"Since European settlement began in about 1850, about 60 to 90 percent of the aspen forests have disappeared, taken over by conifers such as pines, spruce and fir," says Dong Ko, a recent Penn State graduate with a master's degree in geography.

"In just the last 50 years, there has been a 30 percent decline," Ko told attendees at the 86th annual meeting of the Ecological Society of America today (Aug. 7) in Madison, Wis.

Quaking aspen, the most widely distributed tree in the northern hemisphere, is found from coast to coast in a band that includes northern California, the Rocky Mountains, Wisconsin, upstate New York and New England. Beside being noted for their shimmering leaves and the golden color they turn in the fall, aspen are unusual because they grow as clones, putting out vegetative shoots rather than forming seeds from which saplings sprout.

"Much research exists on aspen groves in the intermountain West and especially about their decline there," says Dr. Alan Taylor, professor of geography. "But there is no published information on aspen stands from California. Nothing was known about them."

Assumptions for the decline of the intermountain aspen stands include the suppression of frequent fires, increased livestock grazing, and increased and concentrated herds of native herbivores including deer and especially elk. The same environmental factors were believed to affect California stands as well.

Ko and Taylor studied 20 aspen groves on the California side of the Lake Tahoe Basin. The Penn State researchers identified the ages of the trees in the stands and the types of trees found. Surprisingly, they found only 15 percent or five stands tha
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Contact: A'ndrea Elyse Messer
aem1@psu.edu
814-865-9481
Penn State
7-Aug-2001