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| موضوع: Endangered species السبت مارس 13, 2010 8:40 pm | |
| The causes of endangerment Endangerment is a broad issue, one that involves the habitats and environments where species live and interact with one another. Although some measures are being taken to help specific cases of endangerment, the universal problem cannot be solved until humans protect the natural environments where endangered species dwell.
There are many reasons why a particular species may become endangered. Although these factors can be analyzed and grouped, there are many causes that appear repeatedly. Below are several factors leading to endangerment:
Habitat Destruction
Our planet is continually changing, causing habitats to be altered and modified. Natural changes tend to occur at a gradual pace, usually causing only a slight impact on individual species. However, when changes occur at a fast pace, there is little or no time for individual species to react and adjust to new circumstances. This can create disastrous results, and for this reason, rapid habitat loss is the primary cause of species endangerment. The strongest forces in rapid habitat loss are human beings. Nearly every region of the earth has been affected by human activity, particularly during this past century. The loss of microbes in soils that formerly supported tropical forests, the extinction of fish and various aquatic species in polluted habitats, and changes in global climate brought about by the release of greenhouse gases are all results of human activity.
It can be difficult for an individual to recognize the effects that humans have had on specific species. It is hard to identify or predict human effects on individual species and habitats, especially during a human lifetime. But it is quite apparent that human activity has greatly contributed to species endangerment. For example, although tropical forests may look as though they are lush, they are actually highly susceptible to destruction. This is because the soils in which they grow are lacking in nutrients. It may take Centuries to re-grow a forest that was cut down by humans or destroyed by fire, and many of the world's severely threatened animals and plants live in these forests. If the current rate of forest loss continues, huge quantities of plant and animal species will disappear.
Overexploitation
A species that faces overexploitation is one that may become severely endangered or even extinct due to the rate in which the species is being used. Unrestricted whaling during the 20th century is an example of overexploitation, and the whaling industry brought many species of whales to extremely low population sizes. When several whale species were nearly extinct, a number of nations (including the United States) agreed to abide by an international moratorium on whaling. Due to this moratorium, some whale species, such as the grey whale, have made remarkable comebacks, while others remain threatened or endangered.
Due to the trade in animal parts, many species continue to suffer high rates of exploitation. Even today, there are demands for items such as rhino horns and tiger bones in several areas of Asia. It is here that there exists a strong market for traditional medicines made from these animal parts.
More Factors
Disease, pollution, and limited distribution are more factors that threaten various plant and animal species. If a species does not have the natural genetic protection against particular pathogens, an introduced disease can have severe effects on that specie. For example, rabies and canine distemper viruses are presently destroying carnivore populations in East Africa. Domestic animals often transmit the diseases that affect wild populations, demonstrating again how human activities lie at the root of most causes of endangerment. Pollution has seriously affected multiple terrestrial and aquatic species, and limited distributions are frequently a consequence of other threats; populations confined to few small areas due to of habitat loss, for example, may be disastrously affected by random factors.
How to help to protect the wildlife?
One of the most important ways to help threatened plants and animals survive is to protect their habitats permanently in national parks, nature reserves or wilderness areas. There they can live without too much interference from humans. It is also important to protect habitats outside reserves such as on farms and along roadsides.
You can visit a nearby national park or nature reserve. Some national parks have special guided tours and walks for kids. Talk to the rangers to find out whether there are any threatened species and how they are being protected. You and your friends might be able to help the rangers in their conservation work
Recycle, Reduce, And Reuse • Encourage your family to take public transportation. Walk or ride bicycles rather than using the car. • Save energy by turning off lights, radios and the TV when you are not using them. • Turn off the tap while you brush your teeth and use water-saving devices on your toilet, taps and showerhead. • Ask your parents to buy products and food without packaging whenever possible. Take your own bag to the store. It will reduce the amount of garbage and waste your family produces.
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