TOPIC 4 Systems Invaded by Annual Grasses:
Land Management Tools
This section explores the tools available to land managers for combating the invasion of annual grasses. Scroll down the page to read each sub-section, or click the Land Management Tools drop-down navigation to go directly to a sub-section
Fuel Breaks
Begin by watching Lance Okeson describe importance of fuel breaks.
Proactive fuel breaks (the enhancement of existing roads and vegetation manipulation adjacent to these roads) are an example of a pre-suppression activity that can be used to address the severe problem of large, uncontrolled wildfire outlined earlier. Fuel breaks can constrain fire spread and augment suppression efforts by reducing fire size and frequency, constraining fire growth rate, compartmentalizing fires, providing firefighters better access to the fire, minimizing fire response time, and providing safe locations to establish anchor points and engage in suppression. Three key elements of fuel breaks that improve their function are (from Maestas et al. 2016):
- Disrupt fuel continuity
- Reduce fuel accumulations and/or volatility
- Increase proportion of plants with higher moisture content
Established fuel breaks are a useful tool for managing the size and severity of wildfires, but can’t alone be depended on to stop a wind-driven head fire (Great Basin Factsheet Series #5); they must be designed within the bounds of other ecological, social, and economic considerations which influence potential options and effectiveness (Maestas et al. 2016).
It is critical to examine the landscape context and trade-off between reducing wildfire size and severity and the potential environmental and social impacts (e.g., sage-grouse and other wildlife habitat fragmentation, risk of increasing invasive weeds, effects of non-native plant introductions on native plant communities, impacts to wilderness characteristics, challenges with implementation across multiple jurisdictional boundaries):
- In highly modified landscapes previously impacted by large fires, the benefits of fuel breaks can often outweigh potential risks.
- However, fuel break implementation within relatively intact sagebrush-dominated landscapes requires much more careful consideration of trade-offs, but can be done. See Maestas et al. (2016), Box 1 for an example.
Fuel Break Considerations, Types and Costs
Listen to Lance Okeson describe a fuel break.
There are five main considerations for locating fuel breaks:
- Locate breaks in low to mid-elevation, intact ecosystems that have low resistance to invasive annual grasses (systems with the least capacity for natural recovery following disturbance)
- Locate breaks where necessary for firefighter access and safety
- Plan construction so that breaks are there when you need them
- Use breaks as a long-term strategy to reduce the size and severity of wildfires.
- Factor in medium- and long-term maintenance costs (e.g., road maintenance, spraying, re-seeding) when planning, locating, and constructing fuel breaks.
The main types of fuel breaks (photos from Maestas et al. 2016) include:
- Roads: clearing roads and adjacent roadbeds can be very effective for preventing and/or controlling rangeland wildfires; they are the primary features used for fire suppression and access
- Brown strips/disk lines from 10 to 20 feet wide and are taken down to mineral soil. Ideally implemented in late spring / early summer after last precipitation. However, these fuel breaks must be maintained (re-plowed or chemically treated) and can contribute to erosion.
- Mowed fuel breaks immediately adjacent to roads are the preferred treatment to limit wildfire size in/or near intact sagebrush patches. Mow strips down to 6 to 12 inches, at least 100 to 300 feet wide adjacent to roads on both sides, depending on live fuel loading and resource objective. Maintenance is required, perhaps including chemical treatment and seeding.
- Greenstripping is the process of strategically establishing fire-resistant vegetation to reduce the rate of spread and the intensity of wildfires. This is a preferred method in areas that have undergone conversion to invasive annual grassland or areas highly susceptible to annual grass invasion. Strips 100 to 300 feet wide are recommended.
Species selected for greenstripping should be fire and drought tolerant, palatable, and able to compete with annual species. Seeding is generally conducted in fall/winter and may require limited maintenance and can be grazed. However, improperly chosen introduced species may become invasive. Species to consider: forage kochia; crested wheatgrass (and similar grasses), alone or in combination; low-growing native species.
Costs vary between treatments. Review the chart to understand the different costs (from Maestas et al. 2016, appendix A).
| Fuel Break | Typical Settings | Advantages | Disadvantages | Cost |
|---|---|---|---|---|
| Brown Strips/disk lines |
|
Mineral soil with no fuels is the most effective fuel break |
|
$30-50/ac annually; herbicide may be needed to control weeds |
| Mowed Fuel Breaks | Relatively intact sagebrush communities with adequate perennial understory |
|
|
$30-50/ac, recurring 5-10 years; regular herbicide applications may be needed to control weeds |
| Greenstrips | Areas highly susceptible to annual grass invasion (warm/dry sagebrush sites) or impacted by repeated fire |
|
|
$100-500/ac; depends upon plant materials cost at time of establishment and degree of site prep; may require reseeding if failure |
In these two videos, Lance Okeson first shares some of the potential negative effects or conflicts arising from the design of fuel break projects and then some of his thoughts on how to integrate partners into the fuel break planning process to reduce controversy and conflict.
Livestock Grazing
To begin, watch this short video in which Mike Pellant describes livestock grazing as a fuels management tool.
Livestock grazing influences factors related to fuel characteristics, including the proportions of herbaceous and woody fuel, amount of herbaceous biomass, live/dead fuel mix, and continuity of fuel at a patch and landscape scale. Fuels management programs that incorporate grazing treatments must consider the long-term effects of such treatments on both desired and undesired plant species, with desirability defined by site-specific management goals and objectives (Strand et al. 2014).
To reduce cheatgrass fuels on large areas of rangelands you must strategically repeat appropriate grazing practices over a multi-year period over a diverse landscape under widely different climatic conditions (Pellant restoration course). Spring grazing in annual grass dominated areas is the most effective time to reduce cheatgrass fuel loads before the start of the wildfire season. Fall/winter grazing can reduce carryover fuels but not spring production (fuels).
- Targeted grazing is not an excuse for overgrazing at the pasture/allotment level.
- Grazing must be strategic to reduce fuels and wildfires in zones or strips.
- Targeted grazing must meet both fuels and vegetation/soils objectives in a sustainable manner.
Source: Pellant restoration course
- Following fire, grazing should not resume until site objectives have been met; at a minimum, surviving perennial grasses must have regained productivity and be producing viable seed at levels equal to grasses on unburned sites.
- During the first years after grazing resumes, grazing should be deferred until later in the season after seed maturity or shatter to promote bunchgrass recovery.
- Once grazing resumes, a rotation system (rest, deferred, or decisional) is recommended for maintaining plant production, cover, and appropriate species composition.
- Careful monitoring and assessment is required to determine when grazing may be resumed, whether post-fire grazing management has been effective, and if changes in grazing management are needed.
Source: from Great Basin Factsheet Series #7
How does livestock grazing impact sage-grouse habitat? Begin by watching a short video where Chad Boyd describes how grazing can be used as a fuels management technique.
Boyd et al. (2014) provide a very useful overview of grazing and its effects, positive and negative, on sage-grouse habitat:
- Livestock grazing can directly influence the composition and productivity of herbaceous plants in sagebrush communities. The greatest potential for livestock grazing to affect sage-grouse populations is by influencing nesting or early brood-rearing habitat productivity.
- Managed livestock grazing at moderate intensities can be compatible with maintaining sagebrush/bunchgrass plant communities.
- Sustained heavy grazing can reduce abundance of perennial grasses and lower suitability of habitat for most seasonal habitat needs of sage-grouse.
- Efforts to maximize herbaceous cover in areas frequented by nesting and brooding sage-grouse should be encouraged to increase sage-grouse concealment from nest and chick predators. Livestock grazing should be managed in breeding and brood-rearing habitats to maximize herbaceous growth and maintain functional bunchgrass understories where sagebrush cover exceeds 10%.
- Prescribed grazing can be used as a tool to decrease continuity, amount, and potentially composition of fine fuels in areas prone to annual grass invasion.
- Economic impacts of sage-grouse management practices on ranches vary by both location and degree of change required in livestock management. Changes in season of use, stocking levels, or species grazed will cause changes in the yearlong production cycle of a ranch and differentially affect the economic sustainability of said ranch.
- Rangeland altering practices may or may not be economically feasible depending on cost-share arrangements, changes in production practices, or changes in rangeland and animal productivity. Each practice must be analyzed for the specific situation in which it will occur.
Strand et al. (2014) provide a good overview of livestock grazing and its influence on fuel loads in the sagebrush ecosystem:
- Cover and biomass of perennial herbaceous plants in sagebrush communities can be reduced by heavy (or severe) grazing repeatedly in the spring before the perennial grasses initiate bolting.
- High severity grazing (i.e., >50% utilization), especially in the spring during initiation of bolting of perennial grasses, can suppress competition from native herbaceous plants and cause soil disturbance that can favor annual invasive grasses including cheatgrass.
- Livestock grazing at low/moderate severity (i.e., <50% utilization) generally has little influence on the cover of perennial grasses and forbs.
- Areas grazed by livestock can have more, less, or the same density and cover of sagebrush compared to non-grazed areas. Determining factors include the season and intensity of grazing, species of livestock, ecological site, and site conditions at the time of grazing.
- A window of opportunity may exist for targeted grazing to reduce annual grasses before perennial grasses initiate bolting or during dormancy of perennial grasses.
- Targeted grazing with sheep or goats can reduce the fuel load of shrublands in the short term by reducing woody fuels.
- Livestock grazing can reduce the standing crop of perennial and annual grasses to levels that can reduce fuel loads, fire ignition potential, and spread.
- Grazing after perennial grasses produce seed and enter a dormant state can reduce the residual biomass left on the site, thereby decreasing the fire hazard the following spring and summer.
- Grazing can reduce the continuity of fuels, including the amount of herbaceous biomass between shrubs, in sagebrush ecosystems.
- Economic analyses reveal that grazing treatments in sagebrush ecosystems have the highest benefit/cost ratio when the perennial grasses comprise the dominant vegetation, i.e. prior to annual grass invasion and shrub dominance.
- Extreme fire weather conditions, characterized by low fuel moisture and relative humidity, and high temperature and wind speed, affect wildland fires more than do fuel characteristics, and the potential role of grazing to alter fire behavior becomes more limited.
Chemical Treatment of Nonnative Invasive Plant Species and Seeding
Chemical treatments and seedings are used to decrease invasive species composition and increase native species dominance in areas where native perennial grasses and forbs are insufficient for site recovery (Chambers et al. 2017). Chemical and seeding treatments may be selectively applied in conjunction with prescribed burning or mechanical treatments. Typically, these treatments are in response to clear evidence of a nonnative invasive species threat. Areas of higher priority for chemical and seeding treatments:
- Lower resistance and resilience areas (cells 2A, 2B, 3A, 3B of the resistance and resilience matrix) lacking the ability for natural recovery.
- Recently disturbed areas where recovery will not occur without chemical or seeding treatments.
- Areas where investments have been made and objectives cannot be attained without chemical or seeding treatments.
Fire and Invasives Assessment Tool (FIAT)
FIAT is a tool and process to identify priority habitat areas and management strategies to reduce the threats to Greater Sage-Grouse resulting from impacts of invasive annual grasses, wildfires, and conifer expansion in the western (Great Basin) range. Note that another tool (the Sagebrush Management and Resistance Resilience Tool, SMRRT) will provide a tool for the eastern (Rocky Mountains) range. Using the SMRRT tool, managers will assess key landscapes; management strategies to address threats such as invasive annual grasses will be an outcome. SMRRT is discussed in more detail in the Eastern Range Lesson.
FIAT data is available for the assessment areas shown in the map.
FIAT Outcomes:
- Identify important GRSG-occupied habitats and baseline data layers important in defining and prioritizing habitats (as Habitat Assessment Framework [HAF] assessments are completed, these may provide a data source for defining and prioritizing habitats).
- Assess the resistance to invasive annual grasses and resilience after disturbance and prioritizing emphasis areas for conservation and restoration
- Identify geospatially explicit management strategies to conserve GRSG habitats
Specific goals for fuels management as identified during the FIAT process are:
- Spatially delineate priority areas for fuel management treatments:
- Linear fuel breaks along roads.
- Other linear fuel breaks to create anchor points.
- Prescribed burning which would meet objectives identified in the Conservation Objectives Team report (USFWS 2013).
- Mechanical (e.g., treatment of conifer expansion into sagebrush communities).
- Other mechanical, biological, or chemical treatments.
- If they exist, spatially delineated areas where fuel treatments would increase the ability to use fire to improve/enhance habitats.
- Identify coordination needed between renewable resource, fire management, and fuels management staff to facilitate planning and implementation of fuels treatments.
- Quantify a projected level of treatment within or near habitats.
- Identify treatments (projects) to be planned within or near valued habitats.
- Include a priority and proposed work plan for proposed treatments.
Examples of FIAT outputs/data products:
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