Where does this color come from? The answer to why trees change color and why some trees turn yellow and others red lies in chemistry.
The mixture of red, purple, orange and yellow is the result of chemical processes that take place in the tree as the seasons change from summer to winter. During the spring and summer, the leaves have served as factories where most of the foods necessary for the tree’s growth are manufactured. This food-making process takes place in the leaf in numerous cells containing chlorophyll, which gives the leaf its green color. This extraordinary chemical absorbs from sunlight the energy that is used in transforming carbon dioxide and water to carbohydrates, such as sugars and starch. Along with the green pigment are yellow to orange pigments — carotenes and xanthophyll pigments which, for example, give the orange color to a carrot.
Most of the year, these colors are masked by great amounts of green coloring. But in the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the leaves part of their fall splendor.
At the same time, other chemical changes may occur, which form additional colors through the development of red anthocyanin pigments. Some mixtures give rise to the reddish and purplish fall colors of trees and shrubs such as sumacs and maples, while others show bold yellows. Oaks, on the other hand, display mostly rust and browns. All of these colors are due to the mixing of varying amounts of the chlorophyll residue and other pigments in the leaf during the fall season. Temperature, light and water supply have an influence on the degree and the duration of fall color. Low temperatures above freezing will favor anthocyanin formation producing bright reds. However, early frost will weaken the brilliant red color. Rainy and/or overcast days tend to increase the intensity of fall colors.
As the fall colors appear, other changes are taking place. At the point where the stem of the leaf is attached to the tree, a special layer of cells develops and gradually severs the tissues that support the leaf. At the same time, the tree seals the cut so that when the leaf is finally blown off by the wind or falls from its own weight, it leaves behind a leaf scar.
Most of the broad-leaved trees shed their leaves in the fall. However, the dead, brown leaves of the oaks and a few other species may stay on the tree until growth starts again in the spring. Most of the conifers — pines, spruces, firs, junipers etc. — are evergreen. The needle or scale-like leaves remain green or greenish year-round and individual leaves may stay on for two to four or more years.
The best time to enjoy the autumn color would be on a clear, dry and cool (not freezing) day. Get out and take in the color show. It doesn’t last long.
Information for the above article was provided by the State University of New York, College of Environmental Science and Forestry.
Classes and events
Cutting firewood this fall? There will be a free chain saw safety class tomorrow, on Friday, Sept. 26, from 10 a.m.-noon at the CSU Extension building.
Operating a chain saw can be dangerous. Whether you are out cutting firewood or pruning trees and shrubs, it is important to operate this important tool safely and maintain it for optimum efficiency. Learn techniques and safety tips from experts at this workshop.
No preregistration is necessary, but for information, call the Extension office at 264-5931.
Shred-It event Oct. 2
Prevent identity theft, clean out your file cabinets and support the Archuleta County 4-H program by bringing up to three boxes of papers per person for on-site shredding.
The shred truck will be set up at the downtown Citizens Bank parking lot from 3 to 5 p.m. on Oct. 2.
The cost is $5 per box and all proceeds go to support your local 4-H program.
No registration is necessary, but for questions, call the CSU Extension office at 264-5931.
Free wood chips
We are cleaning up the fairgrounds and all of the wood chips that helped keep things dry during the fair are available to anyone for pick-up. If you are interested, just bring your pickup and haul it away. No need to call the Extension office for permission.
CPR and first aid
CPR and first aid certification classes are offered monthly by the CSU Extension office on the second Monday and Wednesday of each month from 6-10 p.m. Anyone needing to receive or renew certification can register by calling the Extension office at 264-5931.
We will also schedule classes on additional dates with five or more registrations. Cost for the classes is $80 for combined CPR/first aid and $55 for individual CPR or first aid. Group rates are available.
The type of first aid information provided will vary by the needs of the audience. Call the Extension office at 264-5931 for information.
