BAER team specialists completed data collection and analysis for Phase III of the Hermits Peak-Calf Canyon Burn Area (HPCC) on June 29, 2022. The ground burn severity map ( SBS) analyzes 40,150 acres for Pecos Riverand portions of cow stream and Gonzales Arroyo-Pecos Watershed. The map and data display SBS categories of unburned/very low, low, moderate, and high. In the Phase III area, 50% of the acres are either no burn/very low or low SBS, while 16% are moderate SBS and 34% are high SBS.
Land ownership for the Phase III ABS assessment is:
- 39,744 acres in the Santa Fe National Forest (NF) and
- 406 acres of private land.
The BAER assessment team used preliminary remote sensing data based on satellite imagery from June 15 and 17, 2022. Helicopter reconnaissance photos from June 23, 2022 were also used for Headwaters ground truthing Pecos River from previous phases which was used to further refine SBS Thresholds. Field-validated data was only collected on National Forest System (NFS) lands. This information was then used to extrapolate SBS from NFS lands.
The BAER team and the US Geological Survey (USGS) use the SBS map as a tool to estimate post-fire erosion, including the potential for subsequent sediment input, river flows and debris flows.
The BAER assessment team also coordinates with other local and federal agencies such as county and state officials, the Natural Resources Conservation Service (NRCS), the National Weather Service (NWS), and the ‘USGS to share information on burnt watershed conditions and their predicted response during certain rains. events.
The SBS map is an estimate of fire effects on soils and not a measure of direct effects on vegetation. SBS characterizes ground surface and subsurface impact, while vegetation effects are estimates of mortality based primarily on changes in vegetation cover. The Rapid Post-Fire Vegetation Condition Assessment (RAVG) program produces data describing the condition of vegetation after a fire on NFS lands.
Changes in aboveground and understory vegetation cover are often used as initial indicators of overall burn severity, but do not necessarily coincide with SBS.
Changes in soil cover, water impermeability, and physical/biological soil conditions guide interpretations to determine the severity of soil burning. Water repellency can occur naturally in soil and can change with fire. Fire can increase the strength and thickness (or depth) of water-repellent layers in the ground, significantly affecting post-fire water runoff and possibly extending the recovery time of the burned area.
The soil burn severity indicators are located in the General Technical Report 243 – Field Guide for Post-Fire Soil Burn Severity Mapping published at https://www.fs.fed.us/rm/pubs/rmrs_gtr243.pdf.
Low SBS usually occurs when the surface organic layers are not completely consumed and are still recognizable. The structural stability of the aggregates is not changed from their unburnt state, and the roots are generally unchanged because the heat impulse below the soil surface was not great enough to consume or carbonize the underlying organic matter. underlying. The ground surface, including any exposed mineral soil, may appear brown or black (slightly charred), and canopy and understory vegetation will likely appear “green”. A lower risk of accelerated runoff, erosion, flooding, and debris flows is expected within and below these areas compared to moderate and high SBS.
In moderate SBS areas, up to 80% of the pre-fire ground cover (litter and ground fuels) is consumed. Fine roots may be burned at or near the surface but are rarely completely consumed over much of the area, large roots are intact. The color of the ash on the surface is usually blackened with possible gray spots. There may be potential for effective ground cover recruitment from burnt needles or leaves remaining in the canopy that will soon fall to the ground. The dominant site color is often “brown” due to canopy needles and other vegetation burn. The soil structure is generally unchanged. Where greater amounts of reduced ground cover and increased water impermeability occur, increased surface runoff of water from precipitation is expected, especially in places where the canopy of the upper floor no longer exists.
High SBS occurs where all or nearly all of the soil cover and pre-fire surface organic matter (litter, manure, and fine roots) is consumed, and charring may be visible on large roots . The dominant color of the site is often “black” due to extensive charring. Bare soil or ash is exposed and susceptible to erosion, and aggregate structure may be less stable. White or gray ash (up to several centimeters thick) indicates that considerable ground cover or fuels have been consumed. Black charred soils or degraded powdery soils are visible under the thick layers of ash. Sometimes very large tree roots are completely burned from a charred stump hole.
The ground is often grey, orange or reddish at the ground surface where the large fuels were concentrated and consumed.
Typically, there is 100% tree mortality in high SBS, and tree recovery will take many years without planting. In high SBS, exposed bare soil is very prone to post-fire impacts. Rain events on damaged soil can cause excessive soil erosion, which leads to increased sediment deposition volumes in adjacent streams and rivers. There is an increased likelihood of flooding and debris flows. These threats may, individually or cumulatively, increase the risk to human life and safety, property, infrastructure, and significant critical natural and cultural resources.
The HPCC Fire Phase III Ground Burn Severity Map can be downloaded from the InciWeb “Hermits Peak-Calf Canyon Post-Fire BAER” (https://inciweb.nwcg.gov/incident/8104/) in JPEG or PDF version under the “Maps” tab.
For additional background information on understanding soil burn severity, see: Post-Fire Effects – Understanding Soil Burn Severity – InciWeb, the Incident Information System (nwcg.gov).
BAER SAFETY MESSAGE: Anyone near and downwind of burned areas should remain vigilant and aware of weather conditions that may cause rain and increased water runoff. Flash floods can occur quickly during rainfall events. Be ready to act. Current weather and emergency advisories can be found at National Weather Service website: www.weather.gov/abq/.
Hermits Peak – Calf Canyon Post-Fire BAER Assessment information is available at: https://inciweb.nwcg.gov/incident/8104/
# # #