The Scientific Benefits of Prescribed Fire and Forest Stewardship

By Barbara Satink Wolfson, David Benterou, and Jared Childress

On a recent crisp fall day, we had the privilege to assist a cultural burn with Yurok Tribal members on their ancestral lands in Northern California. During a conversation about goals with the Yurok burn boss in charge, he suggested we take a field trip to a nearby ridge where the tribe had done three repeat burns over the past 10 years (an unusual example in fire starved California). 

There we saw an open forest of large Black oaks, a lush understory of California hazel and a carpet of native flowers and grasses. He explained the importance of all these plants to us:  basket material from the hazel, nectar from flowers for pollinators, high-protein bunchgrass forage for Elk and acorns for wildlife plus people. This lovely fire-tended garden was in stark contrast to the dark, impenetrable tangle of vegetation with little diversity, just across the road, where no burning had been done for 100 years, and would be an inferno during the next wildfire.

Black oak forest and CA Hazel field after three Cultural burns in Yurok Tribal territory.

These side-by-side examples made us think about a recent article in the SLV Post by a local author on their opinions on wildfire in California and we felt we should respond with information based on the best available science.

In that article we were pleased to see some accurate information and calls to action, such as the mention that fire-adapted plants flourish after fire, that non-native annual grasses are more flammable, and less sustainable, than native perennial grasses, and that home hardening and maintaining a defensible space are the best, and most cost-effective, ways to increase resilience to wildfire on personal and community levels. However, many other talking points are misleading and unfounded in the majority of the scientific evidence that guides land stewardship in the western US.

For example, the author suggests that pre-colonization, Native Tribes in California used fire in very limited and small-scale ways, such as to prepare the soil to plant food. In reality, California was a “tended wild,” mainly with fire by Native California Tribes. Evidence supports a much broader use of fire by Tribes, typically described as “cultural burning,” prior to colonization, when many of these practices were outlawed by settlers (Keeley, 2002). This burning was vast, as shown by (Stephens et al. 2007), finding on average 4.3 million acres in pre-colonized California burned annually via Tribes and lightning ignitions. To put that in perspective, the fires in 2020 burned roughly 4.2 million acres. In 2005, Stephens and Fry surveyed fire scars in redwood stumps in the Santa Cruz Mountains from the 1600s to the 1800s and estimated the average time between burns during that period to be 12 years. Due to the rarity of lightning in the area, most of the fires they documented would have been started by the local Tribal populations. A variety of books and scientific articles, as well as tribal members themselves, reference a wide range of benefits from cultural burning (Kimmerer and Lake 2001; Lewis and Anderson 2002; Lake et al. 2017, Tom et al. 2023), such as resilience to wildfire and drought, maintaining cultural knowledge and values; improvement of basketry materials, food and medicine plants, and hunting (Greenler et al. 2024; Long et al. 2021). 

While fire can stimulate both native and nonnative plant growth, wildfires and prescribed burns contrast in management goals and have different landscape effects (hence the importance of timing when conducting burns). Prescribed burning works in tandem with long-term land management planning. Its treatments are placed on the landscape, with consideration of long-term management needs, for example, using follow-up treatments to reduce plant invasions, or repeated burns to support meadow restoration. (Many benefits of prescribed burning and why it’s a safe land stewardship tool can be found at calpba.org).

Thus, a prescribed burn is inherently different from a wildfire, where human safety is the primary concern. Prescribed fire intensities and severities are generally lower than wildfires, however prescriptions for mosaicked fire severities can be designed to fit desired restoration outcomes. For instance, canopy scorch tends to be more common in wildfires than prescribed burns leading to potentially undesirable regrowth outcomes. 

Smoke created by wildfires can linger for days or weeks as there is no plan for wildfire, while prescribed fire smoke is planned for optimal weather conditions to minimize community impacts. Submission of plans for smoke management are required for prescribed burns in California, and burns are permitted only within strict weather windows. Studies such as this one by (Kieley et al. 2024) support these differences. The likelihood of extreme wildfire days is expected to increase (Goss et al. 2020), meaning that we are losing our chances to decide what kinds of fire our landscapes experience, and for how long we inhale the smoke.

Jane Manning, local resident lights a prescribed burn in Wilder State Park.

Forest thinning and prescribed fire are proven methods, often called treatments, to reduce wildfire severity, both in tandem or individually. Fuel reduction typically removes the smallest/ shortest trees, called thinning from below, and is the most effective at reducing wildfire related tree mortality (Stephens and Moghaddas 2005). These efforts, often called shaded fuel breaks, are done strategically on ridges and near homes to give firefighters a more effective area to fight wildfire. Besides the plethora of scientific research that supports these treatments in a variety of forested ecosystems (Fallon et al. 2024; Hunter and Taylor 2022; North et al. 2021; Prichard et al. 2021, York et al. 2020), on the ground examples of thinning and prescribed burning treatments that significantly reduce wildfire severity across the western US abound, including this one from the Sierra Nevada. 

Common sense tells us when there is less to burn, the fire will burn at lower severity and this typically plays out in reality. There are no guarantees during extreme wildfire conditions that can overrun the best efforts, but landowners and land managers who rely on the best science to guide their actions can increase the likelihood of positive outcomes.

Featured photo at top of page: Esak Ordonez, a Mutsun Tribal member and local resident lights a prescribed burn.

References

Fallon et al. 2024: https://doi.org/10.22541/essoar.172590227.72370322/v1 
Goss et al., 2000: https://iopscience.iop.org/article/10.1088/1748-9326/ab83a7
Greenler et al 2024: https://doi.org/10.1002/eap.2973 
Hunter and Taylor 2022: https://doi.org/10.3390/f13122042 
Keeley, 2002: https://doi.org/10.1046/j.1365-2699.2002.00676.x
Kimmerer and Lake 2001: https://doi.org/10.1093/jof/99.11.36 
Long et al. 2021: https://doi.org/10.1016/j.foreco.2021.119597 
Prichard et al. 2021: https://doi.org/10.1002/eap.2433 
Stephens and Fry 2005: https://doi.org/10.4996/fireecology.0101002 
Stephens and Moghaddas 2005: https://doi.org/10.1016/j.biocon.2005.04.007 
Swain et al., 2023: (& Kirsten Shive) https://www.nature.com/articles/s43247-023-00993-1 
Tom et al. 2023: https://doi.org/10.1089/eco.2022.0085 
UCANR 2024: https://ucanr.edu/sites/fire/Preparedness/ 

Barbara Satink Wolfson is the Central Coast Area Fire Advisor for the University of California Cooperative Extension.

David Benterou is the Research Associate for the Central Coast and Southern Sierra Nevada for the UC Cooperative Extension.

Jared Childress is the Program Manager for the Central Coast Prescribed Burn Association

Photos contributed by Jared Childress

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