Walk up to a fenced study plot at Fishlake National Forest and you see young aspen stems growing thick and tall. Step a few feet past that fence and you find bare ground where the shoots should be. That sharp contrast shows you Pando aspen decline in a single glance. Chronic browsing eats the young shoots as fast as they sprout, so the trembling giant cannot replace the old trees dying off each year. Talk of Pando dying is not guesswork anymore. This clone keeps thinning because almost nothing new lives long enough to grow up.
The cause is mule deer browsing, and the harm stacks up over decades. Aspen groves like Pando do not grow from seeds the way most forests do. Instead the clone sends up fresh shoots called suckers from one huge shared root system. Those suckers are the only way this giant renews old growth.
To a mule deer, a tender young sucker looks like an open salad bar. The deer crop almost every stem before the wood can harden into bark. A shoot survives only if it climbs past browsing height before a deer strips it. In Pando, almost no shoots get that chance. Year by year, you watch the canopy grow older with no young stems coming up behind.
Here is why that matters so much. The old stems standing in Pando today keep dying off from age, wind, drought, and disease, which is normal for any aspen grove. In a healthy stand, a wave of fresh suckers rushes in to fill each gap the moment one opens. In Pando, browsing strips those suckers out before the young roots take hold, so the gaps stay open. This failure to regenerate is the real engine behind Pando aspen decline. Over time the clone thins into a stand of almost nothing but old wood, with no middle-aged or young trees behind the canopy. You are left with an aspen forest that has no children, and that means no future.
Pando is not a small patch of woods, which is what makes the loss so stark. You are looking at a single living organism, one connected tree that shares the same root system across the whole hillside. Researchers Paul Rogers and Darren McAvoy mapped the full scale in a 2018 study in the journal PLOS ONE. The raw numbers show you just how much is at stake.
You can read the whole decline in a 72-year run of aerial photos. The images show steady thinning across most of the clone, gap after gap where full canopy once stood. Each missing tree is one that never came back. The same study found that mule deer even breach the 8-foot fence built to keep the herd out. So the protected plots need constant patrol and repair. One thing the science has not settled is Pando's exact age, and that debate stays wide open. The downward trend on the ground, though, is not in doubt.
Pulling Pando back means treating the wildlife and the forest as one connected system, not two separate problems. Fences alone will not fix the decline, and neither will a single good year of growth. Deer learn the weak spots in a fence and slip through, so the barriers need real upkeep. To bring the clone back, you protect the ground long enough for a full generation of suckers to grow up.
- Fence well: Build and repair tall, deer-proof fencing so young suckers get a safe head start.
- Ease browsing: Cut the local deer pressure through managed hunts or herd control near the clone.
- Be patient: Protect the plots for years, not one season, so new stems can grow past browsing height.
Do all of that together and the payoff is simple. New stems at last mature into trees before the last old ones fall, and the giant starts to fill the gaps once more. Get that right, and you save the trembling giant from Pando aspen decline.
Read the full article: Aspen Tree: Facts, Care, and the Pando Giant
