LANDFIRE Remap Forest Canopy Bulk Density (CBD) CONUS

LANDFIRE's (LF) Remap Canopy Bulk Density (CBD) describes the mass of available canopy fuel per unit canopy volume that would burn in a crown fire. A spatially explicit map of CBD supplies information used in fire behavior models to determine the spread characteristics of crown fires across the landscape. The CBD mapping process derives field referenced estimates of canopy characteristics through LF Reference Database (LFRDB) plot analysis. Utilizing the LFRDB plots, field referenced CBD values are computed for each plot with the canopy fuel estimation software FuelCalc. In FuelCalc, for tree species that have no crown biomass, an equation for a species with a similar genus is used as a substitute. Species widely considered to be resistant to fire are excluded, for example, Acer and Populus spp. are excluded from the canopy fuel profile because these species are considered relatively inflammable and therefore unavailable. CBD has a series of post processing techniques and logic checks ensuring it is relevant in the context of other fuel products and fire behavior predictions. All non-forest values and non-burnable types such as urban, barren, snow and ice, and agriculture are coded as 0. Some stands dominated by broadleaf species which typically do not permit initiation of crown fire (e.g. Populus spp.) are coded with a CBD of 0.01 kg m-3. In some instances, LF Remap assumes the potential burnable biomass in the tree canopy has been accounted for in the surface fuel model. For example, young or short conifer stands where the trees are represented by a shrub type fuel model will not have canopy characteristics. LF Remap Annual Disturbance products are incorporated into CBD to provide informed changes by disturbance type, severity, and time since disturbance (TSD). Annual Disturbance products provide a pre-disturbance scenario represented by LF Remap existing vegetation products. Reporting of the pre-disturbance scenario helps to calculate CBD, with information about vegetation type, cover, and height impacted by a disturbance. With the use of Annual Disturbance products, CBD also has capable fuels functionality. Capable fuels calculate TSD assignments for disturbed areas using an effective year. For example, year 2020 fuels may be calculated for the year 2020. This new process considers all the existing disturbances included in LF Remap and adjusts the TSD for these to the effective year (2020 in this example), making the products "2020 capable fuels." More information about capable fuels can be found at https://www.landfire.gov/lf_remap.php.