The Science Behind Changing Fall Leaves

What exactly are the scientific processes behind changing fall leaves? If you've wondered, you're in luck. The Mountain Mail explains its all for you. "Under the headline, "Fall Colors Expected in Two Weeks," Mail News Editor Paul Goetz describes exactly how an aspen or cottonwood leaf goes from green to orange, read or gold. While different U.S. Forest Service employees contradict their colleagues in the last story we posted, over when exactly the leaves will change, Goetz's article offered this explanation:

"Increased night length is the primary regulator of autumn leaf change. As days shorten and nights lengthen, biochemical processes in leaves begin to change leaf colors.

"Leaf pigments come from chlorophyll, carotenoids, and anthocyanins.

"Chlorophyll gives trees basic green color. Trees in temperate zones store sugars produced by chlorophyll for their winter dormant period.

"Carotenoids produce yellow, orange and brown in foods such as corn, carrots and bananas.

"Anthocyanins are water soluble and appear in the watery liquid of leaf cells. They produce color in foods such as cranberries, red apples, concord grapes, blueberries, cherries and strawberries.

"Chlorophyll and carotenoids are present in the choloroplasts of leaf cells during growing season.

"Most anthocyanins are produced in autumn in response to bright light and excess plant sugar within leaf cells. During the growing season chlorophyll is continuously produced and broken down and leaves appear green.

"In the autumn, however, chlorophyll production slows, stops and eventually is destroyed, unmasking colors from carotenoids and anthocyanins and the tree exhibits color change. "

You can read the rest of this informative article here.