Post 02102
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Everywhere at timber-line the temperature is low, and on Long’s Peak the daily average is two degrees below the freezing-point. At timber-line snow may fall any day of the year, and wintry conditions annually prevail from nine to ten months. The hardy trees which maintain this line have adjusted themselves to the extremely short growing-season, and now and then mature and scatter fertile seeds. The trees that do heroic service on all latitudinal and altitudinal timber-lines of the earth are members of the pine, spruce, fir, birch, willow, and aspen families. At timber-line on the Rocky Mountains there are three members each from the deciduous trees and the evergreens. These are the Engelmann spruce, limber pine, alpine fir, arctic willow, black birch, and quaking aspen.
A few timber-line trees live a thousand years, but half this time is a ripe old age for most timber-line veterans. The age of these trees cannot be judged by their size, nor by general appearance. There may be centuries of difference in the ages of two arm-in-arm trees of similar size. I examined two trees that were growing within a few yards of each other in the shelter of a crag. One was fourteen feet high and sixteen inches in diameter, and had three hundred and thirty-seven annual rings. The other was seven feet high and five inches in diameter, and had lived four hundred and ninety-two years!
One autumn a grizzly I was following–to learn his bill-of-fare–tore up a number of dwarfed trees at timber-line while digging out a woodchuck and some chipmunks. A number of the smaller trees I carried home for careful examination. One of these was a black birch with a trunk nine-tenths of an inch in diameter, a height of fifteen inches, and a limb-spread of twenty-two. It had thirty-four annual rings. Another was truly a veteran pine, though his trunk was but six-tenths of an inch in diameter, his height twenty-three inches, and his limb-spread thirty-one. His age was sixty-seven years. A midget that I carried home in my vest pocket was two inches high, had a limb-spread of about four inches, and was twenty-eight years of age.