NATURAL VEGETATION
Natural vegetation may be defined as that part of plant communities which has been remaining undisturbed over a long period of time.
Here the individual species adopt them selves to certain soil and climatic conditions and proliferate though natural process. On the basis of appearance of the plant community with respect to form and other characteristics.
the vegetation of India is commonly identified as forest, grasslands and shrubs.
The climate, specially the sun shine and precipitation, deter mines the type of plant species
that can survive in a particular region. On the basis of climatic condition, the vegetation has been classified as: Tropical Evergreen forests, Monsoon forests, Temperate Forests, Grasslands, Tundra, Savanna, Prairie, Alpine and so on.
Note:
1) The International Day of Forests was established on: 21st March
2) 2021 theme: “Forest restoration: a path to recovery and well-being.”
3) International Day of Forests was established by resolution of the United Nations
General Assembly: November 28, 2012
Basic terms:
Flora: Listed by species and regarded as a collective, it describes the plants of a specific area or era.
The collection of plant species that coexist in a specific habitat is referred to as vegetation; this arrangement is also known as an ecological frame.
Forests: A forest is a sizable area that is covered in bushes and trees. It is made up of brush, grassland, and woodlands.
Forest Area: Forests constitute about 23% of India’s total land surface and occupy 746 lakh hectares of land. The Chhattisgarh and MP covers 7217 hectare, Arunachal Pradesh 5110 hectares, Orissa-2857hec, Andhra Pradesh-2724 hec, Maharashtra-2724 hec and Uttaranchal-1887 hectares.
Major Vegetation Regions:
1. Tropical Evergreen or Rain Forests:
These forests occur in areas where the rainfall exceeds 200 cm, the average annual temperature is between 20°C to 27°C and average annual humidity exceeds 77 per cent. The trees are evergreen and dense and forests have a three storied appearance
These forests are found in Western parts of Western Ghats, eastern part of subtropical Himalayas (Teral), north east India comprising Lushal, Cachar, Khasi, Jaintia and Garo hills and most of Andaman and Nicobar Islands.
These forests may be sub divided into the following sub-types:
1) Tropical Wet Evergreen Forests:
They cover 4.5 m. ha area and are found along the western side of the Western Ghats, in a strip running south-west from Arunachal Pradesh, upper Assam, Meghalaya, Nagaland. Manipur, Tripura and Andaman and Nicobar Islands.
Here the rainfall exceeds 300 cm. The forests are lofty, dense, evergreen and multistoried.
• The main species of trees found are Poon, toon, chaplas, rosewood, ebony, Sissoo, ironwood, Gurjan, pila champa etc.
• The undergrowth consists of canes, bamboo, feras, climbers etc.
Due to the dense undergrowth and lack of transport these forests have not been exploited.
ii) Tropical Semi-evergreen Forests:
These forests have an average yearly temperature of between 24 and 27 degrees Celsius, a humidity percentage of 80, and slightly less than 200 cm of rainfall.
Semi-evergreen forests emerge from the decay of evergreen forests. They encompass 1.9 million hectares.
• Evergreen and deciduous trees coexist in these forests, which are located on the western coast, in upper Assam, Orissa, the lower slopes of the eastern Himalayas, and the Andaman and Nicobar islands. Among the significant species are Aini, Semul, Kadam, Irul, and so forth.
iii) Tropical Moist Deciduous Forests: ◆Such forests occur in areas of low annual rainfall of 100 cm to 150 cm.
The main annual ter perature is between 26°C to 27°C, and humidity percent is 60 to 80. These forests are found in a belt running north-south on eastern slopes of western ghat, central plateau including Chotanagpur, Upper Mahanadi Valley and hills of Madhya Pradesh, Himalayan foothills, eastern ghats in Tamil Nadu and Andaman and Nicobar islands.
These forest trees shed their leaves and are the most important forests source of commercial timber.
The species of trees include Sal, teak, Arjun, jarul, laurel, Andaman paduk, ebony, mulberry, Kusum, kanju, ber, gular, palas, haldu, siris, mahua, Semul, har, sandalwood, jamun etc.
Most of these forests have been cleared from level land for cultivation.
iv) Littoral and Swamp Forests:
These forests cover 6 lakh ha and occur in and around tidal creeks and river deltas.
They are found in thickets on western coast at a few places but on the eastern coast they form a continuous belt on the fringe of deltas of Ganga, Mahanadi, Godavari, Krishna and Cauvery. They are densest in Sunderbans, where Sundri trees predominate.
2. Dry Tropical Forests:
These forests occur in areas having annual rainfall between 75 cm to 125 cm, mean annual
temperature of around 23°C to 27°C and humidity between 51 to 58 per cent. Tropical Dry Deciduous:
These forests are found on a very large area in an irregular wide strip running north south from the foothills of Himalayas to Kanyakumari except in Rajasthan, Western Ghats and West Bengal. The important trees include teak, tendu, sal, bijasal, rosewood, palas, bel, lendi, axlewood, anjair, harra, khair etc.
Tropical Thorn Forests: They are restricted to areas where rainfall is very low Le. between 50 cm to 75 cm, the mean than 47 per cent .
annual temperature is between 25°C to 27°C and humidity is less They are found in Kutch, neighbouring parts of Saurashtra, a large strip in south western Punjab, western Haryana, western and northern Rajasthan, Upper Ganga plains, Deccan plateau and lower peninsular India.
Here thorny trees especially acacias predominate.
i) Tropical Dry Evergreen Forests:
These forests occur in areas where the mean annual rainfall is about 100 cm, mean annual temperature is about 28°C and mean annual humidity is 74 percent. These forests are found in the east coast of the peninsula. The important species of trees include khirni, jamun, kokko, ritha, neem, palm, etc.
3. Riparian Forests:
Where the rainfall is less than 50 cm, short trees and grass predominate. These forests are found along banks of rivers and wet lands. Deciduous vegetation like neem, Shisham, pipal, mango, jamun, khair are usually found. Kans
and munj grass are found in abundance.
4. Subtropical Broad Leaved Hill Forests:
The forests are found bat von 915 to 1830 m height above sea level where the mean annual rainfall is between 75 cm to 125 cm. mean annual temperature is between 18°C to 21°C and humidity percent is 80.
These forestsale fou sophist lands of Bastar, Panchmarhi, Mahabaleshwar, Nilgiris, Palni and Khasi hills and lower slopes of Himalaya in West Bengal and Assam
Sach forests are called “Shola’ in South India.
5. Montane Wet Temperate Forests:
These trees are found between 1800 and 3000 meters above sea level in regions with 150 to 300 centimeters of annual rainfall, II°C to 14°C annual temperatures, and 83 percent humidity.
These woods can be found in the upper highlands of West Bengal, Assam, Arunachal Pradesh, Kerala, Tamilnadu, and the Eastern Himalayas. The principal trees that can be found are oak, hemlock, magnolia, birch, plum, deodar, and Indian chestnut.
6. Montane Moist Temperate Forests:
They occur in temperate eastern and western Himalayas between the pine and alpine forests in Kashmir,
Himachal Pradesh, Punjab, Uttar Pradesh, Darjeeling and Sikkim between 1600 to 3500 meters. The forests are predominantly coniferous forests and include trees like pine, deodar, spruce, silver lit, oak, beach, birch, polar, elm, chestnut, maple, rhododendrons etc.
7. Alpine Forests:
Distribution: It occurs above 2700m of altitude in the eastern Himalayas and above 3000m in the western Himalayas. Important Species: It is a dense scrubby forest of Silver Fur, Juniper, Pine, Birch and Rhododendron.
Characteristic Features: The alpine forests give way to alpine grasslands through shrubs and scrub. These extend upwards up to the snowline.
Bugyals: Bugyals are high altitude alpine grasslands or meadows in Uttaranchal (at an elevation between 3-400m and 4000m). These are referred to as ‘nature’s own gardens’.
The topography of the terrain is either flat or sloped. The surface of these bugyals is covered with natural green grass and seasonal flowers.
They are used by tribal herdsmen to graze their cattle. During the winter season the alpine meadows remain snow-covered. During summer months, the Bugyals present a riot of beautiful flowers and grass.
Bugyals have a very fragile ecosystem. Some examples of Bugyals:
1) Auli (near Joshimath) – A premier skil range is located here
2) Gorso
3) Kwanri Bugyal
4) Bedni
5) Panwali and Kush Kalyan
6) Dayara
7) Munsiyari Bugyal
8.Littoral and Swamp Vegetation (Mangrove Vegetation/ Tidal Forests)
Spread: Evergreen mangrove forest is abundant in the tidal deltas of the Ganga, Mahanadi, Godavari, and Krishna rivers.
Rainfall in some regions exceeds 200 cm. Key Tree Species: Nipa, Sundari, Agar, Bhendi, and Keora
Important Animal Species: Common creatures in these woodlands include snakes, gharials, crocodiles, and turtles.
The Ganga Delta’s tidal forests are home to the Royal Bengal Tiger.
Characteristic Features:
The trees are mainly evergreen. Typically they produce tangled webs of arching roots that are exposed during low tides.
This vegetation is an adaptation to two conditions : High water salinity,Flooded at regular intervals
Prominent among these adaptations are the presence of stilt roots, buttress, pneumatophores etc Stilt roots (also called prop root)
Sult roots outgrow the trunk of the mangrove, branches or already existing stilt roots.
As soon as stilt roots reach the ground the tip of the stilt root develops an underground root system with which it connects the stilt root into the ground and then develops one or more further stilt roots which grow arcuately into the air to again run into the ground to develop an underground root system, this process repeats several times.
Buttress Roots – Buttress roots, developed by many trees concerning mangroves, provide stability to huge trees.
The buttress roots can grow up to 10 meters in height. Buttress roots, also called buttresses do not continue their growth underground as they do above, underground buttresses develop a huge amount of small roots that grow in the soil under the buttress root
Pneumatophores-Because of waterlogged conditions, the roots are deprived of oxygen during high tides. Some mangrove roots extend vertically above the ground.
These specialised roots are known as pneumatophores. These have pores which enable the trees to breathe when other roots are submerged under water during high tide.
Known for their ability to support a vibrant aquatic life inside their network of stilt roots, Mangrove shrubs also play a crucial role in the socioeconomic system.
Their protective role as “green shields” prevents coastal erosion and the potentially catastrophic effects of cyclones and tsunamis. Mangroves provide a means of subsistence by supporting aquaculture, providing medicinal herbs, fuel wood, and building materials.
Additionally, they provide heavy metal filtering, fish breeding facilities, and shoreline stabilization.
NOTE: Remarkably, a November 2014 investigation discovered mangrove patches in Karnataka. Due to their small size, the Indian Forest Survey neglected to register these mangrove patches earlier. The report states that Karnataka is home to 300 hectares of mangrove forests distributed over three coastal districts as well as a thriving saltwater ecosystem that is typically found on India’s east coast.
The Sunderbans are named after a well-known species of tree found in mangrove forests called Sundar. Kandla, or tall mangrove vegetation, is a lengthy stretch of dense vegetation found at the confluence of four rivers: the Arabian Sea, the Aghanashini, Gangavali, Sharavati, and Venkatpura.
The study notes that while mangroves have been declining in several parts of the world from timber harvesting and pollution, these forests in Karnataka have in fact grown spatially over the last two decades.
8.Grasslands:
Owing to a short monsoon season followed by a long hot dry season, grasslands equivalent to Steppe/Pampas/Savanna are absent in India. The closed deciduous forest grades into thorny forest without an intermediate park like stage, and there is no steppe type of Grassland between the woodland and the desert.
But locally available types of grassland are: 1. Hilly/Upland Grassland:
Himalayas (generally above 1000m height)
Deccan Plateau Hills (Western Ghats in Karnataka where forests have been cleared) Nilgiris have extensive grassy slopes (grass is often found interspersed with small isolated ‘shola forests”).
2. Low Lands in the plains of Punjab, Haryana, UP, Assam and Bihar.
3. Riverine Grassex:
These are found along the banks of the rivers which provide grazing facilities to cattle especially the bhabar pastures in northern India.
Sholas’ are the mixed dense forests of tropical evergreen and temperate evergreen rainforest species in the Nilgiri Hills.
The patches of shola forests are found mainly in valleys and are usually separated from one another by undulating montane grassland. The shola and grassland together form the shola grassland complex or mosaic.
Also read the brief article about the animal husbandry and Fisheries in India.