(Sample Material) UPSC Mains GS Online Coaching : Paper 1 - "Distribution of Key Natural Resources Across the World"

Sample Material of Our IAS Mains GS Online Coaching Programme

Subject: General Studies (Paper 1 - Indian Heritage and Culture, History & Geography of the World & Society)

Topic: Distribution of Key Natural Resources Across the World

NATURAL VEGETATION AND WILDLIFE

FACTORS AFFECTING VEGETATION

The geographical factors which influence natural vegetation include climate, soil and topography. The main climatic factors are rainfall and temperature. Generally speaking, rainfall is more important than temperature except in the Himalayas. The seasonal rainfall regime, the length of dry season and its relation to the march of temperature, are also important. The amount of annual rainfall has a great bearing on the type of vegetation. Areas receiving 200 cm or more rainfall per annum have stands of evergreen rain forests while monsoon deciduous forests dominate in areas with rainfall between 100 and 200 cm. In areas having 50 to 100 cm rainfall there are drier deciduous or tropical savana grading into open thorny scrub while those with less than 50 cm rainfall have only dry thorny scrub and low open bush merging into semi desert. In higher altitudes of the Himalayas and the hills of the Peninsula at elevation of more than 900 metre above sea level, temperature plays a more important role.

As the temperature falls with altitude in the Himalayan region the vegetal cover changes from tropical to sub­tropical, temperate and finally alpine. Changes in soil conditions have given birth to different types of vegetation in different parts of the country. Mangrove forests, swamp forests, and beach and sandy coastal forests are some of the outstanding examples of influence of soil on natural vegetation. Topography in the narrow sense is responsible for certain minor types e.g. alpine flora, tidal forests, etc.

CLASSIFICATION OF NATURAL VEGETATION

A great variety of vegetation is found in different parts of India due to unequal distribution of rainfall and temperature as well as their seasonal variation, besides varied edaphic and biotic conditions. A generalised classification of Indian forests is, therefore, a difficult job. Various systematic classifications have been made by a number of botanists and ecologists. H.G. Champion (1936) distinguished 116 types of vegetation in India, some with further sub-divisions. Champion’s classification has been much simplified by G.S.Puri( 1960),Legris (1963), Champion and S.K. Seth (1968) and S.S. Negi (1990). Based on the suggestions of these scholars India’s vegetation can be divided into 5 main types and 16 sub-types as per details given below :

A. Moist Tropical Forests

1. Tropical Wet Evergreen
2. Tropical Semi-Evergreen
3. Tropical Moist Deciduous4. Littoral and Swamp

B. Dry Tropical Forest

5. Tropical Dry Evergreen
6. Tropical Dry Deciduous
7. Tropical Thorn

C. Montane Sub-tropical Forests

8. Sub-tropical broad leaved hill
9. Sub-tropical moist hill (pine)
10. Sub-tropical dry evergreen

D. Montane Temperate Forests

11. Montane Wet Temperate
12. Himalayan Moist Temperate
13. Himalayan Dry Temperate

E. Alpine Forests

14. Sub-Alpine
15. Moist Alpine scrub
16. Dry Alpine scrub

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