Putting Aspen Resilience to the Test

photo by Sarah Dunn

photo by Sarah Dunn

Dispatch by Abby Popenoe

If a tree falls in the Fish Lake National Forest and no one is around to hear, it might not make a sound. If that tree is an aspen, though, it will likely grow back in a few years. Every aspen stand is a singular organism, each tree one sprout of a much greater entity living underground, so when individual aspen trees are cut down, the organism is able to resprout. Because of this aspen can withstand great disturbances that endanger the existence of coniferous trees, particularly the threat of fire. If conifers begin to pass aspen in the race for soil nutrients, water, and sunshine, growing taller and shading out aspen, the aspen rely on forest fires to give them a leg up. The caress of flame in the forest grants aspen time to grow before conifers reemerge. 

On the Fish Lake National Forest, prescribed burns have been set on stretches of forest where aspen were being out-shaded by conifers. As new aspen trees shoot up through the charred, bare ground after a fire, finding their way between blackened dead conifers, they live in a perilous state until they can grow tall enough for their buds to be out of reach of elk, deer, and cattle. Forest managers kept cattle off the burned areas for some time after the fire, though often this period was not long enough for aspen’s buds to grow above the reach of hungry cows. Elk, meanwhile, can browse wherever they please, and all too often their chosen fodder is baby aspen. With too many browsers looking to be nourished off young aspen trees after a fire, entire aspen stands may be close to dying off. 

Aspen have been thriving under adversity for tens of thousands of years, but new disturbances posed by humans on public land may be too much for aspen to handle. Elk are exotic animals in much of Utah, introduced to the local area for hunting in 1985, and they are now abundant on the Fish Lake. Cattle are here because of humans as well, having been brought to these mountains much earlier by ranchers who hold grazing allotments on the National Forest. Drought caused by anthropogenic climate change also poses a severe threat to the trees. Aspen depend strongly on water, so shifts to a hotter climate with less predictable precipitation in the Southwest means there is not enough water to go around. With aspen struggling to endure, this forest that belongs to all of us risks losing not only a remarkable tree, but also key forb, grass, and shrub species that rely on its unique habitat. Aspen can withstand a tremendous amount of disturbance; it is our job to make sure they don’t face more than they can handle.