Diverse Divers

Fall is a very active time of year—certainly not as active as spring, but there’s still a lot going on. Insects are closing down their season—many of them preparing to die, once eggs or pupae are set to carry on next spring’s generations. A few insects will go into a deep sleep, to awaken again when the weather warms. Some animals are fattening up for hibernation. A few species of birds are also loading up on food, in preparation for migrating to warmer climes.

One of the most obvious fall transformations that we humans are inclined to notice is the changing color of leaves of deciduous trees—from summer’s green to the many shades of red, yellow, and brown. A deciduous tree’s method of coping with winter is to become dormant—its leaves are too vulnerable to go through a harsh winter, so the tree drops them and hunkers down for a few months.

During summer the leaves have been manufacturing sugars and other nutrients—fueled by the sun and transformed by green chlorophyll. As the tree prepares for winter it first withdraws chlorophyll from the leaves, to be stored and used again when it reawakens in the spring. Some deciduous trees—such as maples—send out anthocyanin during the summer, to discourage insects from eating its leaves. Anthocyanin causes the blazing red color, when the chlorophyll is withdrawn. Other trees use other chemicals to ward off insects (oaks use tannin), and their leaves turn yellow or brown in the fall.

The leaves, robbed of their life-giving chlorophyll, soon die, dry, get cut off from their mother tree, and then fall (that’s the season!) to the ground. I love to sit and watch leaves fly, float, flap, and dive downward—especially when the wind has not dislodged them. The wind causes hundreds to fill the air at once and I can’t follow any single leaf. When the air is still, however, individual leaves break loose and begin their final swan dive. I become almost mesmerized by them. Each one is absolutely unique. Their shape is the main cause of their diverse flight paths—whether they are flat or curled, whether they fall straight down or soar like a paper airplane.

A leaf may begin with a straight dive, then suddenly slip sideways and start to twirl and tumble. Its path can take on intricate patterns, as it descends. Some leaves seem to want to get their dive quickly over, to nestle with their pals on the forest floor. Some seem to try to delay their landing as long as possible, by fluttering slowly this way, then slipping leisurely that way—executing a slow-motion dive. Some flip over and over, while others spin and still others float placidly downward, never once rotating.

Sometimes, as I watch a leaf break from its twig and begin its final voyage, I try to guess what its flight path might be. I’m rarely right. Every leaf seems to pick its own path and then maybe change its mind on the way down. The leaves have spent half a year stuck to the same spot and this is their once-in-a-lifetime opportunity to fly, and many of them merrily soar, while others just dejectedly drop. In fact, many leaves of an oak tree refuse to let go at all in the fall. They stoically hang on all winter and are forced off by next spring’s new growth.

Sometimes I chuckle at how simple my pleasures have become, when I realize that I’ve just passed a quarter-hour absorbed in the infinitely diverse ways in which leaves tumble earthward. It beats the hell out of a television commercial!