Feature Article October 2, 2002
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Changing ColorsAll summer we have been able to enjoy the beautiful colours of the trees around us in varying shades of green, and some, like the Horse Chestnut or Black Locust, with a lovely display of flowers. Now in autumn we can enjoy the fruit of our apple, cherry or other trees, both to look at and to eat.
But we know that as autumn closes in on us, it will bring changes to the trees, most particularly to the deciduous trees. Already we are beginning to see the signs of change. Some of those trees that have their root systems in a swampy area may already have changed colour to some degree, and in areas on high ground where the dry, hot summer has depleted the moisture in the ground, many trees have changed or are in the process of changing. Both these situations are not the healthy change coinciding with cooler weather (though that is part of it), but because the trees are under stress, and like humans they react to stress. Whether or not the tree will be healthy next year is doubtful, unless or even if the stress is not repeated again.
During the summer the trees have been absorbing the sunlight and receiving nourishment. Now the days are shorter and the nights cooler, and the trees are beginning their transition to winter dormancy. With less sunlight, the photosynthesis of food decreases, and the green colours begin to fade, leaving behind yellows, oranges, reds and browns. These colours, caused by chemicals and sugars in the leaves, have been there all summer but have been masked by the green. Now we begin to see a different beauty in our forests.
The colours we see will vary from tree to tree. The foliage of some tree species just turns dull brown and never shows bright colours, or we may see the reds or purples in dogwoods and sumacs. Our Sugar Maple will show a brilliant orange, fiery red or yellow. A beech will turn a golden bronze, oaks will be mostly brownish, while birches and aspen will only have yellow colours. You may see a maple with the side exposed to the sun a bright red, while on the shady side the colour may be yellow.
The intensity or vividness of the colours also depends upon the weather conditions. A warm, dry summer and early autumn rains produce the most vivid colours, while long periods of wet weather in the fall may produce a drabness to the scene.
But there are other changes taking place in the tree. The base of the leafstalk where it is attached to the twig is developing a special layer of cells and gradually the support for the leaf is broken. The leaf falls or is blown off, but nature has healed the break with the cells that have formed. The fallen leaves now become a fertile forest floor as water-absorbing humus, and since they contain relatively large amounts of valuable nutrients, as they decompose, these nutrients are returned to the soil. The leaves are gone - until next spring when the wonderful magical changes will take place once again.
Observations - What is coming to your bird feeders? Please call me at 268-2518.
