洛杉磯野火肆虐!托福考生不可錯過的環境科學背景知識

美國加州洛杉磯野火自2025年1月7日爆發以來持續延燒,造成當地許多房屋毀損,數十萬人被迫撤離家園,甚至有人身亡。除了關心本次洛杉磯野火災情外,趁這個機會來學習托福測驗中可能考出的環境科學主題背景知識及關鍵詞彙。

野火主題有可能出現在托福的多個部分,特別是涉及自然災害、環境保護或氣候變遷等相關內容。考生在準備托福時,若能深入了解這些議題,不僅能提升應試技巧,還能增強對相關閱讀和聽力材料的理解與分析能力。

引發洛杉磯野火可能原因

1.乾旱與氣候變遷

洛杉磯位於乾旱氣候區,由於長期缺水與氣溫升高,使得植物乾枯,易於引發火災。氣候變遷(climate change)加劇了極端天氣的發生,也增加了火災的風險。

2.強風

洛杉磯地區常常受到強風影響,尤其是「聖塔安那風(Santa Ana winds)」,這是一種典型的南加州季節性強風。這種風能夠迅速擴散火勢,將火災範圍擴大。

3.人為因素

露天燒烤、露營、電力設備故障以及違法放火等人為活動也是引發火災的主要原因之一。

洛杉磯野火災情及影響

1.對居民與社區的影響

野火直接威脅居民生命財產安全,導致房屋損毀、居民被迫撤離,而火災帶來的恐懼及壓力,也會造成民眾產生心理創傷。火災還導致了空氣品質惡化,對健康造成長期影響。

2.對生態與環境的影響

火災對當地的植物和野生動物構成嚴重威脅,許多物種因失去棲息地而面臨滅絕危機,破壞了生態平衡。

3.對經濟的影響

野火對當地經濟造成巨大損失,特別是對農業(agriculture)、保險業和旅遊業造成長期負擔。農業方面,許多農田和農作物被火災燒毀,農民面臨直接的經濟損失,並可能需要數年時間才能恢復;保險業方面,大規模災情使得保險賠償金額激增,政府和企業的應急處理成本也隨之上升;旅遊業方面,加州是美國的旅遊熱點之一,火災對當地觀光構成負面影響。

托福考試高頻單字

英文 中文
wildfire 野火
ignition 起火
blaze 大火
drought 乾旱
heatwave 熱浪
climate change 氣候變遷
Santa Ana winds 聖塔安那風
agriculture 農業
vegetation 植被
evacuation 撤離
firebreak 防火線
Los Angeles County 洛杉磯郡

TOEFL TPO真題補充分享

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 take 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 the 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. All of the following are mentioned in paragraph 1 as consequences of logging that can promote forest fires EXCEPT:
A. Fires are accidentally started by loggers.
B. Pieces of flammable wood are left behind in the forest.
C. There is a dense growth of new plants that act as fuel for fire.
D. The most fire-resistant trees are removed by the loggers.

2. What can be inferred from paragraph 2 about forest-fire suppression before 1900?
A.It was more effective than afterward because there were fewer fires to suppress in most regions.
B.There was no official program of forest-fire suppression in the United States.
C.Forest-fire suppression was practiced more for the purpose of protecting homes than for protecting forests.
D.The Forest Service had rules to control forest fires, but the rules were ignored.

3. Why does the author include the quotation “Put out every forest fire by 10:00 A.M.on the morning after the day when it is first reported”?
A.To suggest that the Forest Service’s goals were unrealistic and ultimately unattainable
B.To demonstrate how seriously the Forest Service took their responsibility of fire suppression
C.To support the idea that fire-suppression techniques are most effective early in the day
D.To provide an example of the new methods that resulted in successful firefighting after 1945

問題解答

  1. 以下哪些選項不是第一段提到的伐木後可能促進森林火災的結果?
    答案:A. 火災是伐木工人意外引發的。
    解析:
    第1段提到:
    • 可燃的木材殘留在森林裡(B)。
    • 伐木後新植物密集生長,成為火災燃料(C)。
    • 最耐火的樹木被砍伐帶走(D)。

但文中未提到伐木工人會意外引發火災,因此正確答案是 A。

  1. 根據第二段,可以推斷出1900年前的森林火災撲滅情況是什麼?
    答案:B. 在美國,當時沒有正式的森林火災撲滅計畫。
    解析:
    文章提到美國森林服務局在1900年代初才開始採取火災撲滅政策,這表明在此之前並無正式的火災撲滅計畫,因此選擇 B。
  2. 為什麼作者引用「在火災首次報告的第二天早上10:00前撲滅所有森林火災」這句話?
    答案:B. 為了說明森林服務局對火災撲滅的責任非常重視。
    解析:
    這句話突出了森林服務局的嚴格目標,表明他們對火災控制的高度重視,展現對滅火工作的責任感。

為何托福考生應該關注野火?

野火涉及氣候變遷、生態系統平衡、人類活動與自然環境的互動等多個環境科學話題,這些都是托福閱讀和聽力部分的常見考點。透過了解野火的相關內容,有助於考生掌握相關背景知識和專業詞彙,進一步提升應試表現。

封面圖片來源:美聯社