PROJECT TEAM
Joseph Hover, MSc
Dr. Allan Carroll, PhD
Using aerial surveys to predict forest growth loss
The western spruce budworm (Choristoneura freemani Freeman) is a widespread native defoliator in Douglas-fir dominated forests in British Columbia. The aerial overview survey (AOS) is the primary tool in the detection and delineation of defoliation. AOS information is subsequently used to determine treatment areas and calculate impacts to timber supply. Although dendrochronological studies have linked budworm outbreaks with Douglas-fir growth loss, it’s currently unknown whether defoliation severities estimated during the AOS can predict variation in Douglas-fir growth. Using tree core data collected from 46 sites across BC, we sought to identify and quantify the growth reduction associated with the different levels of mapped defoliation, providing a more accurate estimate for timber volume loss.
“We know that aerial BTK treatment is effective in reducing western spruce budworm population, but does it significantly protect tree growth?”
– Joseph Hover
Protecting tree growth
Bacillus thuringiensis var kurstaki (BTK) is commonly used as a lepidopteran control agent in both agriculture and forestry due to its effectiveness in reducing populations with little to no impact on non-target species. Application via helicopter is the primary tool used to reduce western spruce budworm defoliation damage in British Columbia. While BTK’s efficacy in reducing western spruce budworm populations is well understood, impacts on resulting tree growth is not. Using tree core data, we will pair treated and untreated plots with the goal of determining whether the control measures are effective in the alleviation of defoliation-caused growth loss.
