Bio 6

UNIT-16         MANAGEMENT OF NATURAL RESOURCES

Natural resources can be broadly categorized into two types, viz. exhaustible and non-exhaustible. Management of natural resources is all about their judicious use in a way that the exhaustible resources can last for many generations to come and non-exhaustible resources can be maintained in as pristine form as possible.

CONSEQUENCES OF EXPLOITATION OF NATURAL RESOURCES

There are many consequences of exploitation of natural resources. Some examples are given below:-

Burning of fossil fuels creates air pollution. Excess amount of carbon dioxide in the atmosphere leads to global warming. Some polluting gases; like oxides of nitrogen and sulphur lead to acid rain, which is harmful for living beings. Acid rain is also harmful for monuments and buildings.

Excess exploitation of groundwater leads to a drastic fall in water table. This is the reason many places are experiencing acute shortage of drinking water.

Overuse of fertilisers and insecticides leads to soil pollution and soil erosion.

Many pollutants are directly flown into water bodies. This has resulted in water pollution in many rivers, lakes and even in oceans.

SUSTAINABLE DEVELOPMENT

Development is necessary for making all around economic development. But development often comes with a price in the form of environmental damage. Sustainable development means following certain practices which help in saving our environment from damage. This is necessary for maintaining the earth in a good shape so that future generations can also enjoy the bounty of nature.

Three Rs (Reduce, Recycle and Reuse):

Reduce: We should reduce the consumption of various resources wherever possible. For example; we can reduce the consumption of electricity by switching off lights and other appliances when they are not required. While leaving the home, one should always check for fans and lights and switch them off. This can not only help in saving electricity but also in saving the fuels which are utilised in electricity production. We should immediately repair a leaking tap so that precious water can be saved.

Recycle: There are many items which can be recycled again and again. Recycling is another way of reducing the demand for natural resources. For example; by recycling paper, we reduce the demand for wood and thus help in saving the forest.

Reuse: Many items can be reused many times. For example; old newspaper can be used for packing many items. Old envelopes can be used for doing rough work while doing your homework. Old plastic bottles can be used for many other purposes.

FOREST AND WILDLIFE

Conservation of forests and wildlife is necessary to protect the biodiversity. This is important because loss of biodiversity leads to ecological imbalance. But any conservation effort for forest and wildlife must keep the interests of all stakeholders in mind.

Stakeholders:-The stakeholders who are directly or indirectly affected by forest are as follows:

People living in or around forests; as they depend on various forest produce for their livelihood.

The forest department which is the owner of the forest land.

Various industrialists who depend on forest for many raw materials. For example; the beedi industry needs kendu leaves as raw material. Wood is used as raw material in many industries.

The wildlife and nature enthusiasts.

Before the beginning of the colonial rule in India, forest dwellers were free to utilize the resources from forests as they wished. But things changed when the British rulers took over the control of the forests in India. They restricted the access of forest dwellers to forest resources. This created huge problems for many people who had traditionally been dependent on forests for their survival.

After the independence of India, the forest department took over but the interests of forest dwellers continued to be ignored for a long time. The forest was cut to obtain timber for making railways and for various construction activities. The cleared forest was replaced by planting eucalyptus trees which led to the problem of monoculture. Growing a single species is called monoculture. It disturbs the biodiversity of an area.

LOCAL PEOPLE AND FOREST CONSERVATION

There are many examples which suggest that involvement of local communities is necessary for any conservation effort. The Bishnoi community of Rajasthan is one such example. Amrita Devi Bishnoi is still remembered with reverence for the way she fought for protecting the khejri trees in Khejrali village. She; along with 363 other people; sacrificed her life for the protection of khejri trees in 1731. The ‘Amrita Devi Bishnoi National Award for Wildlife Conservation’ has been named in her honour. Another example is of the nomadic herders of the Himalayas. The nomadic herders used to graze their animals near the great Himalayan National Park. Every summer, the nomadic people brought their herds down the valley so that the sheep could get plenty of grass to eat. When the National Park was made in that area, the nomadic herders were stopped from grazing their sheep in the protected area. Now, in the absence of grazing by the sheep, the grasses grow very tall in the region. Tall grasses fall over and prevent fresh growth of grass. This shows that by excluding and alienating the local people from forests, proper conservation efforts cannot be carried out.

CHIPKO MOVEMENT

The Chipko Movement began in the early 1980s from a small village; Reni in Garhwal district. The women of the village began hugging a tree to prevent the cutting of trees by the contractors. The Chipko Movement later spread to other parts of India. It had been instrumental in stopping deforestation to a large extent.

ARABARI’S EXAMPLE OF PEOPLE’S PARTICIPATION IN FOREST MANAGEMENT

In 1972, the forest department realized its mistake while reviving the degraded sal forests of Arabari forest range. Arabari forest lies in Midnapore district of West Bengal. The earlier methods of policing and surveillance were a total failure as they often led to frequent clashes with local people. It also led to alienation of people from the conservation programme. Then came a forest officer; named A K Banerjee; who was a real visionary. He involved the local people in the revival of 1,272 hectares of forest. In lieu of that the villagers were given employment in silviculture and harvest and were given 25% of the harvest. They were also allowed to gather firewood and fodder against a nominal payment. Due to active participation of the local community there was remarkable revival of the Arabari sal forest. By 1983, the value of the forest rose to Rs. 12.5 crores.

WATER FOR ALL

Water harvesting is an age-old concept in India. Khadins, tanks and nadis in Rajasthan, bandharas and tals in Maharashtra, bundhis in Madhya Pradesh and Uttar Pradesh, ahars and pynes in Bihar, kulhs in Himachal Pradesh, ponds in the Kandi belt of Jammu region, and eris (tanks) in Tamil Nadu, surangams in Kerala, and kattas in Karnataka are some of the ancient water harvesting, including water conveyance, structures. These are still in use at many places. The traditional water harvesting structures are location specific and have been perfected by people over a long period of time. They take into account the local geography and the need of the local people and hence are highly efficient.

The traditional water harvesting structures usually focus on recharging the groundwater rather making an open reservoir. It has several advantages. Unlike surface water; the groundwater does not evaporate and thus loss because of evaporation is prevented. The groundwater does not provide a breeding ground for the mosquitoes and hence is good for public health as well. The groundwater is relatively protected from contamination by human activities.

COAL AND PETROLEUM

Coal and petroleum are the main energy resources for us. But since these are exhaustible in nature so we need to find out alternate sources of energy. Scientists are working on developing some alternate energy sources so that dependency on coal and petroleum can be reduced. Some examples are given below:

• Solar energy is being used to produce electricity at many places. Although the technologies for solar energy are still costly but future prospects look bright.
• Fuel cell is another development which may help in replacing the internal combustion engines from automobiles.
• Hydrogen is being used as fuel in buses and cars in many countries. Hydrogen; when used as a fuel produces water as a byproduct. Thus, hydrogen can be an environment-friendly fuel.

                                      TEXTUAL QUESTIONS

1. What changes can you make in your habits to become more environment-friendly?
Answer-We can be eco friendly by:
→ Using the principle of 3R's i.e. Reduce, Reuse and Recycle.
→ Putting off unnecessary lights and fans.
→ Using unleaded petrol in vehicles.
→ Using local transport like buses or train.
2. What would be the advantages of exploiting resources with short-term aims?
Answer-If resources are exploited with short-term aims it will be very beneficial for the present generation as it will help in growth of economy at a faster rate.
3. How would these advantages differ from the advantages of using a long-term perspective in managing our resources?
Answer-If resources are used in accordance with short term aims, present generation will be able to utilize the resources properly for growth and development.
But if we use resources with long term aims, future generation will also be able to utilize resources for fulfilling its needs.
Thus it would be better to use our natural resources with a long term perspective so that it could be used by the present generation as well as conserved for future use. But it will deprive future generation from the benefits of these resources as resources are exhaustible.
4. Why do you think there should be equitable distribution of resources? What forces would be working against an equitable distribution of our resources?
Answer-Natural resources of the Earth must be distributed among the people uniformly so that each and every one gets his share of the resource.
Human greed, corruption, and the lobby of the rich and powerful are the forces working against an equitable distribution of resources.
1. Why should we conserve forests and wildlife?
Answer-We should conserve forests and wildlife because they are essential for us in following terms:
→ Forest provide us oxygen, they cause rain fall.  → Forest prevents soil erosion.
→ Plants are dependent on animals and birds for their pollination and seed dispersal.  → Forests provide us various medicines. → Various forest products are used as raw materials in industries.
2. Suggest some approaches towards the conservation of forests.

Answer-Some approaches towards the conservation of forests are:
→ Conversion of forests into national parks, sanctuaries.
→ To take help of local people in conserving forest.
→ Not to allow the destruction of forests for making roads, dams and hotels etc.
→ Planting of trees should be increased.
2. Compare the above system with the probable systems in hilly/mountainous areas or plains or plateau regions.
Answer-In plains, the water harvesting structures are crescent-shaped earthen embankments. These are low, straight, and concrete.
In hilly regions, the system of canal irrigation called Kulhsis used for water harvesting. This involves a collection of rain water in a stream, which is then diverted into man-made channels down the hill sides.
Excercise
1. What changes would you suggest in your home in order to be environment-friendly?
Answer-Changes that can be undertaken in our homes to be environment-friendly are:
→ Switch off the electrical appliances when not in use.
→ Turn the taps off while brushing or bathing and repair the leaking taps.
→ Throw biodegradable and non-biodegradable waste into separate bins.
→ Construct composting pits.
→ Food items such as jam, pickles, etc., come packed in plastic bottles. These bottles can later be used for storing things in the kitchen.
2. Can you suggest some changes in your school which would make it environment-friendly?
Answer-Changes that can be undertaken in our schools to make it environment friendly are:

→ Electricity can be saved by switching off lights and fans when not required.
→ Turn the taps off when not in use.
→ Biodegradable and non-biodegradable wastes should be thrown into separate bins.

3. We saw in this chapter that there are four main stakeholders when it comes to forests and wildlife. Which among these should have the authority to decide the management of forest produce? Why do you think so?
Answer-The forest department of the government should have the authority to decide the management of forest produces. This is because the forest department is the care taker of the forest land and is responsible for any damage to the forest.
4. How can you as an individual contribute or make a difference to the management of (a) forests and wildlife, (b) water resources and (c) coal and petroleum?
Answer-(a) Forest and wildlife:
→ We should protest against the cutting of trees (deforestation).
→ We should protest against the poaching of wild animals.
→ We should stop the annexation of forest land for our use.
(b) Water resources:
→ Turn the taps off while brushing or bathing and repair leaking taps.
→ We should practice rainwater harvesting.
→ We should avoid the discharge of sewage and other wastes into rivers and other water resources.
(c) Coal and petroleum:
→We should take a bus or practice car pooling to avoid excessive use of petroleum.
→ We should stop using coal as a fuel (angithis).
(iii)We should use alternative sources of energy such as hydro-energy and solar energy instead of depending largely on coal and petroleum.
5. What can you as an individual do to reduce your consumption of the various natural resources?
Answer-Natural resources such as water, forests, coal and petroleum, etc. are important for the survival of human beings. The ways in which we can reduce the consumption of various natural resources are:
→ We should stop the cutting of trees (deforestation).
→ We should use recycled paper to reduce the cutting down of trees.
→ We should not waste water.
→ We should practice rainwater harvesting.
→ We should practice car pooling to avoid the excessive use of petroleum.
→ We should use alternative sources of energy such as hydro-energy and solar energy.
7. On the basis of the issues raised in this chapter, what changes would you incorporate in your life-style in a move towards a sustainable use of our resources?
Answer-One should incorporate the following changes in life-style in a move towards a sustainable use of our resources:
→ Stop cutting trees and practice plantation of trees.
→ Stop using plastic and polythene bags for carrying goods.
→ Use recycled paper.
→ Throw biodegradable and non-biodegradable waste into separate bins.
→ Waste minimum amount of water while using and repair leaking taps.
→ Practice rainwater harvesting.
→ Avoid using vehicles for short distances. Instead, one can walk or cycle to cover short distances. → To cover long distances, one should take a bus instead of using personal vehicles.
→ Switch off electrical appliances when not in use.
→  Use fluorescent tubes in place of bulbs to save electricity.
→ Take stairs and avoid using lifts.
→ During winters, wear an extra sweater to avoid using heaters.

Bio 5

UNIT-15                            OUR ENVIRONMENT

Environment: Our surrounding is called environment.

ECOSYSTEM;- This is a system of interdependencies among various living beings and non-living things in a given habitat.

Components of Ecosystem

An ecosystem has two types of components, viz. biotic component and abiotic component.

Abiotic Component

All the non-living things make the abiotic component of an ecosystem. Air, water and soil are the abiotic components. Air provides oxygen (for respiration), carbon dioxide (for photosynthesis) and other gases for various needs of the living beings.

Water is essential for all living beings because all the metabolic activities happen in the presence of water. Soil is the reservoir of various nutrients which are utilised by plants. Through plants, these nutrients reach other living beings.

Biotic Component

All living beings make the biotic component of an ecosystem. Green plants play the role of producers; because they prepare the food by photosynthesis. Animals and other living beings play the role of consumers; because they take food (directly or indirectly) from plants. Bacteria and fungi play the role of decomposers; as they decompose dead remains of plants and animals so that raw materials of organisms can be channelized back to the environment.

FOOD CHAIN

A food chain is a simple representation of transfer of energy from the sun to different biotic components of an ecosystem. Sun is the ultimate source of energy. Green plants convert solar energy into chemical energy during photosynthesis. When an animal takes food, this energy is supplied to the animal and the process goes on. A simple food chain can be shown as follows:

Producer → Primary Consumer → Secondary Consumer

FOOD WEB

Real life cannot be as simple as a food chain shown above. In any ecosystem, there can be many food chains which are interlinked at various levels. Thus, many food chains form a network which is called food web.

TRANSFER OF ENERGY THROUGH A FOOD CHAIN

Different levels in the food chain are called trophic level. Out of the energy consumed by an organism at a particular trophic level, 90% is utilised for its own need and rest 10% is left for the organism of the next trophic level. So, very little energy is left for the organism which is at the tertiary level. Let us assume that a green plant makes 100% energy in the form of chemical energy. 90% of this energy would be utilised for its own purpose. This would leave just 10% energy for the primary consumer. Now, primary consumer shall also utilize 90% of energy which was consumed by it. This would leave just 1% energy for (10% of 10 = 1) for the secondary consumer. By this logic, the tertiary consumer would get just 0.1% of energy which was originally made by the green plant. This is the reason, there can be just one or two organisms at the top of the food pyramid. This explains why the population of producers is always the largest in an ecosystem; followed by the population of herbivores and then that of carnivores. Moreover, an herbivore needs to eat many plants in its lifetime to fulfill its energy need. Similarly, a carnivore needs to eat many herbivores in its lifetime.

BALANCE IN THE ECOSYSTEM

There is a delicate balance in an ecosystem; as far as number of organisms at a particular trophic level is concerned. An increase or decrease in population of any organism can disturb this balance. Let us take a hypothetical example to understand this. If all the deer are killed in a jungle, the lions would be left with no food. This would endanger the existence of lions. Once the lions and deer would be finished, it would result in population explosion of green plants. If all the lions die in a jungle, it would create another problem. Since no lion would be left to kill the deer, the population of deer would increase substantially. This will finish off all the green plants and finally even the deer would be left with no food for them.

Biodegradable Substance: Substances which can be decomposed by microorganisms are called biodegradable substances. All the organic substances are biodegradable.

Non-biodegradable: Substances which cannot be decomposed by microorganisms are non-biodegradable. All inorganic substances are non-biodegradable. Many synthetic substances are also non-biodegradable.

OZONE LAYER DEPLETION:

Ozone layer is also known as stratosphere. When ultraviolet radiations act on oxygen, the oxygen gets converted into ozone.

Ozone layer works like a protective shield for living beings. The ozone layers wards off harmful ultraviolet radiations from the sun.

Effect of CFCs: Use of CFCs (Chlorofluorocarbon) has damaged the ozone layer. As a result, the ozone layer has become thinner at certain parts. In 1987, the UNEP (United Nations Environment Programme) succeeded in forging an agreement among different nations to freeze the CFC production at 1986 level. Later, an agreement was signed among different nations to phase out CFCs. It is important to note that CFC is used in refrigerators and aerosol spray. India is also a signatory of that agreement and thanks to the efforts by the United Nations and different environmentalists, the CFC emission has been put under some control.

Problems of Waste Disposal: During our day to day activities, we produce lot of waste. While some of the waste is biodegradable, a large chunk is composed of non-biodegradable substances. Plastic waste is a serious concern because plastic is non-biodegradable. We need to respect our environment and find out ways to reduce the burden on our environment.

                                     TEXTUAL QUESTIONS

1. Why are some substances biodegradable and some non-biodegradable?
Answer-Substances are classified as biodegradable and non-biodegradable because some substances can be decomposed by microorganisms and some cannot.
Substances that are broken down into simple soluble forms are called biodegradable substances and the substances that are not decomposed by microorganisms into harmless substances are called non biodegradable substances.

2. Give any two ways in which biodegradable substances would affect the environment.
Answer-Biodegradable substances affect the environment by:
→ The biodegradable substances such as tree leaves, plant parts, and kitchen wastes can be used as humus after composting. This will enhance the soil fertility.
→ The biodegradable substances mainly contain carbon. These substances after decomposition release that carbon back into the atmosphere.
3. Give any two ways in which non-biodegradable substances would affect the environment.
Answer-Non-biodegradable substances affect the environment by:
→ They contaminate soil and water resources as they cannot be decomposed by micro-organisms.
→ These substances, when accidentally eaten by stray animals, can harm them and can even cause their death.
1. What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
Answer-The various links or steps in a food chain at which the transfer of food and energy takes place are called trophic levels.
The producers form the first trophic level as they manufacture food. The primary consumers form the second trophic level, the secondary consumers form the third, and the tertiary consumers form the fourth trophic level.

In the above fig. Grass is the producer which is eaten by the grasshooper known as primary consumer. Then the grasshooper is eaten by shrew, secondary consumer and lastly shrew eaten up by owl, tertiary conusmer.

2. What is the role of decomposers in the ecosystem?
Answer-Various role played by decomposers in the ecosystem are:
→ They clean the environment.  → They decompose biodegradable substances into useful substances.

→ They release nutrients into soil by decomposing dead and decaying matter, thus making the soil fertile.
→ They maintain the nutrient pool by returning back the nutrients in the pool.
1. What is ozone and how does it affect any ecosystem?
Answer-Ozone (O3) is a molecule, made up of three atoms of oxygen.
Ozone (O3) forms a layer in the upper atmosphere. It is very essential for the life on this planet. It shields the surface of the earth from ultra-violet radiation (UV) coming from sun as these radiations are very harmful causing skin cancer and cataract in humans. It also does harm to the crops.
2. How can you help in reducing the problem of waste disposal? Give any two methods.
Answer-We can help in reducing the problem of waste disposal by these methods:
→ By separating biodegradable substances from non-biodegradable substances.
→ By reducing, reusing and recycling non-biodegradable substances.
Excercise
1. Which of the following groups contain only biodegradable items? (d) Cake, wood and grass
2. Which of the following constitute a food-chain? (b) Grass, goat and human
3. Which of the following are environment-friendly practices? (d) All of the above

4. What will happen if we kill all the organisms in one trophic level?
Answer-If we kill all the organisms of one trophic level it will create an imbalance in the ecosystem. As an Example, In a food chain Grass → Dear → Lion, If we remove all lions then population of deer will increase which will cause over-grazing. This will lead to deforestation. It may even lead to soil erosion causing further conversion of fertile land into barren desert.
5. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?

Answer-Impact of removing all organisms of a trophic level is different for different trophic levels.
For example, if we remove producers from a food chain, no organism will get food, if we remove herbivores from a food chain then carnivores will die and producers will also die due to competition for space and nutrients. No, we can't remove any trophic level without causing damage to the ecosystem as one is dependent on other for their survival. If we remove any one this will create imbalnce in the ecosystem.
6. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

Answer-Biological magnification is defined as the phenomena of accumulation or increase in the concentration of some toxic substances at each trophic level.

The levels of biomagnification will be different at different trophic levels. For example, in a pond of water, DDT was sprayed and the producers were found to have 0.04 ppm concentration of DDT. Since many types of planktons are eaten by some fishes and clams, their body accumulates 0.23 ppm of DDT. Sea gull that feeds on clams accumulates more DDT as one sea gull eats many clams. Hawk, the top carnivore, has the highest concentration of DDT.

7. What are the problems caused by the non-biodegradable wastes that we generate?
Answer-The problems caused by non-biodegradable wastes are:
→ The cause biomagnification.
→ They increase pollution.
→ They make environment unclean.
→ They kill useful microorganisms.
8. If all the waste we generate is biodegradable, will this have no impact on the environment?
Answer-If all the waste generated would be biodegradable this will also create problem. As the numbers of decomposers will be quite low so wastes cannot be broken down into harmless simpler substance at right time. It will became breeding ground for flies causing spread of diseases. It will also emits foul smell which makes the life of people miserable.

9. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

Answer-The damage to the ozone layer a cause for concern because:
→ It causes skin darkening, skin cancer, ageing, and corneal cataracts in human beings.
→ It can result in the death of many phytoplanktons that leads to increased global warming.

To limit the damage to the ozone layer, the release of CFCs into the atmosphere must be reduced. CFCs used as refrigerants and in fire extinguishers should be replaced with environmentally-safe alternatives. Also, the release of CFCs through industrial activities should be controlled.