The mountain pine beetle has killed large numbers of the lodgepole pine trees in the northern mountains of the US state of Colorado. The more recent outbreak of another bark beetle pest, the spruce beetle, is threatening higher-elevation forests of Engelmann spruce. Chemical prevention is effective but too costly for large-scale use. Dead trees increase the incidence of wildfires, and may contribute to climate change as they decay. Uses have been found for the dead wood including composting and in construction, and potentially to make biochar.