Thursday, December 1, 2022

Autumn: A Season of Beautiful Colors

Temperatures have dropped a bit, pumpkin spice can be found in abundance, and unusual gourds are making appearances on front porches throughout the City.

Fall is making its casual entrance to Southlake, but soon she’ll crescendo with foliage of gold, ruby, and orange. While we aren’t on the east coast and won’t experience a blanket of dramatic hues across our city, there are still opportunities to take in some enjoyable leaf peeping in Southlake in the coming weeks. We sat down with Landscape Administrator Keith Martin to learn more about fall foliage and what Southlakers can expect in the coming weeks.

Graphic of fall leaves changing colorsCan you explain what causes leaves to turn vibrant, orange, yellow or red?

K. Martin: During the warmer months, all trees and most plants produce a chemical called chlorophyll which gives leaves their green color pigment and absorbs energy through sunlight. That energy is used to transfer electrons from water gathered from the soil to carbon dioxide gathered from the atmosphere. In the process, the water loses electrons and turns into oxygen, while carbon dioxide gains electrons and turns into glucose, food for the tree. The tree releases the oxygen and stores the glucose to grow strong and healthy. This process is called photosynthesis.

They also produce other chemicals such as carotenoids and xanthophyll which have red and yellow pigments, but the pigments of these chemicals are generally masked by the darker green chlorophyll. In the autumn the days become shorter, and the weather becomes cooler. In deciduous trees, these factors trigger a stop to photosynthesis, the production of chlorophyll, and they ready themselves for dormancy during the colder months. The green color of leaves fades as the chlorophyll begins to break down and the other chemical pigments such as the carotenoids become present. The fall colors of leaves depend on how much of other chemicals are present when the chlorophyll begins to break down. Leaves with more carotenoids tend to be more yellow, while leaves with more xanthophyll are more orange. But, depending on the tree species the leaves will reveal a particular color.

Because it takes a lot of energy for the tree to make chlorophyll, the color change usually happens gradually before the leaves fall off the tree. The tree breaks down the chlorophyll and reabsorbs it, then when it’s warm and sunny enough to grow again, it uses the absorbed molecules to remake the chlorophyll. That way the trees and plants don’t have to make a totally new batch of chlorophyll from scratch, which saves energy.

Picture of Keith Martin using a Biltmore Tool

Keith Martin, Landscape Administrator, measures an oak tree in Bicentennial Park.

Are there species of trees in Southlake that will be particularly beautiful in the fall?

K. Martin: The most colorful trees are generally not native to Southlake and were planted either by the City, during development, or by residents. These are trees such as cultivars of Red Maple, Chinese Pistache, and Red Oaks. All other trees such as Post Oak, Cedar Elm, American Elm, and Hackberry that are most prominent throughout the City generally turn more yellow than red or orange. But this has to do with the temperature and if we are in a drought or have ample rainfall, and how fast temperatures fall.

Bob Jones Nature Center and Preserve in the Fall

Fall leaves line the trail at Bob Jones Nature Center and Preserve.

Where might people find colorful trees during autumn months?

K. Martin: Because they have the most abundant amount of trees Bob Jones Park, the Bob Jones Nature Center, and the Corps property around the lake are probably the best locations to see fall color. People will see Post Oak, Blackjack Oak, Cedar Elm, American Elm, Slippery Elm, Pecan, Black Hickory (mainly at the Bob Jones Nature Center), Ash, Hackberry, and a few other native trees.

But there are plenty of trees around town that can get showy during the fall, as well. It’s a good idea to make it a point to look for them. Sometimes it’s just a matter of noticing. Watch the trees in the FM 1709 medians, local parks, and even in yards for brilliant displays of color. You might be surprised at how much there is to see.

When is the best time to go leaf peeping in Southlake?

K. Martin: Trees should start changing color in middle October to early November. It all depends on species and if there are periods of warm sunny days with cool nighttime temperatures.

We love trees in Southlake! Can you tell us more about how the City will be showcasing trees in the coming months?

K. Martin: Texas Arbor Day is the first Friday in November, November 4th. And we are making plans later in the month for an event to celebrate our trees. Stay tuned for more information on how to be a part of it.

Southlake has been recognized as a Tree City USA city for more than 20 years. We have had a tree preservation ordinance since 1993. We have also been recognized by the Arbor Day Foundation with the Tree City Growth Award for demonstrating higher levels of tree care and community engagement through programs, public education, and continued training.

Protecting and showcasing trees in just a part of our day-to-day work, and it shows. And not just during the autumn months, but year-round.

Southlake has benefited from your educational and practical experience as a forester for 25 years. Can you tell us a little more about your background?

K. Martin: I graduated from Texas A&M with a forestry degree and over the years, I have obtained several certifications to advance my skills and knowledge. The natural environment is so important, and I have really enjoyed being able to contribute to Southlake’s development over time by helping find practical ways to preserve and protect our unique environment.