首页
登录
职称英语
Forestry Forest Fire[img]2012q1/ct_etoefm_etoeflistz_0199_20121[/img] [br] What
Forestry Forest Fire[img]2012q1/ct_etoefm_etoeflistz_0199_20121[/img] [br] What
游客
2025-02-08
27
管理
问题
Forestry Forest Fire
[br] What is prescribed fire?
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、Fire that is caused by lightning
B、Fire that humans carefully manage
C、Fire that inspires artists and writers
D、Fire in areas where people live
答案
B
解析
What is prescribed fire?
The instructor says Prescribed fire, or controlled fire...; ...prescribed burns are carried out every three to five years in one of the national forests. These controlled burns....(2.2)
转载请注明原文地址:http://tihaiku.com/zcyy/3948507.html
相关试题推荐
Philosophy[img]2012q1/ct_etoefm_etoeflistz_0212_20121[/img][br]Withwhichphil
Philosophy[img]2012q1/ct_etoefm_etoeflistz_0212_20121[/img][br]Listenagainto
Philosophy[img]2012q1/ct_etoefm_etoeflistz_0212_20121[/img][br]Whichofthefo
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]Whyd
ForestryForestFire[img]2012q1/ct_etoefm_etoeflistz_0199_20121[/img][br]What
ForestryForestFire[img]2012q1/ct_etoefm_etoeflistz_0199_20121[/img][br]Accor
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
GreekMythologyGreekmythologyconcernstheanci
A—OliverTwistB—PrideandPrejudiceC—TessoftheD’urbervilles
在爆炸性环境内,会影响电气设备选择的因素有()。A.爆炸危险区域的分区
反映项目的偿债能力的指标是( )。 Ⅰ.投资;Ⅱ.偿债备付率;Ⅲ.利息备付率
患者女性,7岁,食冷饮时左下后牙感到酸痛2周,无自发痛史,检查发现颊面深龋,龋蚀
甲企业自行建造的厂房达到规定可使用状态时,发生建造成本2000万元,建造过程中
关于残角子宫,描述不正确的是A.双侧副中肾管融合不全 B.一侧副中肾管发育正常
不合理运输的最严重形式是()。 A.无效运输 B.空驶运输 C.
期货公司变更股权有下列哪些情形应当经中国证监会批准()。A.变更控股股东 B.
可参考淋证辨证论治的西医疾病是A.肋间神经痛 B.痛风 C.腰椎骨质增生
最新回复
(
0
)