Season hopeful for a colorful display
While recently walking along the edge of a secluded creek, I noticed a prelude of what’s to come. Catching an occasional
glimmer of orange in the canopy, I began to grow a little anxious. Although small, the leaf was an indication that the fall season is near — a sure sign that our forests will soon transform into a palette of vibrant colors.
I suspect one would be hard-pressed to find a single person who doesn’t appreciate the vibrant colors of fall. I, too, find the season invigorating and will burn thousands of exposures during the short time when the hardwoods burst with colors. But I also find it interesting what clues the trees it’s that magical time of the year, and the process that causes the foliage to turn.
Well, it all goes back to self-preservation. As living organisms, trees are no different from humans in the sense that they must have food and water to survive.
The root system obviously plays a huge role in absorbing much needed water and nutrients.
And if not for the leaves’ ability to produce carbohydrates, the tree would surely die. The ingredients are simple. A dash of sunlight added to carbon dioxide and water, and Eureka! Carbohydrates are formed and the tree will receive its nourishment.
This process, referred to as photosynthesis, is dependent upon chlorophyll. This chemical is not only responsible for leaves’ green color, but it also absorbs energy from sunlight.
Foliage also sports yellow and orange pigments throughout the spring and summer. The colors, however, are overwhelmed by the greens produced by chlorophyll.
But as the days grow shorter and the temperatures begin to drop, trees automatically undergo a change. This process of converting sunlight to energy, which fuels the food-making process, becomes less efficient.
“And why,” one might ask? Sunlight, or a lack thereof, sets the stage. As leaves age, a corky layer of cells develops between the leaf and stem. In turn, it inhibits the transfer of nutrients.
As night periods grow longer, the optimal time period triggering the necessary chemical reactions leading to color change is reached. As a result, the chlorophyll begins to break down, and the green color that has proved dominant through the spring and summer months begins to dissipate. In turn, the yellow and orange pigments that have remained subdued for several months finally have the opportunity to shine.
According to http://www.esf.edu, “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 such trees as dogwoods and sumacs,” the article explained, “while others give the sugar maple its brilliant orange.”
The website also explained why oak leaves sometimes appear as various hues of brown during the fall season. It’s a result of residue left behind by decaying chlorophyll mixing with other pigments in their leaves.
So that is a general description of how the color changing process works. Now for the big question: What dictates how vibrant each fall will be?
As we’ve all noticed, some falls are brilliant while during other years the forest is drab. Well, there is a reason for this contrast of color spectacles. Temperature, amount of sunlight and water supply play a role in the brilliance of fall foliage and how long the leaves will remain on the trees.
It all begins long before tinges of brilliant colors begin to show up in the forest. In fact, those spring showers that we often see have a bearing on what happens several months down the road. Drought-like conditions during the springtime have an obvious effect on the production of leaves. As a result of these dry conditions early on, the leaves sometimes undergo an “early shutdown,” turning loose and falling to the ground before they’ve had ample opportunity to reach their peak colors in the fall.
So we know that rainfall is essential, but temperature is also a key element of those vibrant hues of reds, oranges, yellows and purples. Ideally, cool, crisp nights and sunny days will continue until the forest undergoes that beautiful transformation.
During these optimal conditions, chlorophyll is broken down more quickly. And as we know, get rid of the chlorophyll and voilà! The colors that have been hidden since early spring suddenly appear.
Although we should long for cool, crisp nights, freezing temperatures, or a frost will have adverse effects. In the worst-case scenario, these cold temperatures can literally kill the leaves.
During the past weeks, we’ve been blessed with perfect conditions and we experienced average precipitation during the spring. So, with a little luck and a lot of help from Mother Nature, we might see a colorful forest during the fall of 2015.