POST-FIRE MAP GUIDE · Reviewed 9 October 2026
Soil burn severity and vegetation burn severity describe different fire effects. A map showing severe vegetation change cannot simply be relabelled a map of severely damaged soil. BARC is a satellite-derived classification used as an input to the soil assessment; BAER teams use field evidence to develop a soil burn severity product. [1] [2]
BARC, BAER and soil burn severity are not interchangeable names
BARC means Burned Area Reflectance Classification. The official FAQ describes a satellite-derived layer of post-fire vegetation condition with high, moderate, low and unburned classes. It supplies an initial spatial classification for the assessment rather than a complete inventory of soil properties. [1]
BAER means Burned Area Emergency Response. It names the assessment and response process, not one spectral index. Teams assess vegetation, soils and watershed function. The Burn Severity Portal distinguishes preliminary BARC products from SBS, or soil burn severity, that has been validated by the team in the field. Older distributions may contain BARC alongside or in place of SBS, so check the actual file and metadata rather than relying on the download’s general label. [2]
| Product or evidence | Question it helps answer | What still needs checking |
|---|---|---|
| BARC | Where does the satellite classification suggest different post-fire conditions? | Was it subsequently checked and adjusted for the soil assessment? |
| Field-validated SBS | How are fire effects on the ground and soil classified? | Assessment date, mapped extent, legend and documented field support. |
| Later recovery observations | Which measured conditions have changed since the assessment? | The variable measured, observation period and connection to the outcome of interest. |
The table is an editorial reading aid, not a new classification scheme. For satellite indices and thematic classes, use the NBR, dNBR and MTBS guide.
Why damage to the canopy does not specify damage to the soil
The Forest Service field guide distinguishes soil effects from vegetation mortality. Heating duration matters as well as heat intensity: a rapidly moving, intense crown fire can produce limited soil effects, while prolonged smouldering beneath woody fuel can cause severe effects locally. The canopy’s appearance alone cannot resolve that difference. [3]
The guide’s ground observations include cover, ash characteristics, soil structure, roots and water repellency. These describe conditions at the surface or within soil that a photograph of green shoots does not directly measure. [3]
Tecnobosque interpretation: label the observation precisely. “The vegetation is greening” describes a visible or remotely sensed response. “Infiltration has recovered” requires evidence about water entering the soil. “Sediment export has declined” requires a sediment outcome. These can be related without being interchangeable measurements.
Worked example: two high-severity totals do not reveal their overlap
Invented map example—not observations from a real fire. Suppose two products cover exactly the same 200 hectares, with valid classifications throughout:
| Illustrative product | Area classified as high severity | Share of the common extent |
|---|---|---|
| Vegetation-severity product | 120 hectares | 120 ÷ 200 = 60% |
| Soil-severity product | 40 hectares | 40 ÷ 200 = 20% |
Those totals do not tell us where the two high-severity areas coincide. The overlap could range from zero to 40 hectares: the 40 hectares of soil-high area could fit entirely outside the 120 hectares of vegetation-high area, entirely inside it, or partly in each.
Now suppose a spatial overlay identifies 25 hectares classified high in both products. That is 20.8% of vegetation-high area, but 62.5% of soil-high area. Both percentages describe the same overlap using different denominators.
The example demonstrates spatial accounting. It does not establish an expected relationship between vegetation and soil classes, validate either product or predict erosion. Differences between totals alone do not prove that one map is wrong.
For a real overlay, align the geographic extent, coordinate reference system, grid and valid-data masks first. Keep missing or excluded areas separate. Record the original class names and assessment dates so that a calculation does not silently mix unlike products or observation periods.
Why visible regrowth does not establish that erosion risk has disappeared
Recovery involves several processes. Hoch and colleagues constrained a hydrologic model with field and remotely sensed observations of infiltration, vegetation cover, runoff and debris-flow activity in three southwestern US burned areas over three to four years. Their modeled rainfall thresholds increased during recovery. Changes involved infiltration, canopy interception, hydraulic roughness and sediment grain size; the relative importance of these factors varied among sites. [4]
That result supports assessing recovery with several measured variables. It does not supply a universal date after which every burned catchment is safe, or a rule that a particular amount of visible green cover removes the hazard.
A separate study by Thomas and colleagues examined a simulation framework in the San Gabriel Mountains. It distinguished runoff-generated debris flows from flows associated with subsurface pore-water pressure. Modeled recovery increased the rainfall intensity required for runoff-generated flows, while the rainfall duration required for the other mechanism decreased. [5]
Tecnobosque interpretation: a trend in one mechanism cannot automatically be described as the disappearance of every post-fire hazard. Preserve the process being studied, its inputs and its geographic scope. These papers are research models, not forecasts for a reader’s property.
For the difference between a burn footprint and downstream exposure, read the post-wildfire debris-flow guide. For the limitations of spectral change after repeated fires, see the reburn severity guide.
A practical workflow for reading a soil severity map
Tecnobosque editorial workflow: document the following before making a statement about an assessment.
- Read the product name literally. Record whether the file is preliminary BARC, field-validated SBS, a vegetation product or another output. Preserve its provider and version.
- Separate the dates. Save the fire dates, image dates, field-assessment dates and publication date. A later satellite image does not automatically update an earlier soil assessment.
- Check the field evidence. Identify what was observed and how it informed the final map. Do not assume a pixel-by-pixel soil survey from the phrase “field validated.”
- Keep the denominator explicit. State the selected area, valid classified area and exclusions. If comparing maps, calculate their spatial overlap rather than inferring it from separate totals.
- Define the claimed outcome. Distinguish ground condition, modeled runoff, measured sediment yield and vegetation response. A claim about one needs evidence for that variable.
- Keep current hazard information separate. Use the applicable official assessment, warnings and closure instructions for an operational decision. This reading workflow supplies no storm trigger or property-level safety determination.
Use Hayman to follow the evidence beyond the map
The Hayman Fire case study follows the evidence from incident history to watershed assessment and monitored treatment outcomes. Read its runoff, peak-flow and sediment-yield results separately. Then ask which result would actually support the claim being made.
A reporting template: “The [named product and version] classifies [area and share] as [original class] within [defined extent]. Its assessment dates are [dates]. Evidence of subsequent recovery consists of [measured variable, method and observation period]. The following outcomes remain unmeasured: [list].”
Official documentation and primary research
- BAER Imagery Support: About BARC / FAQ — the satellite product and its role in soil mapping.
- USGS / Forest Service Burn Severity Portal: BAER — preliminary BARC, field-validated SBS and product distribution.
- Parsons, Robichaud, Lewis, Napper and Clark (2010): Field guide for mapping post-fire soil burn severity. RMRS-GTR-243. DOI: 10.2737/RMRS-GTR-243. See printed pages 3 and 10–16 for definitions and field indicators.
- Hoch, McGuire, Youberg and Rengers (2021): Hydrogeomorphic recovery and temporal changes in rainfall thresholds for debris flows following wildfire. DOI: 10.1029/2021JF006374.
- Thomas and colleagues (2021): Postwildfire soil-hydraulic recovery and the persistence of debris flow hazards. DOI: 10.1029/2021JF006091.