Researcher finds new evidence of western forest decline

CORTEZ, COLO. – In Colorado’s San Juan National Forest, between 7,000 and 10,000 feet, quaking aspen grow in glorious, shimmering groves. In mid-2004, Forest Service rangers noticed the aspen groves sickening. Trees crowns browned in patchy clusters. Their lime-green, spear-shaped leaves dropped. Aerial surveys observed a rapidly widening area of forest illness and death in the years that followed.

Biologist William Anderegg assesses the health
 of quaking aspen in a study plot in southwest Colorado. 

In 2008, William Anderegg drove from California to his parents’ home in Cortez, Colorado, a farming and ranging town south of the National Forest. He also noticed the dying aspens. It was late summer and he’d just graduated from college at Stanford. The compact crowns should have been alight with thick swaying foliage. But on many trees, the branches were bare.

“It was pretty eye-opening to see the forest change so much in my lifetime,” he recalled recently.

Tracking down what killed the trees of one’s youth

William resolved to track down what had killed the trees, where he’d often hunted with his dad. Their hunting ground turned out to offer the first indication of what was becoming possibly the largest loss of aspen ever.

Read the Yale Climate Connections story by daniel Grossman - “Researcher finds new evidence of western forest decline.”