Predicting Fuel Characteristics of Black Spruce Stands Using Airborne Laser Scanning (ALS)

M.Sc student Hilary Cameron (supervised by University of Alberta’s Dr. Jen Beverly)

A natural black spruce stand located in Conklin, Alberta. Black spruce trees typically have crowns that extend to the forest floor with a build up of dead branches and lichen. This allows a surface fire to easily transition into a crown fire compared to other forest types.

Fuel is a key determinant of wildfire behaviour and is therefore a required input to any fire behaviour model. Maps that describe the characteristics of live and dead biomass across large areas (i.e., fuel maps) are a critical input to a wide range of research models and decision support systems that aim to describe potential fire behaviour and inform fire management actions. Directly measuring fuel attributes to create fuel maps is time consuming, expensive and results in a limited inventory of stand attributes across a landscape. As remote sensing technologies become more affordable, the ability to utilize these technologies to create comprehensive fuel maps on small and large scales is becoming increasingly pragmatic.

M.Sc student Hilary Cameron (supervised by University of Alberta’s Dr. Jen Beverly) investigated the viability of using Airborne Laser Scanning (ALS), a form of remote sensing that uses LiDAR, to predict forest attributes that are important to wildfire behaviour in black spruce stands located in Alberta, Canada. Results suggest that detailed fuel maps can be made with ALS and can be a cost-effective alternative to field-based sampling to predict potential wildfire behaviour and support with fire-management decisions.

FULL THESIS

(a) The Fire Behaviour Prediction (FBP) fuel type map shows that the Pelican Mountain Research Site located near Slave Lake, Alberta is almost entirely covered by the C-2 Boreal Spruce Fuel Type. The FBP fuel type map is the main map used to model wildland fire behaviour in Alberta at the present time; however, within-stand variation in fuel structure is ignored in the FBP System fuel classifications. (b) The ALS-derived fuel attributes show that canopy bulk density, a main determinant of wildland fire behaviour, can vary substantially within black spruce stands. Model results also correspond well with field photos that show the model is accurately detecting areas of high (c, top), intermediate (c, middle), and low (c, bottom) canopy bulk density values.

A black spruce stand at the Pelican Mountain Research Site located near Slave Lake, Alberta after a prescribed crown fire burn. Black spruce stands are more susceptible to crown fires compared to many other stand types due to their chemical composition and fuel arrangement.