Here are the solutions, questions, answers, and notes of chapter 8: Natural vegetation which is a part of social science class 9 syllabus of students studying under the Nagaland Board of School Education. However, these notes should be used only for references and additions/modifications should be made as per the requirements.
Introduction
The earth is a unique planet among all the planets. It is the only planet where life exists. The narrow zone where a variety of organisms exist on the planet is known as the biosphere. This chapter deals with natural vegetation, which is a form of life and means plants or trees that grow on their own without any form of human intervention.
Life on earth would be impossible without trees. They provide us with food, fuel etc. Plants and trees come in various shapes and sizes. Plants range from microscopic green plankton in the sea to gigantic coniferous trees so tall we cannot see their tops. Not every type of plants and trees grow in every part of the planet. What type of plant and trees grow in a particular area depends on the soil, relief, and drainage. Plants of a particular region or period are called flora.
In this chapter, you will learn in details about the different trees and plants and where it grows as well as what conditions are required for the growth.
Textual questions and answers
Choose the correct answer
1. The Bakarwal and Gujjar tribes graze their flock of sheep in:
(a) Tropical rainforests
(b) Tropical thorn forests and scrubs
(c) Temperate forests with grasslands
(d) None of the above
Answer: c. Temperate forests with grasslands
2. Given the commercially valuable trees in the forests, how can sustainable resource management practices be applied to ensure their long-term availability?
(a) Clear-cutting large sections of the forests at once
(b) Banning the harvest of all commercial tree species
(c) Implementing selective logging and reforestation programmes
(d) Encouraging unregulated logging to boost the economy
Answer: c. Implementing selective logging and reforestation programmes
3. Which are the most widespread forests in India?
(a) Tropical rainforests
(b) Tropical deciduous forests
(c) Tropical thorn forests
(d) Alpine and Tundra grasslands
Answer: b. Tropical deciduous forests
4. How many biosphere reserves are there in India?
(a) 14
(b) 15
(c) 16
(d) 18
Answer: d. 18
5. Sundarbans Bioreserve is located in which state?
(a) Assam
(b) West Bengal
(c) Meghalaya
(d) Tamil Nadu
Answer: b. West Bengal
6. There are two statements marked as Assertion (A) and Reason (R). Mark your answer as per the codes provided below.
Assertion (A): The Alpine grasslands are most frequented by Gujjars and Bakarwals who bring their sheep to graze here.
Reason (R): As one goes even higher, Tundra vegetation also includes lichens and mosses.
(a) Both (A) and (R) are true and (R) is the correct explanation of (A)
(b) Both (A) and (R) are true but (R) is not the correct explanation of (A)
(c) (A) is correct but (R) is wrong
(d) (A) is wrong but (R) is correct
Answer: b. Both (A) and (R) are true but (R) is not the correct explanation of (A)
7. Consider the statements given below and choose the correct answer.
Statement I: Afforestation is the best means to conserve forests.
Statement II: Overgrazing leads to destruction of forests.
(a) Statement (I) is correct and (II) is incorrect
(b) Statement (I) is incorrect and (II) correct
(c) Both (I) and (II) and incorrect
(d) Both (I) and (II) are correct
Answer: d. Both (I) and (II) are correct
Very short answer type questions
1. Define flora.
Answer: Plant life in general especially plants of a certain region, environment or period is called flora.
2. What is an ecosystem?
Answer: An ecosystem is a complex set of relationships among the living resources, habitats and residents of an area. It includes plants, trees, animals, fish, birds, microorganisms, water, soil, and people.
3. What is meant by ‘natural vegetation’?
Answer: Natural vegetation means any plants or trees that grow on their own or without any form of human intervention.
4. Which three factors determine vegetation types?
Answer: Three factors that determine vegetation types are temperature, heat, and precipitation.
5. Where are tropical rainforests found?
Answer: Tropical rainforests are found in the Western Ghats, the island groups of Lakshadweep, and the Andaman and Nicobar Island.
Short answer type questions
1. Write a brief note on thorn forests and scrubs.
Answer: Thorny trees and bushes comprise the thorn forests and scrubs of India. These forests are found mainly in the north-western part of India, in regions of less than 70 cm of rainfall, i.e. semi-arid areas of Gujarat, semi-arid areas of Rajasthan, semi-arid areas of Madhya Pradesh, Chhattisgarh, Uttar Pradesh, and Haryana. The main plant species of these forests are Cacti, Acacia, Palms, and Euphorbias.
2. What are tropical rainforests?
Answer: Tropical rainforests are only found in the rainy parts of India, i.e., the Western Ghats and the island groups of Lakshadweep, and the Andaman and Nicobar Island. These types of forests grow bushy in areas that receive more than 200 cm of rainfall and experience a short dry season. In these forests, trees grow to the height of up to 60 meters or even above. Ebony, mahogany, rubber, rosewood, and cinchona are some of the commercially important trees of this forest.
3. What are the characteristics of moist deciduous forests?
Answer: These forests are located in areas that receive 200 cm to 100 cm rainfall. The main locations of these forests are eastern slopes of Western Ghats, West Odisha, Chhattisgarh, Jharkhand, North Eastern states and the Himalayan Foothills. Teak is the most important species of these forests. Other commercially important species are khair, shisham, sal, bamboo, kusum, arjun, mulberry, and sandalwood..
4. What are the features of dry deciduous forests?
Answer: These forests are located in areas that receive 100 cm to 70 cm rainfall. Most of these forests are in the rainier parts of the peninsular plateau, plains of Bihar, and plains of Uttar Pradesh. These forests have open stretches of teak, sal, peepal, neem, etc.
Long answer type questions
1. Why have biosphere reserves been set up?
Answer: Biosphere reserves have been set up because of the following reasons:
I. Conserving and maintaining diversity and integrity of the natural heritage in its full form, i.e., physical environment, the flora, and the fauna.
II. Promoting researches on ecological conservation and other aspects of environmental preservation.
III. Providing facilities for education, awareness and training.
IV. Last but not least, to preserve the genetic variety in the crucial natural ecosystem settings.
2. What is the difference between Alpine and Tundra vegetation and temperate forest with grasslands?
Answer: Temperate forests and grasslands gradually decrease at 3600 metres height. At 3600 metres, above sea level the Alpine vegetation flourishes. The growth of trees becomes stunted as they near the snowline. Alpine vegetation mainly includes birches, pines, junipers, and silver fir.
On the other hand, tropical deciduous forests are found in the Himalayan foothills. Then comes the wet temperate type of forests at a height of 1000 to 2000 metres. Temperate forests at the height of 1500 to 3000 metres are full of coniferous trees that include cedar, spruce, pine, deodar, and silver fir.
3. Explain the ways to conserve forests.
Answer: The ways in which forests can be conserved are:
a. We should plant more trees, i.e., afforestation. All communities should be made aware of the importance of forests. This will prevent the reckless cutting of trees.
b. People living near forests should be made aware of the danger of forest fires and how they cause depletion of forest resources.
c. New cities have led to the destruction of forest areas. Therefore, urban growth should be properly planned so that the minimum area under forests is maintained.
d. Overgrazing by animals leads to the destruction of forests. There should be restrictions and control on grazing by domestic animals.
4. Explain the characteristic features of Tropical Evergreen forests.
Answer: The characteristics of tropical evergreen forests are:
I. Tropical rainforests are only found in the rainy parts of India, i.e., the Western Ghats and the island groups of Lakshadweep, and the Andaman and Nicobar Islands.
II. These types of forests grow bushy in areas that receive more than 200 cm of rainfall and experience a short dry season.
III. In these forests, trees grow to the height of up to 60 metres or even above.
IV. As the region is warm and wet throughout the year a variety of lush green vegetation is abundant here.
V. There is no particular time for the trees to shed their leaves so these forests are green in appearance the whole year.
VI. Ebony, mahogany, rubber, rosewood, and cinchona are some of the commercially important trees of this forest.
Extra MCQs
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Extra questions and answers
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Chapter 8 question no 4 short
The three factors that determine vegetation types are:
i)soil
ii)drainage
iii) relief