1. Deforestation
1.1. Why are forest cleared?
1.1.1. Land is needed for urban development, e.g for building houses, roads and factories.
1.1.2. Land is used for growing grassland for animal grazing.
1.1.3. Firewood is a spurce of fuel.
1.1.4. Land is needed for growing crops such as rice.
1.1.5. Wood is used as construction materials and is turned into pulp for making paper.
1.2. What are the effects of deforestation?
1.2.1. Soil Erosion
1.2.1.1. Deforesation cause soil erosion. The leafy canopy of the soil from the impact of the falling rain. Rainwater is retained and absorbed by he roots of the trees, and gradually reloeased to the soil and then to nearby rivers, streams and lakes.
1.2.2. Flooding
1.2.2.1. Soil erosion due to deforestation can lead to floods. The eroded soil may be deposited in rivers and streams, blocking the flow of water. Water level will rise and as a result causing umwanted floods.
1.2.3. Desertification
1.2.3.1. The destruction of land leading to desert-like conditions is called desertification. Desertification results in habitats being lose and the extinction of many species and organism.
1.2.4. Climate Change
1.2.4.1. Deforestation also cause climate changes. Rainwater retained by the roots of plants is lost as water vapour during transpiration. The same water will eventually condense and form as rain and fallback to earth. when trees are cut down, there will be fewer clouds, less transpiration and less rainfall. The area becomes dry and warm, annual rainfall decreases.
2. Global Warming
3. What are the effects of uncontrolled fishing practices?
3.1. Overfishing can lower the numbers of individuals of reproductive age, reducing population sustainability.
3.2. Removing an abundant species from the fish community can alter food chains and the species composition of the community.
3.3. "Ghost" fishing impacts are poorly known, but lost gear can continue to function, catching target, nontarget and protected species.
4. Uncontrolled fishing practices
4.1. How do uncontrolled fishing practices harm the ecosystem?
4.1.1. Humans catch fish for food. As the human population increases, so does the demand for fish. Some species of fish have been cuaght in such a large amount, this made tha population decrease drastically. This term is called over-fishing.
4.1.1.1. Drift nets
4.1.1.1.1. Drift nets are nets that are left to drift in the seas. These nets trap almost everything in their path.
4.1.1.1.2. Shrimps or prawn trawlers drag lsrge fishing nets along the bottom of the sea bed, trapping marine life indiscriminately.
4.1.1.1.3. Scallops dredges scrape the seabed, destroying coral reefs and organism that live on the seabed.