Masters Thesis Part 2
The ongoing outbreak of mountain pine beetle (Dendroctonus ponderosae; MPB) in British Columbia (BC) have reached unprecedented levels under warming conditions since the late 1990’s, impacting more than 18 million hectares of forests across BC. Similarly, warming temperatures and summer drought conditions have resulted in decreased soil and fuel moisture in BC, thus increasing the likelihood of ignition and length of fire seasons, contributing to an increase in the extent and frequency of wildfires. In 2017 and 2018 for example, BC experienced back-to-back record fire seasons burning a combined 2.57 million hectares.
Mountain Pine Beetle Attack Stages
Green (<1 year since attacked)
Red (1 to 3 years since attacked)
Grey (>4 years since attacked)
Our changing climate emphasizes the need to understand the relationship between disturbance events, such as effect of MPB on wildfire behaviour. This is critical to fire management decision making and to the safety of wildfire fighters.
In this study, I identified a set of wildfires in BC that took place in grey-attack stage MPB-affected forest stands in 2017 and 2018 and employed a monoplotting approach (See Part 1) to estimate the headfire front positions at two time periods during each fire, which allowed for calculating the observed wildfire rate of spread (ROS).
I compared these results to ROS estimates from the Canadian Fire Behavior Prediction (FBP) System using the C-3 fuel type, which represents the fuel structure of healthy green pine stands. The results from this comparison allowed for observing the effects of grey-attack stage dead trees on the spread rate of wildfires in BC.
Findings
This analysis showed that observed spread rates were 1.7 times faster than the FBP System C-3 model predictions, indicating faster than expected fire spread in MPB-affected forest stands.