I was walking through the woods the other day enjoying the beautiful autumn weather. It was a brisk 34 degrees outside, chilly for these last few days of October. I kept hearing an unusual pick, pick, pick sound. It definitely was not a bird, or other animal. It was too random and was coming from all around me. Have you ever been in a place where you have heard caterpillar poop drop? I have. When tobacco is hanging in a tobacco barn, you hear that sound from the tobacco horned worms (which are really caterpillars) attached to the leaves.
I stopped and kept listening. It was that same sound, but looking up to the trees I knew it couldn’t be caterpillars with this near freezing temperature. I stood listening and watching, senses alert. Then, I realized it was the sound of leaves falling from the trees. It was so cold that the leaves were nearly frozen, so when they were dropping, hitting not only the ground, but limbs, twigs, and other leaves they were making this light sound.
I wondered how could I be of this age, had a million walks in the woods in all kinds of weather and never have witnessed this before? It was an amazing thing to see and hear. Looking at the fall colors and changes in a new light brought me back to my years in school when I first learned how, and why, the fall colors appear.
I do mean – appear. What I learned long ago, was that the colors you witness in autumn are actually the true color of the leaf, yet it is only visible when the camouflaging chlorophyll breaks down.
The process actually begins in the spring. As temperatures warm and day length increases, chlorophyll production begins in the leaves as they emerge. Leaves are actually like mini-factories producing needed food for the trees. It is chlorophyll that gives leaves their green color. It is also chlorophyll that absorbs the sunlight, and with that energy it transforms carbon dioxide (brought through cells in the leaves) and water into carbohydrates, like sugars and starch. (This is why some refer to trees as the lungs of the Earth. They take in carbon dioxide, and expel oxygen. Another reason why clearing the rain forests is killing us.)
In autumn, as temperatures drop and day length shortens, the leaf factories stop making the sugars and starch. Chlorophyll breaks down, the green color fades, and the trees' true colors that we know and love become visible. Vibrant yellows, (xanthophyll) oranges (carotenes, as in carrots) appear from behind the chlorophyll mask. Red and purple colored leaves get their color through another chemical process in which anthocyanin, or red, is made. Anthocyanin is what makes dogwoods, and sumacs, and other such trees and shrubs display beautiful reds and deep purples.
Knowing about chlorophyll and its role in beautiful autumn colors always makes me look at tree leaves in spring and summer and dream about the beautiful colors the green is masking. Treat yourself this week, take a walk in the woods and enjoy the fall colors!
-- Lynn Youngblood is the Executive Director of the Blue River Watershed Association in Kansas City, Missouri. Reach her at TheGreenSpace@sbcglobal.net