Pando's Root System: What Survival Looks Like at the Ground Level

Aspen trees do not survive western North American conditions by luck. They survive by strategy. Individual stems are relatively short-lived, perhaps a hundred and fifty years in good conditions, but the root system that connects them can survive fire, drought, and the death of every stem above ground, then wait, sometimes for decades, and send up new growth when conditions improve.

Pando, the clonal colony in Fishlake National Forest, has survived for thousands of years by this method. The above-ground portion of an aspen clone can be destroyed entirely, and as long as the roots are intact and have energy stored in their tissues, the organism can begin again. The root systems of aspen clones grow outward slowly, typically only a foot or two per year, which means Pando's current hundred-and-six-acre footprint represents many thousands of years of patient lateral expansion, though age estimates range from about nine thousand years to eighty thousand or more.

The challenge Pando faces now is different from the challenges of the Pleistocene. The deer and cattle that browse the young stems are a new kind of pressure, one that removes the above-ground material before it can photosynthesize enough energy to feed back into the root system. The roots are not dying. They are not sleeping. They are spending energy on new stems that are immediately removed. Eventually that energy budget fails.

Land managers at Fishlake National Forest have erected fenced exclosures around portions of Pando to test whether removing browsing pressure allows regeneration to recover. The preliminary results suggest the roots are still capable of producing viable new stems. The question is whether management can be sustained at the scale the organism requires.