First, it was pine beetle infestation of evergreens. Now, it's also Sudden Aspen Decline (SAD). Approximately 15% of the aspen groves in the Rocky Mountains are afflicted. For some reason, large stands of old aspens are no longer sending out "suckers" to regenerate their groves. The phenomenon was first noticed in the San Juan mountains of southwest Colorado in 2002. The affliction has grown from 30,000 acres in 2005 to over 500,000 acres in only four years.
You can see the effect of pine beetle infestation all along I-70 and particularly in the area around Dillon. The entire mountainside on the east side of Dillon, for example, is brown, brittle, and lifeless, and one lightning strike away from a massive fire. The Wall Street Journal article referenced above says that foresters expect to lose every mature lodgepole pine tree in Colorado!
Researchers believe they understand why the beetles have been thriving. Temperatures in the mountains have been unusually warm over the past several winters, and it takes a long, hard freeze to kill beetle larvae. Also, decades of logging restrictions and a policy of fighting most fires rather than letting them burn have left the forests full of the century-old lodgepole pines that are the beetles' favorite nosh.
Nobody is quite sure what is causing Sudden Aspen Decline. Theories range from drought to natural transition into evergreen. The centuries-long cycle of aspen grove to conifer forest and back again is merely being played out on a grand scale, say some.
In any case, the loss of all lodgepole pines, and the potential loss of all the aspen, may mean that the days of seeing McClure Pass or Vail Valley in its autumnal coating of bright gold may well be over. This is an environmental disaster of the first order.
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