Natural Vegetation And Wildlife Class 09
Our country India is one of the twelve mega bio-diversity countries of the world. With about 47,000 plant species India occupies tenth place in the world and fourth in Asia in plant diversity
Natural vegetation refers to a plant community which has grown naturally without human aid and has been left undisturbed by humans for a long time. This is termed as a virgin vegetation. Thus, cultivated crops and fruits, orchards lonn part of vegetation but not natural vegetation.
Land alfects the natural vegetation directly and indirectly. The nature of land influences the type of vegetation. The fertile level is generally devoted to agriculture. The undulating and rough terrains are areas where grassland and woodlands develop and give shelter to a variety of wild life.
Soil Different types of soils provide basis for different types of vegetation. The sandy soils of the desert support cactus and thorny bushes while wet, marshy, deltaic soils support mangroves and deltajc vegetation. The hill slopes with some depth of soil haveconical trees.
Temperature The character and extent of vegetation are mainly determined by temperature along with humidity in the air, precipitation and soil. On the slopes of the Himalayas and the hills of the Peninsula above the height of 915 metres, the fall in the temperature allects the types of vegetation and its growth.
Photoperiod (Sunlight) The variation in duration of sunlight at different places is due to differences in latitude, altitude, season and duration of the day. Due to longer duration of sunlight, trees grow faster in Summer.
Precipitation In India almost the entire rainfall is brought in by the advancing southwest monsoon (June to September) and retreating northeast monsoons Areas of heavy rainfall have more dense vegetation as compared to other areas of less rainfall.
Forests are renewable resources and play a major role in enhancing the quality of environment. They modify local climate, control soil erosion, regulate stream flow, support a variety of industries, provide livelihood for many communities and offer panoramic or Scenic view for recreation. It controls wind force and temperature and causes rainfall. It provides humus to the soil and shelter to the wild life. India’s natural vegetation has undergone many changes due to several factors such as the growing demand for cultivated land.
Plants occur in distinct groups of communities in areas having similar climatic conditions. The nature of the plants in an area, to a large extent, determines the animal life in that area. When the vegetation is altered, the animal life also changes. All the plants and animalsinan area are interdependent and interrelated to each other in their physical environment, thus. forming an ecosystem.
Human beings are also an integral part of the ecosystem.
How do the human beings influence the ecology of a region?
They utilise the vegetation and wild life. The greed of human beings leads to over utilisation of these resources. They cut the trees and kill the animals creating ecological imbalance. As a result some of the plants and animals have reached the verge of extinction
TYPES OF VEGETATION The following major types of vegetation may be identified in our country .
- Tropical Rain Forests
- Tropical Deciduous Forests
- Tropical Thorn Forests and Scrubs
- Montane Forests
- Mangrove Forests
Tropical Rain Forests
These forests are restricted to heavy rainfall areas of the Western Ghats and the island groups of Lakshadweep, Andaman and Nicobar. upper parts of Assam and Tamil Nadu coast.
They are at their best in areas having more than 200 cm of rainfall with a short dry season. The trees reach great heights up to 60 metres or even above. Since the region is warm and wet throughout the year, it has a luxuriant vegetation of all kinds – trees. shrubs, and creepers ving it a multilayered structure. There is no definite time for trees to shed their leaves As such, these forests appear green all the year round. Some of the commercially important trees of this forest are ebony, mahogany, rosewood. rubber and cinchona.
The common animals found in these forests are elephants, monkey. lemur and deer. The one homed rhinoceros are found in the junges of Assam and West Bengal.
Tropical Deciduous Forests
These are the most widespread forests of India They are also called the monsoon forests and Spread over the region receiving rainfall between 200 cm and 70 cm. Trees of this forest-type shed their leaves for about six to eight weeks in dry summer.
On the basis of the availability of water. these forests are further divided into moist and dry deciduous. The former is found in areas receiving rainfall between 200 and 100 cm. These forests exist, therefore, mostly in the eastem part of the country – northeastern states, along the foothills of the Himalayas. Jharkhand, West Orissa and Chhattisgarh, and on the eastern slopes of the Western Ghats. Teak is the most dominant species of this forest. Bamboos, sal, shisham, sandalwood. khair. kusum, arjun,mulberry are other commercially important species.
The dry deciduous forests are found in areas having rainfall between 100 cm and 70 cm. These forests are found in the rainier parts of the peninsular plateau and the plains of Bihar and Uttar Pradesh. There are open stretches in which Teak. Sal Peepal Neem grow. A large part of this region has been cleared for cultivation and some parts are used for grazing.
The Thorn Forests and Scrubs
In regions with less than 70 cm of rainfall. the natural vegetation consists of thorny trees and bushes. This type of vegetation is found in the north-western part of the country including semi-arid areas of Gujarat Rajasthan, Madhya Pradesh, Chhattisgarh Uttar Pradesh and Haryana. Acacias, palms. euphorbias and cacti are the main plant species. Trees are scattered and have long roots penetrating deep into the soil in order to get moisture. The stems are succulent to conserve water. Leaves are mostly thick and small to minimize evaporation. These forests Gve way to thorn forests and scrubs in arid areas.
In mountainous areas. the decrease in temperature with increasing altitude leads to Lhe corresponding change in natural vegetation. As such, there is a succession of natural vegetation belts in the same order as we see from the tropical to the tundra region. The wet temperate type of forests are found between a height of 1000 and 2000 metres. Evergreen broad-leaf trees such as oaks and chestnuts predominate. Between 1500 and 3000 metres, temperate forests containing coniferous trees like pine. deodar silver fir Spruce and cedar, are found.
These forests cover mostly the southern slopes of the Himalayas. places having high altitude in southern and north-east India. At higher elevations, temperate grasslands are common At high altitudes, generally more than 3,600 metres above sea level. temperate forests and grasslands give way to the Alpine vegetation. Silver sir. junipers. pines and birches are the common trees of these forests. Howeverthey get progressively stunted as they approach the snow-line. Ultimately through shrubs and scrubs. they merge into the Alpine grasslands.
The mangrove tidal forests are found in the areas of coasts influenced by tides. Mud and silt get accumulated on such coasts. Dense mangroves are the common vaneties with mots of the plants submerged under water. The deltas of the Ganga. the Mahanadi. the Krishana, the Godavari and the Kaveri are covered by such vegetation. In the GangaBrahamaputra delta, sundari trees are found, which provide durable hard timber. Palm coconut, keora. agar. also grow in some parts of the delta.