Autumn’s cavalcade explained
Living in Balance
By Jenipher Appleton
The leaves are beginning to change with each passing day. It brings to mind some lines of poetry from my youth.
Now by the brook the maple leans
In all his glory spread.
And all the sumachs on the hills
Have turned their green to red.
Excerpt by Wilfred Campbell of Kitchener
The nights are chilly and the misty mornings bring the sounds of migrating geese and the barbwire fence screeching of Mr. Blue Jay. The sugar maple in our back yard is quickly turning its foliage to a glorious crimson.
What is the cause of all this colour change in our trees and forests? It all gets down to two key components: pigments and chlorophyll.
We associate autumn with reds, oranges, yellows, and browns. All of these pigments exist within the deciduous leaves. However, they remain unseen because of the presence of chlorophyll, which is green.
How it works
Leaves are food factories for trees. The leaves take on water from the roots of the tree, and also carbon dioxide from the air. The tree then uses sunlight to turn water and carbon dioxide into glucose, or sugar, through photosynthesis. Chlorophyll helps make photosynthesis happen. As long as it is present, the leaves remain green.
In autumn, as the days grow shorter and the temperature begins to drop, mother nature helps the trees to take time out for a rest.
As the trees begin to shut down their food factories, the green chlorophyll disappears from the leaves. This in turn allows the other coloured pigments to shine through and give us our beautiful autumn palette.
If the weather is cold and rainy, the colours tend to show mainly yellow and brown hues. On the other hand, if it is warm and sunny with crisp nights, the brilliant reds and oranges are more prevalent.
Evergreens and the like
In autumn you may notice changes in our coniferous (evergreen) trees as well. If needles have been on the pines or spruces for two to three years, they no longer receive as much light. The tree will withdraw the chlorophyll from the needles, which in turn will change to a yellowish hue and eventually be shed from the tree. The remaining needles will stay on the tree through the winter. New needles will grow in spring. Some trees like the tamarack and European larch will shed their needles every fall and are not a true evergreen.
So, get out for a walk in the autumn vistas. It will undoubtedly calm your nerves and lift your spirits!