As summer’s warmth fades away and crisp breezes begin to sweep through Forest County, a transformation unfolds. The lush green canopies of trees across the region start to metamorphose into a dazzling display of vibrant reds, oranges, yellows, browns and this fall especially, purple. This annual spectacle is a testament to the fascinating processes at play in nature.
To understand the transformation, you have look at the role of a pigment called chlorophyll. Chlorophyll is what gives leaves their green color and plays a vital role in photosynthesis, the process by which trees and plants convert sunlight, water, and carbon dioxide into energy-rich sugars. During the spring and summer months, when sunlight is abundant, chlorophyll is in its prime, absorbing sunlight and converting it into energy. This energy is used to fuel the tree’s growth, allowing it to produce leaves and branches.
However, as the days grow shorter and the nights cooler in Forest County during the fall, trees sense the changing seasons. With less sunlight available and decreasing temperatures, the tree’s internal processes begin to shift. The tree recognizes the need to prepare for the harsh winter ahead, and as a result, it starts to conserve energy.
Here’s where the magic begins. The tree begins to break down and reabsorb the chlorophyll from its leaves, allowing other pigments to take center stage. As chlorophyll retreats, the hidden colors of carotenoids (yellow and orange pigments) and anthocyanins (red and purple pigments) become more pronounced. These pigments were always present in the leaves but were overshadowed by the dominant green of chlorophyll.
Carotenoids, responsible for the vibrant yellows and oranges in fall foliage, are present in many tree species, including maples and birches. Their bright colors become more noticeable as the chlorophyll diminishes.
Anthocyanins, on the other hand, are responsible for the stunning reds and purples seen in certain trees like sugar maples. Their production is influenced by factors such as sunlight, temperature, and tree genetics. The more sunlight a tree receives and the cooler the temperature, the more likely it is to produce vibrant anthocyanin pigments.
Not all trees in the Northwoods change colors at the same time or in the same way. The timing and intensity of fall coloration depend on the tree species. Some trees, like oaks, exhibit more subdued colors, with leaves often turning brown before they drop. Meanwhile, the iconic sugar maple trees put on a dazzling display of reds and oranges.
Environmental factors also play a significant role in the fall color display. A warm, wet growing season followed by a cool, dry autumn tends to produce the most brilliant and long-lasting fall colors. This combination promotes the ideal conditions for pigments to shine.
Climate change is altering the timing and intensity of fall foliage in Forest County and other regions. Warmer temperatures and shifts in precipitation patterns can affect the chemical processes within trees and disrupt the usual fall coloration. Conservation efforts and awareness of these changes are crucial to preserving this annual natural spectacle.
Conservation Corner is a weekly article produced by the Forest County Land & Water Conservation Department. For more information contact Steve Kircher, County Conservationist-Land Information/GIS Director at 715-478-1387 or by e-mail at .