An investigation of recent sudden mortality of balsam fir in Eastern North America: Climate, stand and site drivers of mortality
University of New Brunswick
In 2018, a widespread, balsam fir mortality event occurred across the species southern range limit. The purpose of this thesis was to determine the role of climate and local factors as drivers of mortality in Atlantic Canada. A Random Forest model associated a combination of climate anomalies with mortality, notably a summer drought in the previous year. This model was able to predict a similar event that occurred in 1986 with a remarkable accuracy of 95% (kappa = 0.88). Looking at local factors, I find that sites associated with elevated temperatures (i.e., lower elevations and south facing aspects), higher competition for water and taller trees display higher mortality risks. Mortality probability was also associated with low depth to water values with minimal influence observed for drainage and slope variables. This research highlights the vulnerability of balsam fir to drought induced mortality.