Chapter 5 Social Science Geography Natural Vegetation and Wild Life Notes Class 9
1. India is one of the twelve mega biodiversity countries of the world. India occupies 10th place in the world with about 47,000 plant species and 4th in Asia in plant diversity.
2. 15,000 flowering plants in India constitute 6% of the world’s total number of flowering plants. India also has approx. 90,000 species of animal as well as a rich variety of fish in its fresh and marine waters.
3. A plant community that has grown naturally without human aid is called Natural Vegetation.
4. Natural Vegetation that has been left undisturbed by humans for a long time is called Virgin Vegetation.
5. Flora is used to donate plants of a particular region or period and fauna is species of animals of a particular region or period. Flora and Fauna kingdom Constitute bio-diversity of a particular region or period.
6. Relief, climate, and ecosystem are three factors for bio-diversity.
Relief:
1. Land: The nature of land influences the type of Vegetation. Fertile lands support agriculture while undulating and rough terrains have grassland and woodland which give shelter to a variety of wildlife. 2. Soil: Different types of Soil provide basics for different types of vegetation. The sandy soil of the deserts supports cactus and thorny bushes while wet, marshy, dettics soil supports mangroves and deltaic vegetation. The hill slopes with some depth of soil have conical trees.
Climate:
1. Temperature: The character and extent of Vegetation are mainly determined by temperature along with humidity in the air, precipitation, and soil.
2. Sunlight: Due to differences in latitude, attitude, seasons, and duration of the day there is variation in the duration of sunlight.
3. Precipitation(Rain): Areas of heavy rainfall have more dense vegetation as composed to other areas of less rainfall. In India, almost the entire rainfall is brought in by the advancing southwest monsoon (June to Sept)and retreating northeast monsoon.
Ecosystem:
1. All the plants and animals in an area are interdependent and interrelated to each other in their physical environment thus, forming an ecosystem.
2. A very large ecosystem on land having distinct types of vegetation and animal life is called a Biome.
Importance of forests:
1. These are renewable resources and play a major role in enhancing the quality of the environment.
2. They modify the local climate, control soil erosion, regulate stream flow, support a variety of industries, provide a livelihood for many communities, and offer panoramic or scenic views for recreation.
3. It controls wind force and temperature and causes rainfall. It provides humus to the soil and shelter to the wildlife.
4. Natural Vegetation in India has undergone many changes due to several factors such as the growing demand for cultivated land, development of industries and mining, urbanization and over-grazing of pastures.
Types of Vegetation:
1. Tropical Evergreen forests-
1. These forests are restricted to heavy rainfall areas of the Western Ghats and the islands group of Lakshadweep, Andaman, and Nicobar, upper parts of Assam, Tamil Nadu coast.
2. They grow in an area of 200cm of rainfall with a short dry season.
3. The trees reach great heights up to 60cm or even above.
4. Rich vegetation of all kinds -Trees, shrubs, creeper.
5. Forests appear to be green all year-round because there is no definite time for trees to shed their leaves.
6. Commercial important trees- ebony, mahogany, rosewood, rubber, and cinchona.
Tropical Deciduous forests –
1. Most widespread forest in India.
2. These are also called monsoon forests.
3. Receives rainfall between 200cm and 70 cm.
4. Trees of these forests- type shed their leaves for about six to eight weeks in summer.
5. Two types: Moist and dry deciduous.
Tropical thorn forests and Scrubs-
1. These are found in the region with or loss of more than 70 cm of rainfall.
2. The natural vegetation consists of thorny trees and bushes, Acacias, euphorbia and Cacti are the main species.
3. Trees are scattered and have long roots penetrating deep Into the soil to get moisture. The stems are succulent to conserve water.
Montane forests-
1. Montane forests have a succession of natural vegetation belts in the same order as we see from the tropical to tundra region.
2. Between a height of 1000m and 2000m.wet the temperature type of forests containing evergreen broad. Leaf trees such as oaks and chestnuts are pre-dominated.
3. Between 1.5km and 3km temperature forests containing coniferous trees like pine, deadener, silver, fir, cedon are found.
4. At higher elevation,temperate grasslands are common.
5. At higher altitude, generally more than 3.6km above sea-level , Alpine vegetation is found which have silver fir,junipers ,pines and birch trees common.
6. Near show line ,shrubs and scrubs ,they merge into the alpine grassland which are used extensively for grazing by nomadic tribes like the Gunjans and the Bakarwals.
Mangrove Forests-
1. These forests are found in the areas of coasts influenced by tides where mud and silt get accumulated.
2. Dense mangroves are the common varieties with roots of plants submerged under water.These are deltas of the ganga,the mahanadi,the krishna,the Godavari and the kaveri.
3. In the Ganga -Brahmaputra delta, Sundari trees are found, which provide durable hard timber.
4. Palm, Coconut, keora, agar also grow In Some parts of the delta.
5. Royal Bengal tiger is a famous animal also turtles, crocodiles, gharials and snakes are found in these forests.
12. Conservation of flora and fauna –
1. The excessive exploitation of the plants and animals resources by human beings, disturbed the ecosystem About 13,00 plant species are endangered and 20 species are extinct also few animals are endangered and some have become extinct.
13. Causes of these threats are-
1. Hunting by greedy hunters for commercial purposes.
2. Pollution due to chemical and Industrial waste and acid deposits.
3. Reckless cutting of the forests to bring land under cultivation and inhabitation.