- Author: Saoimanu Sope
Hopland REC turns 2018 River Fire devastation into research opportunity
The destructiveness of wildfire flames is easy to see, but dangers may lurk in the ashes they leave behind. A group of UC Davis scientists studied lambs at the UC Hopland Research and Extension Center, investigating whether pastures regrown after a wildfire cause toxic metal residues in grazing animals. The results, published in California Agriculture journal, showed that grazing on regrown pastures did not significantly alter the metal content of the lambs' meat and wool. That's good news for ranchers and consumers from a food safety perspective.
In 2018, the River Fire burned six miles north of Hopland, scorching two-thirds of the land at Hopland REC, including areas in its sheep station. Since Hopland REC conducts ecological and agricultural research, they had data and some meat samples from the sheep flock that lived on site before the River Fire occurred.
“A bunch of researchers came together to brainstorm how we could take advantage of this unfortunate event,” said Sarah Depenbrock, assistant professor and agronomist in the Medicine and Epidemiology department of UC Davis School of Veterinary Medicine.
Burning has played a role in agricultural processes for many years, but wildfires in California are creating a new fire landscape that interests researchers like Depenbrock. “The problem, now, is that these big wildfires probably interact with agricultural land differently than routine prescribed burns,” she said.
Large, older plants on lands that have not recently burned may contain high concentrations of metals, sequestered over years of growth. Mercury is an example of a potentially dangerous metal that can be sequestered in living things over time. These metals may be distributed in ash after the vegetation burns so the scientists examined lambs that had grazed on Hopland REC's recently burned pastures, during the first plant regrowth.
Uncertain results raise more questions
The researchers compared meat from lambs that grazed on regrown pastures in 2019, after the River Fire, to frozen meat samples that were collected the year before the fire. Lead, mercury, arsenic, molybdenum, cadmium, beryllium, cobalt and nickel were not detected in any animal samples. There were, however, a few (3 out of 26) samples that tested positive for the non-essential (potentially toxic heavy metals) chromium and thallium in the group grazing after the fire.
Due to the small number of samples testing positive, researchers could not determine statistically if this contamination was associated with grazing the burn regrowth. The concentrations of chromium and thallium found may or may not be potentially toxic, depending on the specific forms and how much meat a person consumes.
Another aspect of the study included testing lambs' wool to determine if it is a good method of judging the mineral content of its meat. “In general, we learned that it wasn't well-correlated with most meat metal content of interest, which is worth knowing. However, because we did not identify many of the non-essential metals of particular toxologic concern, such as lead or mercury, in any animal samples we could not determine if testing wool would be useful for those metals, as they are in other species,” said Depenbrock. She also notes that the wool from animals whose meat tested positive for chromium and thallium, did not test positive for these metals in their wool.
As the challenges in managing wildfires persist, so does the risk of contamination of food products stemming from grazing livestock.
“We didn't get striking evidence that tells us, when there's a fire, it means everything is contaminated with heavy metals,” said Depenbrock. “But it does raise the question that maybe we should be doing a little bit of surveillance to see if this is spurious or common. And we should be finding a way to screen grazing herds.”
Recommendations to manage copper concerns
“It's a very small study, but it was quite interesting to find that copper was actually lower in the postfire grazing group, which makes me wonder,” Depenbrock said.
Diseases associated with copper deficiency are a major concern in sheep. For example, congenital swayback can result in stillbirth or an animal's inability to stand on its own due to incurable changes to the spinal cord. Other adverse effects include reduced growth rate, anemia, wool defects and fiber depigmentation, and osteoporosis with higher risk of spontaneous fractures. Copper excess can also cause serious and sometimes fatal disease.
Many of the forage sources, grazing areas and rangelands in California are copper deficient, while some feed sources have excess copper. Screening and monitoring livestock herds for trace minerals including copper is crucial.
To test for copper, she advises livestock owners to obtain mineral concentrations from the organs of euthanized or dead animals. Samples from the liver and kidney are the most valuable organs to identify a potential problem in the herd. UC Davis Veterinary Medicine's California Animal Health and Food Safety (CAHFS) labs do this testing routinely.
Second, monitor and record mineral supplementation and, third, maintain updated health records to make informed decisions regarding supplementation based on a herd or flock's known problems. For example, if a producer is not accustomed to supplementing copper, Depenbrock highly recommends working with a veterinarian to start out (as there are numerous copper supplement products of varying concentration on the market), to determine a testing or screening plan, and review health records for problems potentially associated with copper.
To read the full text of the study, visit https://calag.ucanr.edu/Archive/?article=ca.2022a0016.
/h3>/h3>/h3>- Author: Hannah Bird
HREC and Post-Fire Research Opportunities
What is HREC?
The UC Hopland Research & Extension Center (HREC) is a multi-disciplinary research and education facility in Mendocino County located in the foothills of the Coast Range about two hours north of Berkeley. As part of the UC system for over 65 years, we are stewards of more than 5,300 acres of oak woodland, grassland, chaparral, and riparian environments. Elevation at the center ranges from 500 ft to 3,000 ft. HREC currently maintains a research flock of about 500 breeding ewes that have been the subjects of numerous studies on ranching practices, range management, livestock nutrition, wool production and breeding. Field experiments and demonstrations conducted here since 1951 have led to more than 1,500 publications in animal science, entomology, plant ecology, public health, watershed management, and wildlife biology. Our website is hrec.ucanr.edu.
The River Fire
As part of the Mendocino Complex fire, the River Fire burned through HREC on the evening of July 27 and into July 28. Approximately 3,000 acres of our center burned in this fire. Due to the concentrated efforts of Center staff and Cal Fire crews, all of our employees, residents, sheep, livestock dogs, offices and residences were saved. Below please find the burn map of our property. All of the black area to the north was burned and the dark red patches were areas of vegetation that remained unburned. The fire intensity varied greatly as did oak survival. You will see two smaller burned areas in the southern part of the property that were prescribed burns performed in June of this year.
Research Opportunities
While this was a blow to current research, pastures, and water infrastructure, we also see this as a wonderful opportunity. Due to extensive historical data sets and ongoing research projects, coupled with a variety of grazed and ungrazed pastures, and prescribed burn plots for comparison with wildfire, there is enormous potential for pre- and post-fire studies in the fields of:
- Watersheds and hydrology; fire science; plant science; soil science; entomology and parasitology; wildlife and wildlife ecology; rangeland management; grazing practices as fire suppression…..
To support this research, HREC offers:
- A well maintained network of roads that accesses almost all parts of the property, vehicles to use.
- A fully equipped shop staffed by employees skilled in fabrication and repair of research equipment
o Electrical, wood working, welding and metal fabrication, mechanical
- Skilled staff trained in field work techniques, with long histories of successful research support
- Fiber optic internet with Wi-Fi access throughout headquarters, strong cell service in most areas
- A vault of raw data, photos, and final papers from research conducted at HREC.
- Warehouses for storing equipment, a variety of accommodations from dorms to private houses
- Wet and dry lab space (undergoing renovation during fall 2018, available spring 2019)
- Lysimeter with available watering system, electrical connections, and fiber optic access point
- A research flock of sheep consisting of just under 500 breeding ewes, with all needed facilities and RFID tracking
- Fenced pastures and biological reserve areas for different treatment plots and controls
- A fully equipped conference facility with A/V equipment and fiber optic connections
Next Steps
- Zoom meeting on September 7th, 10am. More in depth information, Q&A.
- Field day on October 19th, 10am-5pm. Presentations, brainstorming, Q&A, site tours, available accommodations
- To register for either event follow this link: http://ucanr.edu/survey/survey.cfm?surveynumber=25451
Contact: HREC Interim Director John Bailey, jtbailey@ucanr.edu, (707) 744-1424 x 112