Is It Really Fall?...Ask a Tree!
—Eli Schaffer, Environmental Educator
Source: solarepiphany.com
We can sometimes easily notice large-scale changes in our environment, such as a winter that drops feet of snow in one location during a single storm and then does it again a few weeks later, or a heat wave that brings triple-digit temperatures to us for days at a time. Conversely, the living things outdoors, from microscopic bacteria to towering oak trees, undergo tremendous transformations as a result of barely noticeable changes in temperature, moisture and even the wavelength and duration of light coming from the sun!
These changes occur every year, however, the precise timing of them can depend on a number of factors. The leaves on trees get their emerald green color because plants have mastered the art of renewable energy. They use a chemical called chlorophyll to process sunlight into sugar and starch through photosynthesis. However, even plants have to pay for their solar energy by sending valuable nutrients and water from the ground up through roots, trunks, branches, and stems.
When the internal balance of the chemicals in the plant indicate that the leaves are not producing as much energy as they should be, the plant knows that the Earth--or at least half of it--is beginning to point away from the sun and hard times are ahead. In order to survive the brutal conditions of sub-freezing temperatures and far less sunlight, trees decide to cut their losses and stop wasting nutrients and water on their solar cells (leaves) so they will have reserves for bunkering down. With no leaves, the tree cannot produce new food, so it almost stops growing altogether for the winter. When we cut into a tree we can see the places where the tree transitioned into safe-mode; they make rings that tell us exactly how many winters the tree has been around...how embarrassing!
This Labor Day, the Nature Center was already beginning to see leaves falling. But this fall, many leaves are still green as they fall. Instead of shortening days and increasing wavelength of sunlight acting as cues for the trees, they had a different reason to go into safe-mode early this year--drought. Because Westchester got far less rain than is typical for August, the trees had trouble getting enough water to their solar cells, and decided to pack up the operation early in hopes of wetter seasons in the future. Did you notice leaves falling early this year?
