2013 - Mountain Pine Beetle Ecology Program Research – Practitioner Information Exchange Forum April 24, 25, 2013
Using fires to trigger cone opening in an aerial seedbank in recently dead or healthy jack pine stands. Hyejin Hwang1, Victor Lieffers1, Soung Ryu1, and Dave Schroeder2 1
Department of Renewable Resources, University of Alberta Alberta Environment and Sustainable Resource Development
2
Abstract Mountain pine beetle (Dendroctonus ponderosae; MPB) is a native disturbance agent in western North America. Owing to the recent favorable weather conditions and mature pine forests at large areas, expansion of MPB outbreaks to eastern Canadian boreal forests has raised economic, social, and ecological concerns. Jack pine (Pinus banksiana) is a critical species in Canadian boreal forests and mostly existing as serotinous population. Prescribed burning will be required to promote jack pine regeneration by providing suitable seedbed and heat for cone opening. Our research attempts to model cone opening in relation to char height as a barometer for fire intensity. We hypothesized that fire would induce cone opening more easily in MPB-killed stands than in healthy stands, given increased foliar flammability in MPB-killed stands. Study plots were established in a jack pine stand located at 165 km northeast of Fort McMurray, Alberta in 2007. Plot size ranged from 0.12 to 4 ha with each plot divided into two subplots. Trees were girdled at breast height, simulating >90% success of MPB attack. Paired prescribed burns (treatment and control) then commenced under identical weather conditions in 2009. In 2012, cone opening was assessed in a total of 76 dead and healthy jack pine trees with a wide range of char height. Cones in MPB-simulated trees started opening at lower fire intensity than those in healthy trees likely due to lower foliar moisture content. However, wider variation in cone opening was observed in MPB-simulated trees than in healthy trees. Notes: