BLM REA COP 2010 LANDFIRE - Disturbance (2005)

LANDFIRE disturbance data are developed to provide temporal and spatial information related to landscape change for determining vegetation transitions over time and for making subsequent updates to LANDFIRE vegetation, fuel and other data. Disturbance data include attributes associated with disturbance year, type, and severity. These data are developed through use of Landsat satellite imagery, local agency derived disturbance polygons, and other ancillary data. DATA SUMMARY: The disturbance data are developed through a multistep process. Inputs to this process include; Landsat imagery and derived NBR (normalized burn ratio) data; polygon data developed by local agencies for the LANDFIRE Refresh effort; fire data obtained from MTBS (Monitoring Trends in Burn Severity), BARC (Burned Area Reflectance Classification,), and RAVG (Rapid Assessment of Vegetation Condition after Wildfire) fire mapping efforts; and PAD (Protected Area Database) data.Refresh Event polygon data are provided to LANDFIRE by various local, regional, and national agencies and organizations. Disturbance type and year information is included as attributes for each polygon and transferred to the disturbance grids. Severity is determined by using dNBR (difference Normalized Burn Ratio) data classified into high, medium, and low severity levels based on a statistical comparison with the MTBS, BARC, and RAVG fire severity. Vegetation Tracker (Huang, et. al. 2008) algorithms are used to identify disturbances outside of Refresh Events. VCT data are developed for each year identifying disturbed areas as well as severity. Since disturbance type (i.e. causality) is not determined in the VCT process, a spatial analysis is done comparing the VCT output to buffered (1kilometer) Refresh Events and PAD GAP Status information (land use characteristics). While not providing a precise type of disturbance, this analysis provides information useful for narrowing down the types of disturbance that could or could not typically occur.Each zone has ten disturbance grids, one for each year 1999 to 2008. Each grid is attributed with year, disturbance type (if known, otherwise a description of possible types), severity, and the data sources used to create the data.