Despite a general lack of research on the relationship between roads and fire, available data indicates a strong correlation between the two. This correlation is demonstrated by the relatively high frequency of anthropogenic fire relative to fire caused by lightning, the difficulty in controlling risk factors in roaded areas, and the tendency for fires to start near roads. The perceived need for roads as a tool for fire suppression has significant implications for public lands policy. This review discusses the extent and adequacy of current data and analysis on roads and fire and offers suggestions for much needed additional research.

Natural vs. Human Caused Fires

A primary indicator of a direct relationship between fires and roads is the high frequency of human-caused fires in comparison to fires started by lightning. According to data from the Interagency Fire Center collected between 1988 and 1998, 88.1% of all wildland fires were caused by humans, in contrast to 11.9% started by lightning (Department of Interior, 1999). There is a spectrum of anthropogenic causes of fires, ranging from purely accidental to hopelessly careless. Direct causes include burning carbon particles emitted from car mufflers, burning toilet paper, cigarette butts, improperly contained or extinguished campfires, burning vehicles, and arson.

Risk Factors

The various causes of anthropogenic fire rely upon a common mechanism for dispersal: roads. By facilitating human access to otherwise remote areas, roads are a major factor in the incidence of anthropogenic fires. With all but 4% of our public land already converted in some form into roaded areas, the risk of fire starts on public land is considerable. Furthermore, current agency guidelines for road îclosure" are often far from effective at actually preventing their use by humans on ever more-powerful vehicles. Additionally, the difficulty of controlling human behavior makes limiting risks of anthropogenic fires on roadsides problematic. With limited budgets available for enforcing public land regulations, and variable success in effectively closing roads to human traffic, behavior control by public education is often considered the most effective means of controlling human fire risks (Wilson 1979). Such methods as posting warning signs and public service commercials, however, are moderately effective at best, and do nothing to prevent fires that are not caused by ignorance. The destructive potential of roads, combined with the difficulty of regulating human use and behavior on or near roads, renders prevention of unnecessary roads and the obliteration of roads in highly sensitive areas the most significant means to limiting fire risk associated with roads.

An indirect cause of increased fire risk that is associated with roads is the spread of weeds. It is well documented that weedy species are abundant in disturbed areas such as roadsides (Milburg ad Lamont, 1994; Kopecky, 1988; see also Bibliography Notes, The RIPorter 3.1 and 2.3). Increased runoff, frequent soil disturbance on and around roads, seed dispersal by cars and animals using roads as corridors, and open conditions in the cleared areas around roads account for the preponderance of weeds along roadsides. This increased richness in weedy species, combined with disrupted drainage patterns and altered microclimates in the immediate vicinity of most roads, creates a corridor of fire-susceptible vegetation along roads. According to DøAntonio & Vitousek (1992), the presence of grass weeds tends to increase the frequency and intensity of fire. This implies an increased susceptibility of vegetation to both anthropogenic and lightning-caused fires along roadsides. Road maintenance and construction are also associated with disruption and damage to soils and organic matter, which can reduce soil moisture retention, thereby creating more arid conditions in these areas during fire seasons (Everett et al 1994).

Where Fires Start

In his study of the effects of roads on wildfires in national forests in California, Robert F. Johnson concluded that over 52 percent of man-caused fires occurred within 33 feet of a road edge (Johnson, 1963). Other studies showed similar results, reinforcing the correlation between roads and wildfire (Show et al 1941; California Division of Forestry and USDA Forest Service, 1968). Given the importance of roads to the fire suppression campaign, it is surprising that these studies, over 30 years old, are the most recent analyses of the road problem in fire control. Their results, if not conclusive on their own, indicate a possible causal relationship between human-caused wildfire and roads, and support the need for further research on the subject. Recent analysis of this summerøs wildfires, for example, noted that all of the fire starts in the Skalkaho Valley Complex were in roaded and developed areas, which accounted for 93% of the total area burned (Morrisson et al 2000). Increased attention to data of this kind is needed to adequately assess the extent of the impact of roads on wildfires.

Rethinking Policy

Agency fire policy views road-building and maintenance as an essential tool in fighting wildfires (Show et al, 1941). Roads, it is argued, in addition to serving as firebreaks, provide access to firefighters to remote wildlands, and thereby serve as the foundation of an ardent policy of fire suppression. While it is true that roads can serve as barriers to the spread of fire, this is not always the case, as was seen this summer, when fires in Montana jumped across major roads, including fourlane Interstate 90. That roads provide access to firefighters and their tank trucks is also true, but the question remains as to whether the benefits of roads as a fire fighting tool outweigh the extreme fire risk that is associated with roads.

Research Needs

In designing a network of roads for fire protection on public lands, engineers in the first half of the 20th century envisioned a system of roads that would be supported by an arsenal of fire fighting apparatus that could be deployed on short notice in an aggressive front line attack on fires (Show et al 1941). Given the lack of recent research on the relationship between wildfires and roads, or on the effectiveness of roads as fire suppression tools, further research is needed to adequately assess and reform current use of roads for fire suppression. An effective and well-informed critique of current fire suppression practices will require research on the following questions:

Q. What are current statistics related to the incidence of fires near roads?

Q. What is the relative frequency of roadside fire starts as they relate to traffic volume?

Q. To what extent does road construction and maintenance impact roadside vulnerability to fire?

Q. What are the specific causes of anthropogenic fires? Are they caused by recreationists or industrial activity?

Q. Is there a correlation between fires and ORV use?

Q. What is the relative frequency of fires started in roaded versus roadless areas?

¤ Leslie Hannay is the Program Associate for Wildlands CPR.

Editorøs Note: Wildlands CPR has two interns researching road/fire issues this fall. Weøll keep you posted on their progress.

Bibliography

California Division of Forestry and USDA Forest Service, Region 5. 1968. Fire hazard reduction guide for roadsides. Calif. Dep. Conserv. and USDA.

DøAntonio, C.M. and Vitousek, P.M. 1992. Biological invasions by exotic grasses, the grass/fire cycle, and global change. Annual Review of Ecological Systems 23: 67-87.

Everett, R.L.; M.E. Jensen; P.S. Bourgeron; W.G. Robbins; D.W. Wolf; J.K. Agee; B.A. McIntosh; C.G. Johnson. 1994. Eastside forest ecosystem health assessment. Pacific Northwest Research Station, Portland, OR. USDA Forest Service Pacific Northwest Research Station.

Hammer, K.J. 1986. An On-Site Study of the Effectiveness of the US Forest Service Road Closure Program in Management Situation One Grizzly Bear Habitat, Swan Lake Ranger District, Flathead National Forest, Montana.

Johnson, R.F. 1963. The roadside fire problem. Fire Control Notes 24: 5-7.

Kopecky, K. 1988. Influence of roads on the synanthropization of the flora and vegetation according to observations in Czechoslovakia. Folia-Gedotanica-Phytotaxonomica 23 (2):145-171.

McKelvey, K.S. 1996. An overview of fire in the Sierra Nevada. Status of the Sierra Nevada: Sierra Nevada Ecosystem Project Final Report to Congress: Volume II. Wildland ResourcesCenter Report No. 37. University of California, Davis.

Milberg, P. and B.B. Lamont. 1995. Fire enhances weed invasion of roadside vegetation in southwestern Australia. Biological Conservation 73: 45-49.

Morrisson, P.H., J.W. Karl, L. Swope, K. Harma, and T. Allen. 2000. Assessment of Summer 2000 Wildfires: Landscape History, Current Condition, and Ownership.

Show, S.B., C.A. Abell, R.L. Deering, and P.D. Itchson. 1941. A planning basis for adequate fire control on the southern California national forests. Fire Control Notes 5: 1-59.

Wilson, C.C. 1979. Roadsides- Corridors with high fire hazard and risk. Journal of Forestry, September 1979.