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Sudden Aspen Decline

NPS Photo - J Schmidt - 1977 - Public domain image.
Rapid mortality of mature aspen (Populus tremuloides), known as sudden aspen decline or SAD, has been reported throughout North America, including the southwestern United States. The recent decline is characterized by the rapid dieback (2 to 6 years) of apparently healthy stands of mature aspen and poor suckering. Drought has been a major inciting factor to recent diebacks, with mortality resulting from various combinations of insects and pathogens. Recent research suggests that hydraulic failure of roots and branches and not carbon starvation underlies drought-induced aspen die-offs in Colorado. In documented cases of sudden aspen decline in both Colorado and Arizona, mortality generally decreased with elevation, however, aspen in affected dry, low-elevation (<7,500 ft) sites in Colorado experienced on average >95% mortality between 2000 and 2007. Because drought is thought to be a primary stimulus, there is concern that the warmer and drier conditions predicted for much of western North America could lead to significant increases in aspen mortality. Projections of the contemporary climate profile for aspen into the future suggested that the area occupied by the profile in the western United States should diminish rapidly over the course of the 21st century, decreasing by 10–40% by as soon as 2030.


© 2012 Merriam-Powell Center for Environmental Research
Merriam-Powell Center for Environmental Research
Northern Arizona University
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