Golden and red leaves are always the things in autumn. But because of warming weather, a warmer autumn makes the leaves change color later. Today, red leaves in some countries have arrived one month later than they did over 100 years ago. Some leaves even fall(落下) before turning red. We might lose this beautiful color someday in the future.
How do trees turn red?
In spring and summer, trees make chlorophyll (叶绿素) to grow. When it gets cold, they stop making chlorophyll. The yellow and red pigments (色素) are under the chlorophyll. They show up in autumn.
The red color helps the trees beat the cold by . . .
• making the leaves warm.
• helping trees take in the last nutrients (营养物) from the leaves before they fall.
Late red leaves can be bad for trees.
• Trees may have a shorter life.
• Trees may not grow well next spring.
• Some weak trees may die.