The Percent of Mixed-severity Fire (PMS) layer quantifies the amount of mixed-severity fires relative to low- and replacement-severity fires under the presumed historical fire regime. Mixed severity is defined as between 25 and 75 percent average top-kill within a typical fire perimeter for a given vegetation type.
PMS was derived from the vegetation and disturbance dynamics model VDDT (Vegetation Dynamics Development Tool) (LF 1.0.0 CONUS only used the vegetation and disturbance dynamics model LANDSUM). This layer is intended to describe one component of historical fire regime characteristics in the context of the broader historical time period represented by the LANDFIRE (LF) Biophysical Settings (BPS) layer and BPS Model documentation. This layer is created by linking the BPS Group attribute in the BPS layer with the Refresh Model Tracker (RMT) data and assigning the PMS attribute. This geospatial product should display a reasonable approximation of PMS, as documented in the RMT.
PMS is used in landscape assessments.