Today’s blog
Lynn Murphy Mark
Fall colors
It’s that time of year when green miraculously turns into red, orange, umber, and yellow. There is a tree in Kirkwood that I see every Fall and it is absolutely a luminous deep yellow shade. I look forward to that tree when I’m in the area and my car automatically slows down as I drive past its beauty. On my way home there is a huge Burning Bush that is now all scarlet. The plant has a fancy name, Euonymus alatus. In some language that must mean “I’m glorious in the Fall”.
I don’t understand how one color becomes another completely different shade as the sunlight fades and the air is cooler. So I looked it up. It’s all about photosynthesis. Green leaves happen when chlorophyll is at work, using sunlight to change carbon dioxide and water into sugar and oxygen. In addition chlorophyll absorbs all of the colors in sunlight.
When Fall arrives and nights get longer, the chlorophyll breaks down and leaves lose their green color. But, leaves contain pigments called carotenoids that make the leaves look yellow or the bright orange that we associate with carrots. Red leaves require yet another step: some species of trees produce new pigments called anthocyanins that result in the glorious reds that we see. There is a purpose to the effort it takes to produce anthocyanins. They act as sunscreen for the leaves and also discourage insects from eating the leaves. Then there are the “plain jane” trees whose leaves turn brown and drop off without a show of color.
There is a comforting, orderly set of processes in Nature. I know I can count on trees to respond to the changing seasons the same way every year. I love the onset of Spring, when the green of the new leaves is an absolutely glowing, neon green. Trees are producing their very own food markets to last them through Spring and whatever heat and drought Summer might bring.
The bad news is that climate change with its increasing warmth has already begun to affect how long the leaves stay on trees and how soon the color change begins. Warm weather signals to the trees that it is not time yet to stop making chlorophyll. Scientists have also studied the shortening time between the riot of color and the leaf drop that sends those colors to the ground.
I read that the East Coast economy makes about $30 Billion in tourist money when people travel to see the leaves change colors. From the Carolinas up into the Northeast this time of year brings new people and new money. With color change happening later and lasting less time, the merchants of those places are adversely affected. Another reason for people to take to the streets and protest the very real consequences of climate change.
Yesterday I was driving home on a multicolor street, admiring the foliage. The sight brings me joy and I remember how much I love the onset of Fall. Autumn means cooler days and nights and Halloween and Thanksgiving and football and the World Series. It also means that Christmas Music time is slowly approaching and some day in the not too distant future I can start playing Handel’s Messiah. All of this makes me just plain happy!