HISTORY OF THE ASPENS
Every year about this time, Fall is ushered in by a flush of aspens as their leaves turn to gold. Where I live in the Rocky Mountains of Colorado, the particular aspen is the trembling or quaking aspen. The broad leaf and the flattened stem cause them to flutter in the breeze. It is a particular type of poplar tree calledpopulus tremuloides. As tourists visit New England in Autumn for Leaves and Lobsters, visitors come to Colorado to see the aspens change to dramatic yellows and reds.
The change in color occurs first at the highest altitudes. For example, at 9500 feet, the aspens “peaked” their color change and the leaves began to fall about the third weekend in September. Where I live at 6500 feet, the edges of the aspen leaves are just beginning to turn gold from green.
Aspens are unusual in that they grow in large communal groves or more specifically clonal colonies. These form from a single seedling. They spread widely across the area by roots that come above ground as root suckers. In my yard, they can spread dozens of feet, invariably coming up in the middle of the lawn.
In the Colorado Rockies, snow may come before the aspens change. Last year the first snowfall of the year came the last day of Summer. When that is true, the fragile leaves may die before they turn. Other times the first snow comes after the change, as it did this year. You can see snow and the golden leaves on the ground at the same time.
An aspen tree may die, but the root system remains intact, sending up replacements nearby. In this way, a grove may survive a large forest fire and is very hardy. The trees themselves are subject to a variety of diseases and insects. In urban settings they rarely last more than 20 years, and I’ve taken out half a dozen that have died on my property. However, in forests they may live almost 10 times that length, and the root system longer still.
Many colonies grow larger from year to year, spreading over acres of land. In Utah the oldest known colony, named Pando (“I spread”) is reportedly thousands of years old. On the other side of the Rocky Mountains from me, it is located in Fishlake National Forest and is also considered the largest organism in the world in terms of both volume and mass, measuring 106 acres and 6,000 tons.
Bill Petro, your friendly neighborhood historian