- Author: Daniel K Macon
Barb goatgrass (Aegilops triuncialis L.) is a winter annual grass native to the Mediterranean region and western Asia. According to a UCANR publication, it was introduced to Sacramento and El Dorado Counties via the importation of cattle from Mexico. And it is a growing problem on annual rangelands here in the Sierra Foothills. In some ways, I think of this invasive grass as "medusahead on steroids" - barb goatgrass spikes and joints (seedheads) disperse by attaching to animals, humans, and equipment. I often see new infestations along roads or walkways. Barb goatgrass forms dense stands with a rapidly establishing root system, making it extremely competitive with other annual grasses and forbs. In some areas, barb goatgrass reduces forage quality and quantity by as much as 75 percent - and because livestock tend to avoid the plant (and graze more desirable forages), it can spread rapidly.
Carol and Andy Kramer, who operate a sheep and cattle ranch in Nevada County, have been fighting barb goatgrass for several years. Most recently, they've been working with the Natural Resource Conservation Service (NRCS) through an Environmental Quality Incentives Program contract focused on goatgrass control. Over the course of the last 9 months, Carol and Andy have been working with the Placer Resource Conservation District (RCD) and UCCE to experiment with using prescribed fire to reduce goatgrass and re-invigorate native grasses.
Research suggests that burning goatgrass for two consecutive years offers "excellent control." Sounds pretty straightforward, right?! Not so fast! Fire is an effective control method when most of the fine fuel has dried sufficiently to carry the fire, but when the goatgrass seedheads are still attached to the stem - in other words, in late spring or early summer, when everyone is starting to get nervous about fire in the foothills!
A quick aside about using prescribed fire as a range improvement tool. When I started working with ranchers in California in the early 1990s (when I was just out of college, working for the California Cattlemen's Association), prescribed fire had largely gone out of vogue. This was partly a result of increasing worries about liability, and partly, as I recall, a shift in focus and attitude within the California Department of Forestry and Fire Protection (which became officially known as CalFire in the early 2000s). Today, after a decade of increasingly catastrophic wildfires (and the accelerating spread of invasive weeds like barb goatgrass), prescribed fire is making a comeback - thanks to efforts of many of my UCCE colleagues, RCD staffers and contractors like Cordi Craig and Chris Paulus (who led this effort), and especially of landowners like Carol and Andy!
Obviously, with something as complicated as prescribed burning, you don't simply wake up one June morning and say, "Hey, this would be a great day to light the back pasture on fire!" Carol and Andy (along withCordi and Chris, andUCCE) began planning for this burn last winter. As fire professionals,Cordi and Chris recommended putting a "black line" around the 1.5 acres ofgoatgrass during the winter months, whenCALFIRE burn permits are not required. Carol and Andy invested in water tanks and other equipment, and spent much of the winter and early spring pile burning and creating fire lines. Working together, we also burned several adjacent units to remove ground and ladder fuels in the areas surrounding thegoatgrass site.
Then we all waited! We needed the underlying fuel to be dry enough to burn, but we also needed the goatgrass to hold onto its seedheads. And we needed the right weather conditions. With the wet, cool spring we had in 2023, these conditions didn't arrive until July - well into fire season. This meant that we also needed a permit from CalFire. I've lived and worked in CalFire's NEU unit (which covers Placer, Nevada, and Yuba Counties) - and worked with and around ranchers - for nearly 30 years. I wasn't aware of CalFire ever allowing a rancher to do a prescribed fire for range improvement (or any other reason) in July. But thanks to the Kramer's persistence and Cordi and Chris's experience and knowledge, we received permission to do the burn on July 13.
Carol and Andy started the fire around 9am that morning - temperatures were hovering around 80F, and the relative humidity was just over 50%. Amazingly, we had difficulty getting the vegetation to burn - even as temperatures rose and humidity dropped over the course of the morning. By midday, we'd burned all we could burn, and began mopping up (making sure the fire was completely out).
Walking through the burn, I was amazed by the variability in burn intensity. Some of the goatgrass seedheads were completely consumed; others looked like they had not been exposed to fire at all. Carol collected seedheads from before the burn, as well as singed and apparently unsinged seedheads, to see if there will be any difference in germination (we'll keep you posted). We also started thinking about next year's burn.
One of the biggest challenges in burning for a second consecutive year, I expect, will be whether there is enough fine fuel (other grasses, pine needles, dry leaves, etc.) to carry the fire through the goatgrass. Visiting the site two weeks ago, I was impressed to see native blue wildrye starting to grow in the blackened burn unit (even with very little precipitation since the fire) - we'll be anxious to see what happens once we've had a germinating rain. Even so, we are considering broadcasting a quick-growing, early maturing annual grass (like soft chess (Bromus hordeaceus) this fall so that we have more receptive fuel next spring.
I think we all learned a great deal about the logistics of using fire to manage goatgrass (thanks to Cordi and Chris) - and about the challenges of using prescribed fire during fire season. One of the side benefits, from my perspective, is the demystification of fire generally. This was not a scary burn, even though it happened in the middle of July! While this was partly due to the conditions on the day of the burn, the work that Carol and Andy did to prepare (with Cordi and Chris's guidance) over the many months leading up to July 13 made it successful and safe. We're all looking forward to next year's fire!
- Author: Travis M Bean
New research published in PNAS (Fusco et al 2019) highlights the role of invasive grasses in creating new wildfire regimes at not just local but regional scales. Weed scientists are familiar with the concept of the grass-fire cycle (D'Antonio and Vitousek 1992): exotic grass invasions promote hotter or more frequent fires, which in turn facilitates more extensive grass invasion, causing more fires, etc. Perhaps now is the right time to better educate non-scientists about this critical concept as wildfires take up more of the public's attention.
The invasive grass-fire cycle is happening in real time: Arundo, bromes, goatgrass, and medusahead in California, buffelgrass in Arizona, Hawaii, and northwestern Mexico, Ventenata in the inland Northwest, and cheatgrass across all western states, just to name a few of the major players. The areas affected by these invaders are growing, often exponentially, along with the frequency and severity of the wildfires they help drive.
Management efforts are not keeping pace. Public recognition of the role of invasive grasses in exacerbating wildfires is not widespread, and these fuels and their significance are rarely mentioned in major news media reporting of major wildfires (this recent reporting in the New York Times by Kendra Pierre-Louis is a welcome exception). Take some the recent bushfires in Australia as an example and try to recall any mention of specific fuels in the abundant media coverage.
As the authors of the PNAS paper state, “as concern about US wildfires grows, accounting for fire-promoting invasive grasses will be imperative for effectively managing ecosystems.” The authors point out that the fire management and invasive species management communities could benefit from closer collaboration. An equally important goal is to convey the magnitude and urgency of grass invasions to the public and policy makers so that they can be fully accounted for in our regional and national conversation about mitigating and adapting to the new wildfire regimes.
- Author: Pamela Kan-Rice
- Re-posted by: Gale Perez
“We have all of the nasty non-native Bromus species here in California, and these weeds are key drivers of increasing fire frequency,” said Travis Bean, UC Cooperative Extension weed science specialist based at UC Riverside.
The invasive, non-native Bromus species aggressively outcompete native plants, forming dense stands that grow fast and dry out quickly, becoming highly flammable. Fire can move rapidly through these dense patches of dry grass, especially during windy conditions or on slopes.
“When you have understory of dry Bromus or other weedy grasses, their ease of ignition can allow fire to spread from areas like roadsides where ignition sources are plentiful to more pristine native plant communities,” Bean said. “Additionally, these fast-moving fires can throw embers that allows the fire to jump long distances or even reach high into the air, igniting structures.”
Bean would like to see the fuels in wildfires identified so people have a chance to consider managing them to mitigate the increasing frequency of catastrophic wildfire across the state.
With training, citizen scientists such as California Naturalists could help cities, counties, utilities and government agencies identify the invasive plant species that fuel urban wildfires.
“On a landscape scale, I would focus on managing Bromus anywhere human-caused ignitions occur,” Bean said. “Resources for management are scarce, and these species are widespread and can't be controlled everywhere they occur. Roadsides, hiking trails, and campgrounds are critical areas where people can start fires that spread, so It makes sense to concentrate management there.”
“When I talk to land managers about these species, they recognize that some areas will have to be sacrificed and it may not be possible to eliminate these species from the landscape,” Bean said. They are prioritizing areas with smaller invasive populations where there is an actual chance to eliminate them, or are managing larger populations for containment so they don't spread.”
Timing is everything
The key to reducing the spread of invasive, non-native Bromus species or any annual weed is preventing the plants from producing seeds, Bean said. “Whatever control method you chose, if deployed too early or too late, you gain nothing for considerable expense.” Too early and the plants may simply resprout, while too late and they will have already set seed and further contributed to next year's weed crop.
Herbicide is an effective and inexpensive means of control, though many prefer non-chemical methods. Hand pulling can be effective in small areas, but is discouraged for large patches due to the sheer amount of labor required and risks of actually spreading the weed seeds.
Another way land managers can try to prevent the weeds from spreading is by mowing or grazing with goats, sheep or cattle, Bean said, adding that using livestock can require more intensive management and proper timing is critical.
“For mowing and grazing, the key is to wait until the plants have started to flower, but the seeds are not mature,” Bean said. “If you mow when there's mature seed, you'll just spread the seed and make the problem worse. And once the seedheads mature, grazing animals won't eat it.”
Prescribed fire is another option for containing invasive grasses, but is generally discouraged as there's a very high chance of exacerbating the problem. These Bromus species are very fire-adapted and tend to increase following burns. Prescribed fire should only be used by professional land managers. If this strategy is used, a burn plan, permits and training are essential. If not done correctly, prescribed burns may escape control and become wildfires, producing smoke that impairs visibility on highways, impacts air quality and human health, and damages native vegetation.
“Timing is everything,” Bean said, explaining the temperature difference between the plant and soil surface. “The grass has to be dry enough to carry fire, but not so dry that the seeds have fallen from the plant to the soil surface, where temperatures are much cooler than just a few inches up in the air where the seedheads are. Some research has shown this strategy to have been successfully used for certain invasive grasses like barb goatgrass (Aegilops triuncilias), but is not recommended for Brome species.”
He expects the changing climate to lead to more invasive plant species. “Invasive plants can be more resilient during drought and can quickly bounce back when rain returns, overwhelming natives,” Bean said. “And invasive species are often key drivers of wildfires and increasing fire frequencies and intensities, which prevents the recovery of native plants.“
- Author: Philip Brownsey
Over the last few years a team of UC researchers have explored the potential of using plant phenology to identify when targeted grazing or mowing can be applied to have the largest negative impact on medusahead and barb goatgrass. Phenology refers to the timing of biological events throughout the year and how they relate to climate and landscape. Medusahead and barb goatgrass are mostly typical of other annual grasses in California (Figure 1) in that they germinate after the start of the fall rains, grow through the winter (Figure 2), and then produce reproductive parts, flowers and seeds, in the spring. This research shows that if grazing or mowing are applied before the stem begins to elongate, the effect of these control treatments on seed production is minimal. Applying grazing or mowing treatments after the stem elongates but before the seed head emerges can decrease seed production by more than ten-fold.
Parts associated with the flower and seed head play a big role in why these noxious weeds are undesirable. Both of these grasses produce long, stiff awns that make them unpalatable to livestock (and produce discomfort to people and pets when they become stuck in our clothes). In addition, analysis shows that the nutritional content of these grasses falls below adequate levels as forage for cattle and sheep as they begin to produce flowers and awns (Figure 3). Once seed heads develop mowing or grazing will not prevent the seeds from becoming viable and germinating (Figure 4).
These observations on how the traits of medusahead and barb goatgrass change through the growing season have allowed us to define limits for when targeted grazing and mowing should begin and end. Once medusahead and barb goatgrass become susceptible to defoliation in the spring, there is a 2 to 3 week window during which targeted grazing can be used to treat medusahead (at stocking rates of 1 to 3 Animal Unit Month, or AUMs per acre, depending on the initial standing crop of forage) followed by a 5 week window during which mowing can be effective to treat either medusahead or barb goatgrass. More information on treating these two noxious weeds will soon be available in the UC ANR publication 8567, “Barb Goatgrass and Medusahead: Timing of Grazing and Mowing Treatments” that will be available on the SFREC website and through the ANR Catalog site.
- Author: Jeremy James