LANDFIRE's 2023 Update (LF 2023) Forest Canopy Base Height (CBH) supplies information used in fire behavior models to determine the critical point at which a surface fire will transition to a crown fire in conjunction with other environmental factors (such as wind speed and moisture content). CBH data is continuous from 0 to 9.9 meters (to the nearest 0.1m) and describe the lowest point in a stand where there is enough available fuel (0.25in diameter) to propagate fire vertically through the canopy. Critical CBH is defined as the lowest point at which the Forest Canopy Bulk Density (CBD) is .012kg m-3. Under different scenarios of disturbance and based on previous research incorporating plot-level CBH calculations, CBH for disturbed areas is determined via a set of linear equations relating Forest Canopy Height (CH) and Cover (CC) to CBH. Linear equations for these calculations are derived from Forest Vegetation Simulator (FVS) scenario outputs.
To designate disturbed areas where CBH is modified, the aggregated Annual Disturbance products from 2014 to 2023 in the LF Fuel Disturbance (FDist) product are used. All existing disturbances between 2014-2023 are represented in LF 2023, and the products are intended to be used in 2024 (the year of release).
When using any product from the LF 2023 fuel product suite, users should consider adjusting fuel layers for disturbances that occurred after the end of the 2023 fiscal year (after October 1st, 2023). Disturbances that occurred after the end of the 2023 fiscal year are not accounted for within LF 2023 fuel products. Learn more about LF 2023 at https://landfire.gov/data/lf2023.