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बेसिक इंग्लिश का दूसरा सत्र (कक्षा प्रारंभ : 22 अक्तूबर, शाम 3:30 से 5:30)
Forest as ecological resource and causes of Deforestation
Apr 29, 2015

Forests are formed by a community of plants which is predominantly structurally defined by its trees, shrubs, climbers and ground cover. Natural vegetation looks vastly different from a group of planted trees, which are in orderly rows. The most ‘natural’ undisturbed forests are located mainly in our National Parks and Wildlife Sanctuaries. The landscapes that make up various types of forests look very different from each other. Their distinctive appearance is a fascinating aspect of nature. Each forest type forms a habitat for a specific community of animals that are adapted to live in it.

Forests may be subdivided into natural forests and plantations or manmade forests. Naturalforests are forests composed of mainly naturally grown indigenous (local) trees while plantations are forests established by growing trees by humans. Climate, soil type, topography, and elevation are the main factors that determine the type of forest. Forests are classified according to their nature and composition, the type of climate in which they thrive, and its relationship with the surrounding environment. Indian forests can be divided into the following groups:

(i) Tropical Evergreen and Semi Evergreen forests: 
Evergreen forests grow in the high rainfall areas of the Western Ghats, North Eastern India and the Andaman and Nicobar Islands. These forests grow in areas where the monsoon lasts for several months. Some even get two monsoons, such as in Southern India. Evergreen plants shed a few of their leaves throughout the year. There is no dry leafless phase as in a deciduous forest. An evergreen forest thus looks green throughout the year. The trees overlap with each other to form a continuous canopy. Thus very little light penetrates down to the forest floor. Only a few shade loving plants can grow in the ground layer in areas where some light filters down from the closed canopy. The forest is rich in orchids and ferns. The barks of the trees are covered in moss. The forest abounds in animal life and is most rich in insect life.

(ii) Tropical Deciduous forests:
Deciduous forests are found in regions with a moderate amount of seasonal rainfall that lasts for only a few months. Most of the forests in which Teak trees grow are of this type. The deciduous trees shed their leaves during the winter and hot summer months. In March or April they regain their fresh leaves just before the monsoon, when they grow vigorously in response to the rains. Thus there are periods of leaf fall and canopy re-growth. The forest frequently has a thick undergrowth as light can penetrate easily onto the forest floor.

(iii) Tropical Thorn forests:
These are found in the semi- arid regions of India. The trees, which are sparsely distributed, are surrounded by open grassy areas. Thorny plants are called xerophytic species and are able to conserve water. Some of these trees have small leaves, while other species have thick, waxy leaves to reduce water losses during transpiration. Thorn forest trees have long or fibrous roots to reach water at great depths. Many of these plants have thorns, which reduce water loss and protect them from herbivores.

(iv) Mangrove forests:
They grow along the coast especially in the river deltas. These plants are able to grow in a mix of saline and fresh water. They grow luxuriantly in muddy areas covered with silt that the rivers have brought down. The mangrove trees have breathing roots that emerge from the mudbanks. 




(v) Littoral and Swamp forests:
These are more or less gregarious forests of low height which occur in the seas. The main species is Avicennia marina (99%). Other species like Rhizophora have disappeared over a period of time due to heavy cutting.

(vi) Montane Forest:
They occur in mountainous areas, the decrease in temperature with increasing altitude leads to a corresponding change in natural vegetation. The Himalayan ranges show a succession of vegetation from the tropical to the tundra, which change in with the altitude.

Forest Comunities

Forest type Plants Examples Common Animal Examples Rare Animal Examples 
Himalayan Coniferous,  Pine, deodar Wild goats and sheep Snow leopard, Hangul, Himalayan black bear. Himalayan brown bear, Musk deer,
Himalayan  Broadleaved Maple, oak   Himalayan Wolf
Evergreen North-east, Western Ghats, Andaman & Nicobar  Jamun, Ficus, Dipterocarpus, rosewood, mahogony, ebony Tiger, Leopard, Sambar, Malabar Pigmy Hog, whistling thrush, Malabar Pied, hornbill, tree frogs. Liontailed macaque
Deciduous – Dry Teak, Aini, Terminalia, axlewood Tiger, Chital, Barking deer, Babblers, Flycatchers, Hornbills.  
Deciduous - Moist Sal, white     
Thorn and scrub Babul, Ber, Neem Blackbuck, Chinkara, Fourhorned antelope, Partridge, Monitor lizard. Wolf, Bustard, Florican Bustards
Mangrove Delta Forest  Avicenia Crocodile, shorebirds – sandpipers plovers, fish, crustacean. Water monitor lizard

Forest services :

These include the control of the flow services of water in streams and rivers. Forest cover reduces surface runoff of rainwater and allows ground water to be stored. Forests prevent erosion of soil. Once soil is lost by erosion, it can take thousands of years to reform. Forests regulate local temperature. It is cooler and more moist under the shade of the trees in the forest. Most importantly, forests absorb carbon dioxide and release oxygen that we breathe.
 
Function Benifits
Productive functions
Production of various types of wood, fruits and a wide range of compounds such as resins, alkaloids, essential
oil, latex and pharmaceutical substances.
Protective functions
Provides habitats for various organisms conservation of soil and water, prevention of drought, shelter against
wind, cold, radiation, noise, sounds, smells and sights
Regulative functions
Absorption, storage and release of gases (most importantly carbon dioxide and oxygen), water, minerals, elements and radiant energy. All such functions improve the atmospheric and temperature conditions and enhances the economic and environmental value of the land .Forests also effectively regulate floods and drought and all the biogeochemical cycles.
 
Fig: Main function of Forest

DEFORESTATION
Deforestation is a very broad term, which consists of cutting of trees including repeated lopping, felling, and removal of forest litter, browsing, grazing and trampling of seedlings. It
can also be defined as the removal or damage of vegetation in a forest to the extent that it no longer supports its natural flora and fauna .It is one of the major causes to the environmental degradation which is affected by the agents like small farmers, ranches, loggers and plantation companies. There is a broad consensus that expansion of cropped areas and pastures are a major source of deforestation.
In the beginning of 20th century about 7.0 billion hectares of forests were present over the land of our planet and by 1950 forest covers was reduced to about 4.8 billon. If the present trend continues forests will be reduced to only 2.35 billion ha hectares in 2000A.D.
In a FAQ/UNEP study it was found that about 7.3 million hectares of rich tropical forests every year and about 14 hectare of closed forest every minute are lost.

Causes of Forest Depletion

1. Agriculture: 
Conversion of forests to agricultural land to feed growing needs of people. There are an estimated 300 million people living as shifting cultivators who practice slash and burn agriculture and are supposed to clear more than 5 lakh ha of forests for shifting cultivation annually. In India, we have this practice in North-east and to some extend in Andhra Pradesh, Bihar and M.P. which contribute to nearly half of the forest clearing annually.

2. Demand for firewood :
Firewood has been used as a source of energy for cooking, heating etc.Almost 44% of the total global wood produced fulfils the fuel requirements of the world. Close look at the pattern of utilization of wood produced will show that the developed countries utilize 16% of their share for fuel requirements. India consumes nearly 135-170 Mt (Million tonnes) of firewood annually and 10-15 ha of forest cover is being stripped off to meet the minimum fuel needs of urban and rural poor.

3. Mining:
This causes environmental impacts like erosion, formation of sinkholes, loss of biodiversity, and contamination of soil, groundwater and surface water by chemicals from mining processes. In some cases, additional forest logging is done in the vicinity of mines to increase the available room for the storage of the created debris and soil.
Contamination resulting from leakage of chemicals can also affect the health of the local population if not properly controlled. Extreme examples of pollution from mining activities include coal fires, which can last for years or even decades, producing massive amounts of environmental damage.


4. Urbanisation and developmental projects:
Often urbanisation and developmental activities lead to deforestation. The process of deforestation begins with building of infrastructure in the form of roads, railway lines, building of dams, townships, electric supply etc. Thermal power plants, mining for coal, metal ores and minerals are also important causes of deforestation.

5. Construction of dam reservoirs:
For building big dams, large scale devastation of forests takes place which breaks the natural ecological balance of the region. Floods, droughts and landslides become more prevalent in such areas. Forests are the repositories of invaluable gifts of nature in the form of biodiversity and by destroying these we are going to lose these species even before knowing them. These species could be having marvelous economic or medicinal value. These storehouses of species which have evolved over millions of years get lost due to deforestation in a single stroke.

6. Overgrazing:
Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, or by overpopulations of native or non- native wild animals. Overgrazing reduces the usefulness, productivity, and biodiversity of the land and is one cause of desertification and erosion. Overgrazing is also seen as a cause of the spread of invasive species of non-native plants and of weeds.

7. Slash-and-burn agriculture :
The agricultural technique practiced by the penurious farmers in these regions. They burn a small portion of forest, and plant crops on the nutrient-rich ash. The fertility of the soil, however, does not last long, so the farmers abandon the land and burn different trees. Continuation of such a practice has proven to be detrimental.

Consequences of Deforestation:
Depending on the needs of the social group concerned, deforestation has made it possible for communities to be built. Forest makes way for residential houses, office buildings and factories. Governments are able to built reads to make trade and transport easier and therefore more convenient to residents.
Deforestation can also mean the conversion of forest land to productive land for agricultural uses. This results in better and more abundant production of food and materials, virtually eradicating periods of want and lack. Economically, deforestation has contributed much in giving many communities the opportunity to make positive changes in their times. Unfortunately, the negative consequences of deforestation for outweigh its positive effects. Some of the problems created are: 

(a) Soil erosion and flash flood:
A shrinking forest cover coupled with over exploitation of ground water has accelerated erosion along the slopes of the lower Himalayas and Aravali hills, making them prone to landslides. Destruction of the forests has altered rainfall pattern.

(b)Food problems:
Non suitability of deforested area for conservation. Most of the area that has undergone deforestation is actually unsuitable for long-term agricultural use such as ranching and forming. Once deprived of their forest cover, the lands rapidly degrade in quality, losing their fertility and arability.
The soil in many deforested areas in also unsuitable for supporting annual crops. Much of the grassy areas are also not as productive compared to more arable soils and are therefore not fit for long-term cattle grazing.

(c) Flooding:
Deforestation can results to watersheds that are no logger able to sustain and regulate water flows from rivers to steams. Trees are highly effective in absorbing water quantities, keeping the amount of water in watersheds to a manageable level. The forest also serves as cover against erosion. Once they are gone, too much water can results to downstream flooding, many of which have cause disasters in many parts of the world.
The fertile top soil is eroded and flooded into the lower regions, many coastal fisheries and coral reefs suffer from the sedimentation brought by the flooding. This results to negative effects in the economic viability of many business and fatalities in wildlife population.


(d) Social Consequence:

The social consequences of deforestation are many, often with devastating long-term impacts. For indigenous communities, the arrival of "civilization" usually means the destruction of their traditional life-style and the breakdown of their social institutions. Individual and collective rights to the forest resource have been frequently ignored and indigenous peoples and local communities have typically been excluded from the decisions that directly impact upon their lives. 

(e) Loss of Biodiversity:
Biodiversity” include all variety of life forms. Biodiversity - (biological diversity) is a measure of variation, the number of different varieties, among living things. Biodiversity can be expressed in number of ways, which includes the number of genetic strain (differences) within species and the number of different ecosystem in an area. The most common expression of biodiversity is the number of different species, within a particular area (local biodiversity), or in a specific habitat (habitat biodiversity) or in the world (global biodiversity). Biodiversity is not static. It changes over the time during evolution new species have come up while some species become extinct.

(f) Climate Imbalance:
Deforestation also affects the climate in more than one ways. Trees release water vapor in the air, which is compromised on with the lack of trees. Trees also provide the required shade that keeps the soil moist. This leads to the imbalance in the atmospheric temperature further making conditions for the ecology difficult. Flora and fauna across the world are accustomed to their habitat. This haphazard clearance of forests have forced several of these animals to shift from their native environment. Due to this several species are finding it difficult to survive or adapt to new habitats.

Deforestation substitutes lush green forests with agriculture, grass land or herbs and shrubs with low productivity and little biomass. Enormous quantities of carbon dioxide are set free while loss of plant cover reduces the overall photosynthetic efficiency of the system. Thus while the input of carbon dioxide to the atmosphere is increased its output decreases. Many scientists believe that deforestation has been contributing significant amounts of carbon dioxide to the global atmosphere and thereby to the greenhouse effect or global warming.

(g) Changes in climate and different cycles:
♦ Trees maintain the solar radiation balance by absorbing albedo from the sun.
♦ Approximately 40% of the oxygen is provided by the rainforests in the world.
♦ Trees decrease the level of carbon dioxide in the atmosphere. In other words, the deforestation contributes to the greenhouse effect and global warming.



♦ The burning of the trees contribute to the increase of CO2 level in the atmosphere. 20% of global increase in CO2 is caused by the destruction of rainforests.
♦ Forest maintains global precipitation patterns (distribution of water supply) as water that is evaporated from the rainforest falls as rain in other regions. Without the forests, the hazard of desertification will increase in many areas.

How to tackle Menace of Deforestation?

  • The causers of deforestation are forced to cut down their trees due to their poverty. Hence, it is important to attack the causes of poverty to deal with deforestation issue. Unfortunately, there is no magical solution to the problems caused by deforestation because poverty is an abstruse problem to solve. However, we can still halt and reduce the process of deforestation.

  • Introduction of efficient alternative for fuel woods can reduce the rate of deforestation. For example If we propagate modern technologies and farming techniques to the tropical region, we can reduce the rate of deforestation significantly.

  • Clear cutting of forests must be banned. This will curb total depletion of the forest cover. It is a practical solution and is very feasible.

  • Land skinned of its tree cover for urban settlements should be urged to plant trees in the vicinity and replace the cut trees. Also the cutting must  be replaced by  planting young trees to replace the older ones that were cut. Trees are being planted under several initiatives every year, but they still don’t match the numbers of the ones we’ve already lost.

  • Reduce the usage of wood for construction and making furniture and products. Choose alternative material.

  • Social forestry

  • Policies to increase forest cover

  • Community involvement in forest management.

 


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