Print PageOur understanding of Picea glauca dynamics in the boreal forest is based on the assumption that seeds are killed during wildfire, so that recruitment relies on wind dispersal from burn edges. However, following recent late-season fires in Kootenay National Park, Canada, high densities of germinants were observed far from burn edges, suggesting seed survival within the fire. Furthermore, the heat transfer characteristics of P. glauca cones are nearly identical to those of Picea mariana, a seritonous species in which seeds necessarily survive fire. We thus hypothesize that P. glauca seeds can survive heating by wildfire, but that post-fire recruitment depends on the timing of fire occurrence relative to seed development. Our objectives are to: 1) use physical process simulations to identify conditions under which P. glauca seeds can survive wildfire, and 2) use germination studies to determine the timing of germination ability. We made weekly cone collections from 14 June to 9 September 2010 (345.32 to 1221.27 degree days) at the University of Calgary campus. Cones were used to parameterize a two-dimensional transient heat transfer model of cone heating. This model was implemented in the NIST Fire Dynamics Simulator, a Computational Fluid Dynamics model of crown fire spread typical of boreal forests. Crown fires typical of the boreal forest were simulated.
Results/Conclusions
Model results indicate conditions of fire behavior and cone phenology which permit seed survival. Cones were also used for germination studies, which showed that germination begins around 787 degree days and continues until seed release around 1221 degree days. These results suggest that recruitment can occur from surviving seeds within fires, provided the fire occurs during a relatively short time period when seeds are mature enough to germinate but are still contained in cones.
