Crisp invigorating air, mountains with a bit of first snow up high, aspens with their vivid display of color all herald the end of summer and approaching winter. Fall has its own character. It’s refreshing after the heat of summer by the end of which everything seems a bit tired and ready for a change. Even though we know the cold is on its way, Mother Nature puts on a show as if to say “every season has its own time and own beauty.”
Fall color in the San Juan Mountains of southwestern Colorado is incredibly beautiful and fleeting. Choosing the right time to visit to try to hit peak color can be challenging. Each year varies not only in timing of the color but also in the brilliance. There are many variable factors. Weather, elevation, and rainfall throughout the year all play a role.
This year we went north of Durango and Silverton one weekend and saw quite a bit of color but not as overwhelming as some years. We also went to LaPlata Canyon and the color there had barely started. By the following weekend much of the color was gone north of Durango but LaPlata Canyon had mostly turned.
Most of the color in southwestern Colorado is the brilliant gold of the aspens with patches of the shrubby red Gambel oak. Then there is also the occasional aspen group that turns a burnished red or orange for additional interest. I’ve wondered why some aspen turned red or orange so I did a bit of research and found some rather interesting ideas.
Sensing shorter periods of daylight, trees quit producing chlorophyll, the green pigment that helps capture the sun’s energy. This allows the quieter pigments in the leaf to express themselves. These include yellow (xanthophylls) and orange pigments (carotenoids). Reds and purples come from anthocyanins which are present in red and orange aspens but not in yellow aspens. Scientists think since the red occurs on only some trees it is probably a genetic trait. Research has also shown that yellow trees remained yellow from year to year but one tree selected for its redness at the start of a five-year observation was red only for the first year and yellow each following year, and most of the red and orange leaves fade to bland yellow within a week of falling.
Of course, this also leads to the question of why trees invest in creating pigments other than energy-gathering green at all. Nobody seems to have answered that but some ideas are that red acts as a sunscreen to keep played-out leaves from getting over excited by photons or that color might throw off green-munching bugs or be a tree’s way of showing insects its vigor to ward off attack.
I think I prefer the idea that the brilliant foliage of fall is simply Mother Nature’s way of enticing us to stop and truly look at and appreciate the beauty and wonder of our world.