UNIT X
ECOLOGY

CHAPTER- 13

Organisms and Populations

Ramdeo Misra- Father of Ecology in India

1972- National Committee for Environmental Planning and Coordination

1984- Establishment of Ministry of Environment and Forests

Ecology

Help us to understand how different organisms are adapted to their environments in terms of not only survival but also reproduction

Ecology Vs. Ecosystem

Levels of Organization in an Ecosystem

Major Abiotic Factors

Temperature-

• Mango trees do not and cannot grow in temperate countries like Canada and Germany,
• Snow leopards are not found in Kerala forests and
• Tuna fish are rarely caught beyond tropical latitudes in the ocean

Water-

Many freshwater animals cannot live for long in sea water and vice versa because of the osmotic problems, they would face.

Light-

• Many species of small plants (herbs and shrubs) growing in forests are adapted to photosynthesise optimally under very low light conditions because they are constantly overshadowed by tall, canopied trees.
• The availability of light on land is closely linked with that of temperature since the sun is the source for both.

Soil-

• dependent on the climate, the weathering process, whether soil is transported or sedimentary
• Various characteristics of the soil such as soil composition, grain size and aggregation determine the percolation and water holding capacity of the soils.

Adaptations

• Adaptation is any attribute of the organism (morphological, physiological, behavioural) that enables the organism to survive and reproduce in its habitat.
• Example- Kangaroo
• In the absence of an external source of water, the kangaroo rat in North American deserts is capable of meeting all its water requirements through its internal fat oxidation (in which water is a by product).
• It also has the ability to concentrate its urine so that minimal volume of water is used to remove excretory products.

Desert Plants-

• Have a thick cuticle on their leaf surfaces and have their stomata arranged in deep pits (sunken) to minimise water loss through transpiration.
• They also have a special photosynthetic pathway (CAM) that enables their stomata to remain closed during day time.
• Some desert plants like Opuntia have no leaves – they are reduced to spines– and the photosynthetic function is taken over by the flattened stems.
• Mammals from colder climates generally have shorter ears and limbs to minimise heat loss.  (This is called the Allen’s Rule.)
• In the polar seas aquatic mammals like seals have a thick layer of fat (blubber) below their skin that acts as an insulator and reduces loss of body heat.

Population Growth

• Natality refers to the number of births during a given period in the population that are added to the initial density.
• Mortality is the number of deaths in the population during a given period.
• Immigration is the number of individuals of the same species that have come into the habitat from elsewhere during the time period under consideration.
• Emigration is the number of individuals of the population who left the habitat and gone elsewhere during the time period under consideration.

Growth Models

Exponential growth-

• Resource (food and space) availability is obviously essential for the unimpeded growth of a population.
• Ideally, when resources in the habitat are unlimited, each species has the ability to realise fully its innate potential to grow in number, as Darwin observed while developing his theory of natural selection.
• Then the population grows in an exponential or geometric fashion

Logistic growth-

• No population of any species in nature has at its disposal unlimited resources to permit exponential growth.
• This leads to competition between individuals for limited resources.
• Eventually, the ‘fittest’ individual will survive and reproduce.

Population Interactions

• Both the species benefit in mutualism  and both lose in competition in their interactions with each other.
• In both parasitism and predation only one species benefits (parasite and predator, respectively) and the interaction is detrimental to the other species (host and prey, respectively).
• The interaction where one species is benefitted and the other is neither benefitted nor harmed is called commensalism.
• In amensalism on the other hand one species is harmed whereas the other is unaffected.
• Predation, parasitism and commensalism share a common characteristic– the interacting species live closely together.

Amensalism

Amensalism is any relationship between organisms of different species in which one organism is inhibited or destroyed while the other organism remains unaffected.

Predation

• Predation refers to an interaction between two organisms, predator and prey, where there is a flow of energy from one to another.
• The prey usually suffers a loss of energy and fitness, with a commensurate gain in energy for the predator.

Competition

• Competition is an interaction between organisms or species in which either the organisms or species are harmed.
• Limited supply of at least one resource (such as food, water, and territory) used by both can be a factor.

Mutualism

• Mutualism or inter- specific cooperation is the way two organisms of different species exist in a relationship in which each individual fitness benefits from the activity of the other.
• Similar interactions within a species are known as co-operation.
• The fungi help the plant in the absorption of essential nutrients from the soil while the plant in turn provides the fungi with energy-yielding carbohydrates.

Why very small animals are rarely found in Polar Regions?

Since small animals have a larger surface area relative to their volume, they tend to lose body heat very fast when it is cold outside; then they have to expend much energy to generate body heat through metabolism. This is the main reason why very small animals are rarely found in Polar Regions.

Why altitude sickness?

• This is because in the low atmospheric pressure of high altitudes, the body does not get enough oxygen.
• But, gradually you get acclimatised and stop experiencing altitude sickness.

How did your body solve this problem?

The body compensates low oxygen availability by increasing red blood cell production, decreasing the binding affinity of haemoglobin and by increasing breathing rate.

Many fish thrive in Antarctic waters where the temperature is always below zero. How do they manage to prevent their body fluids from freezing?

• A large variety of marine invertebrates and fish live at great depths in the ocean where the pressure could be >100 times the normal atmospheric pressure that we experience.
• Desert lizards lack the physiological ability that mammals have to deal with the high temperatures of their habitat, but manage to keep their body temperature fairly constant by behavioural means.
• They bask in the sun and absorb heat when their body temperature drops below the comfort zone, but move into shade when the ambient temperature starts increasing.
• The plant produces highly poisonous cardiac glycosides and that is why you never see any cattle or goats browsing on this plant.

Chapter 14
Ecosystem

PRODUCTIVITY

• Primary production is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis. It is expressed in terms of weight (gm-²) or energy (kcal m-²).
• The rate of biomass production is called productivity.
• It can be divided into gross primary productivity (GPP) and net primary productivity (NPP).
• Gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. A considerable amount of GPP is utilised by plants in respiration.
• Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP).
• GPP – R = NPP
• Net primary productivity is the available biomass for the consumption to Heterotrophs (herbivores and decomposers).
• Secondary productivity is defined as the rate of formation of new organic matter by consumers.

DECOMPOSITION

• Decomposers break down complex organic matter into inorganic substances like carbon dioxide, water and nutrients and the process is called decomposition.
• Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal matter, constitute detritus, which is the raw material for decomposition.
• The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and mineralisation.
• Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called fragmentation.
• By the process of leaching, water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts. Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called as catabolism.
• Humification and mineralisation occur during decomposition in the soil.
• Humification leads to accumulation of a dark coloured amorphous substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate.
• Being colloidal in nature it serves as a reservoir of nutrients.
• The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as mineralisation.
• In a particular climatic condition, decomposition rate is slower if detritus is rich in lignin and chitin, and quicker, if detritus is rich in nitrogen and water-soluble substances like sugars.
• Temperature and soil moisture are the most important climatic factors that regulate decomposition through their effects on the activities of soil microbes.
• Warm and moist environment favour decomposition whereas low temperature and anaerobiosis inhibit decomposition resulting in build up of organic materials.

Energy Flow

Except for the deep sea hydro-thermal ecosystem, sun is the only source of energy for all ecosystems on Earth.

Producers-

• The green plant in the ecosystem is called producers.
• In a terrestrial ecosystem, major producers are herbaceous and woody plants.
• Likewise, producers in an aquatic ecosystem are various species like phytoplankton, algae and higher plants.
• All animals depend on plants (directly or indirectly) for their food needs.
• They are hence called consumers and also heterotrophs.
• If they feed on the producers, the plants, they are called primary consumers, and if the animals eat other animals which in turn eat the plants (or their produce) they are called secondary consumers.
• The primary consumers will be herbivores.
• Some common herbivores are insects, birds and mammals in terrestrial ecosystem and molluscs in aquatic ecosystem.
• The consumers that feed on these herbivores are carnivores, or more correctly primary carnivores (though secondary consumers).
• Those animals that depend on the primary carnivores for food are labelled secondary carnivores.

• The detritus food chain (DFC) begins with dead organic matter.
• It is made up of decomposers which are heterotrophic organisms, mainly fungi and bacteria.
• They meet their energy and nutrient requirements by degrading dead organic matter or detritus. These are also known as saprotrophs (sapro: to decompose).
• Decomposers secrete digestive enzymes that breakdown dead and waste materials into simple, inorganic materials, which are subsequently absorbed by them.
• In an aquatic ecosystem, GFC is the major conduit for energy flow.
• As against this, in a terrestrial ecosystem, a much larger fraction of energy flows through the detritus food chain than through the GFC.
• Detritus food chain may be connected with the grazing food chain at some levels: some of the organisms of DFC are prey to the GFC animals, and in a natural ecosystem, some animals like cockroaches, crows, etc., are omnivores.
• These natural interconnection of food chains make it a food web.

ECOLOGICAL PYRAMIDS

The three ecological pyramids that are usually studied are

1. Pyramid of number;
2. Pyramid of biomass and
3. Pyramid of energy

ECOLOGICAL SUCCESSION

• An important characteristic of all communities is that their composition and structure constantly change in response to the changing environmental conditions.
• This change is orderly and sequential, parallel with the changes in the physical environment.
• These changes lead finally to a community that is in near equilibrium with the environment and that is called a climax community.
• The gradual and fairly predictable change in the species composition of a given area is called ecological succession.
• The entire sequence of communities that successively change in a given area are called sere(s).
• In the successive seral stages there is a change in the diversity of species of organisms, increase in the number of species and organisms as well as an increase in the total biomass.
• Examples of areas where primary succession occurs are newly cooled lava, bare rock, newly created pond or reservoir.
• Secondary succession begins in areas where natural biotic communities have been destroyed such as in abandoned farm lands, burned or cut forests, lands that have been flooded.

• Hydrarch succession takes place in wet areas and the successional series progress from hydric to the mesic conditions
• Xerarch succession takes place in dry areas and the series progress from xeric to mesic conditions.
• Hence, both hydrarch and xerarch successions lead to medium water conditions (mesic) – neither too dry (xeric) nor too wet (hydric).
• The species that invade a bare area are called pioneer species

NUTRIENT CYCLING

Ecosystem – Carbon Cycle

Ecosystem – Phosphorus Cycle

ECOSYSTEM SERVICES

• A pond is a shallow water body in which all the above mentioned four basic components of an ecosystem are well exhibited.
• The Abiotic component is the water with all the dissolved inorganic and organic substances and the rich soil deposit at the bottom of the pond.
• The solar input, the cycle of temperature, day-length and other climatic conditions regulate the rate of function of the entire pond.
• The autotrophic components include the phytoplankton, some algae and the floating, submerged and marginal plants found at the edges.
• The consumers are represented by the zooplankton, the free swimming and bottom dwelling forms.
• The decomposers are the fungi, bacteria and flagellates especially abundant in the bottom of the pond.
• This system performs all the functions of any ecosystem and of the biosphere as a whole, i.e., conversion of inorganic into organic material with the help of the radiant energy of the sun by the autotrophs; consumption of the autotrophs by heterotrophs; decomposition and mineralisation of the dead matter to release them back for reuse by the autotrophs, these event are repeated over and over again.
• There is unidirectional movement of energy towards the higher trophic levels and its dissipation and loss as heat to the environment.

• Biodiversity is the term popularised by the socio-biologist Edward Wilson to describe the combined diversity at all the levels of biological organisation
• Genetic diversity: A single species might show high diversity at the genetic level over its distributional range.
• The genetic variation shown by the medicinal plant Rauwolfia vomitoria growing in different Himalayan ranges might be in terms of the potency and concentration of the active chemical (reserpine) that the plant produces.
• India has more than 50,000 genetically different strains of rice, and 1,000 varieties of mango.
• Species diversity: for example, the Western Ghats have a greater amphibian species diversity than the Eastern Ghats.
• Ecological diversity: At the ecosystem level, India, for instance, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows has a greater ecosystem diversity than a Scandinavian country like Norway

Patterns of Biodiversity

Latitudinal gradients:

• The diversity of plants and animals is not uniform throughout the world but shows a rather uneven distribution.
• In general, species diversity decreases as we move away from the equator towards the poles.
• With very few exceptions, tropics (latitudinal range of 23.5° N to 23.5° S) harbour more species than temperate or polar areas.
• Colombia located near the equator has nearly 1,400 species of birds while New York at 41° N has 105 species and Greenland at 71° N only 56 species.
• India, with much of its land area in the tropical latitudes, has more than 1,200 species of birds.
• A forest in a tropical region like Ecuador has up to 10 times as many species of vascular plants as a forest of equal area in a temperate region like the Midwest of the USA.
• The largely tropical Amazonian rain forest in South America has the greatest biodiversity on earth- it is home to more than 40,000 species of plants, 3,000 of fishes, 1,300 of birds, 427 of mammals, 427 of amphibians, 378 of reptiles and of more than 1,25,000 invertebrates.

What is so special about tropics that might account for their greater biological diversity?

Speciation is generally a function of time, unlike temperate regions subjected to frequent glaciations in the past, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification,

1. Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and predictable.
2. Such constant environments promote niche specialisation and lead to a greater species diversity and
3. There is more solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.

How do we conserve Biodiversity?

BIODIVERSITY CONSERVATION

Loss of Biodiversity

• The colonisation of tropical Pacific Islands by humans is said to have led to the extinction of more than 2,000 species of native birds.
• The IUCN Red List (2004) documents the extinction of 784 species (including 338 vertebrates, 359 invertebrates and 87 plants) in the last 500 years.
• Some examples of recent extinctions include the dodo (Mauritius), quagga (Africa), thylacine (Australia), Steller’s Sea Cow (Russia) and three subspecies (Bali, Javan, Caspian) of tiger.
• Presently, 12 per cent of all bird species, 23 per cent of all mammal species, 32 per cent of all amphibian species and 31per cent of all gymnosperm species in the world face the threat of extinction.

Chapter 16
Environmental Issues

• Pollution is any undesirable change in physical, chemical or biological characteristics of air, land, water or soil.
• Agents that bring about such an undesirable change are called as pollutants.
• In order to control environmental pollution, the Government of India has passed the Environment (Protection) Act, 1986 to protect and improve the quality of our environment (air, water and soil).

AIR POLLUTION AND ITS CONTROL

• Smokestacks of thermal power plants, smelters and other industries release particulate and gaseous air pollutants together with harmless gases, such as nitrogen, oxygen, etc.
• These pollutants must be separated/ filtered out before releasing the harmless gases into the atmosphere.
• There are several ways of removing particulate matter; the most widely used of which is the electrostatic precipitator which can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant.

Role of Automobiles-

• Proper maintenance of automobiles along with use of lead-free petrol or diesel can reduce the pollutants they emit.
• Catalytic converters, having expensive metals namely platinum-palladium and rhodium as the catalysts, are fitted into automobiles for reducing emission of poisonous gases.
• As the exhaust passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide and water, and carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas, respectively.
• Motor vehicles equipped with catalytic converter should use unleaded petrol because lead in the petrol inactivates the catalyst.
• In India, the Air (Prevention and Control of Pollution) Act came into force in 1981, but was amended in 1987 to include noise as an air pollutant.

WATER POLLUTION AND ITS CONTROL

Water (Prevention and Control of Pollution) Act, 1974

Composition of waste water

Domestic sewage primarily contains biodegradable organic matter, which readily decomposes – thanks to bacteria and other micro-organisms, which can multiply using these organic substances as substrates and hence utilise some of the components of sewage.

It is possible to estimate the amount of biodegradable organic matter in sewage water by measuring Biochemical Oxygen Demand (BOD).

Sewage from our homes as well as from hospitals are likely to contain many undesirable pathogenic microorganisms, and its disposal into a water without proper treatment may cause outbreak of serious diseases, such as, dysentery, typhoid, jaundice, cholera, etc.

Unlike domestic sewage, waste water from industries like petroleum, paper manufacturing, metal extraction and processing, chemical manufacturing, etc., often contain toxic substances, notably, heavy metals (defined as elements with density > 5 g/cm3 such as mercury, cadmium, copper, lead, etc.) and a variety of organic compounds.

Biomagnification

• A few toxic substances, often present in industrial waste waters, can undergo biological magnification (Biomagnification) in the aquatic food chain. Biomagnification refers to increase in concentration of the toxicant at successive trophic levels.
• This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted, and is thus passed on to the next higher trophic level.
• This phenomenon is well known for mercury and DDT. Figure 16.5 shows biomagnification of DDT in an aquatic food chain.
• In this manner, the concentration of DDT is increased at successive trophic levels; say if it starts at 0.003 ppb (ppb = parts per billion) in water, it can ultimately reach 25 ppm (ppm = parts per million) in fish-eating birds, through biomagnification.
• High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking, eventually causing decline in bird populations.

Eutrophication

• Eutrophication is the natural aging of a lake by nutrient enrichment of its water. In a young lake the water is cold and clear, supporting little life.
• With time, streams draining into the lake introduce nutrients such as nitrogen and phosphorus, which encourage the growth of aquatic organisms.
• As the lake’s fertility increases, plant and animal life burgeons, and organic remains begin to be deposited on the lake bottom.
• Over the centuries, as silt and organic debris pile up, the lake grows shallower and warmer, with warm-water organisms supplanting those that thrive in a cold environment. Marsh plants take root in the shallows and begin to fill in the original lake basin.
• Eventually, the lake gives way to large masses of floating plants (bog), finally converting into land.
• Depending on climate, size of the lake and other factors, the natural aging of a lake may span thousands of years.
• However, pollutants from man’s activities like effluents from the industries and homes can radically accelerate the aging process.
• This phenomenon has been called Cultural or Accelerated Eutrophication.
• During the past century, lakes in many parts of the earth have been severely eutrophied by sewage and agricultural and industrial wastes.
• The prime contaminants are nitrates and phosphates, which act as plant nutrients.
• They over stimulate the growth of algae, causing unsightly scum and unpleasant odours, and robbing the water of dissolved oxygen vital to other aquatic life.
• At the same time, other pollutants flowing into a lake may poison whole populations of fish, whose decomposing remains further deplete the water’s dissolved oxygen content. In such fashion, a lake can literally choke to death.
• Heated (thermal) wastewaters flowing out of electricity-generating units, e.g., thermal power plants, constitute another important category of pollutants.
• Thermal wastewater eliminates or reduces the number of organisms sensitive to high temperature, and may enhance the growth of plants and fish in extremely cold areas but, only after causing damage to the indigenous flora and fauna.

• Solid wastes refer to everything that goes out in trash.
• Municipal solid wastes are wastes from homes, offices, stores, schools, hospitals, etc., that are collected and disposed by the municipality.
• The municipal solid wastes generally comprise paper, food wastes, plastics, glass, metals, rubber, leather, textile, etc.
• Burning reduces the volume of the wastes, although it is generally not completely burnt to completion and open dumps often serve as the breeding ground for rats and flies.
• Sanitary landfills were adopted as the substitute for open-burning dumps.
• In a sanitary landfill, wastes are dumped in a depression or trench after compaction, and covered with dirt everyday.

E-wastes

• Irreparable computers and other electronic goods are known as electronic wastes (e-wastes).
• E-wastes are buried in landfills or incinerated.
• Over half of the e-wastes generated in the developed world are exported to developing countries, mainly to China, India and Pakistan, where metals like copper, iron, silicon, nickel and gold are recovered during recycling process.
• Unlike developed countries, which have specifically built facilities for recycling of e-wastes, recycling in developing countries often involves manual participation thus exposing workers to toxic substances present in e-wastes.
• Recycling is the only solution for the treatment of e-waste, provided it is carried out in an environment friendly manner.

AGRO-CHEMICALS AND THEIR EFFECTS

• In the wake of green revolution, use of inorganic fertilisers and pesticides has increased manifold for enhancing crop production.
• Pesticides, herbicides, fungicides, etc., are being increasingly used.
• These incidentally, are also toxic to non-target organisms, that are important components of the soil ecosystem.
• Addition of increasing amounts of chemical fertilisers can do to aquatic ecosystems vis-à-vis Eutrophication.
• The current problems in agriculture are, therefore, extremely grave.

RADIOACTIVE WASTES

• Initially, nuclear energy was hailed as a non-polluting way for generating electricity.
• Later on, it was realised that the use of nuclear energy has two very serious inherent problems.
• The first is accidental leakage, as occurred in the Three Mile Island and Chernobyl incidents and the second is safe disposal of radioactive wastes.
• Radiation, that is given off by nuclear waste is extremely damaging to organisms, because it causes mutations at a very high rate.
• At high doses, nuclear radiation is lethal but at lower doses, it creates various disorders, the most frequent of all being cancer.
• Clouds and gases reflect about one-fourth of the incoming solar radiation, and absorb some of it but almost half of incoming solar radiation falls on Earth’s surface heating it, while a small proportion is reflected back.
• Earth’s surface re-emits heat in the form of infrared radiation but part of this does not escape into space as atmospheric gases (e.g., carbon dioxide, methane, etc.) absorb a major fraction of it.
• The molecules of these gases radiate heat energy, and a major part of which again comes to Earth’s surface, thus heating it up once again.
• This cycle is repeated many a times.
• The above-mentioned gases – carbon dioxide and methane – are commonly known as greenhouse gases because they are responsible for the greenhouse effect.

Global Warming

• Increase in the level of greenhouse gases has led to considerable heating of Earth leading to global warming.
• During the past century, the temperature of Earth has increased by 0.6° C, most of it during the last three decades.

Reasons-

The measures include cutting down use of fossil fuel, improving efficiency of energy usage, reducing deforestation, planting trees and slowing down the growth of human population.

Effects-

• El Nino effect
• Increased melting of polar ice caps as well as of other places like the Himalayan snow caps
• Rise in sea level

OZONE DEPLETION IN THE STRATOSPHERE

• Ozone is found in the upper part of the atmosphere called the stratosphere, and it acts as a shield absorbing ultraviolet radiation from the sun.
• UV rays are highly injurious to living organisms since DNA and proteins of living organisms preferentially absorb UV rays, and its high energy breaks the chemical bonds within these molecules.
• The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units (DU).
• Ozone gas is continuously formed by the action of UV rays on molecular oxygen, and also degraded into molecular oxygen in the stratosphere.

Reason-

• Chlorofluorocarbons (CFCs)
• Although ozone depletion is occurring widely in the stratosphere, the depletion is particularly marked over the Antarctic region.
• This has resulted in formation of a large area of thinned ozone layer, commonly called as the ozone hole
• UV radiation of wavelengths shorter than UV-B, are almost completely absorbed by Earth’s atmosphere, given that the ozone layer is intact.
• But, UV-B damages DNA and mutation may occur.
• It causes aging of skin, damage to skin cells and various types of skin cancers. In human eye, cornea absorbs UV-B radiation, and a high dose of UV-B causes inflammation of cornea, called snow-blindness, cataract, etc.
• Such exposure may permanently damage the cornea.
• Recognising the deleterious effects of ozone depletion, an international treaty, known as the Montreal Protocol, was signed at Montreal (Canada) in 1987 (effective in 1989) to control the emission of ozone depleting substances.

Chlorofluorocarbons (CFCs)

• CFCs discharged in the lower part of atmosphere move upward and reach stratosphere.
• In stratosphere, UV rays act on them releasing Cl atoms.
• Cl degrades ozone releasing molecular oxygen, with these atoms acting merely as catalysts; Cl atoms are not consumed in the reaction.

DEGRADATION BY IMPROPER RESOURCE UTILISATION AND MAINTENANCE

DEFORESTATION

• Deforestation is the conversion of forested areas to non-forested ones.
• According to an estimate, almost 40 per cent forests have been lost in the tropics, compared to only 1 per cent in the temperate region.
• The present scenario of deforestation is particularly grim in India.

Reasons-

• Slash and burn agriculture or Jhum cultivation mainly
• Over grazing

Reforestation

Reforestation is the process of restoring a forest that once existed but was removed at some point of time in the past. Reforestation may occur naturally in a deforested area.

People’s Participation in Conservation of Forests can be seen from the following-

• The Government of India has recently instituted the Amrita Devi Bishnoi Wildlife Protection Award for individuals or communities from rural areas that have shown extraordinary courage and dedication in protecting wildlife.
• Chipko Movement of Garhwal Himalayas- In 1974, local women showed enormous bravery in protecting trees from the axe of contractors by hugging them.
• Realising the significance of participation by local communities, the Government of India in 1980s has introduced the concept of Joint Forest Management (JFM) so as to work closely with the local communities for protecting and managing forests. In return for their services to the forest, the communities get benefit of various forest products (e.g., fruits, gum, rubber, medicine, etc.), and thus the forest can be conserved in a sustainable manner.