Aspens in trouble?

It's nearly impossible to imagine Colorado without its signature aspen trees. But stands of aspens are dying out throughout the state, and foresters are alarmed.

The most recent die-off: in the Dolores Ranger District's Turkey Knolls near Mancos. “I think we’re going to see huge changes in 30 to 40 years,” said Phil Kemp, forester with the Dolores Public Lands Center, in an AP story:

Kemp first noticed the change in aspen stands two to three years ago, but the first official report of dying aspens in Southwest Colorado came when the U.S. Forest Service’s forest health management group did an aerial survey of the area, marking the changes in aspen stands.

Dying aspens have been recorded in other states as well, but there is no apparent pattern, said Wayne Shepperd, research forester with the Forest Service’s Rocky Mountain Research Stationin Fort Collins. “It seems to be occurring at different places and to various degrees,” he said. “We have lots of questions, but no answers. We haven’t seen anything like this in Colorado before."

Kemp and the team of researchers have not been able to determine why the aspen stands are dying or why the mortality may be occurring at this point, but they suspect repeated years of drought, as well as insects and disease, may play a role. Without the needed moisture, aspens are weaker and less resistant to insects and disease.

This is from a story by Gazette writer Bill McKeown in March 2006:
Colorado’s shimmering stands of aspen trees, as potent a symbol of this state as its soaring peaks, are in danger of disappearing.

That’s the sobering conclusion of the Colorado State Forest Service’s recently released annual report on the health of the state’s forests. Colorado’s 4 million acres of aspens are reaching the end of their natural life cycle of about 120 years. But foresters already have seen troubling signs the trees may not regenerate themselves through their extensive system of roots and suckers, the author of the report, Jen Chase, said last week.

All over Colorado, aspens are being choked off by an invasion of conifers, a generic name for the cone-bearing evergreens that dominate the state’s forests. ... This cycle of birth, death and rebirth of aspens has occurred every century or so since the deciduous trees first sprouted in the moist glacial soils of the last Ice Age. But the coming cycle of dieoff lacks a crucial component of rebirth: fire. New life in the forests, experts say, requires the kind of fires that Coloradans have done their darnedest to prevent for a century. ...

Because fire has been suppressed for more than a century, vast swatches are now covered in tall, weedy conifers whose shade is blocking new aspens. ... Foresters ... say Colorado will inevitably lose some of its 4 million acres of aspens permanently. ... (and) favor prescribed burns of conifers to reduce fire danger, create clearings for aspens and create forests that contain trees of different ages. ... On a small scale, aspen stands can be rejuvenated by using machinery to slice through the extensive root system, spurring the production of new suckers. ... Whatever strategies are used, it will take many years, many dollars, a lot of hard work and the understanding of residents and environmentalists, the foresters say.