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.
I. Choose the correct answer.
1.ln which state is Simlipal biosphere reserve located?
Answer: a. Odisha
2. The Bakarwal and Gujjar tribes graze their flock sheep in :
Answer: b. Tropical thorn forests and scrubs
3. Tropical Rainforests are not found in which region of India?
Answer: d. Thar desert
4. Which are the most widespread forests in India?
Answer: b. Tropical deciduous forests
5. Cacti, acacia, palms and euphorbias are the main plant species of which type of vegetation?
Answer: d. Alpine and Tundra grasslands
6. Temperate forests at the height of 1500 to 3000 metres are full of coniferous trees that include
Answer: d. all of these
7. How many biosphere reserves are there in India?
Answer: d. 18
8. Sundarbans Bioreserve is located in which state?
Answer: b. West Bengal
II. 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.
7. What type of plants are found in Temperate Forests with Grasslands?
Answer: Types of plants found in Temperate Forests with Grasslands are Cedar, Spruce, Pine, Deodar, and Silver fir.
8. At what heights are Alpine forests found?
Answer: At more than 3600 meters height Alpine forests found.
III. 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.
5. Why has India a rich heritage of flora and fauna?
Answer: India’s flora ranges from those types that are found in the tropics to those found in the Arctic region. This variation in vegetation is due to the country’s different relief, temperature, and rainfall conditions. Most of the areas in the Himalayas and Peninsular India regions have indigenous flora. Some of the plants are exclusive to Indian soil. The varied flora of the country allows animals of different needs to exist leading to a rich heritage of flora and fauna.
IV. 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.
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.