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Why Do Some Trees Produce 'Ghost Leaves' After Autumn?
为什么有些树在秋天后还会留下‘幽灵叶片’？
精读先不看文字，完整听一遍。
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Marcescence is the botanical term for trees holding dead, brown leaves through winter instead of dropping them.枯叶宿存是植物学术语，指树木在冬季保留枯黄落叶而不脱落。
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Oak, beech, and hornbeam species often show this trait, especially in younger branches or shaded areas.橡树、山毛榉和鹅耳枥等树种常表现出这一特征，尤以幼枝或荫蔽处为甚。
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Retained leaves may deter deer browsing by making twigs look less tender or more difficult to reach.残留叶片可能通过让嫩枝显得不那么柔嫩或更难取食，从而减少鹿类啃食。
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The abscission layer—the cell barrier that normally severs leaves—fails to fully form in some individuals.离层（正常情况下切断叶片的细胞屏障）在部分个体中未能完全形成。
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Cold snaps before leaf drop can freeze cellular processes, locking leaves in place until spring winds remove them.落叶前的寒潮会冻结细胞活动，使叶片滞留至春季大风将其吹落。
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Scientists found marcescent trees lose fewer nutrients because dead leaves slowly leach minerals back into bark.科学家发现，枯叶宿存树木养分流失更少，因枯叶缓慢将矿物质析出并回补树皮。
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Wind resistance from clinging leaves may help young trees withstand winter storms and snow loads.附着叶片增加的风阻，或可帮助幼树抵御冬季风暴与积雪压力。
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This trait appears more common at forest edges, suggesting ecological adaptation rather than random mutation.该特征在林缘更为常见，表明其属生态适应而非随机突变。
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Genetic studies link marcescence to regulatory genes affecting hormone sensitivity in fall.基因研究表明，枯叶宿存与调控秋季激素敏感性的基因相关。
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Observing ghost leaves helps foresters assess tree health, microclimate effects, and climate-driven phenological shifts.观察‘幽灵叶’有助于林务人员评估树木健康、微气候影响及气候驱动的物候变化。
精读 · 大约 10 分钟
听 → 读 → 学表达 → 懂 → 今天会说这一句 → 跟读录音 → 自己说一句。
③ 学 · 重点表达
- Genetic studies link marcescence to regulatory genes affecting hormone sensitivity in fall. 基因研究表明，枯叶宿存与调控秋季激素敏感性的基因相关。
- Observing ghost leaves helps foresters assess tree health, microclimate effects, and climate-driven phenological shifts. 观察‘幽灵叶’有助于林务人员评估树木健康、微气候影响及气候驱动的物候变化。
- The abscission layer—the cell barrier that normally severs leaves—fails to fully form in some individuals. 离层（正常情况下切断叶片的细胞屏障）在部分个体中未能完全形成。
④ 懂 · 选一选
⑤ 今天会说这一句
Genetic studies link marcescence to regulatory genes affecting hormone sensitivity in fall.
⑥ 跟读并录音
Genetic studies link marcescence to regulatory genes affecting hormone sensitivity in fall.
第一版：录下来、回听、再听标准音。系统打分以后再加。
⑦ 说 · 自己来一句
用今天的表达，自己说一句。
例子：Genetic studies link marcescence to regulatory genes affecting hormone sensitivity in fall.
已记下。连续天数以后会显示在课表里。
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