Final report for FW24-008
Project Information
Targeted or prescribed grazing services have become a popular vegetation management tool on the West Coast, and particularly the Central Coastal range of California. With the area’s high annual production of fine fire fuels this poses a risk to communities within this large Wildland Urban Interface and provides a secondary income source for livestock operators with small ruminant animals. While the opportunity to graze provides additional income, it often poses a threat to the condition of their animals. The contradiction stems from the unrealistic expectation of land managers, land management agencies, and landowners around the necessary level of reduction to address fire risk. This project provides preliminary results on the level of reduction that reduces fire risk without compromising the health of the environment or livestock and helps better understand what level of grazing promotes native species composition.
The original intent of the project was to burn the plots post-grazing; however prescribed burning conditions are variable and were not met in the window of time available to burn the landscape. To provide useful results, the BLM collected vegetation composition data and solicited opinions from fire managers post-grazing to provide preliminary results on effectiveness of fuels reduction and native species composition within the grazed plots. Late blooming native species like hayfield tarweed and common madia are green at the peak of fire season in this region. When a wildland fire passes through patches of these species it is often slowed or stops all together – these assumptions are currently being studied by the UC Davis McLaughlin Reserve. Thus, the collection of vegetation composition data collected in the next growing season. Native species are – in general – more resilient and resistant to fire. Managing for native species composition as opposed to total elimination of fine fire fuels could result in a better adapted ecosystem and create a more manageable fire environment for wildland fire personnel. Management for native perennial species also helps to maintain soil moisture as the fine annual grasses often deplete soil moisture early in the growing season. A higher level of soil moisture prevents fire spread, especially in August through September, the peak of fire season.
- Determine what level of grazing reduces hazardous fine fuels to a level easily managed by wildland fire personnel.
- Provided preliminary results to land managers and livestock operators to help both parties better understand the appropriate level of impact while not degrading body condition of the livestock.
- Empower land managers to consider long-term impact alongside their seasonal fuel reduction goals, i.e. soil condition, native species composition.
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May 1st 2024 |
-Define appropriate plots -Photo and video capture green season |
Jaime Irwin (PI) supported by Kayleigh (TA) for determining |
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June 15th 2024 |
-Measure Available forage -Photo and video capture dry out prior to grazing treatment |
Jaime Irwin (PI) supported by Kayleigh (TA) for measurement of forage |
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July 15th-August 15th 2024 |
-Evaluate body condition of all animals pre graze (Video document scoring process) -Graze research plots to predetermined levels of impact and record factors (Stocking rate, number of days, acreage grazed per paddock, additional strategies, supplementation) -Evaluate body condition of animals from each group post graze (Video document scoring process) -Take Photos and Video of impact immediately after graze |
Jaime Irwin (PI) with Kaos sheep and Team Members |
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September 2024 |
-Take video of RDM levels 1 month after grazing impact -Video record the collection of the following Data: -Measure RDM -Measure Soil surface temperature -Measure Soil Moisture -Measure Species diversity -Assess Fire Risk |
Jaime Irwin (PI) will schedule site assessment with CalFire Representative to Assess Fire Risk of each Plot, Kayleigh (TA) performing measurement of RDM, Soil temp/moisture and assessment of plant species diversity and assessing Fire risk of each plot. |
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October 2024 |
-Compile all photo and video documentation to create an educational video that truthfully represents project results. -Provide this video to producers, professionals and |
Jaime Irwin (PI) will organize field day with Kayleigh (TA) |
Cooperators
- - Technical Advisor
- - Producer
Research
The project takes place on BLM managed land in the Northern California Coast Range characterized by the Mediterranean Climate which often produces fine, flashy fuels in the Oak Savannah ecosystem. The fuels present a safety risk to communities in the wildland urban interface throughout the region. Target grazing attempts to address these safety concerns but poses a risk to livestock given the poor forage quality during the season of treatment. This study hopes to address the concerns of the livestock operators for their livestock as well as the communities they are trying to protect.
Six, 5 acre plots with 3 different levels of impact. All six plots will be characterized by the same soil and vegetation type. Each level of impact will have a supplemented group and a group not offered supplement. Sheep will graze at a density of 100 head per half acre per day (or until level of impact is achieved) in order to best replicate average target grazing project demand and approach.
Data will be collected 4 times throughout the project: green season, dry season pre graze, immediately following graze, one month post graze. Photo points and line transects will be established pre-treatment and data will be collected from these locations throughout project implementation. Data collected will include soil coverage determined using Residual Dry Matter calculations, soil temperature, soil moisture and plant species diversity along established transects. One month post-grazing a CalFire representative will assess the fire risk in all 6 plots.
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TEST PLOT/GROUP OF 100 HEAD |
LEVEL OF IMPACT/SUPPLEMENT? |
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PLOT 1/GROUP A |
High Impact/ No Supplementation |
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PLOT 2/GROUP B |
High Impact W/ Supplementation |
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PLOT 3/GROUP C |
Med Impact/ No Supplementation |
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PLOT 4/GROUP D |
Med Impact W/ Supplementation |
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PLOT 5/GROUP E |
Flash Graze/ No Supplementation |
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PLOT 6/GROUP F |
Flash Graze W/ Supplementation |
Data will be analyzed to determine whether a lower level of impact is sufficient to reduce fuel load and provide the community protection in the wildland urban interface, while also maintaining the condition and health of the livestock performing the work, and maintaining the health of the landscape.
The results of this study are in general assumptions and based on nearly 7 years of cooperation of prescribed grazing activities between the Bureau of Land Management Ukiah Field Office and Kaos Sheep Outfit. There is not currently science to reference or back much of these assumptions and this presents challenges to landowners, land managers, and grazing operators when planning prescribed grazing projects. The more formalized plot data collection is an attempt to quantify the qualitative data collected throughout the last 7 years and to provide some information to these stakeholders on the appropriate level of grazing impact needed to achieve community protection while maintaining animal welfare.
Preliminary results reveal that there is obvious elimination of fire to carry in plots grazed the heaviest and taken to near bare ground conditions. However, there are fuels control benefits in plots grazed to maintain a level of residual dry matter and these plots provide safety zones for wildland firefighters and provide management control of fire even with more material present. In the lighter grazed plots, the fire manager stated that even with more material fire would have difficulty moving through unless driven by strong wind. The lighter grazed plots also maintained more soil moisture and when visited the following growing season a greater native species composition than those grazed to near bare ground. In lighter grazed plots uniformity of grazing was lacking, this heterogeneity provides ground cover but also breaks up the thatch which prevents the spread of fire and allows competitive release for native plants. Post vegetation composition data revealed that any level of grazing promotes native species composition. However, the greatest native species composition was shown in Plot 3 where medium level of grazing impact and no supplementation was applied. All plots showed a reduction in yellow starthistle composition and where the species was observed the small, localized patches are manageable. This provides more feasible treatment post grazing and achievable localized control. In the following growing season Plot 3 showed the lowest annual production, this is particularly interesting because in the previous growing season, plot 3 had one of the highest annual production weights. This preliminary shows that vegetation can be controlled even in the next growing season with a moderate level of grazing. Plot 3 showed the greatest overall reduction in fire fuels as well as the highest native species composition in the following growing season. There was no yellow starthistle in Plot 3 and almost exclusively hayfield tarweed, a native forb that is green at the peak of fire season dominated. For all plots, there is effective fire fuels reduction and localized control of invasive species.
The disturbance provided by prescribed grazing allows competitive release for natives and the ability to establish and outcompete nonnatives. There was minimal or no thatch present in all plots which is the greatest fire carrying fuels component and the greatest limiting factor to native species composition based on previous grazing experience and practice. Nonnative species present were mostly palatable and forageable annual grasses like soft chess and wild oats. An interesting thing noted was pollinators in high abundance in the following growing season. Most all plots were dominated by hayfield tarweed and common madia. These species are late flowering, native annual forbs. In much of the oak woodland throughout the region the niche these two species fill has been overtaken by yellow starthistle which is favored by nonnative honey bees. However the two native species provide foraging resources for native pollinators and these species were observed in high densities in August of 2025. Interesting future studies could include pollinator diversity studies pre and post prescribed grazing activities.
Weights of sheep were recorded before, during and after implementation of the prescribed grazing project but the condition of sheep can only be judged by an experienced grazing operator. Viability of the herd is generally determined over the course of the grazing season. The feast, famine cycle of the prescriptive grazing season is stressful on the herd. This can lead to mortality, abortion, and overall loss of vitality. Weights of sheep were hard to correlate with level of impact for each plot. Further study and capacity is needed to define exactly how each prescriptive treatment affects the overall vitality of the animals performing the service.
Pre-Grazing Green weights
Elevation: 2122 ft Air Temp: 77°F Humidity:56%
Field Notes:
Green vegetation weights were captured by clipping a 10 cmx 10 cm square in two locations within each plot. Total 12 vegetation weights were captured. For each sampling location the dominant vegetation (dominant -> least dominant) was recorded along with the soil surface temperature. Vegetation weights differed throughout plots as soil conditions and soil moisture are variable throughout. The average of each plot was calculated to better understand the total reduction in biomass because of prescribed grazing. Average pounds per acre were calculated utilizing methods listed in California Guidelines for Residual Dry Matter Management on Coastal and Foothill Annual Rangelands (Bartolome et.al. 2020).
Plot 1:
- Sample 1
- Dominant Species: Field bindweed (Convolvulus arvensis)*, wild oats (Avena fatua)*, medusahead rye (Taeniatherum caput-medusae)*
- Soil surface temperature: 83°F
- Veg weight: 51 grams
- Sample 2
- Dominant Species: Soft chess (Bromus hordeaceus)*, miniature lupine (Lupinus bicolor), California poppy (Eschscholzia californica), medusahead rye (Taeniatherum caput-medusae)*
- Veg weight: 52 grams
- 4,944 lbs production per acre
Plot 2:
- Sample 1
- Dominant Species: Lemmon’s needlegrass (Eriocoma lemmonii), silver lupine (Lupinus albifrons), soft chess (Bromus hordeaceus)*, bur clover (Medicago polymorhpa)*, field bindweed (Convolvus arvensis)*, subterraneum clover (Trifolium subterraneum)*, miniature lupine (Lupinus bicolor), nit grass (Gastridium phleoides)*
- Soil surface temperature: 82°F
- Veg weight 51 grams
- Sample 2
- Dominant Species: Medusahead rye (Taeniatherum caput-medusae)*, miniature lupine (Lupinus bicolor), field bindweed (Convolvus arvensis)*, nit grass (Gastridium phleoides)*, meadow barley (Hordeum brachyantherum)
- Veg weight: 51 grams
- 4,896 lbs production per acre
Plot 3
- Sample 1
- Dominant species: mugwort (Artemisia douglasiana), California poppy (Eschscholzia californica), soft chess (Bromus hordeaceus)*, vetch ssp (Vicia ssp.)*, yarrow (Achillea millefolium), field bindweed (Convolvus arvensis)*
- Soil surface temperature: 86°F
- Veg weight: 125 grams
- Sample 2
- Dominant species: California brome (Bromus carinatus), California poppy (Eschscholzia californica), soft chess (Bromus hordeaceus)*, nit grass (Gastridium phleoides)*, meadow barley (Hordeum brachyantherum)
- Veg weight: 105 grams
- 11,040 lbs production per acre
Plot 4
- Sample 1
- Dominant species: Soft chess (Bromus hordeaceus)*, California poppy (Eschscholzia californica), miniature lupine (Lupinus bicolor), subterraneum clover (Trifolium subterraneum)*, field bindweed (Convolvus arvensis)*
- Veg weight: 90 grams
- Soil surface temperature: 95°F
- Sample 2
- Dominant species: Medusahead rye (Taeniatherum caput-medusae)*, soft chess (Bromus hordeaceus)*
- Veg weight: 43 grams
- 6,384 lbs production per acre
Plot 5
- Sample 1
- Dominant species: Lemmon’s needlegrass (Achnatherum lemmonii), Soft chess (Bromus hordeaceus)*, medusahead rye (Taeniatherum caput-medusae)*, Cirsium ssp. (native)
- SST: 88° F
- Veg weight: 58 grams
- Sample 2
- Dominant species: Lemmon’s needlegrass (Achnatherum lemmonii), soft chess (Bromus hordeaceus)*, California poppy (Eschscholzia californica), meadow barley (Hordeum brachyantherum), medusahead rye (Taeniatherum caput-medusae)
- Veg weight: 60 grams
- 5,664 lbs production per acre
Plot 6
- Sample 1
- Dominant species: Silver bush lupine (Lupinus albifrons), wild oats (Avena fatua)*, yarrow (Achillea millefolium), California poppy (Eschscholzia californica), Lemmon’s needlegrass (Achnatherum lemmonii)
- Veg weight: 107 grams
- SST: 90°F
- Sample 2
- Dominant species: Harding grass (Phalaris aquatica)*, yellow starthistle (Centaurea solstitialis)*, medusahead rye (Taeniatherum caput-medusae)*, soft chess (Bromus hordeaceus)*, Lemmon’s needlegrass (Achnatherum lemmonii)
- Veg weight: 110 grams
- 10,416 lbs production per acre
*: denotes nonnative species
Preliminary Results 05/17/2024:
Average annual production = 7,224 lbs per acre
Plot vegetation weights were highly variable across the site. In this dynamic landscape this is expected. To account for this variability the average annual production was calculated to help understand the fuel loading reductions post prescribed grazing. It was noted that in plots with higher native species abundance that annual production was generally higher, suggesting that managing for greater abundance of native species could provide greater annual forage for livestock or wildlife. Of the 19 species identified 8 were nonnative accounting for almost 50% of species identified.
Utilizing the US Geological Survey Land Treatment Exploration Tool the “heatload” of the project was determined. This tool utilizes the incident radiation, and accounts for aspect, slope and latitude. Within the project area 47% was within the Moderate High Heat Load and 53% was within the Moderate Low Heat Load.
08/08/2024
Pre-Grazing Dry weights
The same plots were sampled prior to grazing to determine the pre-grazing fuel loads/ vegetation production.
Plot 1
- Sample 1
- Dominant Species: Wild oats (Avena fatua)*, medusahead rye (Taeniatherum caput-medusae)*, Subterraneum clover (Trifolium subterraneum)*, soft chess (Bromus hordeaceus)*
- Veg weight: 11 grams
- Sample 2
- Dominant species: Soft chess (Bromus hordeaceus)*, common madia, (Madia elegans), medusahead rye (Taeniatherum caput-medusae)*, miniature lupine
- Veg weight: 5 grams
- RDM: 769 lbs per acre
Plot 2
- Sample 1
- Dominant species: Soft chess (Bromus hordeaceus)*, hayfield tarweed (Hemizonia congesta ssp. lutescens), medusahead rye (Taeniatherum caput-medusae)*
- Veg weight: 31 grams
- Sample 2
- Dominant species: Plantago ssp. (Plantago ssp), soft chess (Bromus hordeaceus)*, wild oats (Avena fatua)*, silver bush lupine (Lupinus albifrons)
- Veg weight: 32 grams
- RDM: 3,024 lbs per acre
Plot 3
- Sample 1
- Dominant species: Medusahead rye (Taeniatherum caput-medusae)*, soft chess (Bromus hordeaceus)*, California oat grass (Danthonia californica)
- Veg weight: 83 grams
- Sample 2
- Dominant species: Silver bush lupine (Lupinus albifrons), wild oats (Avena fatua)*, soft chess (Bromus hordeaceus)*, Lemmon’s needlegrass (Achnatherum lemmonii), field bindweed (Convolvus arvensis)*
- Veg weight: 103 grams
- RDM: 8,928 lbs per acre
Plot 4
- Sample 1
- Dominant species: mugwort (Artemisia douglasiana), soft chess (Bromus hordeaceus)*, medusahead rye (Taeniatherum caput-medusae)*, Subterraneum clover (Trifolium subterraneum)*
- Veg weight: 67 grams
- Sample 2
- Dominant species: silver bush lupine (Lupinus albifrons), medusahead rye (Taeniatherum caput-medusae)*, plantago ssp.
- Veg weight: 43 grams
- RDM: 5,280 lbs per acre
Plot 5
- Sample 1
- Dominant species: Harding grass (Phalaris aquatica)*, silver bush lupine (Lupinus albifrons), medusahead rye (Taeniatherum caput-medusae)*
- Veg weight: 151 grams
- Sample 2
- Dominant species: Soft chess (Bromus hordeaceus)*, yellow starthistle (Centaurea solstitialis)*, medusahead rye (Taeniatherum caput-medusae)*, plantago ssp.
- Veg weight: 30 grams
- RDM: 8,688 lbs per acre
Plot 6
- Sample 1
- Dominant species: Soft chess (Bromus hordeaceus)*, yellow starthistle (Centaurea solstitialis)*, hayfield tarweed (Hemizonia congesta ssp. lutescens), medusahead rye (Taeniatherum caput-medusae)*
- Veg weight: 25 grams
- Sample 2
- Dominant species: Medusahead rye (Taeniatherum caput-medusae)*, soft chess (Bromus hordeaceus)*, California poppy (Eschscholzia californica), hayfield tarweed (Hemizonia congesta ssp. lutescens), field bindweed (Convolvus arvensis)*
- Veg weight: 47 grams
- RDM: 3,456 lbs per acre
Average RDM pre-prescriptive grazing: 4,448 lbs per acre
*: denotes nonnative species
Post Grazing Residual Dry Matter Measurements
BLM Utilized the California Guidelines for Residual Dry Matter Management on Coastal and Foothill Annual Rangelands (Bartolome et.al. 2020). This area is characterized as a “Annual grassland/hardwood range– annual understory with variable oak or shrub canopy with average annual rainfall between 12 and 40 inches. Woody cover was 0-25% and slope was 0-10%. RDM measurements for this site type are to be no lower than 500 lbs per acre in order to maintain rangeland health.
Plot 1 RDM: 1 gram
RDM per acre: 96 lbs
Plot 2 RDM: 1.56 grams
149 lbs per acre
Plot 3 RDM: 5 grams
480 lbs per acre
Plot 4 RDM: 6 grams
576 lbs per acre
Plot 5 RDM: 10 grams
960 lbs per acre
Plot 6 RDM: 26 grams
2,496 lbs per acre
Results of any level of grazing show there is significant reduction of fine fire fuels no matter the intensity of grazing. Only plots 3,4,5,6 achieved RDM levels which Bartolome et. al. suggest are necessary to maintain rangeland health. While land managers are generally not considering rangeland health an overall goal of fire fuels reduction the numbers in plots 1 and 2 suggest it should be taken into further consideration given the extremely low levels of RDM and the ability of the landscape to withstand this sustained intensity of grazing over many growing seasons.
Research outcomes
This was a pilot study to better understand where compromises need to be made between land managers and livestock operators to achieve fuels reduction that diminishes impacts to the environment and minimizes the impact on livestock condition. With further study and development these preliminary results can help guide future research to definitively conclude that you can effectively protect communities by reducing fine fire fuels, while maintaining livestock condition, and fostering a more fire resistant and resilient landscape without taking treatment areas to bare ground while promoting native species composition long-term and maintaining livestock health.
Education and Outreach
Participation summary:
We realized hiring a videographer and coordinating with one would not be possible for the project as the main two weeks of grazing was intense. This required coordination with herder on site in order to effectively move sheep between plots. The team purchased a drone and videoed the progress. In the outreach video the range and sheep condition is documented.
We will still hire a video editor to create an educational video that 1) shares about the difficulty grazers face in balancing livestock needs with hiring company goals 2) provides footage of varying levels of impact achieved in test plots 3) offers insights provided by collected data 4) captures fire professionals assessments of risk in varying levels of RDM.
This video will be posted to Youtube, with comments enabled. It will be made available to producers by networking with CA wool growers, our local RCD and UC ext offices. We also intend to provide this video to a new website called Match.graze in hopes it can be offered as a resource to landowners interested in grazing. We intend to send our findings and final video out to contract grazers all over the west coast using our own broad network and contract grazing contact lists made available through UC ANR.
The video produced from this work will be posted to YouTube in advance of the 2026 Society For Range Management Meeting. In addition an abstract was submitted to SRM for inclusion in the 2026 meeting. A poster will be presented at the event if the abstract is approved. This will help spread the message intended from this project and hopes to further the collaboration between land managers and livestock producers.
Education and Outreach Outcomes
An educational video will be posted to YouTube and a poster will be presented at the 2026 Society For Range Management meeting.