Posts Tagged: wildfire
In 2020, 9,000 fires scorched more than 4 million acres of California, a record-breaking year, reported Alejandra Borunda in National Geographic. Fires burned through homes and oak forests, grasslands and pines — and also through patches of giant sequoias and coast redwoods, respectively the most massive and the tallest trees on earth.
Giant sequoias are not the oldest living trees, but some have been growing in Sierra Nevada forests for more than 3,200 years. They are found in 68 groves on the Sierra's western flank. The state's redwood forests grow in a narrow strip along the coast of Northern California and Southern Oregon.
The 2020 fires burned through about 16,000 acres of sequoia groves, about a third of their total area. In redwood forests of the Santa Cruz Mountains, 40,000 acres burned.
But because redwoods are well-adapted to fire, they'll likely recover pretty quickly, said Scott Stephens, a UC Berkeley fire scientist. “In some ways, this fire could make redwoods more dominant in the landscape," he said, because other trees — like the hardwoods or Douglas firs that crowded the local forests — died outright in the burns.
However, scientists are concerned one cause of the fires, climate change, could have additional impacts on these natural treasures.
Since the mid-1800s, temperatures in the western U.S. have increased by 1.6 degrees Fahrenheit. Fog banks are fading in coast redwood territory, and snows are less consistent in the Sierras. The changes leave redwoods and sequoias without their preferred climate conditions.
The most responsible thing to do now, Stephens said, is to “take the opportunity that has been handed to us,” and make a plan to go back in and burn again—soon, within the next few years.
UC Cooperative Extension forestry advisor Lenya Quinn-Davidson agrees that California must manage fire to help the trees survive. Tree-ring records show that humans have influenced the fire regime for better and worse as long as they've been in these forests.
“The empowering message there is, human management can actually override the effects of climate in a fire contest,” Quinn-Davidson said. “It's not just a climate story. We can't just throw in the towel, feel overwhelmed, and tell ourselves these trees are done for. That's not true!”
When the Detwiler Fire broke out near his family's ranch in 2017, Tony Toso was home to take defensive action to protect his family and animals. The Mariposa County rancher feels fortunate that he was on site.
“We were on the front end of the fire damage and it started on a Sunday,” recalled Toso. “Had I not been home that day, it would have been very difficult for me to access my property and help keep our livestock safe. Within a matter of hours of the fire starting, the CHP had our county road closed and would not let anyone in.”
Emergency personnel close roads around wildfires for the safety of people and to prevent them from impeding fire suppression efforts. When fire threatens large ranching operations, ranchers need to move their livestock out of harm's way and make sure they have feed and water. While volunteer groups can assist in rescuing dogs, cats, and a few sheep or horses, they don't have a rancher's knowledge, expertise and experience that are essential for managing hundreds of cattle at large-scale ranching operations.
To help rural communities prepare for wildfire, it would be helpful for farmers and ranchers to have a plan in place to coordinate with first responders, according to Max Moritz, UC Cooperative Extension wildfire specialist. Ag Pass is a program developed in Ventura County to identify farmers and ranchers to firefighters, law enforcement and other emergency personnel so they can allow them onto their property to rescue animals and identify access roads and water sources.
“Because fires are increasingly impacting people and are not going away anytime soon, we need to figure out approaches to sustainably live on fire-prone landscapes. In a broader sense, the Ag Pass is another way that we can adapt to, and coexist with, wildfire,” Moritz said.
Matthew Shapero, UC Cooperative Extension livestock and range advisor, and Moritz have written a publication to guide people who would like to create an Ag Pass Program for wildfire preparedness in their own locale.
“Our neighbors had cattle just north of us and they tried to get in and could not,” said Toso. “An Ag Pass in that situation, would have been a huge benefit had I not been at home and then wanted to access my property.”
In Ventura County, agricultural workers can apply for identification cards from the Central Ventura County Fire Safe Council, which verifies farm information through the county's pesticide applicator permit database. Ag Pass members provide detailed maps of their farms that show access roads – including many that don't show up on other maps.
Shapero, who works in Ventura and Santa Barbara counties, has been working with ranchers and county agencies to create an Ag Pass program in Santa Barbara County.
“The last few fire seasons have made a program like the Ag Pass more urgent than ever, especially as awareness of wildfire's impacts to agriculture has grown,” Shapero said. “We hope that this publication provides localities with a workable blueprint that will expedite the adoption of this or similar programs.”
Shapero has been working with Anthony Stornetta of Santa Barbara County Fire and representatives of other agencies to develop a training for Ag Pass participants in Santa Barbara County.
“After being at the Carr, Sonoma, Creek and Camp fires for months at a time, I started developing the program from the fire side and presented it to California Cattlemen's Association a couple years ago,” Stornetta. “This was a great collaborative effort. After meeting with our fire safe council, we are looking at the program being fully adopted very soon.”
In September, the Bear Fire raged through the Plumas National Forest where 400 of Dave Daley's cattle roamed to graze. The fifth-generation rancher wrote in moving detail of his grueling search for surviving cows in the rugged terrain during the wildfire and posted it to the California Cattlemen's Association website.
“I was unable to get access initially,” Daley said. “After working with our sheriff, I was able to get access through his office. But it required a deputy to take his time every day for 10 days to meet me at the roadblocks and escort me for several miles into our cattle range. I am very thankful for their willingness to do so. However, it was probably not the best use of their time when they were dealing with so many crises simultaneously and the fire was still raging. If there had been an Ag Pass system, that would have simplified the process, freed up law enforcement and given me a chance to save more cattle.”
Toso, the Mariposa County rancher and president of the California Cattlemen's Association, thinks a program as described in the UC Cooperative Extension publication benefits both ranchers and first responders.
“We can not only help protect ranching families, but we can use the opportunity to build working relationships and create trust between landowners and emergency personnel, as well as provide valuable information to those first responders from knowing the lay of the land,” he said. “Helping other counties and our member ranchers get a program on the books with their respective counties will be a priority for our organization.”
“Given each community's unique agency and personnel structure, it is our belief that the Ag Pass is best administered at the local or county level, however we are working with the state to see if policy measures can be developed that would simplify and support the Ag Pass concept,” Shapero said.
The training developed for Santa Barbara County includes an overview of hazards and safety issues, entrapment avoidance, incident organization, fire behavior, working with law and fire liaisons, access to incident, carding and certification. Stornetta anticipates the Santa Barbara County training will be held in spring 2021 and hopes it can be used in other counties as well. Ranchers who are interested in the Ag Pass training should contact Stornetta or Shapero.
“Preparing for Disaster: Establishing an Ag Pass Program in Your Community,” can be downloaded for free at https://anrcatalog.ucanr.edu/pdf/8685.pdf.
In less than a decade, some of the burned expanses from this year's megafires could burst into intense flames again, reported Ula Chrobak in Scientific American.
Frequent, low-severity fires, which clear out patches of low-lying vegetation and dry leaf litter, have an preventative effect. Research shows that areas burned by megafires are more likely to become susceptible to fires again.
UC Cooperative Extension forestry advisor Susie Kocher said that a century ago, before officials quashed all wildfires, only 5% to 10% of Sierra Nevada fires would burn at high severity. Today, the proportion of high-severity fires is between 40% and 60%.
“That's way outside of what we think would have been natural,” Kocher said.
After high-severity fires, the landscape is scorched and shadeless. Without mother trees, it may take a long time, or even be impossible, for conifers to move back in. With open land and sunlight, shrubs sprout amid downed dead pines, which over time accumulate dead twigs and leaves. If there is a spark, the shrubbery and fallen wood can sustain another large fire.
“Ultimately, all of these lands are going to need management within anywhere from two to 10 years —and probably closer to two to five years after a fire—to maintain that reduction in fuel,” said Kate Wilkin, a fire scientist at San José State University. As climate change makes California hotter and drier, increasing the propensity for monstrous fires, this need will only grow.
After another record year for California wildfire, concern is now turning to the soil impacted by firestorms, reported Sarah Klearman in the Napa Valley Register.
High-temperature flames can incinerate vegetation and destroy plant root systems, said Toby O'Geen, UC Cooperative Extension soil specialist at UC Davis. The loss of vegetation destabilizes the landscape, making it vulnerable to serious erosion or flooding.
"The most important way to battle erosion is to have surface cover - living vegetation anchoring your soil," O'Geen said. "We have none of that. If you have soil with existing susceptibility (to erosion) and now nothing to hold it in place, it's a new disaster."
Particularly catastrophic fire can make the soil surface water repellent, which allows water to pond up and release higher concentrations of run-off water even when rainfall is low.
"That creates more massive erosive events - it gives rise to accelerated erosion, and in some extreme instances, mudslides," O'Geen said.
A summer of smoke and ash in many parts of California has raised questions about the safety of produce growing on farms and in the garden, eggs laid by chickens who peck around in ash-laden areas, and remediation needed to safely and effectively grow food in the future.
UC Agriculture and Natural Resources brought together experts who have researched the effects of previous fires' fallout and studied soil contaminants to share their insight in a two-hour webinar now available on YouTube.
“The No. 1 health concern during a fire is smoke inhalation, and it's been well documented that wildfire smoke can negatively impact both the heart and the lungs,” said Claire O'Brien, a pharmacology and toxicology doctoral student at UC Davis. “However, the chemicals found in the smoke don't just stay in the air. They can deposit onto plants and into soil and water.”
Although every fire is unique, some generalizations can be drawn from research conducted following previous fires. UC Cooperative Extension food systems advisor Julia Van Soelen Kim detailed a study conducted following the October 2017 wildfires in Sonoma County and across the North Bay.
With the help of UC Master Gardener and community volunteers, the researchers collected over 200 samples of homegrown collard greens, lettuces, kale and chard that were exposed to wildfire smoke and ash. A subset of the samples were analyzed by a private laboratory.
“There was very low concern about chemicals on produce,” Van Soelen Kim said. “No samples had detectable levels of lead, arsenic, mercury or chromium. And that's a huge sigh of relief.” However, analytical results vary by site, site history and by fire event, and few have pre-fire baseline data to compare with.
Van Soelen Kim said basic food-safety practices should be followed when preparing to eat food grown in a home garden, regardless of ash or smoke contamination.
“You should always wash your hands before and after harvesting, and wash your produce in running water to mitigate any kind of potential risk,” she said.
Are backyard chicken eggs safe to eat?
Another study outlined at the webinar used a similar process to determine whether there might be contaminants in the eggs laid by backyard poultry that live and feed in areas exposed to wildfire ash and smoke.
Scientists know from previous research that chickens exposed to lead in their environment can produce eggs with high lead content and that heavy metal content of ash from urban wildfires is higher than from rural wildfire.
“We combined those two pieces of research with what we know that chickens do all day: they peck at the ground for hours on end,” said Todd Kelman, a veterinarian in the School of Veterinary Medicine at UC Davis. “That makes for a pretty good hypothesis that urban wildfire could pose a risk for the production of eggs and poultry that contain heavy metals.”
Kelman and his team put out a call for eggs from backyard poultry and received samples from 344 premises in fire-affected and non-fire-affected areas of California.
Surprisingly, egg samples that contained higher lead levels came from parts of the state that were not directly impacted by ash and smoke.
“Did our data support our hypothesis that proximity to urban wildfire is a driving source for lead in eggs of backyard poultry? The answer is not so much,” Kelman said. “So, is it safe to eat eggs from your backyard poultry? We can't give you a definitive answer to that question. But we do suggest you assess your risk and reduce the risk of contamination.”
Practices that reduce the risk include keeping chickens off the ground, using a chicken feeder that prevents spillage onto the ground and making calcium readily available, for example in the form of oyster shells, because calcium can prevent the absorption of lead. Making sure that chickens are provided uncontaminated water is also an important part of risk reduction.
For confirmation on the safety backyard chickens and their eggs, lab tests for eggs are available for $60 from the California Animal Health and Food Safety Laboratory at UC Davis, or chickens may be submitted to CAHFS for necropsy.
Are soils safe for growing food after a fire?
Fire effects on soil is another consideration in burned areas, said UC Cooperative Extension urban agriculture advisor Rob Bennaton.
“Fires heat topsoil layers. They reduce the amount of living micro-organisms at the site of the burn, and also affect organic matter and nutrients. Ash deposits over time may make soils more alkaline,” he said. “As a result of these combined factors, there are temporary changes in nutrient levels and the capacity for soils to exchange nutrients for optimal plant growth and nutrition.”
With proper land care and management, soils can be remediated over time.
“It won't happen overnight. Soils were developed over millions of years,” he said.
Some ways to improve safety when gardening in fire-affected areas including keeping the soil covered with wood chips or other landscape mulch to reduce airborne soil dust. Use drip irrigation to prevent up splash onto the undersides of growing vegetables. Promote good drainage, especially at the bottom of slopes to prevent the concentration of contaminants.
Lab tests are often needed to determine the soils' post-fire characteristics. “Don't guess, but test,” Bennaton said.
The UC Master Gardener Program can provide technical assistance to help home gardeners find resources for home soil testing, he said.
Additional resources and information shared during the webinar include:
Post-fire soil resources and soil testing information
- UCCE publication on Soils in Urban Agriculture with soil testing & sampling information
- The UC ANR Healthy Soils Website, which has many resources worth reviewing.
- Tips for Interpreting Soil Analysis
- UC Master Gardener of Sonoma County 2018 workshop video “Effects of fire on soil”
Post-fire food safety
- Research on produce safety and backyard chicken egg safety after the 2017 wildfires in California is available on this web page. To view a past webinar recording with these research findings, click this link.
- Poultry wildfire resources from the UC Davis School of Veterinary Medicine:
- Best Practices for Produce Safety After Fire
- Understanding Risk: A community guide for assessing the potential health impacts of locally grown produce exposed to urban wildfire smoke
Firewise and sustainable home landscaping design in the defensible space zone
- Visit the UC Master Gardener Program of Sonoma County firewise landscaping web page.
- For a recent firewise & sustainable design and maintenance video by the Resilient Landscapes Coalition.
Impact of smoke & ash on plants