科学素养与生活应用·英语30篇（4）

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秋叶变色之谜：超越温度的化学机制

Leaf color change begins when shorter days trigger hormonal shifts inside tree tissues.
Chlorophyll breaks down slowly, revealing pre-existing yellow and orange carotenoid pigments.
Red anthocyanins form anew in fall as sugars get trapped in leaves under sunny, cool conditions.
Soil moisture and nutrient levels also influence pigment intensity and timing each year.
Maple trees produce vivid reds because they actively synthesize anthocyanins before leaf drop.
Scientists analyze leaf samples with spectrophotometers to quantify pigment ratios precisely.
Climate change is altering typical color onset dates and duration across temperate forests.
Some trees retain green leaves longer due to genetic traits affecting abscission layer formation.
Photographers and ecologists alike use leaf-color maps to track seasonal ecosystem responses.
Understanding this chemistry helps predict forest health and carbon cycle feedbacks.