The Decline of the Quaking Aspen

“The effect of the presence of the wolves can be greater than just the wolves eating some of the elk,” Ripple says. It may also have changed the elks’ foraging habits because they no longer had to remain in clearings where they could see approaching wolves. They were free to dine in the heart of the grove.

The wolf was reintroduced in Yellowstone in 1995, “and they have done really well,” Ripple says. “Their numbers have multiplied greatly.”

So to test out the wolf-elk theory, the Oregon researchers have established 115 permanent aspen plots, some in “high wolf use areas, and some in low wolf use areas,” Ripple says. It will take several years, but the experiment should tell whether the presence of the wolf keeps the elks out of the aspen regeneration areas.

In the grand scale of things, the decline of the wolf throughout the West may be only a minor player in the decline of the aspen. Most experts believe the primary reason for the decline is competition with conifers which reach such great heights that they block out the sun from the shade-intolerant aspen.

That’s the way nature designed the system — the aspen, like the alder and other species — is a transitional plant, thriving until bigger trees move in and take over. But why should conifers be making more inroads today than they did in the past?

The Aspen Has a Trump Card

Many experts believe fire suppression provides the most plausible explanation. Fire wipes out conifers, as well as aspen, but the aspen has a trump card.

Aspen groves are essentially hundreds of trees growing from the same root.

“The entire organism is an interconnected root system, so the whole stand of trees, every tree in that stand, is a clone, or genetically identical,” Ripple says.

Most of the bio mass of the system is below the ground, where it is protected from fire. So when fire moves in, it destroys the growth above the ground, wiping out the conifers as well, but the aspen grove remains healthy below the ground.

After the fire, new aspens spring up from the root system, and there aren’t any conifers left to block out the sunlight that is so essential for their growth.

The Forest Service is experimenting in a number of regions with letting fires continue to burn, putting nature back at the helm. But of course that isn’t practical in populated areas, and fires do wipe out conifers which are more valuable as timber resources than aspen.

The aspen, it turns out, isn’t worth much on the timber market, except for pulp.

But it is a wonderful thing to behold. I remember walking through aspen groves in New Mexico as a kid, listening to the soft music of their fluttering leaves, wondering what they were trying to say.

Perhaps they were saying “help.”

Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.

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