Seasonal changes evident as winter approaches

By Julie Buehler
Speical to the Turnagain Times

As the days get shorter and the nights get darker, I find myself looking for my headlamp and grabbing an extra jacket. Whether I’d like to admit it or not, the season is starting to change. Here in Portage Valley the local critters have been seen eating salmon, munching on berries, and gathering up mushrooms. Watching these animals gear up for winter got me thinking about the local plants. What is it that plants do to prepare for winter?

During the summer, trees photosynthesize or use sunlight to convert water and carbon dioxide into oxygen and sugar to make food. Trees also use the chemical chlorophyll to help make enough food to grow in the summer and store for the wintertime. During the winter there is not enough sunlight or water for trees to keep making food. Instead the trees shutdown and live off the food they made during the summer.

If you take a careful look at a leaf, you will notice that at the base of the leaf is a special layer of cells called the “abscission” or separation layer. All summer long nutrients go in and out of the leaf through this layer. During the fall, this layer begins to swell and cuts off the flow of nutrients between the tree and the leaf. The green chlorophyll fades from the leaf and bright orange and yellows appear. These colors have actually been there all along, but the green of the chlorophyll has masks these colors.

Locally, the colors you see most are oranges and yellows. Both are color pigments that come from carotene and xanthophylls. The brown color in leaves is mostly from tannin, a bitter waste product left in the leaves. Combinations of these pigments give us a range of colors each fall. For the best displays; cool, sunny autumn days produce brighter colors than warm wet weather.

In addition to deciduous trees that lose their leaves, there are many coniferous (“evergreen”) trees in the area. These trees keep most of their leave during the winter, because they have specialized needles that are resistant to cold and moisture loss.

Whether you want it to happen or not, seasonal changes are inevitable. Although the local critters and plants don’t have a headlamp or a jacket to throw on, they too are gearing up for winter in their own unique way.