Conclusion
Post fire ecosystems often provide early seral successional habitats, where many critical grizzly bear foods thrive. Throughout the 20th century forest fire suppression has become very effective and resulted in a significant reduction of fire on the landscape. Fully understanding the consequences of decreased fire on the abiotic and biotic factors in many of these ecosystems is difficult. In Banff National Park, area burned by fire each decade has decreased from approximately 40,000 ha in the late 1800's to less than 500 ha, between 1950 and 1980 (White 1985). This considerable decrease in fire has likely contributed to a decrease in the composition and quality of grizzly bear habitat. Recent research indicates that Banff's grizzly bear population has the lowest reproductive rate of any studied population (Garshelis et al., 2005), which has likely contributed to its current negative growth rate (Sawaya et al., 2012). Parks Canada has invested the majority of its efforts towards reducing human caused mortality. While these efforts have been successful at reducing mortality (Bertch and Gibeau 2009) they have contributed little towards increasing the reproductive rate. With Banff's current grizzly bear population in decline (Sawaya et al., 2012), and no obvious solutions to further decrease mortality, it becomes imperative that critical habitat for these grizzlies must be established to regenerate positive population growth. Prescribed fire appears to be a logical application to establish grizzly bear habitat, as it follows Parks Canada's mandate of maintaining ecological integrity and it can be applied in areas without promoting increases in human access. Furthermore, from this preliminary study, prescribed fire appears to increases the shrub and fruit density or percent cover of many critical food items including: Amalancher anifolia, ants, Ribes oxycanthoides and Rubus ideas. Overall there was a significantly greater density of fruit production in prescribed fire sites than in the forested controls. Only Vaccinium scoparium was found in significantly greater coverage in forested controls than in the prescribed fire locations.
Of the terrain variables considered, elevation was the most significant factor influencing the outcome of grizzly bear foods. It was significant in three of the four permutational analyses. As expected the influence of elevation differs depending on the grizzly bear food species. Hedysarum spp, for example, was found at greater abundance at higher elevation locations whereas Shepherdia canadiensis shrub density was more pronounced at lower elevations sites. Burn severity had a significant effect on grizzly bear foods in post fire sites. As expected, lower severity burns typically influenced a elevated response in bear food production (Fig. 10). This is likely because higher severity fires present greater lethal damage to rhizomes and other plant structures resulting in a delayed establishment of these plant species. Parks Canada has only conducted prescribed fire for less than 30 years, therefor understanding the longterm outcome of higher severity burns on grizzly bear food production remains unknown.
To effectively use fire as a management tool in establishing grizzly bear habitat, it is essential to understand the different fire, terrain, and forest variables that contribute to the post fire habitats. The results from this study will help assist establishing prescribed burn plans to meet these objectives. This research outlines that prescribed fires can effectively enhance certain critical grizzly bear foods. As well, it demonstrates that fire components, such as burn severity and timing of fire, can effect the outcome of certain food items and therefor need to be carefully considered. Prescribed fire appears to effectively enhance fruit production in Banff National Park. Fruit sources provide the primary energy source for grizzly bears in the late summer and early autumn in Banff and other Rocky Mountain locations (Hamer and Hererro 1987; Hamer et al. 1991 and Munroe et al. 2006). Increasing the amount of available fruit, as well as alternative food sources, has the potential to increase the reproduction success and ultimately establish a positive population growth of Banff grizzlies.
Of the terrain variables considered, elevation was the most significant factor influencing the outcome of grizzly bear foods. It was significant in three of the four permutational analyses. As expected the influence of elevation differs depending on the grizzly bear food species. Hedysarum spp, for example, was found at greater abundance at higher elevation locations whereas Shepherdia canadiensis shrub density was more pronounced at lower elevations sites. Burn severity had a significant effect on grizzly bear foods in post fire sites. As expected, lower severity burns typically influenced a elevated response in bear food production (Fig. 10). This is likely because higher severity fires present greater lethal damage to rhizomes and other plant structures resulting in a delayed establishment of these plant species. Parks Canada has only conducted prescribed fire for less than 30 years, therefor understanding the longterm outcome of higher severity burns on grizzly bear food production remains unknown.
To effectively use fire as a management tool in establishing grizzly bear habitat, it is essential to understand the different fire, terrain, and forest variables that contribute to the post fire habitats. The results from this study will help assist establishing prescribed burn plans to meet these objectives. This research outlines that prescribed fires can effectively enhance certain critical grizzly bear foods. As well, it demonstrates that fire components, such as burn severity and timing of fire, can effect the outcome of certain food items and therefor need to be carefully considered. Prescribed fire appears to effectively enhance fruit production in Banff National Park. Fruit sources provide the primary energy source for grizzly bears in the late summer and early autumn in Banff and other Rocky Mountain locations (Hamer and Hererro 1987; Hamer et al. 1991 and Munroe et al. 2006). Increasing the amount of available fruit, as well as alternative food sources, has the potential to increase the reproduction success and ultimately establish a positive population growth of Banff grizzlies.