PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Understanding landscape pattern and mountain pine beetle management in British Columbia.

Hughes, Josie^*,1, Fall, Andrew², Shore, Terry³, Riel, Bill³, Eng, Marvin⁴, Hall, Peter⁴, ¹ Research Consultant, Nelson, British Columbia, Canada² Simon Fraser University, Burnaby, British Columbia, Canada³ Canadian Forest Service, Victoria, British Columbia, Canada⁴ British Columbia Ministry of Forests, Victoria, British Columbia, Canada

ABSTRACT- Some forest landscapes are more susceptible to mountain pine beetle impact (Dendroctonus ponderosae Hopkins) than others, and which management strategies are appropriate depends on forest condition. Our goal is to generalize from particular cases to understand interactions between habitat abundance and distribution, beetle abundance and distribution, and management strategies, while remaining realistic enough to assist managers. The question is how variation among the landscapes of British Columbia alters the impact of beetles and relative efficacy of management. First, we analyzed host and beetle patterns in 57 sample landscape units across British Columbia. We built a pattern generation model to recreate essential aspects of these 57 units, including the abundance of habitat in various susceptibility classes, the clumpiness of habitat, the abundance of beetle infestations of various severity classes, the relationship between infestation severity and habitat quality, and the dispersion of beetles. The range of variability in an array of simulated landscapes is informed by the variation we see in real landscapes, but in the simulated landscapes we vary factors independently, and distinguish real effects from stochasticity with replicates. We simulate mountain pine beetle dynamics and forest management on 90,000 ha simulated forest landscapes (10 replicates of each). Trivially, we find that the impact of beetles increases significantly with initial host and beetle abundance. More interestingly, the clumpiness of hosts has no significant effect on the progress of infestations. Host pattern could, in the extreme, have some effect, but among our sample landscapes pattern does not vary enough to make this an important factor. In contrast, whether beetles are dispersed, or clumped far from the bulk of suitable habitat can have a significant effect, especially if habitat is scarce. Beetle management is most effective when beetles are scarce, and the amount of infested area above which beetle management can no longer prevent an outbreak is fairly low (1-2%, depending on the allowable cut). At this threshold, the subtleties of beetle management, host abundance, and beetle distribution become more important.

Key words: Dendroctonus ponderosae, simlation modeling, forest management, landscape pattern