Estimating canopy bulk density and canopy base height for conifer stands in the interior Western United States using the Forest Vegetation Simulator Fire and Fuels Extension.This article is part of a larger document. View the larger document here.
The Forest Vegetation Simulator Fire and Fuels Extension (FFE-FVS) is often used to estimate canopy bulk density (CBD) and canopy base height (CBH), which are key indicators of crown fire hazard for conifer stands in the Western United States. Estimated CBD from FFE-FVS is calculated as the maximum 4 m running mean bulk density of predefined 0.3 m thick canopy layers (Sando and Wick 1972). Canopy base height is estimated in a similar fashion as the lowest height at which the running mean bulk density of canopy layers exceeds a predefined threshold of 0.011 kg m-3 (Scott and Reinhardt 2001). Because estimates of CBD and CBH from FFE-FVS are derived from estimates of the bulk density of canopy layers, their values depend both on the biomass of canopy fuel and on the manner in which fuel is distributed vertically within the crowns of trees that make up the canopy (Keyser and Smith 2010).