What to do if the aspen don’t change color
September 26, 2007
One benefit of living in the mountains is that you become an expert on what must be a major contributor to the buildup of atmospheric carbon dioxide that causes the Arctic ice cap to melt and the sea level to rise, thus imperiling life as we know it.I refer, of course, to the changing color of aspen leaves, a spectacle that inspires a myriad of metro residents to drive around the mountains this time of year, burning much gasoline in the process. Those aspen viewers often spend some money in little mountain towns, thereby easing the local transition from “summer, when you might make a little profit,” to “seven or eight very slow months.”Around Labor Day every year, I start getting inquiries: “When are the aspen going to be at their peak this fall?”We used to figure about Sept. 17, an easy date to remember in Salida because it’s also the average date of the first killing frost. But as of Sept. 24, there had been no frost in town and few surrounding aspen have changed colors.I check them every morning when I walk the dog along the river and railroad tracks just east of town. Along the way there are several panoramic views that spread from the Sangre de Cristo range to Monarch Ridge and north along the Sawatch Range to Mount Harvard.When the aspen change, great golden bands and patches glow on the mountain flanks. But it hasn’t happened yet.Several theories have been advanced. These days, just about every untoward event gets blamed on global warming, and so if the climate is warmer, then the trees should stay in summer form longer.While global warming may explain some changes in the scenery (i.e., old tourist books say the Angel of Shavano snow formation peaks around July 4, and in recent years it’s more like Memorial Day before the angel melts away), it doesn’t explain the aspen. The color change is not brought about by a decrease in temperature, but by the diminishing hours of sunlight.In a sense, the leaves don’t actually change color. The tree responds to decreased daylight by halting its production of chlorophyll, the green chemical of photosynthesis that turns sunlight, air and water into plant material. When the chlorophyll fades away, the yellow carotenoids that were present in the leaf all along become visible.This year, though, a lot of the local chlorophyll is refusing to fade away even though the days are still getting shorter.Some locals have theorized that the Sudden Aspen Decline Syndrome, observed with dying stands in the San Juan Mountains, could have moved north. But there’s no real evidence for that.The most logical explanation is that we had more moisture than usual in July and August, with thunderstorms on many afternoons. According to Ann Ewing at the local U.S. Forest Service office, the wet conditions encouraged the growth of an “aspen leaf blight fungus,” which smites the leaves just as they’re about to shut down for the year anyway.”Basically, the leaves will just turn black and fall off, instead of turning yellow,” she said, adding that “It doesn’t seem to hurt the tree, though.”On an excursion to Breckenridge a dozen days ago, I noticed a few golden aspen around Leadville, so I called a friend there yesterday for an update. He said the display still hasn’t peaked, and the yellow doesn’t seem as vibrant this year, “but it still should be a pretty good show by the end of the week.”Our aspen do seem to be acting up: mysteriously dying in the San Juans, refusing to change colors in the central mountains, changing later than usual in the highest country.This could hurt tourism, but there may be a way around it. We know that people will come to the mountains and spend money to see trees that have changed colors. And when I was in Summit County earlier this month, I saw thousands of trees that had been a rather monotonous gray-green now displaying a diverse panoply of red, yellow and orange needles.So if the aspen are failing us, we should quit complaining about the pine bark beetle epidemic that produces colorful needles, and instead start promoting it as yet another glorious natural spectacle to admire and cherish, well worth the trip up from the city.Ed Quillen is a writer in Salida, Colo., where he produces regular op-ed columns for The Denver Post and publishes Colorado Central, a small regional monthly magazine.