Natural Vegetation : UPSC / HCS
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Natural Vegetation : UPSC / HCS
Vegetation refers to the plants collectively found in a particular area or habitat. Vegetation is a broader term than flora, which means plant diversity of an area. There are different factors affecting natural vegetation. This article will take you through the following contents:
- Factors affecting natural vegetation
- Types of vegetation changes with annual rainfall
- Types of forests
- Vegetation refers to the plants collectively found in a particular area or habitat.
- Vegetation is a broader term than flora, which means plant diversity of an area.
- Natural vegetation refers to a plant community that has been left undisturbed over a long time, so as to allow its individual species to adjust themselves to climate and soil conditions as fully as possible.
- That is why crops are not included in the natural vegetation.
- Virgin vegetation-Undisturbed by the human beings and it can be found in the area where human reach is not possible like Himalayan region and Sunderban delta region.
- Endemic vegetation- The virgin vegetation is only found in India.
- Exotic vegetation- the virgin vegetation which has come from outside of India.
- India occupies tenth place in the world and fourth in Asia in plant diversity- about 15,000 flowering plants in India which account for 6% of the world’s total number of flowering plants.
Factors affecting natural vegetation
Land: Affects the natural vegetation directly and indirectly
- Fertile land --for agriculture
- Undulating and rough terrains -- For grasslands and woodlands and give shelter to a variety of wildlife
- sandy soils -- support cactus and thorny bushes
- wet, marshy, deltaic soil --mangroves and deltaic vegetation
- Temperature falls with Height and affects the type of vegetation and its growth, and changes it from tropical to subtropical temperate and alpine vegetation.
- sunlight varies at different places due to differences in latitude, altitude, season, and duration of the day.
- Due to the longer duration of sunlight, trees grow faster in sunlight
Areas of heavy rainfall have more dense vegetation as compared to other areas of less rainfall.
Type of Vegetation changes with Annual Rainfall.
200 cm or more--Evergreen Rain Forests
100 to 200 cm---Monsoon Deciduous Forests
50 to 100 cm---Drier Deciduous or Tropical Savanna
25 to 50 cm---Dry Thorny Scrub(Semi-arid)
Below 25 cm---Desert (Arid)
On the basis of certain common features such as predominant vegetation type and climatic regions.
Indian forests can be divided into the following groups:
- Tropical forests
- Montane forests
- Alpine forest
Tropical forest further divided into
Moist Tropical Forests
- Tropical Wet Evergreen
- Tropical Semi-Evergreen
- Tropical Moist Deciduous
Dry Tropical Forests
- Tropical Dry Evergreen
- Tropical Dry Deciduous
- Tropical Thorn
Tropical wet evergreen forest
- The trees of these forests do not shed their leaves together.
- The tropical rain forest appears like a thick canopy of foliage, broken only where it is crossed by large rivers or cleared for cultivation.
- The sunlight cannot reach the ground due to the thick canopy.
- The undergrowth is formed mainly of bamboos, ferns, climbers, orchids, etc.
- Annual rainfall exceeds 250 cm
- The annual temperature=25°-27°C
- The western side of the Western Ghats Some regions in the Purvanchal hills.
- In the Andaman and Nicobar Islands.
- Hardwood: The timber of these forests is fine-grained, hard, and durable.
- It has high commercial value but it is highly challenging to exploit due to dense undergrowth, absence of pure stands and lack of transport facilities ·
- The important species of these forests are rosewood, mahogany, aini, ebony, etc.
Tropical semi-evergreen forest
- Transitional forests between tropical wet evergreen forests and tropical deciduous forests.
- Comparatively drier areas than tropical wet evergreen forests.
- Annual rainfall is 200-250 cm
- The dry season is not short like in tropical wet evergreen forests.
The western coast, Assam, Lower slopes of the Eastern Himalayas, Odisha, and Andamans.
- The semi-evergreen forests are less dense.
- The main species are white cedar, hollock, and kail.
- Trees usually have buttressed trunks with abundant epiphytes.
Tropical moist deciduous
- also called the monsoon forests
- Annual rainfall 100 to 200 cm.
- Mean annual temperature=27°C
- The trees drop their leaves during the spring and early summer when sufficient moisture is not available.
- The general appearance is bare in extreme summers (April-May).
- These forests occupy a much larger area than the evergreen forests but large tracts under these forests have been cleared for cultivation.
- In northeastern states along the foothills of the Himalayas, eastern slopes of the Western Ghats
- Hills of eastern Madhya Pradesh and Chhattisgarh, Chota Nagpur plateau, Odisha, Parts of West Bengal, and Andaman and Nicobar islands.
- The main species found in these forests are teak, sal, amla, Jamun, bamboo, shisham, hurra, mahua, Kusum, and sandalwood, etc.
Tropical dry evergreen
- Along the coasts of Tamil Nadu.
- Annual rainfall of 100 cm(mostly from the north-east monsoon winds in October-December)
- Mean annual temperature = 28°C.
- The growth of evergreen forests in areas of such low rainfall is a bit strange
- Short statured trees, up to 12 m high, with complete canopy.
- The important species are Jamun, tamarind, neem, etc.
Tropical dry deciduous
- Annual rainfall is 70-100 cm.
- Similar to tropical moist deciduous forests and shed their leaves in the dry season with the only difference that they can grow in areas of comparatively less rainfall.
- They represent a transitional type – moist deciduous on the wetter side and thorn forests on the drier side.
- The forests are composed of a mixture of a few species of deciduous trees rising up to a height of 20 meters.
- found in rainier areas of the Peninsula and the plains of Uttar Pradesh and Bihar, Madhya Pradesh, Rajasthan.
- The important species are teak, axlewood, rosewood, common bamboo, red sanders, laurel, satinwood, etc.
Tropical thorn forest
- Annual rainfall less than 50 cm.
- The mean temperature is 25°-30°C.
- The trees are low (6-10 meters maximum) and widely scattered.
- consist of a variety of grasses and shrubs.
- scrub vegetation found here.
- Important species found are babool, ber, and wild date palm, Khair, neem, khejri, palas, etc.
Semi-arid areas of southwest Punjab, Haryana, Rajasthan, Gujarat, Madhya Pradesh, and Uttar Pradesh
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