It happens every year: The green leaves of spring and summer lose their chlorophyll and voila, the colors of autumn are born.
Each year is a little different, but the process is the same. The best colors seem to occur when we have adequate precipitation during the spring and summer and sunny days and crisp cool nights in the fall. Early freezes or big storms can diminish fall color rapidly.
Currently, there are some moderate pockets of color over central and northern New England, and the highest of elevations are nearing peak color. Columbus Day weekend (Oct. 12-14) is often one of the better periods to view foliage. The weekend of the Head of the Charles race (Oct. 19-20) is also usually a wonderful time to take pictures of the colors.
Grade-school science reminds us that the leaves of a tree have chlorophyll — a green photosynthetic pigment — which changes as the leaves prepare to fall from the trees. The purpose of the green substance is to trap light energy from the sun; it’s then used in combination with carbon dioxide and water to make sugars in the process of photosynthesis. Chlorophyll is critical for photosynthesis, which helps plants get energy from light.
In addition to chlorophyll, there are two other pigments present in many of the leaves. Carotene and xanthophyll, which are orange and yellow, respectively, are hidden by the green chlorophyll during the course of the spring and summer. As the chlorophyll dies, the yellow and orange are revealed.
Perhaps more interesting are the anthocyanins, which are produced as the chlorophyll is being broken down. Unlike other pigments, this one, which is red, is not present until the chlorophyll starts to wane.
Since these processes happen in leaves at different rates, the colors we observe also will happen over time. This is why the idea of peak foliage is a little bit of a misnomer.
By the time the term “peak” is applied to a particular area, many of the leaves already have turned and there is often a significant amount of leaf drop. Some of the early maples that are very red in color turn weeks before the oaks, which tend to be purple or a ruddy brown.
In fall, there are trees that turn amazing colors. I think it’s worth heading on a foliage hike or drive several times during the fall so you can capture all the varieties of trees rather than wait for just one perfect weekend.
The red maple is one of the best known and does have that red or red-orange color early in the fall. Sugar maples go through a transition from green to orange-yellow and even red before dropping their leaves.
Hickories, elms, birches, and tulip trees tend to be more on the yellow side. Poplar and aspen trees are known for their yellow color.
Grab your camera and your favorite pumpkin-anything and take advantage of this wonderful time of year. Before you know it, gray and white will dominate our landscape.
Follow Dave Epstein on Twitter @growingwisdom.