Pine Bark Beetle and Dwarf Mistletoe Infestation in a Remnant Old-Growth Stand

Abstract

Abstract. We examined the incidence of bark beetle (Coleoptera: Curculionidae: Scolytinae) colonization and subsequent mortality, and the presence of dwarf mistletoe (Arceuthobium vaginatum subsp. crytopodum) within a rare remnant old-growth stand of ponderosa pine. In 2011, 96% of the old growth trees were remaining with additional dense ingrowth of ponderosa pine (Pinus ponderosa Douglas ex. Lawson) within the understory of the oldest trees. We compared the old-growth stand to abutting stands of ponderosa pine: a low-density seed-tree cut and a high-density post-1900 second growth. The old-growth stand had levels of bark beetle colonization similar to the seed-tree stand, and both of these stands had significantly more bark beetles than the high-density stand. Across all sites, bark beetles were found in higher numbers in the 51–60 cm diameter class. We found a trend between the proportion of trees infected per site and the percentage of trees with bark beetle activity, although a direct relationship be...