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Posts Tagged: Wildfire

Wildfires are devastating to the soil

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.

An area near Shaver Lake where the 2020 Creek Fire burned most of the living vegetation and old tree stumps. (Photo: Jeannette Warnert)
Posted on Monday, November 9, 2020 at 11:52 AM
Tags: soil (20), Toby O''Geen (5), wildfire (149)
Focus Area Tags: Environment

Smoke and ash from wildfire may have lingering impacts in food production

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.”

Always wash your hands before and after harvesting, and wash your produce in running water to mitigate a potential risk. (Photo: Evett Kilmartin)

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.

Keeping chicken feed off the ground and providing clean water are two ways to reduce the risk of contaminated eggs. (Photo: USDA)

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.

The UC Master Gardener Program can provide technical assistance to help home gardeners find resources for home soil testing. (Photo: USDA)

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

Post-fire food safety

Firewise and sustainable home landscaping design in the defensible space zone

Impact of smoke & ash on plants

Posted on Tuesday, November 3, 2020 at 8:17 AM
Tags: ash (1), food safety (31), Julia Van Soelen Kim (1), Rob Bennaton (1), smoke (1), Todd Kelman (1), wildfire (149)
Focus Area Tags: Food, Yard & Garden

Climate change is converting cities into 21st century ghost towns

In California, most ghost towns were created when a local industry collapsed. Now, climate change is more often to blame when booming communities whither and die, reported Daniel Cusick in E&E News.

In an eerie horror story released just before Halloween, Cusick wrote about five towns around the nation that have died or are dying from climate-related disasters. Historic Shasta and Helena, Calif., are featured in one of the vignettes. 

"Those are two towns that are getting more ghostly," said Yana Valochovich, UC Cooperative Extension forestry advisor in Humboldt and Del Norte counties.

A 19th-century mining town, Shasta City had been a preserved tourist destination in Shasta State Historic Park since 1937 when it was burned in the 2018 Carr Fire, the seventh most destructive wildfire in California history. Helena, a 170-year-old pioneer mining settlement, burned in the Helena Fire of 2017.

There almost certainly will be more "dead towns" as fires consume more of Northern California, Valochovic added.

The Helena Fire of 2017 burned down a pioneer mining town. (Photo: U.S. Forest Service)
Posted on Friday, October 30, 2020 at 11:14 AM
Tags: climate change (96), wildfire (149), Yana Valachovic (19)
Focus Area Tags: Environment

California must become a fire-adapted civilization, UCCE expert says

The vast California acreage burned in 2020 and the protracted smoky skies should signal state residents and officials to adapt to a new reality, reported Ezra David Romero on Capital Public Radio. The 4 million acres of wildland burned this year isn't unprecedented.

Before 1800, 4.5 million or more burned every year in California, according to a UC Berkeley study.

Tragic as they are, parts of the 2020 fires will bring some areas back to natural equilibrium.

UCCE forestry advisor Michael Jones.
"Some areas are going to be hit really hard . . . and will have trouble recovering," said Michael Jones, UCCE forestry advisor in Lake County. "But other areas will look phenomenal. They'll look fantastic and they'll do exactly what we want these systems to do."

However, the burns are unprecedented in California's modern, highly populated times. 

“I don't think that we can have another season like this without something fundamentally shifting,” he said “This is another indication of how we need to think differently about how we approach managing fire, and how we need to become more of a fire-adapted civilization."

It may be "a tough pill to swallow," but Jones told Romero that smoky skies could become a year-long reality because of prescribed burns in cooler months and a prolonged wildfire season in the warmer months.

“People are exhausted,” Jones said, “they're scared and don't understand this fundamental shift and change.”

Jones says the current fire season should also force people to rethink where communities should be built.

Posted on Tuesday, October 6, 2020 at 3:51 PM
Tags: Michael Jones (3), wildfire (149)
Focus Area Tags: Natural Resources

North Coast forests are more dense and dry, fueling fires

Five of California's six largest fires have occurred in 2020, reported Julie Cart in CalMatters.

Lenya Quinn-Davidson.
“There is a collective sensation that we are reaching a tipping point,” said Lenya Quinn-Davidson, a fire specialist with the University of California Cooperative Extension. “This year was not just the fluke burning horrifically. This is 3.2 million acres of fire that burned in a month.”

Quinn-Davidson is based in Humboldt County, with typically rainy, foggy redwood forests. However, she said, the forests don't resemble their former state.

"They are suffering from the same things that the rest of the state forests are. They are poorly managed and have fuels buildup," Quinn-Davidson said. 

Redwood and pine forests are many times more dense than at any time in their history.

"We are now entering a new regime, the climate is changing and we are seeing drier conditions and we are seeing a longer fire season. We are not getting that fall precipitation," she said.

The state's 2018 Fourth Climate Assessment included dire predictions for the North Coast: “Future wildfire projections suggest a longer fire season, an increase in wildfire frequency, and an expansion of the area susceptible to fire.”

Average annual maximum temperatures in Mendocino, Humboldt, Del Norte, Lake, Trinity and Siskiyou Counties could increase by as much as 9 degrees through the end of the century, the report concluded.

Scott Stephens
“The weather and climate is impacting these areas. Last year we were at  60% of average precipitation. We're drier than normal,” said Scott Stephens, a fire scientist at UC Berkeley. “So when lighting strikes, you get an overwhelming number of ignitions in fuels that have been preconditioned to burn.”

The fog that reliably blankets the North Coast is dissipating. Research from UC Berkeley found that fog frequency has declined by a third compared with a century ago.

Even here in Humboldt County — we are right on the ocean, basically in a rainforest  — people are starting to look around and say, ‘Is my house ready for a wildfire?' I'm hearing those conversations,” Quinn-Davidson said.

Posted on Wednesday, September 30, 2020 at 9:01 AM
Focus Area Tags: Environment

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