31 October 2023
This is a favorite time of the year for many people because they can enjoy the changing colors of the trees and become “leaf peepers”.
Contrary to what some people believe, it does not take a frost to start the transformation. During the growing season, trees are constantly making food. The leaves contain chlorophyll that turn solar energy into food and produce the green color we see all season. As the amount of daylight wanes, chlorophyll production decreases and the green changes to another hue. Always present in the leaves is xanthophylls and carotenes but now as the green disappears, we get to see the orange and yellows that we associate with autumn. Tannins are also part of the leaf all year long and will result in the inevitable brown. Anthocyanins are produced in the fall and they are responsible for the reds and purples.
Each variety of tree and environmental conditions control the timing and intensity of the change. Temperature, moisture in the soil, and amount of daily sunlight have an effect. Warm, sunny days means the chlorophyll will continue to be produced. Cooler nights slow the plant’s respiration (yes, they do breathe) and will continue the sugar accumulation. Cloudy days and warm nights mean less sugar production and will produce more vibrant colors. Heavy rain, hot and dry summers, and freezing temperatures affect the intensity of the colors and the length of time we have to enjoy them.
In the northeastern United States some of the most common native deciduous (those that shed their leaves) are the sugar maple (Acer saccharum), yellow birch (Betula alleghaniensis), and American beech (Fagus grandifolia).
Sugar maples are gorgeous in the fall. Their dark green leaves morph into yellow, burnt orange, and red. The leaves form opposite each other and are about 4 inches wide with shallow lobes and wide, coarse teeth.
They are found as borders along the highway and will grow to up to 75 feet in height and will spread almost as much, to 40 or 50 feet. They like moderately moist soil but don’t like anything salty. With proper location they can live for 400 to 500 years. Besides providing us with gallons of tasty syrup in the spring, they are also highly prized for flooring, furniture, and other building projects.
Yellow birches are interesting because they produce catkins, or elongated flowers, in the late summer and will continue on the tree through winter. In the spring these catkins turn a pink or purple and will release pollen. In the autumn, the leaves change to gold and yellow.
This tree is relatively slow growing and will reach to about 100 feet tall at maturity. Their canopy of leaves are often described as looking like a candelabra. They can make great shade trees or be used on slopes to accommodate their lateral root systems. They are a strong support system to both butterflies and moths and attract a number of different song birds.
An American Beech is a little different in that its leaves alternate as compared to the sugar maple where the leaves are opposite each other. The elliptical leaves have pointed tips with coarse teeth. In the summer they are green and change to golden yellow and then change to a pale brown. Although it is a deciduous, they often retain their leaves through the winter. It will grow to 50 or 70 feet tall but will send out suckers, which can be annoying. Its bark is smooth and light gray and will stand out in the landscape. It has a shallow root system.
While considered a hard wood, it is not generally sturdy enough for flooring or furniture of any quality. However, its beechnuts are roasted and eaten and have been used as a coffee substitute, but raw seeds should be avoided. The inner bark is used as a thickening agent in cereals, breads and soups. They are host to caterpillars and are a favorite of deer, raccoons, red foxes, and American martens. Black bear females will eat a lot of them to provide calories for the winter and their high protein will help in the reproduction process of the species.
