Pressing the Reset Button: Prescribed Fire Clears the Slate

Prescribed Fire as a Valuable Ecological Tool

 

Firefighters create a defensible space around the burn unit by burning in a black line.

Firefighters create a defensible space around a prescribe unit by burning-in a “black-line.”

Native Wisdom

Fire has influenced the appearance and structure of California’s landscapes for millennia. Fire occurs naturally in the wild, through lightning strikes and volcanic events, and it was common practice for native peoples to expertly exploit fire for their own purposes. They harvested the foods that fire made available (acorns, native grains, edible bulbs, wildflower seeds, etc.) and deliberately set fires to reduce wood fuel, on which dangerous wildfires thrive.

The European settlers who followed did not use the landscape in the same way, and when native peoples disappeared from the land, the use of fire as a tool all but vanished. In fact, over the last century, fire suppression has become the norm.

Lost Ground

Today, we experience catastrophic forest fires, fires exacerbated by a build-up of fuels as a result of years of fire suppression. Our recent and distorted relationship with fire—the certainty that all fires must be quelled or avoided—has not only added to the danger of major fires in the wild; the practice has benefited aggressive annual alien grass species, which grow unchecked without natural or well-timed deliberate (“prescribed”) fires. During the last century of fire suppression, introduced alien grasses have overrun many California landscapes.

Many of these non-native grasses are unpalatable to grazing livestock, which obliges ranchers to use much more purchased feed. This is expensive and ecologically unsound. From a land-management perspective, these introduced alien grasses flourish on rangeland when not controlled by grazing livestock, posing a lethal threat to native landscapes.

An Ecosystem Alien

Among the primary goals of our research on Mitsui Ranch (see Restoring Ecosystem Services) is control of a particularly resilient species of alien annual grass called medusahead (Elymus [Taeniatherum] caput-medusae). Medusahead is almost completely inedible to cattle, and its silica-containing cell walls make it persist in the environment for many years, even after it has died out.

Because cattle avoid it, medusahead spreads uninhibited throughout the range and soon takes over; what appear to be lush rangelands are actually very poor-quality medusahead, useless for grazers. In addition, medusahead’s persistence after death causes the accumulation of dead plant material to shade out competing (native) species—native grasses that withstand California’s climate, benefit the soil, and provide excellent forage for both wild and domestic grazing animals.

This dominant stand of medusahead shows the typical appearance at the end of the growing season when seeds are ready to fall to the ground.

This dominant stand of medusahead shows the typical appearance at the end of the growing season, when seeds are ready to fall to the ground.

Fortunately, medusahead has an Achilles’ heel: A well-timed prescribed fire can eliminate 95 to 99% of the medusahead plant and seed crop. If the fire is set before the medusahead seeds dry and drop to the ground, and when the seeds are still in the “soft dough” stage, control is nearly complete. A properly timed fire acts as a biodiversity “release” by clearing all the above-ground vegetation, releasing seeds lying dormant in the soil to germinate and grow without competition from other plants. As if starting from scratch, a poor landscape quickly returns to its nourishing, resilient, native state.

Though the seed heads on the green medusahead are not quite ready to burn, the heat generated from burning the dry medusahead nearby will kill the green ones.

Although the seedheads on the green medusahead are not quite ready to burn, the heat generated from burning the dry medusahead nearby will kill the green ones.

Use of Fire in Our Research Project

Last spring we collaborated with several local fire agencies, led by the California Department of Forestry and Fire Protection (CalFire), to conduct a 10-acre prescribed fire to eliminate medusahead grass in our research site in Corral Meadow. Because we proposed burning such a small area, our prescribed fire successfully qualified as a training burn. This kept costs low and allowed senior firefighters to use the occasion to instruct new recruits, or those who needed exposure to new techniques.

Our burn also created an opportunity to teach water-conservation techniques: A major focus was to collect and pile smoldering cow pats in one place before extinguishing them with water, rather than spraying each individual pat as it was encountered. This resulted in a huge reduction in water consumption by the engines.

Battalion Chief Stangeland instructs a trainee in establishing a black line. After wetting the mowed line, fire is applied to the grass next to it. Once a sufficient amount of grass burns, it is immediately extinguished with water. The entire burn unit is circumscribed using this method.

CalFire Battalion Chief Brent Stangeland instructs a trainee in establishing a black-line. After wetting the mowed line, fire is applied to the grass next to it. Once the desired amount of grass has burned, it is immediately extinguished with water. The entire burn unit is circumscribed using this method.

Burn Method

In mid-June, we used a weed-whip to cut the Corral Meadow medusahead stalks to soil level, encircling the area to be burned with a barrier of stubble. This would act as a fire line. On the morning of the 26th, all agencies descended on Corral Meadow with their equipment. A CalFire helicopter landed in an adjacent meadow to stand by in case the fire escaped the fire line. Fire crews began establishing a wider and safer fire line by “black-lining,” a practice in which firefighters wet either side of the mown strip of grass and burn between the wet areas. (Black-lining widens the area between the mown fire line and the area to be burned, giving firefighters a safe zone from which to operate; the burned area won’t burn again.)

Fire crews create a safe buffer for prescribed fire by starting fire near the mowed fire line and allowing it to burn a wide swath before extinguishing it with hoses. The black line, combined with the mowed line, provide a more easily defensible space during the main fire.

Fire crews create a safe buffer for prescribed fire by starting fire near the mowed fire line and allowing it to burn a wide swath before extinguishing it with hoses. The black-line, combined with the mowed line, provides a more easily defensible space during the main fire.

Once the entire burn area had been ringed by a black-line, crews ignited the interior, working into (towards) the wind. The technique is called “back-firing,” because the wind pushes against the flames that are working to consume fuels, keeping them in check. This method encourages what experts call a “cool burn”; flames generally don’t get large, and the wind keeps the advancing fire under control.

CalFire crews use drip torches to burn strips of vegetation as the main body of fire backs into the prevailing wind.

Fire crews use drip torches to burn strips of vegetation as the main body of fire backs into the prevailing wind.

An Excellent Outcome

The fire went off beautifully, thanks to all agencies involved. About an hour after ignition, all 10 acres had been evenly burned. The fire did a very thorough job of killing the medusahead seed—much better than any other control method we could have used. Significantly, by using fire we ensured that the field was ideally prepared for planting native grass seeds the following fall.

While not completely consumed by flames, these seed heads, which were green prior to burning, are no longer viable.

While not completely consumed by flames, these seedheads—which were green prior to burning—are no longer viable.

These seed heads were dry prior to fire and were completely consumed by flames.

These seedheads were dry prior to the fire and were completely consumed by flames.

The success of this occasion augurs many more successes in the future. Restoration of native grasses on the ranch is off and running.

Prescribed fire eliminated all dry standing vegetation, thereby creating a clean slate for replanting. Deep-rooted perennial grasses like this Harding grass will die back but immediately regrow from energy stored in deep roots.

Prescribed fire eliminated all dry standing vegetation, creating a clean slate for replanting. Deep-rooted perennial grasses such as this Harding grass (Phalaris aquatica) will die back but immediately regrow from energy stored in deep roots.

 

Acknowledgements

On behalf of the Sonoma Mountain Ranch Preservation Foundation, we extend a hearty thank-you to the following:
CalFire Battalion 12 engines, dozer, and crew; CalFire Boggs Mountain helicopter 104; Rancho Adobe, Bennett Valley, Schell-Vista, and Glen Ellen Fire Protection Districts, for providing engines and/or water tenders; Delta 4 Inmate Crew; and Sonoma County Fire & Emergency Services (Wes Kitchel). Particular thanks to Battalion Chief Brent Stangeland, for organizing the burn day, and to our neighbor Captain Dan Pierce (Glen Ellen FPD), for lending his knowledge of the local landscape.

Finally, we thank all our neighbors here on the mountain for their trust, patience, and faith in what we’re attempting to accomplish with our research on the Mitsui Ranch.

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