十万个为什么·科学阅读30篇（2）
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Why Do Some Trees Shed Leaves Only in Spring — Not Autumn?
为什么有些树只在春天落叶，而不是秋天？
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Most deciduous trees lose leaves in autumn to conserve water during cold winters.
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But certain species like the Indian coral tree drop old leaves only in early spring.
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This timing helps them avoid drought stress while preparing for new growth simultaneously.
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Their leaf-shedding is triggered by rising temperatures and longer daylight hours, not cold.
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Scientists found that specialized hormones respond to photoperiod cues more strongly than temperature here.
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The process allows rapid flowering before new leaves block sunlight from blossoms.
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Roots remain active year-round, storing energy for synchronized leaf and flower emergence.
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Unlike temperate trees, these species evolved in tropical climates with distinct wet-dry cycles.
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Botanists use this trait to study how climate change affects seasonal plant behavior.
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Researchers monitor leaf-fall patterns across decades to track ecosystem adaptation rates.