What factors are contributing to the current extensive mountain pine beetle outbreak in Colorado?
Three main factors, apparently happening concurrently, have fostered a perfect storm resulting in the intensive mountain pine beetle outbreak in Colorado. First, extensive areas of continuous lodgepole and ponderosa pine forests are growing with characteristics that make the stands susceptible to mountain pine beetlesuch as the presence of large-diameter trees and dense stands with a high proportion of host trees. Second, drought conditions began in Colorado in the late 1990s, becoming severe by 2000. This lack of moisture stresses trees, which then become more susceptible to mountain pine beetle attack. Third, cold winter temperatures are a primary mortality agent of the mountain pine beetle, and during the last decade or so, Colorado has not experienced sufficiently cold temperatures to trigger significant insect mortality.
