From Site Visit to Spark: Yolo PBA’s First Burn
The Yolo Prescribed Burn Association hosted its first prescribed burn at a private ranch north of Capay, CA on Saturday, June 17, 2023. The 27-acre rangeland burn was a success thanks to many volunteers, landowners, firefighters from local fire agencies and the CAL FIRE Lake Napa Unit, California Burn Boss Phil Dye, and Burn Boss Trainee and Yocha Dehe FireFighter Charlie Jahelka! The burn served as a capacity building training exercise with a larger goal of invasive weed control in rangeland.
The burn site is located on a private cattle ranch near the crossroads of County Road 15b and County Road 85, in an area that is classified as high to very high fire severity according to CAL FIRE’s Fire Hazard Severity Zones latest map. The 27-acre site was chosen thanks to its rolling terrain (slopes of 0-25%) and open grassland – a great site for a training burn due to its low to medium complexity.
Additionally, the burn area was chosen due to an infestation of barbed goat grass (Aegilops triuncialis) and yellow starthistle (Centaurea solstitialis). Barbed goat grass is an invasive, annual grass that is unpalatable to cattle and outcompetes more favorable and native vegetation. The grass goes to seed late in the spring season, which means an early summer burn is needed to consume the biomass before seed maturation and dispersal (i.e., when seedheads are still attached to the stems). Yellow starthistle is a highly competitive invasive that forms dense stands of sharp and spiny plants. The sharp spines and hairs make it unpalatable to cattle and wildlife. For yellow starthistle control, burning is most effective when flowers or rosettes first appear. At this stage, yellow starthistle will still be green, but surrounding dried, annual grasses serve as a fuel source to kill the seed. For both barbed goatgrass and yellow starthistle, two years of burning is needed to effectively control the plants and diminish the seed bank, a factor included in the burn plan.
Preparation and Permits
Preparation for this burn was months in the making with the very early foundational work starting in December of 2022 with site tours and consultation with California Burn Boss Phil Dye. Burn Bosses are individuals that are trained fire practitioners that may be federally or state-certified to plan, organize, and execute prescribed burns. Burn Bosses write or certify burn plans that serve as a written prescription for prescribed fire including the weather conditions under which the burn will be conducted, equipment and personnel needed to safely conduct a burn, ignition and holding plans, and contingency plans in the event conditions change or a fire escapes containment. The burn plan also contains management objectives, fuel considerations, and special considerations for the surrounding areas.
Within the burn plan are necessary steps to prepare the site for fire. In the case of the PBA’s inaugural burn, site prep included keeping cattle out of the burn unit for a few months prior to the burn, creating containment lines, and mowing around permanent structures. Cattle were excluded from the site in order to ensure that fuels were at a desirable density to carry fire throughout the burn unit. To keep fire inside the burn unit, containment lines were created along already existing two track ranch roads. The landowner used a dozer to expose bare mineral soil around the burn unit. Additionally, ten feet on the inside of the containment line was mowed around the unit to create a buffer area that would slow fire as it approached the containment line. Thus, reducing the likelihood the fire would jump the containment line.
Lastly, CAL FIRE requires a permit during wildfire season, typically from May through November. This short form has a required safety video, site information, contingency planning, and a map of the burn unit. A CAL FIRE representative will conduct an inspection of the burn unit to ensure proper preparation and safety measures have been taken before issuing the burn permit.
Weather and Burn Window
Because prescribed burning relies on a “burn window”, prescribed burns cannot be 100% confirmed until the days leading up to the burn where meteorological conditions can be assessed. A burn window is when the environmental and weather conditions are balanced so that fire will accomplish its objectives while remaining under control and safe. Conditions that are continually assessed before and throughout the burn are wind speeds, humidity, and temperature. These conditions are outlined in a prescription in the burn plan that helps fire practitioners decide whether a burn should move forward or be delayed.
For the rangeland prescribed burn, the prescription was as follows:
Element | Lower Limit | Desired | Upper Limit |
Temperature (F) | 60 | 70 | 95 |
Relative Humidity (%) | 80 | 50 | 13 |
Mid-Flame Wind Speed (mph) | 2 | 5 | 13 |
Fine Dead Fuel Moisture (%) | 10 | 7 | 4 |
Probability of Ignition (%) | 30 | 50 | 70 |
In order to proceed with the burn, conditions must fall within this range of values. Each condition is assessed in relation to the other. For example, the desired temperate for the day was 70 degrees, but the burn could proceed if it was higher than 70 degrees to an upper limit of 95 degrees. For the day of the burn, conditions were optimal and allowed us to proceed on schedule.
Test Fire and Firing
To begin the prescribed fire, a test fire is conducted in a representative area to confirm that fire behavior characteristics will fall within the prescription and to verify smoke dispersion. The test fire was lit at the top of the burn unit on the steeper end of the burn area. Once conditions were assessed and it was verified to be safe to proceed, firing commenced. The ignition plan, also outlined in the Burn Plan, utilized backing and flanking fire to begin the burn. Backing fires move against the wind (or down-slope) and therefore move much slower than a head fire. A flanking fire is set at the side of the burn unit parallel to the wind. These two firing techniques were used to establish plenty of “black” or burned area to be a buffer between the burn site and the surrounding steep and vegetated slopes. This ensured that there was a larger perimeter around the burn unit especially in areas where there was a higher threat of escape. Once sufficient black was established at the top and sides of the burn unit, a head fire was used create high intensity combustion of the fuels and as a training opportunity for participants. A head fire is fire that moves with the direction of the wind or up-slope. Fire that is pushed by the wind moves faster and has longer flame lengths. Backing and flanking fires are used to mitigate the potential danger of a head fire and are used for lower intensity consumption of fuels.
During firing, PBA volunteers learned to fire with drip torches and use 1-2-3 strip firing. Strip firing is when three people, each assigned a number, with drip torches fire in lines parallel to each other, but are staggered at different distances from each other. In a 1-2-3 formation, the number one person is closest to the control line and is in the lead. In a 3-2-1 formation, the number one person is the last.
Left: PBA volunteers and the landowner watch as the burn is continued from the test site. Middle: Volunteers on the firing squad use drip torches to extend the fire into the middle of the burn unit. Right: Although the burn was pretty uniform, crews had to go back to burn a few spots that were missed during the initial firing.
Mop Up
Mop-up is one of the most important phases of prescribed fire as it ensures the fire is sufficiently put out with little chance to rekindle. During firing, holding crews were designated to ensure that the fire stayed within containment lines and didn’t spark spot fires outside of the burn unit. Once firing was complete, all crews switched over to mop-up and began by securing the perimeter of the burn unit and working inward.
Although it can vary depending on the fire, this rangeland burn required 100% extinguishment. This decision largely depends on the landowner and input from local fire departments and CAL FIRE. Because this unit is located in a high fire area and surrounding fuels were fairly dry, the decision was made for 100% extinguishment. Additionally, because the site is rangeland, participants need to walk the entire site to ensure that any cow patties within the unit were extinguished. If left untouched, cow patties can continue to smolder for many hours after a fire.
Left: Volunteers stand under a shade structure after the burn for a debrief with Phil Dye, California Certified Burn Boss. Right: The 27 acre burn unit viewed from afar after mop-up was completed.
Lessons Learned
Overall, the burn was a success thanks to the hard work of many Yolo County fire agencies, landowners, and volunteers coming together to make this burn happen. Although the PBA learned a lot when it comes to communication, firing strategies, and logistics, the biggest take away from this burn is the overwhelming support and interest for prescribed fire in Yolo County. The Yolo PBA is thankful to have the support and insight from local and state fire agencies and the willingness for collaboration to train and build prescribed fire capacity in our community.
Next Steps
With hot temperatures moving in, the window for prescribed burning closes until late fall and early winter brings cooler temperatures and higher humidity. Until then, the Yolo PBA is looking to set up trainings, site visits, and other educational events in preparation for when we can burn again. Stay connected by subscribing to our newsletter by visiting the Yolo PBA program page. Let us know what you want to see from the Yolo PBA by filling out a survey, linked here.
Left and right: PBA volunteers learn from Madison Fire Department firefighters how to properly extinguish a smoldering fire.
