How to Protect the World's Largest Living Thing

Pando is a clonal colony of quaking aspen, genetically confirmed as one organism linked at the roots. J. Zapell/Wikimedia Commons

Walking through this aspen grove in Utah, you could be forgiven for missing the forest for the trees. That's because this isn't really a grove of 40,000 individual aspen trees, but rather 40,000 clones of one organism — a single root system spread across 43 hectares in Utah. It's the most massive living thing known to science.

It has been named Pando, Latin for "I spread," and scientists believe it may be anywhere from 2,000 to 1 million years old. Sadly, however, this magnificent organism is dying. An influx of hungry deer and cattle, which eat Pando's young stems, is playing a large part in its demise, but climate change-induced drought, insects and disease aren't helping, either.

“It’s falling apart on our watch,” Utah State University researcher Paul Rogers told New Scientist in 2016. “The old trees are dying, and the young ones are being eaten.”

Clone wars

Pando, quaking aspen colony in Utah
Pando consists of more than 40,000 clones, but grazing animals and human activity are hindering its ability to regenerate. Scott Catron/Wikimedia Commons

In a new study, published this week in the journal PLOS One, Rogers and colleague Darren McAvoy shed new light on Pando's decline. Using recent ground surveys, along with an analysis of aerial photographs spanning 72 years, they show how the ancient grove is thinning out, with fewer young clones surviving to replace the older trunks as they die. This is partly due to overgrazing on young shoots by mule deer, which are reportedly seeking shelter from hunters and other human activity, but also by cattle that forage seasonally in Fishlake National Forest.

And thanks to 72 years of aerial photography, the study also reveals how the thinning of Pando's crown has corresponded with growing human activity in the area, particularly the installation of cabins and campgrounds in recent decades. These developments have encouraged grazing animals to congregate near Pando, Rogers says, preventing the grove from regenerating itself as it has for millennia.

"If this were a community of humans, it would be as if a whole town of 47,000 had only 85-year-olds in it," he tells the New York Times. "Where is the next generation?"

On the fence

aspen trees at Fishlake National Forest, Utah
Aspen trees paint the landscape at Utah's Fishlake National Forest in autumn. Mark Muir/U.S. Forest Service

Yet Rogers and his colleagues aren't content to watch this marvel vanish. Fencing hasn't always successfully protected Pando, but the researchers point to one well-fenced and well-managed section, where some clones have grown tens of feet within a few years. In 2016, Rogers reported that a fenced section had more than eight times as many stems per hectare after three years than an unfenced area.

"It was a neat surprise that we can get pretty good results with fencing alone," Rogers told New Scientist.

If this success can be replicated throughout the grove, it might give Pando the space it needs to recover. Yet it's unclear whether fully fencing off Pando is a practical option. It's a huge area to enclose, and fences or walls can negatively affect the natural ecosystem around Pando, which is also important for its long-term health.

Rogers has been looking into other tactics, too, like burning vegetation to stimulate tree growth, clearing juniper bushes among the clones and cutting mature aspens — all methods that have been shown to promote new sprouts in the past.

But keeping out herbivores may be the most important factor, and aside from fencing them out, researchers say raising public awareness about Pando's plight could also be a powerful tool in preserving this ancient "forest of one."