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Continued...
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 An Eastern fence lizard on a juniper trunk. I still had questions after this hike. I wondered why aspens predominate in the valley near Lost Lake. The aspen grove differs from the rest of the forest, which is a mixture of piņon, ponderosa, and juniper. I saw no obvious solution to why aspens should grow in this one spot. I decided to compare my box at the aspen grove to a control area at Milk Ranch Canyon. What environmental characteristics favor the growth of aspens near Lost Lake? I thought that higher altitudes and cooler temperatures would probably create a good climate for aspen. I also thought that the extra water that ran into the valley would make it an ideal area for aspens. After my expedition of August 11, I decided I needed tools: a pedometer to measure the size of the aspen grove, an altimeter to measure altitude, and a psychrometer to measure humidity. I predicted that the altitude at the aspen grove would be higher than the altitude at Milk Ranch Canyon. I also predicted that the aspen grove would have a higher humidity than the control area at Milk Ranch Canyon.
September 7, 2002: Lost Lake Some aspens had patches of bark missing. The first layer of bark was scraped away, revealing a layer of green chlorophyll. The trees were scraped between my shoulder and eye level. On a few of the scraped trees, I found short brown and white hairs. Elk must have scraped the trees, trying to reach the inside bark of the trees. Walking back to the car, I saw a horned lizard and scarlet gilia. |
I was interested in the green chlorophyll I saw underneath the aspen bark. At home, I consulted Ann Zwinger's Aspen: Blazon of the High Country, from which I learned that while most trees collect energy only through their leaves, aspens also use their bark to collect the sun's energy. "The ability of aspen to photosynthesize almost year-round, even at temperatures below freezing, adds about 2 percent to the tree's net photosynthesis" (p. 4). Photosynthetic bark helps aspens recover from insect damage and frosts, and allows aspens to grow in coniferous ecosystems where other deciduous trees cannot grow.  Even in years of drought prickly pear cacti bloom profusely. The cacti store water so that they can bloom and be pollinated even in dry years. I also wondered about wildlife benefiting from aspens. In Colorado, on a vacation, I once saw an abandoned beaver lodge surrounded by felled aspens. I wondered why the beavers had cut so many trees. Since then, I have read that beavers eat aspen bark, but cut down twice as many trees as they can gather food from. Cutting trees not only feeds the beavers but also files down their ever-growing teeth. Deer and elk also benefit from aspens. Both deer and elk graze on aspen leaves when the aspens are young and small. Elk also "bark" aspen, scraping the outer bark with their teeth in search of the green chlorophyll. "Elk and aspen are almost synonymous in the West," writes Zwinger, "and aspen stands on the first day of hunting season are not good places for hikers to be" (p. 24). The summer of 2002 was a summer of drought. I knew the elk had survived the drought when I found elk tracks and saw the damage caused by elk "barking" aspen trunks. Since I have not seen any bear tracks or bear scat this summer, I wonder whether the bears survived the drought. I hope they found a corridor to a moister valley.
September 16, 2002: Milk Ranch Canyon At Milk Ranch Canyon, in a randomly chosen area, I marked off a box 50 yards square. A tall ponderosa, two junipers, and a cliff rose formed its corners. At 2:23 pm, I checked the temperature, humidity, and elevation. It was 64°F, with 30 percent humidity, and the elevation was 7,500 feet. The sky was clear and sunny. |
