The Dieleman grassland on Grouse Mountain near Smithers was burned in May 2002 by the BC Ministry of Forests and Range (Veenstra and Haeussler 2002). Immediately after the burn we located 5 plots within areas of young aspen adjacent to the grassland and flagged 8-10 trees in the following categories: unburned, lightly burned (singed base, low
scorch height) and severely burned (charred, partially consumed tree base and roots, higher scorch height) (Figs. 1-2). One plot was subxeric and located on shallow soils near bedrock, three plots were submesic and located on shedding sites with moderately deep soils or colluvium, and one plot was mesic and located in deep soils on a slightly receiving site. No unburned trees were found on the subxeric plot nor on one of the submesic plots.
In August 2002 and June 2008 we relocated the ribboned aspen trees and assigned each tree a vigour rating based on foliage condition and the amount of live crown. The vigour ranking was not based on the degree of scarring on the trunk. 0 = dead, 1 = poor, 2 = fair, 3 = good, 4 = excellent. No trees were rated as excellent. In 2008 we also noted the frequency and size of aspen suckers within the plot.
Repeated measures ANOVA was used to test for differences in mortality rate and aspen vigour by year and burn severity. We used linear regression to test for a relationship between aspen mortality and vigour and the soil moisture regime.
