In the West, skies are often dulled by wildfire smoke whether a fire actively burns near you or not. In December 2017, the Thomas Fire burned 281,893 acres in Ventura and Santa Barbara counties in Southern California. The first two hours of the fire burned 500 acres, and the next two hours incinerated 20,000 acres in front of the Santa Ana winds. The fire affected nearly 60,000 acres of grazing land. Ventura’s ag industry suffered more than $171 million in losses.
After the fire, Matthew Shapero, a livestock and range adviser for the University of California Cooperative Extension in Ventura County, received two main questions from producers. “The first one was, ‘How did the fire impact the rangeland soil seed bank? Should I reseed to speed recovery?’” Shapero recalls, “and the second question was, ‘How soon can I resume grazing on my ranch after the fire has gone through? If I continue to graze, will it negatively impact the recovery of the land?’”
Shapero turned to scientific studies to find the answers but found a lack of published research applicable to how fire impacts rangeland in the chaparral ecosystem. It is important, no matter your location, to seek ecosystem-specific information to aid range and pasture recovery. Because Shapero couldn’t find postfire chaparral research, he decided to set up experiments to answer these questions to help producers learn how to best respond to future wildfires.
To reseed or not to reseed
The Thomas Fire skipped across the landscape in front of the Santa Ana winds. Sometimes it gained an acre a second. Because of this, fire lightly skimmed certain areas and deeply scorched others. Ranchers wondered if they should reseed their annual grass pastures to accelerate recovery.
To find out, Shapero collected soil samples from ranches that burned at various levels of severity. He potted the soil in his greenhouse, planted annual grass seed, watered and waited.
As grass sprouted, or failed to do so, Shapero measured seed germination according to the soils’ burn severities. He fully cataloged the study results but has yet to publish his research. The most significant difference in the annual grass species growth was between grassland pastures that burned at a high severity and those that burned at a low severity.
“This indicates,” Shapero explains, “pastures that were not grazed prior to the fire — with standing biomass — burned hot enough to negatively impact and limit the grass seed bank. In grazed pastures which held little biomass, the soils’ seed bank was not impacted.”
This research suggests that farmers and ranchers may consider reseeding annual grassland that was ungrazed prior to fire and contained standing biomass, because the seed bank may be unable to germinate.
Annual grasses, which predominate in Southern California, depend on healthy soils to germinate seed every year. Rangelands in other areas of the West, as in Washington state, are dominated by perennial grasses.
Richard Fleenor, the state plant materials specialist with the USDA Natural Resources Conservation Service in Washington state, says it’s important to evaluate both the soils and grass crowns in perennial grasslands after a wildfire.
“The fire may have just burned through the grasses,” Fleenor says of evaluation, “and the grass crowns are still alive. If so, the grasses will be fine with rest. But if the fire burned into those crowns, the grasses are dead. That’s when you want to reseed.”
Wildfires often cause invasive plant species to spread quickly across the landscape opened of existing vegetation, before native or non-native naturalized grasses re-establish. After the Thomas Fire, yellow starthistle thrived. “Planting a grass cover,” Shapero says, “may have prevented those hot spots of yellow starthistle encroachment.”
To learn how immediate grazing impacts the landscape and to compare the benefits of deferred grazing, Shapero installed an exclosure cage that limited or prevented cattle from grazing selected monitoring plots. The cages were placed where ranchers didn’t have the luxury of removing cattle and grazed the area immediately after the fire, and where grazing was deferred for six months.
“I mimicked what I thought would be a typical and realistic ranching practice,” Shapero explains. “I set up the exclosures immediately after the fire and kept them in place until peak grass stand production in May.”
The forage production and species composition of these areas, both within and outside the exclosures, will be monitored through 2020. Shapero will determine if there’s any difference between immediate grazing and deferred grazing after a fire. Because Shapero has only one spring’s data collection, he is reluctant to report results.
“Anecdotally,” Shapero says of observations, “deferred grazing doesn’t seem to have increased grass recovery at this time. Now, if I had done a different experiment with permanent exclosures, maybe I’d see longer-term impacts from grazing immediately postfire. But these landscapes are ranched, and realistically, cattle will be present at some point during the year.”
If a livestock producer would like to defer grazing, the NRCS cost-shares through its Environmental Quality Incentive Program to help offset the financial impact of resting burned pasture and rangeland. NRCS cost sharing may be available to defer grazing up to two years, if needed.
Tactics offer look at ways to ‘get back’ from a fire
There are a range of aids and tactics available to farmers and ranchers who have been hit by wildfires. Here’s a rundown of some key areas:
Livestock fencing. The loss of fencing can be the most financially burdensome after a wildfire. Because of this, the Farm Service Agency’s Emergency Conservation Program often cost-shares with producers to re-install fence after a wildfire. “In Douglas County, here in Washington state,” Fleenor says, “many people switched to pipe-fence corners and H-braces after their most recent wildfire. The cost share covered most of the increased cost of metal fencing, which will handle fire better the next time.”
Firebreaks. Firebreaks can be created by grazing livestock intensely along the ranch perimeter or in buffer zones around structures. Another option is to plant low sod-forming, wiry grasses, such as sheep fescue, in a 30-foot-wide strip to reduce the spread of fire. “Planting or grazing firebreaks on the windward side,” Fleenor explains, “can slow down fire. Often this gives enough time for you and the fire crews to arrive and stop the fire before it gets going again.” NRCS offers cost share on fuel break and firebreak practices in wildfire-prone areas.”
Build smart. It is recommended that there be a defensible space of at least 100 feet around structures. Buildings with metal roofs often fare the best because sparks can’t readily ignite them. Another critical consideration is nonelectric water sources. Water storage tanks installed on hill slopes can provide enough elevational drop to maintain water pressure. “In the Thomas Fire,” Shapero recalls, “one rancher sprayed an ignited hay pile for six hours, without electricity, and consequently saved his nearby home.”
Enroll in NAP. The Farm Service Agency’s Noninsured Crop Assistance Program is worth the relatively small cost. NAP is producers’ primary source of insurance regarding wildfire. Learn more at fsa.usda.gov.
Hemken writes from Lander, Wyo.