Identification Information Citation Originator: USDA Forest Service, Geospatial Technology and Applications Center, BAER Imagery Support Program Publication Date: 2025-01-22 Title: Soil Burn Severity Dataset for the Johnson Fire occurring on the Bitterroot National Forest Publication Information Publication Place: Salt Lake City, Utah, USA Publisher: USDA Forest Service Geospatial Data Presentation Form: raster digital data Online Linkage: https://burnseverity.cr.usgs.gov/baer/baer-imagery-support-data-download Description Abstract: This soil burn severity dataset was derived from Landsat 9 data and field validated by a Forest Service Burned Area Emergency Response (BAER) team. It is based upon an initial Burned Area Reflectance Classification (BARC) dataset created by analyzing satellite imagery. A pre-fire and post-fire Landsat 9 scene were processed to develop a differenced Normalized Burn Ratio (dNBR) image. The dNBR image attempts to portray the variation of burn severity within a fire and captures the combined effects of the fire to vegetation and soil components of the ecosytem. The preliminary BARC dataset was assessed by a Forest Service BAER team and modified, if necessary, based on field conditions. Purpose: These data were created by the USDA Forest Service Geospatial Technology and Applications Center (GTAC) to support Burned Area Emergency Response (BAER) teams. Supplemental Information Fire Name: Johnson Agency: USDA Forest Service Type of assessment: Emergency Fire size (as mapped): 8716 acres Pre-Fire Imagery Date : 2023-10-08 Post-Fire Imagery Date : 2024-10-26 Output Dataset Projection: NAD_1983_UTM_Zone_12N Datum: D_North_American_1983 Spheroid Name: GRS_1980 Mapping Comments: None Product List johnson_mt4586711371420240725_sbs.tif = Soil burn severity (SBS) dataset in raster format johnson_mt4586711371420240725_SBS.png = PNG thumbnail version of the SBS Time Period of Content Multiple Dates/Times Single Date/Time Calendar Date: 2023-10-08 (pre-fire image) Single Date/Time Calendar Date: 2024-10-26 (post-fire image) Currentness Reference: Severity data correspond to the date of the post-fire image. Status Progress: Evaluation of methods in process Maintenance and Update Frequency: As needed Spatial Domain Bounding Coordinates West Bounding Coordinate: 281681.68963831477 East Bounding Coordinate: 299081.68963831477 North Bounding Coordinate: 5095927.749934182 South Bounding Coordinate: 5077087.749934182 Keywords Theme Theme Keyword Thesaurus: none Theme Keyword: Wildland Fire Theme Keyword: Wildfire Theme Keyword: Burned Area Emergency Response Theme Keyword: BAER Theme Keyword: dNBR Theme Keyword: Fire Severity Theme Keyword: Burn Severity Theme Keyword: USDA Forest Service Place Place Keyword Thesaurus: none Place Keyword: MT Place Keyword: Johnson Fire Access Constraints: These data are publicly available. Use Constraints: There are no restrictions on use, except for reasonable and proper acknowledgement of information sources and limitations as preliminary/draft data. Data Set Credit: USDA Forest Service Native Data Set Environment: GeoTiff Data Quality Information Positional Accuracy Horizontal Positional Accuracy Horizontal Positional Accuracy Report: Landsat data are terrain corrected using ground control points and processed to an RMSE of less than 1/2 pixel. Lineage Process Step Process Description: These data products are derived from Landsat 9 data. Pre-fire and post-fire scenes are analyzed to create a differenced Normalized Burn Ratio (dNBR) image. The dNBR image portrays the variation of burn severity within the fire. The pre- and post-fire images are terrain corrected and further processed to convert top of atmosphere reflectance. The Normalized Burn Ratio (NBR) is computed for the pre- and post-fire images using the following formula: (NIR Band - SWIR Band) / (NIR Band + SWIR Band) = NBR The Differenced NBR is computed to determine severity by subtracting the post-fire NBR from the pre-fire NBR: (PreNBR - PostNBR) = dNBR After field data collection in the burned area, the Burned Area Emergency Response (BAER) team adjusted the Burned Area Reflectance Classification (BARC) vegetation severity thresholds to reflect soil burn severity characteristics and build the soil burn severity (SBS) map. Generally, soils showed more moderate burn severity characteristics under low and high vegetation burn severity. The unburned and very low category did not change from the BARC thresholds (0-69). The low soil burn severity ranged from 70 to 125, lower than the BARC values of 70-132. Soils exhibited moderate soil burn from 126 to 215, a broader range than BARC values of 133-202. High soil burn severity covered less area and range (216-255) than BARC categories (203-255). Soils mapped in low severity BARC categories exhibited scorched and charred fine roots (<0.25 cm), black and grey ash, and >50% consumption of ground cover, which indicated moderate instead of low soil burn severity. Similarly, soils mapped in high BARC severity categories displayed recognizable organic matter on the forest floor (~20% remaining), scorched or unchanged very fine and fine roots, and deeply charred or consumed coarse woody debris on the forest floor. Additional Comments: The initial SBS analysis for the Daly Fire was completed on 9/29/24. The fire continued to burn into late October and the decision was made to obtain new BARC imagery and update the SBS. The same SBS thresholds determined in September were used for the updated SBS data. Original BARC thresholds: Unburned/Low threshold = 72 Low/Moderate threshold = 116 Moderate/High threshold = 214 Revised SBS thresholds: Unburned/Low threshold = 69 Low/Moderate threshold = 124 Moderate/High threshold = 215 General descriptions of the severity classes are below: Unburned / Very low: The area after the fire was indistinguishable from pre-fire conditions. This does not always indicate the area did not burn (i.e. canopy may be occluding the burn signal). Low: Areas of surface fire with little detected change in cover and little detected mortality of the dominant vegetation. Little to no change in the soil color, structure and condition occured. Moderate: This severity class is between low and high and means there is a mixture of detected effects on the dominant vegetation. High: Areas where the canopy has high to complete consumption. Changes to soil structure, color and condition are significant and hydrophobicity may have occured. Spatial Data Organization Information Direct Spatial Reference Method: Raster Raster Object Information Vertical Count: 1 Spatial Reference Information Horizontal Coordinate System Definition Planar Map Projection Map Projection Name: NAD_1983_UTM_Zone_12N Map Projection Parameters Standard Parallel: 0.0 Standard Parallel: 0.0 Longitude of Central Meridian: -111.0 Latitude of Projection Origin: 0.0 False Easting: 500000.0 False Northing: 0.0 Planar Coordinate Information Planar Coordinate Encoding Method: row and column Coordinate Representation Abscissa Resolution: 30.0 Ordinate Resolution: 30.0 Planar Distance Units: Meter Geodetic Model Horizontal Datum Name: D_North_American_1983 Ellipsoid Name: GRS_1980 Semi-major Axis: 6378137.0 Denominator of Flattening Ratio: 298.257222101 Distribution Information Resource Description: Downloadable Data Metadata Reference Information Metadata Date: 2025-01-22 Metadata Contact Contact Information Contact Organization Primary Contact Organization: USDA Forest Service, Geospatial Technology and Applications Center (GTAC) Contact Person: BAER Imagery Support Contact Address Address Type: mailing address Address: 125 S. Sate St., Suite 7105 City: Salt Lake City State or Province: UT Postal Code: 84138 Contact Voice Telephone: 801 440 3255 Contact Electronic Mail Address: baerimagery@usda.gov