NCERT 9th Class (CBSE) Social Science: Natural Vegetation and Wild Life 

Question: Why does India possess a great variety of flora and fauna?

Answer:

1. Different types of soil: India has almost all major types of soils. It has alluvial soil which is very fertile, black soil, laterite soil, desert and mountain soil. The sandy soils of the desert support cactus and thorny bushes while wet, marshy deltic soils support mangroves and deltic vegetation.
2. Different climatic conditions: Different climatic conditions prevail in India. At some places, the temperature is at 55°C and at other, it is about – 45°C. So it supports all types of plants. Some places receive a rainfall of more than 1000 cm, and some receive only 50 cm. This also helps in growing different type of plants.
3. Sunlight: Sunlight is one of the important factors responsible for the growth of vegetation. Due to the longer duration of sunlight, trees grow faster in most parts of India.
4. Precipitation: Precipitation also plays a vital role in the growth of different types of vegetation. Tropical rain-forests are found in the Western Ghats due to heavy rainfall.

Question: Write any two points of difference between
(i) Dry deciduous
(ii) Moist deciduous.

Answer: Difference between dry deciduous forests and moist deciduous forests:-

1. Dry Deciduous Forests:
   Dry deciduous forests are found throughout the northern part of the country, except in the north eastern part. It is also found in Madhya Pardesh, Gujarat, Andhra Pradesh, Karnataka and Tamil Nadu.
2. They are found in the areas where the rainfall is between 70 cm to 100 cm.
3. The dominant species of trees found in these forests are Teak, Sal, Peepal etc.

Moist Deciduous Forests:

1. Moist deciduous forests are found almost throughout the India except in the western and north western part of India.
2. These forests are found in the areas where the rainfall is between 100 cm to 200 cm.
3. The dominant species of trees in these forests are Shisham, Sal, Teak, Mango, Rosewood etc

Question:Mention any four characteristics of the thorny forests water.

Answer:

1. This type of vegetation is found in regions with less than 70 cm of rainfall.
2. This type of vegetation is found in the north-western part of the country including the semi-arid areas of Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Uttar Pradesh and Haryana.
3. Acacias, palms, euphorbias and cacti are the main plant species.
4. Trees are scattered, and have long roots penetrating deep into the soil in order to get moisture.
5. The stems are succulent to conserve
6. Leaves are mostly thick, and small to minimize evaporation. .

Question: Mention any four characteristics of the mangrove tidal forests.

Answer:

1. The mangrove tidal forests are found in the areas of coasts influenced by tides. Mud and silt get accumulated on such coasts.
2. Dense mangroves are the common varieties with roots of the plants submerged under water.
3. The deltas of the Ganga, the , Mahanadi, the Krishna, the Godavari and the Kaveri are covered by such vegetation.
4. In the Ganga-Brahamputra delta, the sundari trees are found, which provide a durable hard timber. Palm, coconut, keora, agar also grow in some parts of the delta.