首页
登录
职称英语
Forestry Forest Fire[img]2012q1/ct_etoefm_etoeflistz_0199_20121[/img] [br] Accor
Forestry Forest Fire[img]2012q1/ct_etoefm_etoeflistz_0199_20121[/img] [br] Accor
游客
2025-02-08
32
管理
问题
Forestry Forest Fire
[br] According to the instructor, how does the elimination of fire endanger the forest?
We all know that change is a fact of life. For North American forests, change often comes in the form of fire. After thousands of years of living with fire, many plant and animal species have come to depend on its periodic presence. Without fire, ecosystems can stagnate and lose their diversity of life.
In the past, before we understood the role that fire plays in the natural life cycle of our forests, our goal was to prevent or contain all forest fires. For almost ninety years, our land management agencies tried to eliminate fires. In many cases, we protected the trees, but at the expense of the forest community. Now we know that fire is a natural agent that rejuvenates a forest. And we know that fire suppression can actually threaten the lives of healthy trees. So, today our policy is to allow natural fires to burn under close observation and to set "prescribed" fires under carefully controlled conditions.
Research shows that forests go through natural fire cycles. Periodic fires are necessary for several reasons. Fire removes nutrients from standing dead trees and returns them to the earth, where they become available to the root systems of new trees. Fire also opens the forest to sunlight. Openings in the tree cover benefit a variety of wildlife by stimulating the growth of lush green plants, which are eaten by several species of animals.
Fire is nature’s way of controlling insect infestations. By contrast, fire suppression preserves dead wood that harbors insect pests, like the larvae of the mountain pine beetle. These beetle larvae feed on the inner bark of some trees, which blocks the flow of nutrients and eventually kills the trees. When dead trees burn during periodic outbreaks of fire, the heat kills off great numbers of beetles and larvae, providing a natural method of pest control.
The exclusion of fire from the ecosystem is creating unhealthy, overcrowded forests that contain more fuel for larger, more severe fires. For example, when a huge fire threatened a grove of giant sequoias in California, observers noted that the flames were fed by dead wood and combustible debris that had accumulated on the forest floor over years of fire suppression.
A large-scale, intense forest fire causes more significant impacts to water, soil, and air resources than a managed prescribed fire. Prescribed fire, or controlled fire, has several purposes. Chiefly, it reduces the hazard of more serious wildfires by periodically burning accumulated weeds, brush, and other plants. If done carefully, prescribed burning also releases nutrients back into the soil and controls insect pests. In Florida, prescribed burns are carried out every three to five years in one of the national forests. These controlled burns keep the forest open and reduce the growth of problem species.
We recognize that fire is a natural and revitalizing process that enhances the diversity of the forest. However, we also know that fire has consequences. There may be smoky, hazy skies and patches of blackened forest for a long time after a fire. There’s also the risk of a fire becoming too large and threatening inhabited areas. But we have to accept these realities if our forests are to retain their ecological balance.
选项
A、Insect populations die without the heat provided by fire.
B、Dead wood and litter accumulate as fuel for large fires.
C、Too many people move into the forest, destroying wildlife habitat.
D、Animal populations grow too fast for the forest to support them.
答案
B
解析
According to the instructor, how does the elimination of fire endanger the forest?
The instructor says The exclusion of fire from the ecosystem is creating unhealthy, overcrowded forests that contain more fuel for larger, more severe fires; ... the flames were fed by dead wood and combustible debris that had accumulated on the forest floor over years of fire suppression. (2.2)
转载请注明原文地址:http://tihaiku.com/zcyy/3948506.html
相关试题推荐
ZoologyAnimalDefenses[img]2012q1/ct_etoefm_etoeflistz_0219_20121[/img][br]Wh
ZoologyAnimalDefenses[img]2012q1/ct_etoefm_etoeflistz_0219_20121[/img][br]Wh
ZoologyAnimalDefenses[img]2012q1/ct_etoefm_etoeflistz_0219_20121[/img][br]Wh
Philosophy[img]2012q1/ct_etoefm_etoeflistz_0212_20121[/img][br]Whichideasare
Philosophy[img]2012q1/ct_etoefm_etoeflistz_0212_20121[/img][br]Listenagainto
ConversationLearningResourceCenter[img]2012q1/ct_etoefm_etoeflistz_0206_20121
ConversationLearningResourceCenter[img]2012q1/ct_etoefm_etoeflistz_0206_20121
ConversationLearningResourceCenter[img]2012q1/ct_etoefm_etoeflistz_0206_20121
ForestryForestFire[img]2012q1/ct_etoefm_etoeflistz_0199_20121[/img][br]Accor
ForestryForestFire[img]2012q1/ct_etoefm_etoeflistz_0199_20121[/img][br]Liste
随机试题
[originaltext]W:Tim,didyougetyourticketfortheconcertFriday?M:Itrie
B
轴屋面檐部共需多少根挑檐木?() A.7 B.8 C.9 D.1
公路水运工程试验检测机构应当建立健全档案制度,保证()。A、档案齐备 B、内
患者男,50岁。因心前区出现压榨样疼痛3小时,伴冷汗、恐惧急诊入院。下列检查中,
D-洋地黄毒糖属于A.6-去氧糖B.6-去氧糖甲醚C.2,6-二去氧糖D.α-氨
人参贮藏时含水量应控制在A.5%~10%B.12%~15%C.15%~20%D.
索鞍是()。A.斜拉桥的构件 B.联结吊杆与主缆的构件 C.支撑主缆
阻塞性肺气肿最常见的病因是A、支气管哮喘 B、支气管扩张 C、慢性支气管炎
某土方工程,施工合同约定:工程无预付款,进度款按月结算,工程保留金从第一个月起按
最新回复
(
0
)