I wrote a poem about the Tree in our circle last year and how if glows in the fall. As I sit for breakfast, my kitchen window looks at the upper part of the tree and it brings me much joy. Every year, I am in awe of the changes and fall colours it displays.
As I sent some photos of the trees to some friends and mentioned it looked different every year, one of them asked “How so?
And I realized once again that we walk around without seeing the intricacies and beauty that surround us all. Fall changes are appreciated as an experience that fills our senses but do we see details and do we understand the process?
Here are some comparative photos from last year and this year on the same date and a little bit of science behind the phenomenon:
As it becomes cooler and we are all preparing for winter so are trees when food and nutrient production through photosynthesis is no longer efficient.
When chlorophyll, what gives the green color to leaves, breaks down and disappears, the other compounds in the leaf become visible. Depending on the type of trees, these carotenoids and xanthophylls give yellow, gold and orange leaf colors. These are the most common, transforming birches and poplars into yellow and gold beauties.
But the ones we all want to see and that impress me the most are trees that contain the most sugar, namely maples and oaks. Their darker hues are the result of Anthocyanins, which are a by-product of extra sugar. The higher sugar content, the darker the leaves get. Here, they are plentiful and are the most appreciated.
Maple leaves, which also contain carotenoids and are prone to high sugar, usually turn a glorious colour of orangy-red sometimes mixed with yellows which we all love.
Why are leaf colours different from year to year? It is all based on temperature and precipitations.
Timing-wise, a cooler summer generally leads to earlier changes which can be seen as early as mid-september while a warm summer delays the process until October. This explains why changes are visible earlier in the Laurentides and the Townships where temperatures are cooler.
If there is not enough rain during preceding months, the tree will be stressed for lack of moisture which will lead to a different process. It will start changing earlier or leaves will fall or be blown off before the full change is on display.
So, colors will be different depending on these conditions, even if some trees have the same DNA.
As for the tree in our circle, its leaves were more yellow last year, dryer and fell early.
The color display we witness here in the fall is breathtaking, a symphony of colours that lasts only a few weeks.
Lets enjoy it as much as possible!
Suzanne
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Enviroart by Suzanne Bélair, IAF, AFC 