Tuesday, November 18, 2008

Changing Seasons

Although the spring (March-May), with its bright green color and abundant wildlife, is considered by many to be the "best bang for your buck" season at the Francis Beidler Forest Audubon Center, every season offers something special. This year, foliage (in and out of the swamp) has been especially colorful. A terrific explanation for this can be found at the U. S. Department of Agriculture's Forest Service webpage (see excerpt below).

How does weather affect autumn color?
The amount and brilliance of the colors that develop in any particular autumn season are related to weather conditions that occur before and during the time the chlorophyll in the leaves is dwindling. Temperature and moisture are the main influences.

A succession of warm, sunny days and cool, crisp but not freezing nights seems to bring about the most spectacular color displays. During these days, lots of sugars are produced in the leaf but the cool nights and the gradual closing of veins going into the leaf prevent these sugars from moving out. These conditions-lots of sugar and lots of light-spur production of the brilliant anthocyanin pigments, which tint reds, purples, and crimson. Because carotenoids are always present in leaves, the yellow and gold colors remain fairly constant from year to year.

The amount of moisture in the soil also affects autumn colors. Like the weather, soil moisture varies greatly from year to year. The countless combinations of these two highly variable factors assure that no two autumns can be exactly alike. A late spring, or a severe summer drought, can delay the onset of fall color by a few weeks. A warm period during fall will also lower the intensity of autumn colors. A warm wet spring, favorable summer weather, and warm sunny fall days with cool nights should produce the most brilliant autumn colors.

Today's high wind will clear from the trees most of the leaves that were set to drop. With the leaves off, the swamp offers a perspective unavailable during the rest of the year. The old-growth Bald Cypress (Taxodium distichum) trees are visible in profile from the crown to the buttress, which is awe-inspiring. Occasionally, it even gets cold enough for the water to freeze!

Images by Mark Musselman

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