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Q: Why do some trees lose their leaves in winter, while pine trees do not?

A: Trees that lose their leaves during the winter are called deciduous, from the Latin word meaning “to fall off,” and the loss of leaves allows them to survive. Broad leaves, such as oak or elm, have a high surface area to capture sunlight for photosynthesis, but they also have many pores that allow water to escape into the air. When the ground is frozen, they would not be able to replace the water lost through leaves, and they would die, said biologist Eric Davies of the University of Nebraska. The leaves change color because the dominant green chlorophyll is the first constituent to break down, allowing other colors to show through. The needlelike leaves of pine trees have few pores, and they are coated with a waxy substance that further reduces water loss, so they can safely retain the leaves.