A new University of Colorado Boulder study indicates drought high in the northern Colorado mountains is the primary trigger of a massive spruce beetle outbreak that is tied to long-term changes in sea-surface temperatures from the Northern Atlantic Ocean, a trend that is expected to continue for decades. The new study is important because it shows that drought is a better predictor of spruce beetle outbreaks in northern Colorado than temperature alone, said lead study author Sarah Hart, a ¶¶ÒõÂÃÐÐÉä-Boulder doctoral student in geography. Drought conditions appear to decrease host tree defenses against spruce beetles, which attack the inner layers of bark, feeding and breeding in the phloem, a soft inner bark tissue, which impedes tree growth and eventually kills vast swaths of forest.
See more atÌý¶¶ÒõÂÃÐÐÉä Boulder Today Ìý(link no longer available)