Dispatch by Elizabeth Greenfield
What does a healthy forest look like? Check your preconceived images of an ideal forest at the door. If you can see through an aspen stand, said ecologist Mary O’Brien, you are looking into its future as a dead aspen stand. Though perhaps beautiful, without age diversity, a homogenous aspen copse will not survive into perpetuity.
Aspen are not like most trees. The bulk of the organism lies underground in the root structure, trees breaking through the soil merely to photosynthesize and send sugar to the roots. One root system consists of multiple trees, all genetically identical clones. As mature trees die, the clone is sustained by the younger stems constantly regenerated by the root system.
The Pando clone in central Utah’s Fishlake National Forest has stayed intact and spread for 80,000 years. Though aspen trees only live to be a couple hundred years old, Pando has continuously manifested new identical versions of itself on common ground. Occupying 106 acres and weighing around 13 million pounds, Pando is the world’s largest and oldest organism, surviving climactic fluctuations of the last ice age, as well as periodic drought and fire.
As you intersect Pando on Highway 25, look on either side and you’ll notice a perplexing uniformity in the aspen stands, but regional contrast. In one securely fenced area, the aspen are thick and ranges in age and height. Across the highway, the aspen are much denser, like a tree farm before preliminary thinning, all stems nearly identical in height and size. With a transition as short as a fence is wide, Pando morphs suddenly into an old-growth aspen forest, emulating a crop ready to harvest, each stem easily visible due to nearly non-existent underbrush and young aspen. In other words, this part of Pando is doomed.
The primary cause of such gloomy prospects are browsing ungulates—deer, introduced elk, and cows on nearby national forest grazing allotments. Ungulates relish in the tasty treat of young aspen stems. Until they reach a height of six feet, aspen are susceptible to browsing. When the apical meristems—the agent of aspen growth—are browsed off, aspen cannot grow tall enough to establish themselves and survive. Thus, fencing and protecting aspen is critical to secure their survival, like in the fenced area of Pando supporting aspen of all ages. Broken or unmaintained fences don’t effectively ward off browsing ungulates, as visible in the old-growth part of Pando that has very few young intact aspen.
If Pando is to continue spreading over the next two centuries and live to 80,200 years, the fences need to be maintained or the browsers need to go. But the reality is that virtually all national forest land in southern Utah is roamed by ungulates who browse aspen, and that likely won’t change. It’s not just about Pando surviving to beat its own superlatives, but maintaining intact ecosystems wherever aspen grow to be resilient, healthy forests in the face of climatic change.