- Author: Devii R. Rao
Authors: Felix Ratcliff, Devii Rao, Sheila Barry, Luke Macaulay, Royce Larsen, Matthew Shapero, Shane Dewees, Max Moritz, Rowan Peterson, and Larry Forero
The widespread and severe wildfires in California during the past several years highlight the importance of understanding how land management practices such as cattle grazing affect wildfire risk. The California Cattle Council recently funded a UC Cooperative Extension project to evaluate how much fine fuel (grasses and other plants) are eaten by cattle on rangelands, and how this may affect wildfire behavior. These results have not yet been published, but preliminary results are presented here.
Cattle Numbers
The study found that about 1.8 million beef cattle grazed California's rangelands, which include grasslands, oak woodlands, and shrublands, in 2017. Beef cows were by far the most abundant beef cattle class, with 677,000 on range in the state. This was followed by steers, heifers, and bulls.
Fuel Removal by Cattle
Beef cattle are found grazing in every county in California, except San Francisco and they consumed 11.6 billion pounds of fuel in 2017. Our analysis which was based on county crop reports, Agricultural Census data, and UC Cooperative Extension data showed that cattle consumed vegetation across about 19.4 million acres of rangeland, primarily privately-owned. However, some grazing also occurs on federally-owned and other public lands too, especially in the mountain and desert regions of the state.
The amount of fuel consumed per acre varied greatly based on region (Figure 1). The average amount of fuel removed across grazed rangelands in the state was 596 pounds per acre. This number varied from 174 pounds per acre in the southeast interior region to 1020 pounds per acre in the San Joaquin-Sierra Region (Figure 2). Fine fuel reduction on any given ranch can differ greatly (either higher or lower) from the region-wide estimates in this study. Figures 3, 4, and 5 show examples of 500, 1,200, and 3000 lbs./acre of grassland vegetation.
Figure 1. Beef cattle grazing regions of California
Figure 2. Pounds per acre of fuel reduction on grazed rangelands in each region, based on county crop reports
Figure 3. 500 lbs./acre of grassland vegetation
Figure 4. 1,200 lbs./acre of grassland vegetation
Figure 5. 3,000 lbs./acre of grassland vegetation
These fuel removal estimates are based on the best available data, but this data does not describe the complex details and variation of cattle grazing across the state. There is a need for more consistent and accurate accounting of cattle numbers and grazed acres across the state to better understand grazing's impact on fire fuels.
These regional values of fuel removal are much lower than the amount of vegetation or forage that grows naturally in these regions in most years. Valley grasslands in the interior of the state generally produce 2000 pounds of forage per acre or more in an average year (Becchetti et al. 2016, Bartolome 1987). Coast range grassland sites in central and northern California generally produce more than 3000 pounds of forage per acre (Larsen et al. 2020, Becchetti et al. 2016). Coastal prairie sites can be highly productive, producing more than 4500 pounds per acre on average in the central coast (Larsen et al. 2020). The highest production years can see double the average production in any given region, and the lowest production years can be less than 25% of average production. The relatively low amounts of fuel removal reflect conservative stocking strategies, which are used by many ranchers across the state as a way to guard against drought and the unpredictable nature of forage production (Macon et al. 2016).
Influence of Cattle Grazing on Wildfire Behavior
Maintaining flame lengths below four feet is often cited as a critical threshold that allows fire fighters to safely access an area from the ground without heavy equipment (Andrews and Rothermel 1982). Fire behavior models developed for this study suggest that maintaining fine fuels at or below 1200-1300 pounds per acre during spring and summer will keep flame lengths below four at wind speeds up to 40 mph. This number is affected by other factors however, and during very dry weather conditions, fine fuels may need to be kept at or below 800 pounds per acre to keep flame lengths below 4 feet. These numbers are useful for interpreting the impacts of reducing fuel levels, but they still need to be experimentally validated in California.
In addition to reducing fine fuels, cattle grazing can also reduce rangeland fuels by preventing or slowing encroachment of shrubs and trees onto grasslands. This is valuable from a fire safety perspective because shrubs can increase fire hazard and fire intensity (Ford and Hayes 2007, Parker et al. 2016).
Reducing fire hazard is not as simple as grazing rangelands to bare soil or even to low level of fuel. Rangeland managers need to balance different management goals. They aim to leave some forage on rangelands at the end of the grazing season (before the first fall rains) to protect soil from erosion, support future forage production, avoid growing some types of weeds, and often provide fall forage for their cattle. In some areas, it is important to leave more than 1200-1300 pounds of forage per acre to achieve these goals, so reducing fuel loads will have to be done carefully to avoid conflicts with other management targets (Bartolome et al. 2006).
Conclusions
Cattle grazing plays an important role in reducing fine fuels on grazed rangelands in California. Without grazing we would have hundreds to thousands of additional of pounds/acre of fine fuels on the landscape, potentially leading to larger and more severe fires. The bulk of this fuel reduction occurs in regions of the state with higher forage production per acre. Therefore, while average fuel reduction rates are higher in these regions, residual fuels may not be low enough across all grazed rangelands (even in regions with high fuel reduction rates) to avoid long flame lengths. Fortunately, cattle do not generally consume forage uniformly at the field, ranch, or region scale. At many locations within grazed rangelands, there will likely be patches that are grazed low enough to significantly alter fire behavior, and patchy fuels can slow fire extent and rate of spread.
Widespread and severe wildfires are predicted to increase over time in California. This “new reality” requires that we take advantage of all the tools in our management toolbox to protect public safety while meeting our broader rangeland management objectives. Grazing all rangelands to ideal fuel levels is not logistically feasible or compatible with management goals. However, there are opportunities to improve fire safety in California by grazing rangelands that are not currently being grazed or even by increasing grazing intensity on very lightly grazed areas. The number of beef cows in California today are only about 57% of their peak numbers in the 1980s (CDFA 2010-2018). This reduction is mirrored by declines in public lands grazing. Strategic implementation of cattle grazing, including potentially fee-for-service agreements, on key private and public lands can meet multiple natural resource objectives, while also lowering fire hazard through reducing fine fuels, reducing fuel continuity, and slowing or stopping shrub encroachment into grasslands.
This research was funded by the California Cattle Council.
REFERENCES
Andrews, P.L. and R.C. Rothermel. 1982. Charts for interpreting wildland fire behavior characteristics. General Technical Report INT-131. US Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station.
Bartolome JW. 1987. California Annual Grassland and Oak Savannah. Rangelands, 9:122–125.
Bartolome, JW, WE Frost, NK McDougald, M. Connor. 2006. California Guidelines for Residual Dry Matter (RDM) Management on Coastal and Foothill Annual Grasslands. University of California, Division of Agriculture and Natural Resources, Rangeland Monitoring Series, Publication 8092.
Becchetti T, George M, McDougald N et al. 2016. Rangeland Management Series: Annual Range Forage Production, University of California, Agriculture and Natural Resources.
California Department of Food and Agriculture (CDFA). 2010 – 2018. California Agricultural Statistics Review. California Department of Food and Agriculture, Sacramento, California.
Ford LD & Hayes GF. 2007. Northern Coastal Scrub and Coastal Prairie. In: Barbour M, (ed.). Terrestrial Vegetation of California, 3rd Edition. University of California Press, p. 180–207.
Larsen, R., M. Shapero, M. Horney, L. Althouse, D. Meade, K. Brown, D. Rao, K. Striby, C. Rigby, K. Jensen, D. Conestro, K. Lindsteadt, S. Covello. 2020. Forage Production Report, California Central Coast, 2001 – 2019. University of California Agriculture and Natural Resources. Accessed online August 2020 at: http://cesanluisobispo.ucanr.edu/Custom_Program355/Forage_Production_Report/.
Macon, DK., S Barry, T Becchetti, JS. Davy, MP. Doran, JA. Finzel, H George. 2016. Coping with drought on California rangelands. Rangelands 38(4):222-228.
Parker, V. T., R. B. Pratt, and J. E. Keeley. 2016. Chaparral. Pages 479-508 in H. Mooney, and E. Zavaleta, editors. Ecosystems of California—a source book. University of California Press, Berkeley, USA.
- Author: Devii R. Rao
For information about the NAP program, click here. The Noninsured Crop Disaster Assistance Program (NAP) coverage is federal crop insurance that covers crop losses from natural adversities such as drought, hail and excessive moisture. NAP covers losses from natural disasters on crops for which no permanent federal crop insurance program is available. September 1, 2020 is the deadline to purchase a NAP policy on native grass for grazing.
For information about the USDA'S Coronavirus Food Assistance Program click here. The deadline to apply is September 11.
San Benito Santa Clara NAP Deadline Reminder (003) edit jv - Copy
USDA CFAP ANNOUNCEMENT edit - Copy
- Author: Devii R. Rao
Registration is now open for Part 1 of our upcoming National Preparedness Month webinar series. Part 1 focuses on connecting livestock owners to local and statewide leaders in emergency response. The webinar will be held on Wednesday, September 2, 2020 from 1:00-2:30 PM.
Register online for free: https://ucanr.edu/prepmonth2020
You can find general emergency preparedness information online including suggested preparedness activities during September, here: https://www.ready.gov/september
Click here to see the flyer for additional details. Please feel free to share this with friends and colleagues.
More information to come soon about Part 2: Wildfire Preparedness.
If you have any questions, please don't hesitate to reach out to Rebecca Ozeran at rkozeran@ucanr.edu!
The workshop will focus on Fresno and Madera County resources, but everyone is welcome.
Part 1 Webinar Flyer
- Author: Gabriele Ute Maier
By GabrieleMaier, CE Specialist Beef Cattle Herd Health & Production and Josh Davy, County Director Cooperative Extension, Tehama County
Blue-green algae, also known as cyanobacteria, can be found in surface water like ponds. These photosynthetic bacteria do not necessarily pose a threat and are actually part of the ecosystem that provides oxygen to other micro-organisms. Under certain conditions, though, a so-called algal bloom may lead to a dramatic increase in their numbers and their subsequent die-off releases toxins into the water. Warm weather, stagnant water, and nitrogen or phosphorus fertilizer runoff are risk factors that can result in these algal blooms. Some slow flowing creeks and rivers can also be impacted – every year the Klamath Rivers seems affected and Clear Lake is known to have had problems as well. Mild winds can push and concentrate blue-green algae on the water's edge. You will see scum, foam, or a mat of algae, or they can look like paint floating on the water surface. Their color can vary between blue, bright green, brown or reddish.
Blue-green algae produce two types of toxins, neurotoxins and hepato-toxins (liver toxins). Both types can lead to sudden death in cattle if they drink water from ponds where blue-green algae were blooming. Dogs playing in or drinking from ponds and other animals have also been affected. Exposed cattle can have bloody diarrhea, be weak or seem confused. Often the only sign is sudden death. Those animals surviving hepatotoxic toxin exposure can develop what is called photosensitization caused by liver damage, a term for describing that their skin is more sensitive to light, where the skin, especially the lighter areas like muzzle, teats, or vulva peels off. Blue-green algae toxicity is in any case a severe problem and ranchers should be on the lookout to avoid their cattle becoming exposed.
When you are suspecting a blue-green algae bloom, the best way to avoid problems is to prevent access to the water source by fencing off the pond and providing a different water source. Toxin levels will increase as the cyanobacteria die. Once the water has cleared up, the best way to assure the water is safe again is to test at the lab. Toxins likely distribute evenly throughout the water so pumping water from the bottom of the pond may not be safe. However, this can be a good method of prevention. Cattle standing in small ponds depositing nutrients can exacerbate conditions and lead to algal blooms. Smaller water bodies are more vulnerable, because a larger volume of water helps dilute the nutrient load, but large lakes and reservoirs are not immune and have been impacted as well. Diverting water from a pond to a water trough and then fencing off the pond can decrease the nutrient load and help prevent algal blooms. The Natural Resources Conservation Service (NRCS) can help cost share with this and other livestock water development projects.
If you are in doubt whether you have blue-green algae in your pond, there are a few simple tests to distinguish them from normal harmless water plants or other types of algae. Wear gloves for all these tests to avoid contact with toxins. Thrust a stick onto a mat of algae and pick it back up – if it comes back looking like it has been dipped in paint, it is blue-green algae. If it comes back with threadlike algae dangling from it, it is a different type of harmless algae. Another way to check for blue-green algae is to fill a mason jar or other clear container about ¾ with water and refrigerate overnight in a secondary container like a clear plastic bag to avoid any contact between the jar and other surfaces. Carefully inspect the next day; if all the algae are at the bottom, they are likely not blue-green algae. If they are floating at the surface, they are likely blue-green algae. These tests are not 100 % accurate but can be helpful in assessing the situation. If you identify blue-green algae in your pond, that does not necessarily mean that they pose a threat at that time. It does mean, however, that you should watch for algal blooms where toxins are released.
Testing at CAHFS lab is also possible. The lab offers an algae toxin panel, which is priced at $605 to test for 4 different toxins (Anatoxin-A, Cylindrospermopsin, Microcystins, Saxitoxins) or $165 for individual toxins. Testing requires 500 ml (about 1 ½ pints) of water that should be shipped on ice to the lab.
If one or more animals die acutely, it is important to consider a postmortem examination to try to determine if an algal toxin is the cause of death. The liver damage associated with exposure to hepatotoxic blue-green algae is dramatic and this can indicate the need to test for microsystins in water or gastro-intestinal content samples. The neurotoxic blue-green algae toxin does not cause any changes in organs after death, but gut contents can again be tested to help determine a cause of death.
Copper sulfate is a way to treat the water and kill the algae but can lead to high copper levels in the water, which can be harmful to cattle. Sheep are particularly susceptible to copper toxicity. Any treated drinking source should be tested for copper levels prior to allowing sheep to consume the water after a copper sulfate treatment. It is important to follow label directions to ensure enough product is used to be effective, but not an excessive amount that can cause toxicity to animals. Bleach can also be a successful treatment. If a pond is treated it will be necessary to determine the volume of the pond, so the proper amount of product is applied. UC ANR publication 8681 demonstrates a method for measuring pond volume. In addition, rapid die-off of algae can lead to large amounts of toxins being released into the water making it unsafe even though it appears clear. For this reason, and to ensure ample time for the product to work, livestock should be excluded from the treated water source until the treatment period is over.
More sophisticated technical solutions are available but come with a price tag. Devices that emit ultrasound waves prohibit microscopic algae from floating to the water surface where algae need to spend time for photosynthesis, which is the plants' way of turning sunlight into energy. Blue-green algae will not survive without that energy source. Full systems adapt the emitted ultrasound frequencies according to an algorithm and monitor water quality in real-time alerting the user to any changes in algae levels. The advantages of this system are that the algal cells are not lysed and do not release their toxins into the water and no chemicals must be used that could be potentially harmful to non-target species. A ballpark figure is about $1,200 / surface acre for larger water bodies. Smaller, less sophisticated units are also available. The disadvantage of this system is that it is less effective in shallow water below 3-4 feet.
Mechanical aeration and mixing are other ways to decrease blue-green algae but require an electrical power source and systems maintenance. Mixing is more effective for deeper water bodies (> 45 ft).
Another thing to keep in mind is that cyanobacteria have been around for billions of years and know a thing or two about evolution. They can adapt to their environment, so whatever you do to control them it's important to stay a step ahead of them and not rely on the same method over time.
- Author: Devii R. Rao
USDA is providing critical support to our nation's farmers and ranchers through the Coronavirus Food Assistance Program (CFAP). CFAP provides vital financial assistance to producers of agricultural commodities with financial assistance that gives them the ability to absorb sales declines and increased marketing costs associated with the COVID-19 pandemic.
Click here to see the flyer with more information and instructions about how to apply.
FSA CFAP Livestock Fact Sheet-2020-5-26-20