TPO的全称是TOEFL Practice Online,即
下面是
TPO 20
Reading
In the United States, it had been common practice since the late 1960s no to suppress natural forest fires. The “let it burn” policy assumed that forest fire would burn themselves out quickly, without causing much damage.
However, in the summer of 1988, forest fires in Yellowstone, the most famous national park in the country, burned for more than two months and spread over a huge area, encompassing more than 800,000 acres. Because of the large scale of the damage, many people called for replacing the “let it burn” policy with a policy of extinguishing forest fires as soon as they appeared. Three kinds of damage caused by the “let it burn” policy were emphasized by critics of the policy.
First, Yellowstone fires caused tremendous damage to the park’s trees and other vegetation. When the fires finally died out, nearly one third of Yellowstone’s land had been scorched. Trees were charred and blackened from flames and smoke. Smaller plants were entirely incinerated. What had been a national treasure now seemed like a devastated wasteland
Second, the park wildlife was affected as well. Large animals like deer and elk were seen fleeing the fire. Man smaller species were probably unable to escape. There was also concern that the destruction of habitats and the disruption of food chains would make it impossible for the animals that survived the fire to return.
Third, the fires compromised the value of the park as a tourist attraction, which in turn had negative consequences for the ocal economy. .with several thousand acres of the park engulfed in flames, the tourist season was cut short, and a large number of visitors decided to stay away. Of course, local businesses that depended on park visitors suffered as a result.
Listening
Actually fires are natural part of ecological cycle and their role is not just destructive but also creative. That is why the “let it burn” policy is fundamentally a good one, even if it sometimes causes fires of the 1988 Yellowstone fire. Let’s look at what happened after 1988 Yellowstone fire.
First, vegetation. As you might imagine, scorched areas were in time colonized by new plants. As a matter of fact, the plants in Yellowstone became more diverse because the fire created an opportunity for certain plants that could not grow otherwise. For example, areas where the trees have been destroyed by fire could now be taken over by smaller plants that needed open and shaded space to grow. And another example, seeds of certain plants species won’t germinate unless they’re exposed to very high levels of heat. So, those plants started appearing after the fire as well.
It’s a similar story with the animals. Not only did their population recover, but the fire also created new opportunities. For instance, the small plants that replaced trees after the fire created an ideal habitat for certain small animals like rabbits and hares. And when rabbits and hares started thriving, so did some predators that depended on them for food. So, certain food chains actually became stronger after the fire than they were before.
And last, fires like 19888 Yellowstone fire would be a problem for tourism if they happened every year. But they don’t. it was a very unusual combination of factors that year, low rainfall, unusually strong winds, accumulation of dry undergrowth that caused fire to be so massive. This combination has not occurred since and Yellowstone has not seen such a fire since 1988. Visitors came back to the park next year and each year after that.
网整理
如需更多资料，请来网!