Canadian Forest Service Publications
Assessment of post-beetle impacts on natural regeneration of lodgepole pine. 2009. Egger, K.N.; arocena, J.; Green, S.; Kennedy, N.; Massicotte, H.; Tackaberry, L.; Scholefield, S Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, B.C. Mountain Pine Beetle Working Paper 2009-07. 22 p.
Issued by: Pacific Forestry Centre
Catalog ID: 30128
In 2004, a wildfire near the Kenney Dam in north-central British Columbia burned approximately 10,000 hectares of forests. This ecological disturbance presented a unique opportunity to study natural and artificial regeneration in burned mountain pine beetle (Dendroctonus ponderosae Hopkins) infested stands. Mountain pine beetle has been documented as a natural disturbance agent that may precede wildfire in lodgepole pine forests (Pinus contorta var. latifolia). In this study, we characterize lodgepole pine regeneration and the related micro-site conditions across a range of disturbance scenarios associated with mountain pine beetle (MPB) infestation and wildfire; identify limitations for the germination, survival, recruitment and growth of natural and artificial regeneration in relation to the effects of site moisture, fire severity, and competition by vegetation; and provide guidance on how to manage beetle-infested lodgepole pine stands subsequently burned by wildfires. Germination, survival and recruitment of lodgepole pine seedlings over two growing seasons were compared on 18 disturbance plots with three fire severity classes, two moisture regimes, two seed provenances, and two seedbed types. In the growing seasons following the fire (2005 and 2006), seeded plots experienced bursts of spring germination followed by continuous minor waves of new germination that ended by August 2006. Wet sites experienced a higher level of natural regeneration, and the density of seedlings increased with decreasing fire severity. On dry sites, new germinants were rare due to the impact of high and moderate fire severity, and the highest germination rates existed where fire severity was lowest. Seed provenance did not influence germination and survival rates. In contrast to the germination, survival, and recruitment results, growth rates were highest on the dry sites and increased with increasing fire severity. Thus, although recruitment on dry sites is unlikely to sufficiently restock lodgepole pine stands, the survivors show the highest growth rates. Conversely, recruitment on wet sites was sufficient to restock these stands, but seedling growth rates will likely be impeded by competing vegetation. We found no evidence that the survival or growth of recruits on dry sites was affected by the adverse impacts of the beetle and burning on soil properties, and lower diversity of ectomycorrhizal communities and nitrogen-cycling communities.