Subalpine Forest Regeneration following Mountain Pine Beetle Outbreak in Routt and White River National Forests, Colorado

摘要

The recent mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB) outbreak throughout North America has affected thousands of hectares of lodgepole pine (Pinus contorta Douglas var. latifolia Englemann) in northern Colorado. This severe disturbance in subalpine forests has created conditions leading to the advance regeneration and new recruitment of the shade-tolerant species Englemann spruce (Picea Englemannii) and subalpine fir (Abies lasiocarpa). Contrarily, a variety of factors including canopy opening and litter depth limit lodgepole pine seedling regeneration in MPB-attacked lodgepole pine stands. Significantly higher densities of subalpine fir and Englemann spruce seedlings following MPB outbreak suggest that severe MPB outbreak accelerates the succession of lodgepole pine and mixed subalpine stands toward a canopy codominated by more shade-tolerant species.