Alternative strategies required to boost health of vital creek corridor
The creek corridor at Bouverie Preserve in Glen Ellen — a critical wildlife passage also frequented by students immersed in nature education — is at risk of destruction by future wildfires because of hazardous levels of tree mortality.
Hundreds of trees along the Stuart Creek corridor have been killed or damaged by the 2017 Nuns Fire, Sudden Oak Death, and prolonged drought. While many dead trees have been cut and moved to the side of the road, the sheer volume of material is not manageable with typical methods such as pile burning, biochar kilns, chipping, or hauling offsite.
We began investigating alternative strategies that would be more cost-effective, ecologically mindful, and productive.
New technology promises 90% fewer emissions
Air curtain burners, a relatively new tool used to burn large fuels (logs, branches, and previously cut trees) with very little smoke production, seemed like an exciting option. In the air curtain process, heavy fuels are loaded into a large rectangular box, ignited and burned at high temperatures using a forced “curtain” of air that recirculates hot gases and smoke particles into the box to reburn. According to the Clean Burn Company, air curtain burning results in 90% fewer emissions than open burning. In addition to improved emission rates, air curtain burners can process significantly more dead material than open burning in the same period.
Air curtain burner comes to Bouverie Preserve
To prepare for the air curtain burning, Spye General Engineering was contracted to cut hazardous downed fuel to the appropriate length and stage them for easy loading into the burner at strategic locations along the Canyon Trail.
In May 2023, Clean Burn Company owner Eric Carlson brought an air curtain burner to Bouverie Preserve. This new prototype, with tank-like tread that allows the machine to navigate tough terrain without being trailered, is the first of its kind. The design was born out of Carlson’s own need, after 16,000 trees on his property were killed by a recent wildfire. His company employs around 40 off-season firefighters to operate the machines.
As enthusiastic crew tossed fuel into the burner, nearby observers squinted at the intensity of the heat and stood in awe of the complete absence of smoke.
The total amount of fuel removed from the canyon with the air curtain burner in one week equates to 43 tons, or 86,000 pounds. “I am so pleased with the efficiency of the air curtain burner! Thanks to a grant from the Wells Fargo Foundation and the National Fish and Wildlife Foundation, we were able to test a new tool and share the success with our partners, including the Sonoma Valley Wildlands Collaborative and Bay Area Air Quality Management District. A big win on so many levels!” shared Jennifer Potts, resource ecologist at Bouverie Preserve.