Why is there a need for conservation?

Why is there a need for conservation?

1. To revent the extinction of plant and animal species.


2. To maintain a stable and balanced ecosystem, which prevents disruption of natural cycles such as water and carbon cycles and global warming.


3. To maintain a large genepool, whereby many wild plants and animals possess favourable genes.


4. To ensure the conservation of marine life, a major source of human food.


5. Conversation is of scientific value. We learn about evolution from studying wildlife.


6. Conservation preserves natural scenery and wildlife for people to appreciate. Natural resources for outdoor recreational activities such as fishing, biking and skiing are also maintained.


7. To maintain biodiversity. Rainforests, especially rainforests, house a large variety of species of animals and plants, many of which are of great economic importance as they are sources of raw material for for industries, medicinal drugs, natural insecticides and food.

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Discuss the impact of human activities on our ecosystem.

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Natural resources are resources supplied by nature that are used by humans. Air, water, soil, wildlife and forests are renewable natural resources, as long as humans do not overuse them. As for fossil fuels, they take millions of years to form naturally and cannot be replaced once they are used, thus they are known as non-renewable natural resources.

Deforestation

• Deforestation is the clearing of forests.




• Many forests are cleared to meet the increasing demands for land and materials such as wood.




• With modern technology, forests are being cleared at a much faster rate than they can be replaced.




• This leads to the loss of habitats.




• This causes soil erosion, where topsoil, the most fertile layer of the soil, to be washed away or eroded during heavy rain due to no protection as the trees are not tall enough or there are no trees at all.




• Eroded soil may be deposited in rivers and streams, thus resulting in flooding.




• When sunlight falls directly onto the soil, water will evaporate at a much faster rate from the soil, which then hardens, causing the land to become barren. Plants will not be able to grow in the soil. The destruction of land leading to desert-like conditions is called desertification. Consequently, habitats are lost and many species of organisms become extinct. Overgrazing by animals also lead to desertification because the plants cannot regenerate fast enough.




• Deforestation also causes climate changes. Rainwater that is retained and absorbed by the roots of tress is lost as water vapour during transpiration.

Uncontrolled fishing practices

• As humans catch fish for food, the increasing human population increases the demand for fish. Some species of fish have been caught in such large numbers that their populations have drastically decreased. These species are over fished.




• Modern fishing gear catches marine life indiscriminately, such that it does not distinguish between the targeted catch and and immature organisms or unwanted species, such as turtles, sharks and dolphins, which are unintentionally caught.




• Although these "accidental catches" are dumped back into the sea, they often die.




• Other methods of fishing also destroy the seabed and marine habitat.




• If fishing practices are not controlled, some species of fish will be caught faster than they can be replaces. Young fish that are caught will not have a chance to grow.

http://web.mit.edu/12.000/www/m2011/finalwebsite/graphics/intro/OVERFISHINGfromPEW.gif

Eutrophication

• Chemical fertilisers cotaining nitrates and phosphates are used to increase the yield of crops.




• However, overuseage of these fertilisers may lead to water pollution.

Biomagnification

http://library.thinkquest.org/04oct/01590/pollution/culturaleutroph.jpg



• Refers to the increase in the concentration of a substance, such as the pesticide DDT, that occurs in the food chain as a consequence of food chain energetics and low (or non-existent) rate of excretion/degradation of the substance.




• Organisms feeing at higher levels in a foo chain can accumulate huge amounts of DDT from eating their prey. DDT may not be poisonous to large organisms in small amounts but may be harmful in larger amounts.

http://www.pollutionissues.com/images/paz_01_img0027.jpg

Describe the carbon cycle.

Carbon is constantly being removed from and released into the environment, in the form of carbon dioxide. Hence, the carbon dioxide concentration in the environment remains relatively constant. The various processes by which carbon, in the form of carbon dioxide, is removed from and released into the environment make up the carbon cycle.

1. During photosynthesis, carbon dioxide is absorbed from the atmosphere by green plants and used to manufacture carbohydrates, for example, glucose.


2. Glucose may be changed to other organic ocmpounds such as fatx, amino acids and proteins.


3. When animals feed on green plants, the carbon compounds become part of the bodies of these animals. On the other hand, the carbon compounds may also be preserved in fossil fuels such as coal, natural gas and oil.

Release of carbon dioxide into the environment

Carbon dioxide is released into the environment through:

• Respiration: As living organisms respire , carbon compunds such as glucose are broken down in their bodies and thus carbon dioxide is released into the environment.


• Combustion: When fossil fuels like coal and natural gas are burnt or undergo combustion, carbon compounds that were preserved in the fossil fuels are broken down and carbon dioxide is released into the environment.


• Decay: The bodies of organisms decay when they die, which, in turn, are broken down into simple substances by decomposers. Carbon dioxide is one of the simple substances are absorbed by decomposers and become part of their bodies. When the decomposers respire, carbon dioxide is released into the environment.

The carbon cycle is important because it ensures that there is a continuous supply of carbon dioxide for plants to carry out photosynthesis. Photosynthesis converts energy from the sun into chemical energy in food, which other non-photosynthetic organisms can use to stay alive. The carbon cycle also enables energy to flow through the ecosystem. Carbon compounds carry the trapped solar energy from organism to organism in the food chain of an ecosystem.

http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/earth_system/carbon_cycle_NASA.jpg

What happens to most of the energy in ecosystems?

The first source of energy in an ecosystem is the sun. As the sun's energy flows through the ecosystem, some of it is lost to the environment as heat. Energy that is lost as heat cannot be recycled. Thus, in an ecosystem, energy flow is non-cyclic or linear.

Let's see how the sun's energy flows through the ecosystem.

1. First source of energy is the sun


2. Chlorophyll in producers absorb light energy and converts the light energy into chemical energy during photosynthesis.


3. Energy in the producers is passed from one trophic level to another by feeding.


4. As the flow of energy through the ecosystem is non-cyclic, energy is released as heat to the environment. This heat energy is not returned to to the same system or organisms that produced in it. Hence, it cannot be recycled in the ecosystem.


5. Dead organisms and egested and excreted materials contain trapped chemical energy and use some of it for their needs. The rest of the energy is lost as heat.

http://www.dlese.org/cmb/images/Flow%20of%20Energy%20in%20Ecosystems.jpg

Why are short food chains better?

As energy is lost at each trophic level, lesser and lesser energy is available for the organism at the next level as we go down the food chain.

Thus, food chains are naturally short. The shorter the food chain, the more energy is available to the final consumer because less energy is lost to the environment.

Hence, we say that shorter food chains are more efficient in energy transfer.

eg. more energy will be available to a man if he feeds directly on crop plants grown on a given area, rather than eating the cattle that feed on hos crop plants.

https://www.cbd.int/images/youth/food-chain.jpg

What are ecological pyramids?

Ecological pyramids are used to compare the trophic levels in a food chain.

Pyramid of numbers

• Allows us to compare the number of organisms present in each trophic level at a particular time.

http://upload.wikimedia.org/wikipedia/en/thumb/9/9d/Pyramid_of_numbers.png/400px-Pyramid_of_numbers.png

Pyramid of biomass

• Allows us to compare the mass of organisms present in each trophic level at a particular time.


• Constructed based on the standing mass (dry mass of organisms in each trophic level at any one time ) of organisms.

http://www.botany.uwc.ac.za/sci_Ed/grade10/ecology/images/pyra6.gif

What is the relationship between a predator and a prey?

A predator is an organism that kills and feeds on other organisms.

The organism that is eaten is called the prey.




Their relationship

As the predator feeds on the prey, the number of predators depends on the number of prey.

For example, zebra (prey) and lion ( predator),

When there is an increase in the number of zebras, the lions will have a lot of prey to prey upon, and thus the lions will also reproduce faster.

Subsequently, due to the increasing amount of lions, there will be lesser zebras.

Thus, with the decreasing number of zebras, some of the lions will starve and the lion population will decrease.

After that, with lesser predators, the zebra population will increase again.

The cycle continues.

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