Estimating Forest Fuels Attributes Using Laser Altimetry Data

Project details
Laser altimetry can provide relatively precise measurements of canopy top height, vertical canopy distribution, surface roughness and ground surface topographic elevation. Laser altimetry technology uses light (usually laser) emissions to measure ranges between itself and a reflective surface. Airborne laser instruments emit pulses of electro-magnetic radiation toward the earth and collect the backscatter using nanosecond-resolution clocks to time the roundtrip propagation of each pulse. Earth surface structural parameters like slope and vegetation height are determined by analysis of the intensity and the temporal distribution of backscatter radiation collected from each pulse.

NCLFA has studied the relationships between airborne laser altimetry derived surface roughness, surface fuel volume and fire behavior fuel models at the Tenderfoot Creek Experimental Forest and the Lubrecht Experimental Forest, both in western Montana. A fraction of the laser pulses are reflected from objects under tree canopies, providing three-dimensional representations of individual features such as coarse woody debris. Ongoing research shows that laser altimetry can: provide accurate information on total fuel load at 9 hectares plot size; can provide a comparison of fuel loads in varying plots; and can define what fuel types exist in each plot. Roughness measurement may give more consistent representation than what a fuels measurement has ever given, and is certainly a less time-consuming way to measure fuels than traditional by-hand counts.

Principal Investigator: Carl Seielstad