Dale Bartos, aspen ecologist with the Rocky Mountain Research Station, is cautious about using climate-based forecasts to predict an end to aspen.

"I see aspen moving up and down the hillsides with climate change," he said. "As it dries out, we may see aspen on the lower end move up the hill. I don't think the answer is cut and dried."

Others foresee a grim outlook for a tree long associated with the appeal of the West.

"What we think will happen is that aspen will disappear in some areas and there will not be anything we can do about it," said SAD expert Wayne Shepperd.

A study by the federal Rocky Mountain Research Station presented just such a scenario. It predicted the near total disappearance of aspen in the Rocky Mountain region by 2090.

The research, to be published in Forest Ecology and Management, concludes that up to 41 percent of Western forests would be unable to support aspen by 2030. That figure would rise to 75 percent by 2060 and as much as 94 percent