Photo Illustration

The leaves of thousands of trees have spent the summer shading our streets and parks, backyard cookouts and school playgrounds.

Soon most of them will change color and fall to the ground, marking the end of the summer growing season.

Summer officially ends today when the length of darkness becomes more than the length of daylight each day. We will continue to see less daylight than darkness every day until the end of fall in late December.

The shorter days and cooler nights are the two main reasons the leaves change color and eventually fall to the ground.

When viewed from nearby hills, the neighborhoods of Marietta and Parkersburg are covered by thousands of trees holding millions of leaves.

“I love fall, watching the trees change from green to wonderful bright colors,” said Grady Smith, co-chair of the Marietta Tree Commission, of the 10,000 or so trees that blanket Marietta with millions of leaves during the summer.

“Trees keep the canopy cool and absorb a lot of moisture and eliminate a lot of storm runoff in the city,” added Smith. With the onset of fall “some species lose all their leaves, some lose them gradually, and some keep them until they are shoved off by new leaves in the spring.”

As a volunteer at the Washington Works Nature Trails, Dave Johnson keeps an eye on the leaves year-round.

“Fall is one of my favorite seasons, I love watching the forest open up and being able to see through it.” For the animals that live under the tree canopy the loss of the leaves sends them a message. “It’s a signal to them to either leave or get ready to hibernate.”

“Our nature trails have around 50 different tree labels. We have brought in additional native trees as well. I love the temperature change in fall, It’s a great time to take a walk in the woods,” Johnson added of the trails that are open to the public along Dupont Road near U.S. 50 and the Blennerhassett Bridge.

“With the thinning trees you get to see the shapes of the stumps and root balls,” said Johnson. His favorite trees include the Sweetgum “because of the color” and the Paw Paw tree. “If you are in the woods in late September when the fruit is ripe it will have a sweet aroma.”

Leaves change color because the chlorophyll that produces sugars to feed the trees quits working as the daylight decreases. The green of chlorophyll masks the colors produced by chemicals called carotenoids and anthocyanin that provide all the wonderful shades of reds and yellow, browns and orange that we see through the fall.