LANDFIRE (LF) disturbance products are developed to provide temporal and spatial information related to landscape change. Historical Disturbance (HDist) is developed from the base LF Disturbance products (and attribute code system) to represent the 'history of disturbance' for a 10-year span. Each year's disturbance scenarios are checked against time relevant LF vegetation to check for logical inconsistencies. Errant disturbance codes are flagged and updated to a discard code with the remaining disturbance codes cross walked to Fuel Disturbance (FDist) codes. HDist development involves a comprehensive review of fuel and disturbance attributes.
Starting with LF Remap, HDist replaces Vegetation Disturbance from previous LF versions incorporating pre-disturbance vegetation logic (based on disturbance year and vegetation type).
A significant refinement to the LF Remap process was adopted to more accurately represent vegetation within disturbed areas for fuels use, allowing LF Remap to provide "capable fuels" products. What this means is that the Time Since Disturbance (TSD) assignments for disturbed areas have been calculated using an effective year. Year 2019 fuels, for example, may be calculated for the year 2019. This new process considers all the existing disturbances included in LF Remap and adjusts the TSD for these to the effective year (2019 in this example), making the products "2019 capable fuels."
By synchronizing TSDs for surface and canopy fuels, these refinements improve performance of fire behavior modeling and reduce the need for local LF users to update the vegetation and fuel conditions to represent current conditions when using the data operationally. LF Remap fuel products in areas mapped as disturbed within the past 10 years (disturbances since 2009) are delivered with this "capable fuels" functionality.
Disturbances older than 10 years follow the existing LF protocol for removal from FDist and are represented by more recent non-disturbed LF Remap 2016 vegetation. All non-disturbed fuel is based on LF Remap, which is the newest fuel vegetation available.
LF uses HDist in the development of several subsequent layers, including the Fuel Disturbance product.