Photo Credit: Jerry Boyer
Color Change Progress Report
September 14th – September 21st
With temperatures getting cooler by mid next week, leaves will continue to darken in color at a consistent rate. It is possible that an increase in the amount of rain towards the middle of the following week (post-Friday) may slightly diminish the red present throughout the foliage as the pigment that gives the leaves their red color is water soluble. The current color change in the Spearfish area is marked at 50% of its peak. Colors are expected to peak in mid-October if the weather continues on its current trajectory.
Ever wonder why the colors of leaves change during the fall? Check out the info below!
Nature’s beauty is often the result of very practical responses an organism has to its environment. We reap the visual and aesthetic benefit as observers and stand in awe often not understanding how precise every change in our environment is. The color palette that autumn brings is one such change that draws thousands of visitors from around the world to Spearfish Canyon. The end of August and the approach of September brings a variety of factors that contribute to the canopy of red, yellow, and orange capturing the attention of so many.
Why do leaves change color?
The colors of leaves are determined by certain pigments they carry in their cell walls. A combination of the variance in temperature, sunlight, precipitation, and humidity changes the amount of each pigment present in the leaf. Before falling from the branches they grow on, leaves will begin to darken in color. The color green, which they wear through most of the spring and summer, is a result of the first pigment known as chlorophyll.
Why are leaves green?
Chlorophyll exists in the leaves of every plant and is an essential part of its existence. It absorbs the sun’s rays and converts them into food for the plant. Chlorophyll absorbs every color present in the wavelength except for green and as a result, reflects it, causing our eyes to perceive it as the color of the leaf.
Why do leaves turn red, yellow, or orange?
Autumn in the northern hemisphere, where the United States is located, means lower average temperatures, less humidity, and shorter days with less sun. These changes indicate to plants that it’s time to protect themselves from the harsh cold that awaits them in the coming months. Leaves change color because a combination of these factors diminish the amount of chlorophyll they carry. Since the plant is no longer producing food, the high amount of chlorophyll present throughout the summer is no longer needed. The absence of chlorophyll means other colors are free to make themselves known.
Red: The pigment known as anthocyanin reflects the color red. A rainy fall will diminish the red color present in a leaf because anthocyanin pigments are water-soluble or dissolved in water.
Yellow: A protein known as flavonol is responsible for the yellow color visible throughout the autumn months.
Orange: Carotenoids, the fourth pigment present in leaves, absorbs the blue-green wavelengths while reflecting yellow and red. This results in the orange color we see.
Why do leaves fall?
Leaves act as veins that carry water and other nutrients to and from the tree. As winter approaches, the harsh temperatures indicate to the plant the need to sever the connection between its body and its leaves. By closing its veins, the plant protects the water and nutrients it has collected throughout the summer months from the freezing temperatures. The leaves eventually die and fall as a result.
How do plants eat through autumn and winter?
Plants store sugar in their roots which they utilize as their leaves fall during autumn. The stored food allows the plant to survive through spring when the temperature warms and the intensity of the sun increases again. Without a need to grow during the winter, the plant is able to make this store of sugar last as long as necessary.