首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Forestry Forest Fire According to the instructor, how does the elimination of fire endanger the forest?
Forestry Forest Fire According to the instructor, how does the elimination of fire endanger the forest?
admin
2012-01-14
52
问题
Forestry Forest Fire
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:https://kaotiyun.com/show/KUyO777K
0
托福(TOEFL)
相关试题推荐
Youshouldspendabout20minutesonQuestions27-40whicharebasedonReadingPassage3below.THEINGENUITYGAPIngenuity,as
CompletethesentencesbelowusingNOMORETHANTWOWORDSfromthepassage.Writeyouranswersinboxes23-26onyouranswershe
Youshouldspendabout20minutesonQuestions27-40whicharebasedonReadingPassage3below.TheRainmakerSometimesideasj
CompletethesentencesbelowusingNOMORETHANONEWORDfromthepassage.Writeyouranswersinboxes32-35onyouranswershee
Youshouldspendabout20minutesonQuestions1-13,whicharebasedonReadingPassage1below.AAmericanstodaychooseamong
AncientPeopleinSaharaOnOct.13,2000,PaulSereno,aprofessorfromtheUniversityofChicago,guidedateamofpalaeon
HowdesertsareformedA.Adesertreferstoabarrensectionofland,mainlyinaridandsemi-aridareas,wherethereisal
Gestures—especially______ones.Flashcardscanbedifferentcoloursaccordingtothe______.
Thelecturersaysthatanessayislike______toaspecificquestion.【33】
Whichattitudeisassociatedwiththefollowingpeopleduringtheconversation?ChooseSIXanswersfromtheboxandwritetheco
随机试题
某行政单位20X9年12月发生如下经济业务:(1)1日,用行政经费拨款购买复印机一台,以银行存款支付价款30000元。(2)2日,购入维修用材料5000元,以转账支票支付。(3)8日,收到应全额缴存的预算外资金40000元,存入银行。(4)9日,将
下列关于肾上腺糖皮质激素的叙述,正确的是
(1)简述单价合同的特点以及在单价合同中承包商不平衡报价的几种形式。(2)某工程Q工作面发生以下原因引起停工:2003年9月30日至10月3日承包人的设备出了故障;监理工程师向承包人提供后续图纸比规定的时间晚了10天(10月1日至10日);10月
某工程双代号网络计划中各节点的最早开始时间与最迟开始时间如下图所示,该计划表明()。
下列对于税务行政复议的管辖原则理解正确的是()。
我国的官方证券监管机构是()。
《洗冤集录》的作者是()
以下关于非对称加密算法说法中不正确的(18)。
请根据以下各小题的要求设计VisualBasic应用程序(包括界面和代码)。(1)在名称为Forml的窗体上建立两个名称分别为Commandl和Command2、标题为“显示”和“清除”的命令按钮,一个名称为Textl、初始内容为空的文本框,程序运
A、Heliveswithafirst-yearstudentB、HewantedtoliveinanapartmentC、Heisn’tanewstudentD、Hewasassignedspaceinad
最新回复
(
0
)