Biological evaluation of mountain pine beetle activity on the Arapaho National Recreation Area (ANRA) and of dwarf mistletoe on ANRA recreation sites

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Lodgepole pine mortality due to mountain pine beetle (MPB) (Dendroctonus ponderosae) increased steadily in the Arapahoe National Recreation Area (ANRA) from 1997 to 2001 and remained high in 2002 according to aerial surveys. Potential MPB management areas designated by the Sulphur Ranger District were ground surveyed to determine the status of the beetle population. Selected campgrounds were surveyed for MPB attacked trees and systematically surveyed for dwarf mistletoe. Strip samples recorded the number of trees infested by MPB in 2001 and 2002 in four different areas covering over 125 acres. MPB infestation rates increased from 2001 to 2002 in all areas sampled. The 2002:2001 attack ratio varied from 1.4:1 to 3.1:1 and infested trees/acre in 2002 varied from 1.5 to 20.9, indicating that MPB populations are above endemic levels in all areas sampled. Analyzing areas based on management objective and MPB abundance will help select the best management tactics for a given area. No new mountain pine beetle infestations were found in Arapahoe Bay and Willow Creek campgrounds which had received preventive insecticide applications to protect high value trees. Dwarf mistletoe information for ANRA campgrounds was collected through systematic ground surveys and analysis of existing stand exam data. Willow Creek, Green Ridge and Sunset Point campgrounds had light dwarf mistletoe infection with stand dwarf mistletoe ratings (DMR) from 0.0-0.5. Moraine, Big Rock and Roaring Fork Camping Loops at Arapahoe Bay had moderate infection levels with stand DMR from 0.5-3.0. Heavily infected stands with DMR over 3.0 were found in Stillwater Bay and Cutthroat Bay Campgrounds. Management recommendations for stands infested with dwarf mistletoe are discussed.