Predicting black spruce fuel characteristics with Airborne Laser Scanning (ALS)

Abstract

Wildfire decision support systems combine fuel maps with other fire environment variables to predict fire behaviour and guide management actions. Until recently, financial and technological constraints have limited provincial fuel maps to relatively coarse spatial resolutions. Airborne Laser Scanning (ALS), a remote sensing technology that uses LiDAR (Light Detection and Ranging), is becoming an increasingly affordable and pragmatic tool for mapping fuels across localised and broad areas. Few studies have used ALS in boreal forest regions to describe structural attributes such as fuel load at a fine resolution (i.e. ,100 m 2 cell resolution). We used ALS to predict five forest attributes relevant to fire behaviour in black spruce (Picea mariana) stands in Alberta, Canada: canopy bulk density, canopy fuel load, stem density, canopy height and canopy base height. Least absolute shrinkage and selection operator (lasso) regression models indicated statistically significant relationships between ALS data and the forest metrics of interest (R 2 $0.81 for all metrics except canopy base height which had a R 2 value of 0.63). Performance of the regression models was acceptable and consistent with prior studies when applied to test datasets; however, regression models presented in this study mapped stand attributes at a much finer resolution (40 m 2 ).

Predicting Wildfire Fuels and Hazard in a Central European Temperate Forest Using Active and Passive Remote Sensing

“…Their regression model validation produced RMSEs of 0.27 (R 2 = 0.84) and 0.024 (R 2 = 0.88) while including 101 and 57 field sampling locations, respectively. Cameron et al [30] reported a RMSE of 0.098 (R 2 = 0.78) whilst using 52 training samples. Considering the low number of samples in the present study, a RMSE of 0.069 (R 2 = 0.73) was acceptable, especially as CBD is only one of multiple components of the FH assessment.…”

“…LiDAR-derived metrics produced for this analysis include several basic descriptive statistics that have been proven useful when modeling vertical structure for forestry applications [21,[29][30][31]. A large portion of the metrics (>60%) is related to the height values of laser returns (Z-dimension).…”

Stand-Level Fuel Reduction Treatments and Fire Behaviour in Canadian Boreal Conifer Forests

“…The relatively short stature of natural boreal conifer forests [55,66] means that maximum achievable CBH through pruning is limited in comparison with species such as ponderosa pine (Pinus ponderosa) and Douglas fir (Pseudotsuga menziesii), which are characterized by substantially higher tree heights [67]. It is also noteworthy that in mature stands represented by the C-2 fuel type, black spruce tree crowns can extend nearly to the ground, such that thinning alone cannot be relied upon to elevate CBH.…”

“…The sensitivity of crown fire initiation predictions to assumptions about surface fuel load and surface fuel consumption is illustrated in Figure 4 for fuel-treated black spruce stands at the Pelican Mountain research site in Alberta. Given the field-measured mean CBH of 3.45 m documented by Cameron [55] and assuming 100% foliar moisture content, Van Wagner and Byram models indicate that surface fuel consumption ≤ 0.72 kg/m 2 would be required to inhibit crown fire development under relatively low surface fire spread rates of ≤ 5 m/min, which would drop to fuel consumption thresholds of ≤ 0.36 kg/m 2 and ≤ 0.24 kg/m 2 for inhibiting crown fires at rates of spread of 10 and 15 m/min, respectively.…”

“…Reductions in CBD from thinning is intended to limit sustained crown fire spread in situations when high wind speed, fast rate of spread, and high surface fuel consumption (SFC) lead to a surface fire intensity that exceeds the critical fire intensity needed for vertical spread into crown fuels [25]. Field-measured CBD for fuel-treated black spruce stands in Alberta had mean and maximum values of 0.19 and 0.34 kg/m 3 [55], respectively. Following Van Wagner [9], the critical minimum rate of crown fire spread that would be required to sustain a crown fire in these stands would be 15.8 and 8.8 m/min, given mean and maximum CBDs, respectively.…”