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Difficulty: EasyCentral Ideas

For much of the twentieth century, forest management policies in the western United States prioritized the immediate suppression of all wildfires. However, ecologists have since determined that this practice has inadvertently threatened the giant sequoia (*Sequoiadendron giganteum*). Giant sequoias possess thick, fire-resistant bark and rely on low-intensity forest fires to clear competing undergrowth, which creates nutrient-rich soil and allows sunlight to reach seedlings. Furthermore, the intense heat from these fires is required to open the trees' tightly closed cones, facilitating seed dispersal. By preventing these natural fire cycles, suppression efforts have hindered the reproduction of giant sequoias and allowed shade-tolerant trees to crowd out new growth, demonstrating that periodic fire is essential for the long-term survival of the sequoia ecosystem.

Which choice best states the main idea of the text?

  1. Natural, low-intensity forest fires are necessary for giant sequoias to reproduce and survive.Answer
  2. B
    Forest management policies in the western United States have historically focused on fire suppression.
  3. C
    Giant sequoias have developed thick bark to prevent their cones from opening during fires.
  4. D
    Without human intervention, wildfires would have completely destroyed the giant sequoia forests.

Answer

Natural, low-intensity forest fires are necessary for giant sequoias to reproduce and survive.
The correct answer accurately summarizes the passage's main point: that giant sequoias rely on low-intensity fires for clearing competing undergrowth, opening their cones for seed dispersal, and ultimately surviving.

Step-by-Step Solution

1
Identify the primary subject and the author's argument regarding that subject in the passage.
The passage discusses giant sequoias and explains how historical fire suppression policies have threatened them because these trees depend on fires for reproduction and clearing competing growth.
Establishing the main subject and the author's core claim is the first step in finding the central idea.
2
Evaluate the choices to find the one that accurately summarizes this relationship.
The statement that natural, low-intensity forest fires are necessary for giant sequoias to reproduce and survive directly reflects the main point of the passage.
The correct answer must represent the central idea of the entire text.

Key Concept

Identifying the central idea of a passage requires distinguishing between background context, secondary details, and the author's primary argument.
Estimated Time:1m 0s
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