Our forests have become prone to catastrophic wildfires and insect and disease epidemics because many of Colorado's Front Range forests are stressed, possibly beyond the range of historic variability. Stressed trees have weakened defenses against insect and disease problems. Additionally, wildfires that burn through overcrowded forests can be very difficult to control and can have devastating results. Since then, fire suppression has maintained the even-aged nature of these forests. In the absence of fire or mechanical thinning, nature will provide other means of reducing forest density, such as major insect and disease outbreaks.
Trees turn reddish-brown in late spring or summer following the previous summers successful attacks.
MPB outbreaks will usually take hold in areas of stressed or overmature trees. Once established, MPB is more apt to attack nearby trees, vigorous or not. The probability of catastrophic events can be reduced with broad-scale vegetation management. Managed forests can provide a mosaic of structural types across the forest, improve wildlife habitat, and help maintain healthy watersheds that are more resistant to catastrophic wildfire, insect and disease events. It can take a year for the leave trees in a stand to respond to thinning.