Annual grasses
Low
Variable
Low–moderate risk
High risk
Moderate–high risk
Moderate–high (erosion, wildlife, habitat)
Overview
Fire has been used by many cultures over millennia to clear land of woody vegetation or to stimulate growth of preferred plant species. Today, prescribed fire is one tool used for treating invasive plants, reducing fuel load, and maintaining habitats in fire adapted landscapes. In California, it has been used most successfully as a tool to control non-native annual grasses in grassland habitat. Eradication of any weed population is unlikely using this technique alone, but it can be a valuable part of an integrated approach when used properly.
Fire removes thatch and aboveground vegetation. Depending on timing and intensity, it also kills grass seeds and exposes bare soil. Its effect on habitat is dependent on plant community, timing, intensity, and burn frequency. In general, prescribed fire works best on annual grass species with fire-sensitive seeds that are short-lived and held on the plant until at least late spring. In California, prescribed fire has been used most effectively on barbed goatgrass (Aegilops triuncialis). Under optimal conditions, it has also proven to be moderately effective on medusahead (Elymus caput-medusae), ripgut brome (Bromus diandrus) and yellow starthistle (Centaurea solstitialis).
Along with reducing target plants, using fire in grasslands can lead to an increase in non-native broadleaf forbs. When used in shrubland or riparian habitat, fire can lead to a loss of beneficial perennials and an increase in problematic fire-tolerant weeds, especially where they are already established at low densities. Though fire is not very selective, land managers can often avoid damage to desirable trees, shrubs and other perennials with a well-managed, lower intensity burn. Fire should not be used in habitats that are not adapted to fire, such as desert scrub or many riparian systems. The success of a prescribed fire at controlling a target weed will depend on timing, fuel load and fire intensity. Whereas high fire intensity may be most effective at killing seeds, it also increases the potential to kill desirable perennial plants and will be more likely to become uncontrolled.
Fire is less popular as a management tool than it once was in California, due to air quality concerns and the recent increase of large, destructive wildfires throughout the state. Public safety is the most important factor in determining if a prescribed fire can be conducted. Native habitat, sensitive species, and cultural resource impacts must also be evaluated.
How to Use
Burning requires substantial planning and coordination. Burn plans, permits and protocols specific to the local area, local fire department approval and air quality permissions ae all required; a plan typically takes from one to four years to complete. The plan outlines implementation protocols and assesses risks, and is typically valid for up to three years before a new one is needed. Actual timing of the burns is then determined several months ahead of time. Local fire departments can provide information about local ordinances and regulations that may affect timing or feasibility.
The California Department of Forestry and Fire Protection (Cal Fire) is a key partner in most burns. Through their Vegetation Management Program, or VMP https://www.fire.ca.gov/programs/resource-management/resource-protection-improvement/vegetation-management-program/ they generally take on a significant portion of the costs associated with implementing a burn and assume the liability if a fires escapes containment. Associated costs to the landowner and/or land manager generally include staff time for preparing a VMP plan, coordination with Cal Fire and other partners, and smoke fees.
Often when there is a controlled burn, local and state firefighting authorities use it as an opportunity to train their staff. If your site is part of a training, the fire department usually takes care of all necessary permitting.
Burns on public lands can only be conducted by trained, Red Card or similarly certified individuals. The Red Card (also known as Incident Qualification Card) is an interagency certification that a person is qualified to work on an active burn. Significant site preparation is required to limit the fire to the target area. (If sites are remote, off-road vehicle access needs to be permitted.) Burn perimeters get marked and assessed, minimum width of perimeter lines is determined, and final line locations are decided. Then the lines are cut, typically by crews using hand tools to obtain the minimum widths of mineral soil and adjacent fuel reduction zones. On the day of the prescribed burn, hose lays can act to enhance secure perimeters.
The success of a burn is dictated by timing and burn intensity. In order to be most effective, burns should be conducted before seed set or seed release and after fuels have dried sufficiently to carry a fire hot enough to kill seeds. Successive burns that occur 2-3 years in a row at the optimal time to kill seeds are the most effective but are difficult to achieve due to reduced fuel loads in years 2 and 3. In dry environments, burns are most effective and least harmful when conducted in a wet year because desirable perennials plants and trees can more easily recover from fire damage, and the fire will have sufficient fuels to travel across a landscape.
Barbed goatgrass, medushead, and ripgut brome can be successfully controlled with fire (assuming burns occur in optimal conditions and are repeated) because their seeds remain on the plant later than most species and because they may have seeds that are more susceptible to heat. By remaining in the grass canopy, their seeds are exposed to higher heat from fire than are the seeds of other species that have dropped to the ground. Plant phenology must be monitored to ensure burns are conducted no earlier than the “boot” stage for grasses (when flower heads have formed and are just about the emerge) and prior to seed drop. In most years there will be a relatively short window when fuels have dried sufficiently to burn well and when seeds of target species have not yet dropped.
Yellow starthistle can also be controlled by burning in early summer before viable seeds are produced but after fuels have cured. In the field, this translates to the early flowering stage (2-5%). As with the grasses, burns must be under optimal conditions for at least two consecutive years and effective second year control is often difficult because of lack of fuels.
Without additional follow-up, non-native annual grasses will recover once treatments are stopped, generally returning to pre-treatment levels in 2-4 years. Complete burns are more effective than burns where some patches are unburned or lightly burned. Achieving complete burns multiple years in a row can be difficult because new fuels may not accumulate quickly enough. Treatment effects may be maintained for up to three years and longer for barbed goatgrass.
Special Tips
Temperature, fuel load and intensity of a burn can be modified by the following techniques:
- Burn when vegetation moisture content is higher in order to reduce risk of fire escape and damage to desirable perennial vegetation.
- Use back burns that are started ahead of a main fire along a fire break to reduce fuel available for a head fire. They are cooler and will leave more standing biomass.
- Head fires, the leading fronts of fires, are hotter and burn more material.
- Cut non-native grasses, forbs or woody species and allow them to cure on site before burning to increase fire intensity.
- Seed non-invasive annual grasses prior to second and third year burns to increase fuel loads for successive burns.
Optimal Conditions for Use
This technique works best when implemented just before flowering stage or at early seed set of the target plant and when a site has sufficient dry fuel to carry a burn.
Caveats
Burning may facilitate the spread of other weeds that were not specifically targeted. These include many species of broadleaf forbs and perennial invasive grasses such as Harding grass (Phalaris aquaticus), fountain grass (Pennisetum setaceum), and velvet grass (Holcus lanatus).
Several conditions may prohibit the use of burning as a management tool:
- Air quality conditions and regulations
- Regional fire danger (influenced by wind conditions, temperature, and vegetation moisture content)
- Presence of surrounding development or highly sensitive resources
- Presence of sensitive biological or cultural resources in the area to be treated
- Lack of skilled/trained personnel
- Logistical or other constraints on optimal timing
Potential Hazards to Humans, Environment, and Cultural Resources
Human hazards. Fires can kill, and smoke impacts air quality and can cause respiratory issues. Planning and permits are designed to minimize these hazards. Prescribed fires should only be conducted by qualified and trained professionals. Depending on land ownership and local jurisdictions, federal fire agencies, Cal Fire and local fire agencies must be consulted and under most situations will take the lead in conducting the burns for the land management organization.
Sensitive species. Risks to sensitive species (e.g., birds, rodents, reptiles, arthropods, desirable plants) should be considered prior to burning. The ideal timing for a burn, based on the effectiveness in controlling the target weed species, may overlap with timing that results in more impacts to sensitive species, for instance nesting bird species. Ground nesting bird surveys must be conducted prior to prescribed burns being conducted during the nesting season. Nests with a buffer determined by a qualified biologist should be protected from fire. In grasslands, mortality of snakes and lizards is common in a burn. Most grassland small mammals are protected from the heat of fire in their underground burrows. Small mammals that build above-ground nests (e.g., woodrats) will likely be killed. Surveys can be conducted for rare plants and other organisms (e.g., listed butterflies) and they can be protected if they are at a stage that makes them vulnerable to mortality or prevents seed set, if that is a goal. If it is necessary to leave unburned areas within the prescribed fire footprint, it will decrease the treatment effectiveness. These areas should be treated once it is appropriate or they will act as sources of recolonization.
Cultural resources. Known cultural resources should be protected during controlled burns. Discuss protection measures with fire crew leads. Unit boundaries can be modified to avoid sites or protected as "stay-out zones" within larger units.
Erosion risk. Fire has the potential to remove all aboveground biomass protecting the soil from erosion. Significant soil movement including mudslides can occur following fires on steep slopes. Therefore, controlled burns should not be conducted on steep slopes above areas with human infrastructure or sensitive aquatic habitat that may be impacted by sediment deposition.
Consider Combining with the Following Non-Chemical Methods
Fire is best used in combination with other techniques to improve its effectiveness and reduce the risk of unintended impacts. Mowing non-target species and allowing cut material to cure prior to a burn will result in hotter fires that may kill more seeds or perennial species. Mowing can be effective as a follow-up after target species have re-sprouted or germinated the following year. Solarization of problem areas, manual removal, and spot treatment with herbicide are all commonly used techniques employed to improve control following a prescribed fire.
Don’t Use This Technique When/For
Do not use fire as a management tool to treat weeds in shrublands. Repeated burning will kill shrubs and lead to type conversion to non-native annual grassland. Burning appears ineffective for rattail fescue and for many annual forbs and most biennials and perennials with underground storage structures.
Supplementary Information
In California, only six species were reported to be targeted for control using fire by more than one source. The six are barbed goatgrass, ripgut brome, medusahead, yellow starthistle, French broom and Scotch broom. Goatgrass seems to be the species that is controlled best by burning. There were often more reports of unsuccessful control efforts using fire for each species than successes. Successful control of a target species often resulted in a shift to communities dominated by non-native annual forbs. Despite the lack of success of fire to control individual species, there was more or less consensus that fire is a valuable grassland management tool in California. Removal of non-native annual grass thatch, returning a natural process to the land, and maximizing native species diversity with an intermediate disturbance regime were the primary reasons stated for justifying the use of fire in grasslands.
Other than the three annual grass species, ripgut brome (Bromus diandrus) appears to be the only species regularly targeted for control (DiTomaso et al. 2006, Moyes et al 2005, Principe personal experience). There is, however, extensive use of fire reported to manage grassland dominated by non-native annual grasses. Non-native annual grasses species respond differently to fire. Amatangelo et al. (2008) found that large-seeded species and small-seeded species responded differently to various levels of shade and litter and were affected by fire. DiTomaso et al. (2006) and unpublished data from Santa Rosa Plateau Ecological Reserve (SRPER) indicate fire effects on annual grasses are more strongly tied to how long seeds are retained on the plant and the susceptibility of seeds to heat than to seed size. In general at SRPER, effectiveness one year following a single fire was Fair to Excellent for brome grasses (Bromus diandrus, B. madritensis and B. hordeaceus), Fair for wild oats (Avena sp.), and Ineffective for rattail fescue (Festuca myuros), which was found to increase following some burns (Principe unpublished data). DiTomaso et al. (2006) report the seeds of Bromus diandrus and B. madritensis, along with medusahead and barbed goatgrass, remain in the inflorescence longer than most grasses, where they are susceptible to being killed heat. Marty (2015) found non-native annual grasses as a functional group were reduced by 35% for one year following a single burn. Marty (2015) and data from SRPER (Principe unpublished data) indicate non-native annual grass cover quickly returned to pretreatment levels without treatment, often within only one year, but almost always within four years.
The general consensus appears to be there are many non-native annual forbs that respond positively to fire. Marty (2015) found results similar to those at SRPER that non-native annual forb cover was enhanced by burning. Marty (2015) found non-native annual forb cover was nearly 100% greater in burned plots than unburned plots, but only for a single year. Following fires at SRPER, Erodium increase by two to ten times in the first year after fire. Moyas et al. (2005) found black mustard (Brassica nigra) more or less replaced ripgut brome (Bromus diandrus) in the first year after a fire as the dominate species. Interestingly, if non-native annual grasses are replaced by late-season non-native annual forbs like yellow starthistle or summer mustard (Hirschfeldia incana), despite these species dominating end of the season cover estimates, there are early season annual native forbs that can reach extremely high cover and set seed before the non-natives greatly increase in size. Owl’s clover has been observed to do this in both northern California at sites with yellow starthistle and southern California at sites with summer mustard. Yellow starthistle was the only non-native annual forb reported to be targeted using fire in California by experts and the literature indicating the widespread recognition that fire is generally not effective against this functional group and often benefits it.
DiTomaso et al. (1999) report it took three consecutive years of burning to reduce the yellow starthistle seedbank by 99%. DiTomaso et al. (2006) and all experts reported using fire combined with herbicide greatly increases effectiveness of control. Based on these recommendations, plant phenology must be monitored to ensure burns are conducted when the first flowers are being produced.
Marty 2015 cites the results of the D’Antonio et al. 2006’s meta-analysis assessing fire effects in California grasslands which analyzed the results of 28 studies and could not find a consistent effect of fire on native or exotic species. This is generally because one non-native species or functional group is generally replaced by another in the presence of fire.
DiTomaso and Johnson (2006) report that it is difficult to control biennial and perennial herbaceous species with fire. DiTomaso and Johnson (2006) report that there have been several reports from eastern states of fire successfully controlling perennial grasses, but they do not report success in California. DiTomaso and Johnson (2006) report most of the problematic invasive woody species resprout from the base and are thus difficult to control with fire. For brooms (e.g. French [Genista monspessulana] and Scotch [Cytisus scoparius]), it is reported that fire effectively kills mature plants but flushes the seedbank. Multiple fires reduce cover, but broom recovery is relatively fast once treatment is stopped due to the long-lived seed bank (DiTomaso and Johnson 2006, NPS staff personal communication). Broom control requires a long-term commitment using multiple strategies including cutting, herbicide and/or seeding with grasses (non-native annual) to increase fuel loads after the first burn treatment (DiTomaso and Johnson 2006, NPS staff personal communication).
In working with partners to burn, it can be very difficult to achieve optimal timing. As a result of non-optimal timing of burns, a long-term prescribed fire program in southern California grasslands found widely variable responses of a suite of annual grasses to burning. Even the primary target species ripgut brome which was generally reduced by over 90% occasionally was not effectively controlled by fire due to fires being conducted too late (Principe unpublished data).
As a functional group, non-native annual forbs generally increase after fire, especially Erodium species. Marty (2015) and data from SRPER found significant short-term increases in non-native annual forbs, primarily because of Erodium increases. Fire and other disturbances are often used to stimulate germination of the non-native forb seed bank to allow follow up treatments to be more effective. As a result, a single fire with no follow-up treatment may result in greater non-native forb cover (see discussion above). The only forb reported in the literature or experts to be targeted solely with fire was yellow star thistle. Multiple well-timed complete burns can significantly reduce the cover and seed bank of yellow starthistle under optimal conditions (DiTomaso et al 1999; Kyser and DiTomaso 2002). Despite this one example of yellow starthistle being controlled with fire, all experts reported using other techniques combined with fire to try to control this species as fire alone was not effective.
DiTomaso and Johnson (2006) report most highly invasive woody species are difficult to control with fire. Part of the reason is that some of the most problematic species are favored by fire while others tend to increase following fire (DiTomaso and Johnson 2006). There are multiple “desirable” native trees and shrubs that are more susceptible to fire than invasive woody species.
Rate of plant spread and seed production of target weeds does not seem to affect efficacy of burning for their control, since three species with high rates of spread (barbed goatgrass, yellow starthistle, and meadusahead) can be controlled with burning. Seed life has more of an impact, with species with longer-lived seeds being more difficult to control in successive years with fire. Winter annuals are controlled more easily than plants that germinate in other seasons or opportunistically.
In oak woodlands in southern California, fire does not appear to be an effective control tool, at least directly under trees due to much greater non-native annual grass cover under trees and poor fuel consumption leading to little impacts to seed production and accumulated thatch/litter (Principe unpublished data).
If fire is the only tool employed, then there are non-native species from all functional groups that could proliferate with its use. Perennial grasses such as Harding grass, velvet grass, and fountain grass (Pennisetum setaceum) can benefit. DiTomaso and Johnson (2006) state, “Typically, controlled fires or wildfires promote invasive perennial forbs.” This would include onionweed, knapweeds, fennel, artichoke thistle and poison hemlock (biennial). Many highly invasive annual forbs (thistles, tocalote, yellow starthistle, mustards, Erodium) increase after fire and some proliferate. Moyes et al. (2005) reported that black mustard (Brassica nigra) became a near monoculture after a single burn. Arundo (Arundo donax), brooms, tree tobacco (Nicotiana glauca) respond vigorously to fire. Japanese honeysuckle (Lonicera japonica), tree-of-heaven (Ailanthus altissima), Russian-olive (Elaeagnus angustifolia), and saltcedar (Tamarix ramosissima) are favored by fire (DiTomaso and Johnson 2006). Other invasive woody species have a tendency to increase following fire, including sweetbriar rose (Rosa eglanteria), Himalaya blackberry (Rubus armeniacus [=R. discolor]), cutleaf blackberry (Rubus laciniata), English hawthorn (Crataegus monogyna), and common pear (Pyrus communis) (DiTomaso and Johnson 2006 citing Pendergrass et al. 1988).
References
Amatangelo, Kathryn L., Dukes, Jeffrey S. and Field, Christopher B. 2008. Responses of a California annual grassland to litter manipulation. Journal of Vegetation Science. https://doi.org/10.3170/2008-8-18415
D’Antonio, C., S. Bainbridge, C. Kennedy, J.W. Bartolome and S. Reynolds. 2006. Ecology and restoration of California grasslands with special emphasis on the influence of fire and grazing on native grassland species. A Report to the David and Lucille Packard Foundation, University of California, Santa Barbara, CA, USA.
Davy, J. S., J. M. DiTomaso and E. A. Laca. 2008. Barb goatgrass. University of California Division of Agriculture and Natural Resources Publication 8315. Davis, California. anrcatalog. ucdavis.edu/pdf/8315.pdf
DiTomaso, J.M., M.L. Brooks, E.B. Allen, R. Minnich, P.M. Rice and G.B. Kyser. 2006. Control of invasive weeds with prescribed burning. Weed Technology 20:535–548.
DiTomaso, J.M., S.F. Enloe and M.J. Pitcairn. 2007. Exotic Plant Management in California Annual Grasslands. Pages 281–296 in M.R. Stromberg, J.C. Corbin and C.D’Antonio (eds). Ecology and management of California grasslands. Berkeley, CA: University of California Press. sfc.smallfarmcentral.com/ dynamic_content/uploadfiles/152/DiTomaso%20Ch22%20Stromberg.pdf
DiTomaso, J.M., K.L. Heise, G.B. Kyser, A.M. Merenlender and R.J. Keiffer. 2001. Carefully timed burning can control barbed goatgrass. California Agriculture 55:47–53.
DiTomaso, J.M., G.B. Kyser and M.S. Hastings. 1999. Prescribed burning for control of yellow starthistle (Centaurea solstitialis) and enhanced native plant diversity. Weed Science 47:233–242.
DiTomaso, J.M. and D.W. Johnson (eds.). 2006. The Use of Fire as a Tool for Controlling Invasive Plants. Cal-IPC Publication 2006-01. California Invasive Plant Council: Berkeley, CA. 56 pp.
Kyser, Guy B. and Joseph M. DiTomaso. 2002. Instability in a grassland community after the control of yellow starthistle (Centaurea solstitialis) with prescribed burning. Weed Science 50(5), 648-657, (1 September 2002). https://doi.org/10.1614/0043-1745(2002)050[0648:IIAGCA]2.0.CO;2
Marty, Jaymee T. 2015. Fire effects of plant biodiversity across multiple sites in California vernal pool grasslands. Ecological Restoration Vol. 33, No. 3, 266-273.
Marty, Jaymee T., Sara B. Sweet, and Jennifer J. Buck-Diaz. 2015. Burning Controls Barb Goatgrass (Aegilops triuncialis) in California Grasslands for at Least 7 Years. Invasive Plant Science and Management, 8(3):317-322.
Moyes, Andrew B., Martha S. Witter, and John A. Gamon. 2005. Restoration of Native Perennials in a California Annual Grassland after Prescribed Spring Burning and Solarization. Restoration Ecology Vol. 13, No. 4, pp. 659–666.
Authors and Credit
Lead Author: Zachary Principe, Stewardship Ecologist, The Nature Conservancy (TNC)
Co-authors:
Pamela Beitz, Integrated Pest Management Specialist, East Bay Regional Parks District
JP Marie, Putah Creek Reserve Manager, University of California
Additional Contributors:
Mitchell Joseph
Bamford, Field
Coordinator I, Big Chico Creek Ecological Reserve
Andrea Craig, Project
Coordinator, The Nature Conservancy
Alison
Forrestel, Chief
of Natural Resource Management and Science, National Park Service
Eli Goodsell, Ecological
Reserves Director, Chico State Enterprises
Brent Johnson, IPM Program
Manager, National Park Service
Jaymee Marty, Ecologist, Marty
Ecological Consulting, Inc
Trish Smith, Regional
Ecologist, The Nature Conservancy
Robin Wills, Region Fire
Management Officer, National Park Service
Marti Witter, Fire Ecologist, National
Park Service
Roger Wong, Fire
Management Officer, National Park Service
Efficacies
| Rating | |||
|---|---|---|---|
| Plant | Flowering Period | ||
| Winter | Ineffective | ||
| Spring | Fair | ||
| Summer | Good | ||
| Fall | Fair | ||
| Multiple Seasons | Ineffective | ||
| None | Ineffective | ||
| Plant | Germination | ||
| Winter | Fair | ||
| Winter / Spring | Fair | ||
| Spring / Summer | Fair | ||
| Opportunistic | Ineffective | ||
| Plant | Palatability | ||
| Yes | No Information | ||
| No | No Information | ||
| Partial | No Information | ||
| Plant | Plant Growth Form | ||
| Grass | Fair | ||
| Forb | Fair | ||
| Shrub | Poor | ||
| Tree | Poor | ||
| Vine | Ineffective | ||
| Plant | Plant Type | ||
| Annual | Fair | ||
| Biennial | Poor | ||
| Perennial | Ineffective | ||
| Plant | Propagule Production | ||
| Low (<1000/square meter) | Fair | ||
| Moderate (1000–10,000/square meter) | Fair | ||
| High (>10,000/square meter) | Fair | ||
| Plant | Rate of Spread | ||
| High (doubling in <10 year) | Poor | ||
| Moderate (50–75% increase in 10 years) | Fair | ||
| Slow Rate (25% increase in 10 years) | Fair | ||
| Plant | Resprouting / Regenerative Capacity | ||
| Low | Poor | ||
| Moderate | Poor | ||
| High | Ineffective | ||
| None | Fair | ||
| Plant | Seed Life | ||
| Short (≤3 years) | Fair | ||
| Moderate (4–10 years) | Fair | ||
| Long (>10 years) | Ineffective | ||
| Plant | Type of Reproduction | ||
| Seed | Fair | ||
| Vegetative | Ineffective | ||
| Seed & Vegetative | Ineffective | ||
| Plant | Type of Vegetative Reproduction | ||
| Rhizome / Stolon / Stem | Ineffective | ||
| Bulb / Corm / Tuber | Ineffective | ||
| Root sprout / Sucker / Crown sprout | Ineffective | ||
| Site | Existing Desirable Plant Cover | ||
| <10% | Fair | ||
| 10–25% | Fair | ||
| 26–50% | Fair | ||
| 51–75% | Fair | ||
| >75% | Fair | ||
| Site | Ground Condition | ||
| Muddy | Ineffective | ||
| Smooth | Fair | ||
| Cobbly | Poor | ||
| Rocky | Ineffective | ||
| Site | Habitat | ||
| Marsh / Wetland | Poor | ||
| Riparian | Ineffective | ||
| Grassland | Fair | ||
| Shrubland | Poor | ||
| Woodland / Forest | Poor | ||
| Site | Level of Tolerable Disturbance | ||
| Low | Fair | ||
| Medium | Good | ||
| High | Good | ||
| Site | Slope | ||
| Flat | Fair | ||
| Moderate (10–40%) | Fair | ||
| Steep (>40%) | Poor | ||
| Site | Target Area | ||
| <40 square feet | Fair | ||
| 0.001–0.01 acre | Fair | ||
| 0.02–0.1 acre | Fair | ||
| 0.2–1 acre | Fair | ||
| 2–10 acres | Fair | ||
| 11–50 acres | Fair | ||
| 51–100 acres | Fair | ||
| >100 acres | Fair | ||
| Site | Targeted Invasive Plant Cover | ||
| <1% | Good | ||
| 1–10% | Good | ||
| 11–25% | Fair | ||
| 26–50% | Fair | ||
| 51–75% | Fair | ||
| >75% | Fair | ||
| Site | Vehicle Accessibility | ||
| Roadside | Fair | ||
| <100 feet from road | Fair | ||
| 100–1000 feet from road | Fair | ||
| >1000 feet from road | Fair | ||
