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Windy Post-Fire BAER

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Sequoia National Forest
U.S. Forest Service
1839 S. Newcomb St
Porterville, CA 93257

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BAER Information
Phone: 707-853-4243
Hours: 8am-8pm

Windy Post-Fire BAER Soil Burn Severity Map Released

Windy Post-Fire BAER Burned Area Emergency Response
Announcements – 10/19/2021

WINDY POST-FIRE BAER SOIL BURN SEVERITY MAP RELEASED

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USDA Forest Service Burned Area Emergency Response (BAER) assessment teams are multi-disciplinary teams sent to federal lands following significant wildfires. Their role is to characterize the fire effects to watersheds, identify imminent post-fire threats to human life, safety, property, infrastructure, critical natural and cultural resources. Once the assessment is complete, the team develops BAER emergency treatment recommendations to mitigate identified risks. After the assessment, local land managers work with other BAER team members to implement and the assessment team’s recommended treatments and action stabilization measures.

The team begins their assessment immediately after the fire threat passes. Their focus is on direct effects to the burned watersheds caused by the fire rather than from fire suppression activities which is handled separately by the Incident Management Team managing the fire. Post-fire conditions such as loss of vegetation and change in the soil levels could increase the likelihood of floods and may cause potential debris and sediment flow impacts.

BAER specialists recently completed their field data evaluation and analyzed 97,456 acres of the Windy Fire to produce a Soil Burn Severity (SBS) map. The map and the data display SBS categories of burn severity including Unburned/Very Low, Low, Moderate, and High. Approximately 43% of the 97,456-acre fire are either Unburned/Very Low and/or Low SBS, while 47% sustained a Moderate SBS and about 10% High SBS.

The SBS map also shows the acreage for each of the landowners for the 97,456 acres to be: 75,275 acres for the Sequoia National Forest; 19,401 acres for the USDI Bureau of Indian Affairs; 1,774 acres of private/other lands; and 1,006 acres for the USDI Bureau of Land Management.

It is important to note that the BAER team assesses the effects on soils and not the effects to vegetation. SBS characterizes the soil surface and below-ground impact, whereas vegetation effects are determined based on mortality and vegetation canopy changes.

Changes in soil cover, water repellency, and soil physical/biological changes determine the severity burn level of the soil. Changes in water repellency are a frequently-discussed fire effect.  Water repellency is a natural soil property. Fire can increase the severity and thickness of the water repellent soil, significantly affecting post-fire water runoff.

Low SBS indicates only partial consumption of fine fuels while litter coverage remains relatively intact on the soil surface. Burning time at the soil surface was short, leaving root systems and root structure undamaged. Vegetative recovery time in the low category will vary based on ecological community but is expected to recover in the short-term.

Moderate SBS indicates nearly all soil cover of vegetative litter and fine fuels was consumed or converted to ash. Because soil cover is significantly reduced, accelerated water runoff is expected. Charring of the mineral soil occurs in Moderate SBS as well as shallow root burning. The extent of the burning of the leaves and needles on the trees (aka tree canopy) can be unpredictable and can range from high to relatively low mortality which is why a closer look at the ground is required to determine the actual severity level of the soil burn. Water repellency is often found at the surface and is increased for both in severity and thickness of the water repellent soils which reduces the ability of precipitation to infiltrate the soil surface.

High SBS is the result of higher intensity fire behavior or longer burning time at the soil surface. As a result of the high heat, nearly all the soil cover of vegetative litter and fuels has been consumed leaving bare soil prone to the impacts of precipitation and resulting water runoff. The surface mineral soil has been reduced to powder (single grain) and often several inches thick. This single grain soil is very easily transported or moved during rain events resulting in excessive soil erosion and sediment loading in rivers, streams, and creeks. The roots in the High SBS areas tend to be completely consumed by the resulting heat of the fire above the soil surface. Water repellency does not exist at the surface because water repellent compounds have been vaporized and tend to be found below the powdered soil surface, but the repellency thickness and more severe burning tend to be much greater than a Moderate SBS soil. Generally, there is 100% tree mortality in High SBS soils. Fire-adapted shrubs and vegetation such as bear clover, manzanita, and deer brush tend to come back with vigor because of root sprouts. However, because seed sources are consumed in these High SBS areas, conifers may take many years to re-establish without tree planting.

The Windy BAER assessment team used initial remote sensing imagery with field-validated soils data, to develop and produce the final SBS map. The BAER team and the US Geological Survey (USGS) both use the SBS map as an analysis tool to estimate post-fire flows, debris flow probability, erosion, and sedimentation flow rates.

The Windy Fire soil burn severity map can be downloaded at the “Windy Post-Fire BAER” InciWeb site (https://inciweb.nwcg.gov/incident/7866/) as a JPEG or PDF version under the “Maps” tab.

SPECIAL NOTEEveryone near and downstream from the burned areas should remain alert and stay updated on weather conditions that may result in heavy rains and increased water runoff. Flash flooding may occur quickly during heavy rain events-be prepared to take action. Current weather and emergency notifications can be found at the National Weather Service websites:

www.weather.gov/sto/ and www.weather.gov/hnx.

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