LANDFIRE's 2023 Update (LF 2023) 40 Scott and Burgan Fire Behavior Fuel Models (FBFM40) product represents distinct distributions of fuel loadings found among surface fuel components (live and dead), size classes, and fuel types (Scott and Burgan 2005). The fuel models are described by the most common fire carrying fuel type (grass, grass/shrub, brush, timber, or slash), loading and surface area-to-volume ratio by size class and component, fuel bed depth, and moisture of extinction. FBFM40 contains more fuel models for every fuel type than 13 Anderson Fire Behavior Fuel Models (FBFM13) and the number of fuel models representing relatively high dead fuel moisture content is increased. In FBFM40 fuel models with an herbaceous component are dynamic, to simulate curing, rather than remaining constant. To create the FBFM40 product, expert rulesets were developed to understand how different types of disturbance would change pre-disturbance fuel models to post disturbance fuels, based on the severity and time since disturbance. These rulesets are represented in the LF Total Fuel Change (LFTFC) Tool and Database for both disturbed and non-disturbed areas. In LF 2023 non-disturbed fuels are the same as LF 2016 Remap for natural vegetation. To designate disturbed areas where FBFM40 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://www.landfire.gov/data/lf2023.