:
The ecological services provided by our forests may be summed up as follows:

✔ Production of Oxygen: The main greenhouse gas carbon dioxide is absorbed by the forests
as a raw material for photosynthesis. Thus forest canopy acts as a sink for carbon dioxide
thereby reducing the problem of global warming caused by greenhouse gas CO2
✔ Wildlife habitat: Forests are the homes of millions of wild animals and plants. About 7
million species are found in the tropical forests alone.
✔ Regulation of hydrological Cycle: Forested watersheds act like giant sponges, absorbing
the rainfall, slowing down the runoff. They control climate through transpiration of water and
seed clouding.
✔ Soil Conservation: Forests bind the soil particles tightly in their roots and prevent soil
erosion. They also act as wind breakers.
✔ Pollution moderators: Forests can absorb many toxic gases and can help in keeping the air
pure and in preventing noise pollution.
3.1.3 Over Exploitation of Forests
✔ Man depends heavily on forests for food, medicine, shelter, wood and fuel.
✔ With growing civilization the demands for raw material like timber, pulp, minerals,
fuel wood etc. shot up resulting in large scale logging, mining, road-building and
clearing of forests.
✔ Our forests contribute substantially to the national economy.
✔ The international timber trade alone is worth over US $ 40 billion per year.
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✔ The devasting effects of deforestation in India include soil, water and wind erosion,
estimated to cost over 16,400 crores every year.
3.1.3.1 Deforestation
▪ Deforestation means destruction of forests.

▪ The total forests area of the world in 1900 was estimated to be 7,000 million hectares which
was reduced to 2890 million ha in 1975 fell down to just 2,300 million ha by 2000.
▪ Deforestation rate is relatively less in temperature countries, but it is very alarming in tropical
countries.
▪ Deforestation is a continuous process in India where about 1.3 hectares of forest land has
been lost.
▪ The per capita availability of forest in India is 0.08 hectares per person which is much lower
than the world average of 0.8 hectares.
▪ The presence of waste land is a sign of deforestation in India.
Causes of Deforestation:
Major causes of deforestation are listed below:

a) Development projects
b) Shifting cultivation
c) Fuel requirements
d) Construction of dams
e) Growing
food needs
Consequences of deforestation:
Some of the effects of deforestation are listed below:

a) Effect on climate
1. Global warming
2. Less rainfall
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3. Hot climate and others.
b) Effect on biodiversity
1. Loss of medicinal plants.
2. Loss of timber, fuel wood and others.
c) Effect on resources
1. Loss of land resource
2. Loss of soil fertility
3. Soil erosion
4. Drastic changes in biogeochemical cycles
d) Effect on economy
1. Increase in medicinal values
2. Demand of industrial products and others
e) Effect on food
1. Loss of fruit production
2. Loss of root based foods
Case Studies
Desertification in hilly regions of the Himalayas:
∙ Desertification in Himalayas, involving clearance of natural

forests and plantation of monocultures like Pinus roxburghi,
Eucalyptus camaldulensis etc., have upset the ecosystem by
changing various soil and biological properties.
∙ The area is invaded by exotic weeds. These areas are not able to
recover and are losing their fertility.
Disappearing Tea gardens in Chhota Nagpur:

Following the destruction of forest rainfall declined in Chhota Nagpur to such an extent that
tea-gardens also disappeared from the region.
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Waning rainfall in Udhagamandalam:
∙ The rainfall pattern was found to fluctuate with wooded land area in
the hills. When the Nilgiri mountains had luxuriant forest cover
annual rainfall used to be much higher.

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I

ENVIRONMENTAL SCIENCE AND ENGINEERING

UNIT No: III NATURAL RESOURCES

3.1 Forest Resources

Unit -III NATURAL RESOURCES

3.1 Forest resources

3.1.1 Introduction to forest resources

3.1.2 Uses of Forests

forests for his daily needs.

other uses as in packing articles, matches, sports goods etc.

which is estimated to be more than $300 billion per year.

and for development of dams.

The ecological services provided by our forests may be summed up as follows:

3.1.3 Over Exploitation of Forests

✔ Our forests contribute substantially to the national economy.

estimated to cost over 16,400 crores every year.

▪ Deforestation means destruction of forests.

Major causes of deforestation are listed below:

Some of the effects of deforestation are listed below:

3. Hot climate and others.

Desertification in hilly regions of the Himalayas:

∙ Desertification in Himalayas, involving clearance of natural

Disappearing Tea gardens in Chhota Nagpur:

Waning rainfall in Udhagamandalam:

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