Question 84·Hard·Central Ideas and Details
City planners once favored planting only a handful of tree species along urban streets because uniform canopies were thought to simplify maintenance and create a cohesive look. Recent surveys, however, show that neighborhoods dominated by one or two tree species lose canopy cover more rapidly than those with greater tree diversity. When an insect pest or fungal pathogen gains a foothold, it can sweep through a monoculture block in a single season, forcing the city to remove and replace every infected tree. By contrast, mixed plantings slow the spread of most pests, allowing workers to treat or remove the few affected trees before the damage becomes widespread.
What does the text most strongly suggest about neighborhoods with diverse tree species?
For central-idea/detail questions, locate the exact lines that discuss the topic in the question and use contrast cues (e.g., “however,” “by contrast”) to paraphrase the author’s comparison. Then eliminate choices that introduce new claims (like preventing outbreaks from starting) or contradict stated trends (like similar canopy-loss rates), and select the option that matches the passage’s cause-and-effect relationship.
Hints
Identify the line about diverse plantings
Find the sentence that begins “By contrast”—it explains what happens in mixed plantings.
Connect pest spread to canopy loss
Ask: If pests spread more slowly, what does that imply about how quickly many trees would need to be removed?
Watch for claims the passage never makes
Be careful with choices that talk about outbreaks being less likely to begin, or that claim canopy loss happens at the same rate in diverse and non-diverse neighborhoods—those points aren’t supported.
Step-by-step Explanation
Clarify what the question is asking
The question asks what the text most strongly suggests about neighborhoods with diverse tree species. So you should look for what the passage implies about greater tree diversity/mixed plantings compared with monoculture plantings.
Find the comparison the author makes
The passage contrasts low-diversity plantings with diverse plantings:
- Neighborhoods dominated by one or two species “lose canopy cover more rapidly” than those with greater diversity.
- “By contrast, mixed plantings slow the spread of most pests,” so workers can treat/remove “the few affected trees” before damage becomes widespread.
Draw the supported inference
If pests spread more slowly in mixed plantings, a pest is less likely to wipe out an entire block quickly. That means diverse neighborhoods are less likely to experience rapid, large-scale canopy loss from pests.
Choose the option that matches the inference
The choice that best matches the idea of slowed spread and damage not becoming widespread is:
They are less likely to experience rapid, large-scale tree loss due to pests.