Lodgepole pine stand dynamics as a result of mountain pine beetle attack in central British Columbia

At the time this study was conducted, the central interior of British Columbia was experiencing a mountain pine beetle (MPB) epidemic. Baseline data were collected in the southern portion of the Lakes TSA, the Entiako Protected Area, and the Cheslatta Community Forest in order to describe stand level conditions immediately post MPB epidemic and to make recommendations on post MPB management. Data collected were attack rates, tree mortality and regeneration in mature, mesic and sub mesic, pine dominated stands in the dry cool Sub-Boreal Spruce subzone (SBSdk). Fifty-six percent of the trees were attacked. MPB attack increased with increasing stand age and diameter class but did not differ between site types. Stand-level mortality was as high as 91%, and the wood volume killed exceeded 68%. A chronosequence index (for time since attack) based on a combined assessment of time since attack and percentage of trees killed within each attack status category was developed. The percentage of stems killed decreased from the oldest attacked stands to the most recently attacked. However there was no trend for mean tree diameter killed using the same index. Twenty-eight percent of the mature trees were alive and unattacked when surveyed in 2004. Pine (58%) and spruce (38%) were the two most common species of advanced regeneration. The mean density of advanced regeneration was 710 stems per ha (sph): 226 sph saplings and 484 sph seedlings. Not all regeneration was healthy (expected to become mature trees when released); healthy regeneration totalled 465 sph. The distribution of advanced regeneration was uneven: 40% of the plots contained no regeneration. No pine germinants were found and no MPB killed tree had fallen. Regeneration met minimum stocking standards in 12.5% of the stands surveyed, and the potential for near term regeneration appeared low. Hazardous tops were by far the most common defect. The SBSdk in the area studied was significantly affected by MPB and the abundance of suitable host for the beetle declined. In areas that contribute to the timber harvesting land base, some form of silvicultural intervention may be warranted.