Aspen, often called trembling or quaking aspen, is the most widely distributed tree species in North America, ranging from Alaska to Newfoundland and down the inter-mountains to Mexico. The states of Utah and Colorado have the largest portion of natural aspen acreage in the World.
Populus tremuloides is the most beautiful fall tree the western United States has to offer. But a die-back is killing older, mature aspens that exceed 80 years in age. Silviculturists have not used the tiresome "global warming" excuse this time. Still, these scientists don't know the exact cause but have some strong opinions as to the reason(s) why.
Possible causes for the aspen die-back or what is called sudden aspen decline are a reduction of fire in older stands, a long-standing western drought and overgrazing which increases the presents of insects and disease. Younger aspens can cope with most natural pests but an aging population loses much of its resistance to pests. Colorado has lost over 138,000 acres of over-mature aspen forests to die-back.
Getty/Digital Vision Image