Why do leaves flash brilliantly before tumbling to the forest floor?
It’s tempting to believe that trees just want to look good one last time before winter, but leaf color change isn’t deliberate and has no benefit to trees or leaves. Instead, it’s just a pleasant (for people!) by-product of chemical processes occurring within the cells of leaves. Shortening day length in the fall reduces and eventually halts the production of green chlorophyll, which is necessary for leaf cells to produce sugars (or tree food) from sunlight. The decline of chlorophyll in the leaves reveals other pigments, the yellow, orange and brown carotenoids and the reddish anthocynanins. Not all trees have anthocyanins in their leaves, but those that do might vary in the intensity of leaf color based on weather. A combination of cool nights and sunny days in early fall produces and locks more of the red pigments in the leaves. Wet or dry conditions during the year also influence autumn colors. Not all trees change color at the same time. Sassafras and sumac typically start the dis
