Natural vegetation of India: Evergreen, Deciduous, Montane, Thorn & Mangrove

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 form part of vegetation but not natural vegetation.

The term flora is used to denote plants of a particular region or period. Similarly, the species of animals are referred to as fauna. 

FACTORS AFFECTING DISTRIBUTION OF NATURAL VEGETATION

Relief

• Land affects natural vegetation directly and indirectly. Nature of land influences the type of vegetation. Agriculture is typically focused on fertile level. Grassland and forests grow on undulating and rough terrains, providing shelter for a variety of species.
• Soil: Different types of soils provide basis for different types of vegetation. Sandy soils of desert support cactus and thorny bushes, while wet, marshy, deltaic soils support mangroves and deltaic vegetation. Conical trees can be found on hill slopes with some depth of soil.

Climate

• Temperature: Temperature, air humidity, precipitation, and soil moisture all play major roles in determining the type and amount of vegetation. Above a height of 915 meters, the Himalayan slopes and the hills of the Peninsula experience a transition in vegetation from tropical to subtropical temperate and alpine because of fall in the temperature. 
• Photoperiod (Sunlight): The variation in duration of sunlight at different places is due to differences in latitude, altitude, season and duration of the day. Trees grow more quickly in the summer because the days are longer.
• Precipitation: The advancing southwest monsoon (June to September) and retreating northeast monsoons are responsible for approximately all of India’s precipitation. Compared to areas with less rainfall, strong rainfall regions have denser vegetation.

TYPES OF VEGETATION

MAJOR TYPES OF VEGETATION IDENTIFIED IN INDIA

• Tropical Evergreen Forests
• Tropical Deciduous Forests
• Tropical Thorn Forests and Scrubs
• Montane Forests
• Mangrove Forests

TROPICAL EVERGREEN FORESTS

• Regions: 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. 
• Climatic Conditions: 
  • Rainfall: They are at their best in areas having more than 200 cm of rainfall with a short dry season. 
  • Temperature: 18-30 degrees Celsius.

• Features: 
  • Trees reach great heights up to 60 meters or more. 
  • The region has a lush vegetation of all kinds, including trees, shrubs, and creepers, giving it a multi-layered structure because it is warm and humid throughout the year.
  • There is no definite time for trees to shed their leaves. As such, these forests appear green all the year round. 
• Flora: Ebony, mahogany, rosewood, rubber and cinchona. 
• Fauna: Elephant, monkey, lemur and deer. One horned rhinoceroses are found in the jungles of Assam and West Bengal.
  
  

TROPICAL DECIDUOUS FORESTS

• Regions: Most widespread forests of India. These forests exist mostly in eastern part of the country — north-eastern states, along foothills of Himalayas, Jharkhand, West Odisha and Chhattisgarh, and on eastern slopes of the Western Ghats.
• Climatic Conditions:
  • Rainfall: They are also called monsoon forests and spread over the region receiving rainfall between 70 cm and 200 cm. 
  • Based on availability of water, these forests are further divided into moist and dry deciduous. 
  • Moist deciduous forests are found in areas having rainfall between 100 and 200 cm. 
  • Dry deciduous forests are found in areas having rainfall between 70 cm and 100 cm.

• Flora: 
  • Teak is the most dominant species of moist deciduous forest. Bamboos, sal, shisham, sandalwood, khair, kusum, arjun and mulberry are other commercially important species.
  • Dry deciduous 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 and neem grow. 
• Fauna: Lion, tiger, pig, deer and elephant. 

THORN FORESTS AND SCRUBS

• Regions: This type of vegetation is found in north-western part of the country, including semi-arid areas of Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Uttar Pradesh and Haryana.
• Climatic Conditions: 
  • Rainfall: Regions with less than 70 cm of rainfall. 
• Features: 
  • 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 minimise evaporation. 
• These forests give way to thorn forests and scrubs in arid areas

• Flora: Acacias, palms, euphorbias and cacti are main plant species.
• Fauna: Common animals are rats, mice, rabbits, fox, wolf, tiger, lion, wild ass, horses and camels.

MONTANE FORESTS

In mountainous areas, decrease in temperature with increasing altitude leads to corresponding change in natural vegetation. 

Wet Temperate Forests

• Wet temperate type of forests is found between a height of 1000 and 2000 meters. 
• Evergreen broad-leaf trees, such as oaks and chestnuts predominate. 

Temperate Forests

• It is between 1500 and 3000 meters.
• 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. 

Temperate grasslands at higher elevations:

• At higher elevations, temperate grasslands are common. 
• Flora: At higher altitudes, mosses and lichens form part of tundra vegetation.
• Fauna: Kashmir stag, spotted dear, wild sheep, jack rabbit, Tibetan antelope, yak, snow leopard, squirrels, Shaggy horn wild ibex, bear and rare red panda, sheep and goats with thick hair.

MANGROVE FORESTS

Mangroves are salt-tolerant plants, also called halophytes that are adapted to harsh coastal conditions of tropical and subtropical intertidal regions of the world receiving rainfall between 1,000 to 3,000 mm and temperature ranging between 26-35 C.

• Region: 
  • Deltas of Ganga, Mahanadi, Krishna, Godavari and Kaveri are covered by such vegetation.
  • The mangrove tidal forests are found in the areas of coasts influenced by tides. Mud and silt get accumulated on such coasts. 
• Features: 
  • Dense mangroves are the common varieties with roots of the plants submerged under water. 
  • In the Ganga Brahmaputra delta, Sundari trees are found, which provide durable hard timber. 
• Flora: Palm, coconut, keora, agar, etc., also grow in some parts of the delta. 
• Fauna: Royal Bengal Tiger is the famous animal in these forests. Turtles, crocodiles, gharials and snakes are also found in these forests.

Benefits of Mangroves:

1. Act as a Buffer Zone between the land and sea.
2. Protect the land from erosion. 
3. Act as nature’s shield against cyclones, ecological disasters and as protector of shorelines. 
4. Breeding and nursery grounds for a variety of marine animals. Harbour a variety of life forms like invertebrates, fish, amphibians, reptiles, birds and even mammals like tigers.
5.  Good source of timber, fuel and fodder. 
6. Main source of income generation for shoreline communities like fisher folk. 
7. Purify the water by absorbing impurities and harmful heavy metals and help us to breathe a clean air by absorbing pollutants in the air. 
8. Potential source for recreation and tourism.

More than 35% of world’s mangroves are already gone. The figure is as high as 50% in countries like India, Philippines and Vietnam, while in Americas they are being cleared at a rate faster than tropical rainforests. Status of Forest report states that India’s mangrove cover rose by 54 sq. km. in 2019 compared to 2017.