Spatial patterns and factors influencing spruce budworm infestation in Eastern Canada forests
University of New Brunswick
A spruce budworm (Choristoneura fumiferana Clem.; SBW) outbreak in Québec spread southward into New Brunswick in 2014. This thesis used spatial analyses of 5 years of SBW population data in northern New Brunswick and tree defoliation data in Québec to examine spatial patterns and factors influencing SBW infestation. Local previous-year SBW population level, proximity to outbreak hot-spots, and April degree-days were important in predicting SBW population levels in New Brunswick, although relationships were inconsistent across years. Models incorporating spatial stuctures [sic] explained 68–79% of the annual variance, and performed better than non-spatial models. A combined-year model with R [squared] = 0.53 consistently underestimated upcoming-year populations. Defoliation patterns quantified in 57 plots in Québec were clustered in 28-47% of cases, which had higher plot-level defoliation and higher deviations. Plot-level defoliation and basal area explained 80% of the variance in individual-tree-defoliation. The thesis contributed to efficient sampling allocation and insecticide treatment targeting infestation.