托福official39阅读第3篇Forest Fire Suppression题目解析

Forest Fire Suppression
Forest fires have recently increased in intensity and extent in some forest types throughout the western United States. This recent increase in fires has resulted partly from climate change the recent trend toward hot, dry summers and partly from human activities, for complicated reasons that foresters came increasingly to understand about 30 years ago but whose relative importance is still debated. One factor is the direct effect of logging, which often turns a forest into something approximating a huge pile of kindling (wood for burning): the ground in a logged forest may remain covered with branches and treetops, left behind when the valuable trunks are carted away; a dense growth of new vegetation springs up, further increasing the forest's fuel loads; and the trees logged and removed are of course the biggest and most fire-resistant individuals, leaving behind smaller and more flammable trees.

Another factor is that the United States Forest Service in the first decade of the 1900s adopted the policy of fire suppression (attempting to put out forest fires) for the obvious reason that it did not want valuable timber to go up in smoke, or people's homes and lives to be threatened. The Forest Service's announced goal became "Put out every forest fire by 10:00 A. M. on the morning after the day when it is first reported." Firefighters became much more successful at achieving that goal after 1945, thanks to improved firefighting technology. For a few decades the amount of land burnt annually decreased by 80 percent. That happy situation began to change in the 1980s, due to the increasing frequency of large forest fires that were essentially impossible to extinguish unless rain and low winds combined to help. People began to realize that the United States federal government's fire-suppression policy was contributing to those big fires and that natural fires caused by lightning had previously played an important role in maintaining forest structure.

The natural role of fire varies with altitude, tree species, and forest type. To make Montana's low-altitude ponderosa pine forest as an example, historical records, plus counts of annual tree rings and datable fire scars on tree stumps, demonstrated that a ponderosa pine forest experiences a lightning-lit fire about once a decade under natural conditions (i.e.., before fire suppression began around 1910 and became effective after 1945). The mature ponderosa trees have bark two inches thick and are relatively resistant to fire, which instead burns out the understory - the lower layer - of fire-sensitive Douglas fir seedlings that have grown up since the previous fire. But after only a decade's growth until the next fire, those young seedling plants are still too low for fire to spread from them into the crowns of the ponderosa pine trees. Hence the fire remains confined to ground and understory. As a result, many natural ponderosa pine forests have a parklike appearance, with low fuel loads, big trees spaced apart, and a relatively clear understory.

However, loggers concentrated on removing those big, old, valuable, fire-resistant ponderosa pines, while fire suppression for decades let the understory fill up with Douglas fir saplings that would in turn become valuable when full-grown. Tree densities increased from 30 to 200 trees per acre, the forest's fuel load increased by a factor of 6, and the government repeatedly failed to appropriate money to thin out the saplings. When a fire finally does start in a sapling-choked forest, whether due to lightning or human carelessness or (regrettably often) intentional arson, the dense, tall saplings (young trees) may become a ladder that allows the fire to jump into the crowns of the trees. The outcome is sometimes an unstoppable inferno.

Foresters now identify the biggest problem in managing Western forests as what to do with those increased fuel loads that built up during the previous half century of effective fire suppression. In the wetter eastern United States, dead trees rot away more quickly than in the drier West, where more dead trees persist like giant matchsticks. In an ideal world, the Forest Service would manage and restore the forests, thin them out, and remove the dense understory by cutting or by controlled small fires. But no politician or voter wants to spend what it would cost to do that.

1.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

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【题目翻译】下面哪句话最能表达文章中突出显示的句子中的基本信息?错误的选择会以重要的方式改变意义,或者遗漏重要的信息。 A:人类活动引起的气候变化是近30年来火灾增加的主要原因。 B:虽然人类活动肯定被认为是一个因素,但森林学家仍在争论气候是否在最近的火灾增加中起作用。 C:由于复杂的原因,在过去的30年里,在炎热干燥的夏季发生的火灾数量有所增加。 D:气候变化和人类活动都是导致最近森林火灾增加的原因,尽管这些因素的作用仍未达成一致。 【判定题型】:根据题目问法,题目要求选择和高亮句意思逻辑都最为接近的句子,故判断本题为句子简化题。 【句子分析】题根据题干找到高亮部分:This recent increase in fires has resulted partly from climate change (the recent trend toward hot, dry summers) and partly from human activities, for complicated reasons that foresters came increasingly to understand about 30 years ago but whose relative importance is still debated. 本句大意是:最近森林火灾的增长一部分是气候变化(夏天变得更干更热)和人类活动的原因,虽然这些复杂原因谁更重要还在争论中。 【选项分析】 A.选项A说人类活动导致气候变化,错误; B.选项B说森林学家还在争辩气候变化算不算一个导致森林大火的原因,错误,只是在争辩谁更重要; C.选项C说在夏天的森林大火增多,本句没有具体说到在哪个季节森林大火多,错误。 D.符合文意,正确。





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