Wildland fire hazard and risk: Problems, definitions, and context

Abstract

The risks, hazards, and relative severity of wildland fires are presented here within the ecological context of historical natural fire regimes, time, space, and process. As the public dialogue on the role and impacts of wildland fire increases, it is imperative for all partners to converge on clear and concise terminology that defines risk, hazard, and the characteristic (or uncharacteristic) nature of wildland fire. These terms must be defined in the context of scale—both spatial and temporal. The concept of historical natural fire regimes involves a classification of the characteristic, or “natural” processes and effects associated with wildland fire occurring in sustainable ecosystems. When a wildland fire occurs within the time, space, and severity parameters of the historical natural fire regime, the fire can be called natural, or “characteristic”. The milieu of disturbance effects we call catastrophic, such as economic losses, damages to communities and structures, or impacts on short-term aesthetic values involve social, cultural, and economic values and risks—none is directly associated with ecological values, damages, or risks. In the context of technical risk assessments, the term “risk” considers not only the probability of an event, but also includes values and expected losses. However, within the fire community it refers only to the probability of ignition (both man- and lightning-caused). ‘Hazard’ refers to the state of the fuel, exclusive of weather or the environs in which the fuel is found. Unlike many common uses of the term ‘severity’, fire severity refers specifically to the effect a fire has on wildland systems. It is inappropriate to use the term severity to describe the behavior of the fire phenomenon itself. Instead, we should confine its use to that relating only to a fire's effect. Finally, I discuss the limitations and conflicts to integrating all social, cultural, economic, health, and safety values in our public and policy-forming dialogue relating to fire risk, hazard, and severity. Typical risk assessments consider all relevant endpoints, including socio-economic, management, as well as ecological elements. Herein, I use the Black Mountain 2 Fire from August 2003 in the northern Rockies to illustrate the spatiotemporal extent of fire's impacts on the endpoints. When expressed over all affected spatiotemporal scales, the overlay of all endpoints from this synthetic scenario results in a “decision space” ranging in time from an hour to a century, and in space ranging from a few square meters to the continent.

Introduction

Although Kierkegaard wisely advises that the past should inform one's understanding and grasp of the future, the uncharacteristic nature of many recent wildland fires seems to have diverted much of our attention to the present. We have found ourselves breathlessly describing the extraordinary behavior and extent of fires such as those observed in the autumn of 2003 near San Diego, California. Media attention on towering “fire tornadoes”, the devastation of structures and communities, and the massive outlays of financial, human, and mechanical resources have quite effectively obscured our perception of the complex and diverse nature of fire we only recently began to acknowledge. As Maguire reminded us (this volume) on risk attitudes, “the currency of events distorts our memory (and understanding).” Clearly, the currency of the fires in southern California and elsewhere has distorted our memories. All fires are once again “bad” fires, most large fires are characterized as catastrophic, and our current attention has once again been diverted from the role of fire in ecosystem sustainability to an urgency for mitigation of wildfire risks, whatever they may be.

The current language used when addressing the perceived ‘risks’ and ‘hazards’ associated with wildland fire could be better understood by looking backwards to the very inception of forest policy in this country. In an 1899 article in National Geographic, Gifford Pinchot described this nation's forest legacy: “The forest is as beautiful as it is useful … perhaps no other natural agent has done so much for the human race and has been so recklessly used and so little understood.” Pinchot's article then characterized the relation of forests and forest fires, where he described fire as “… one of the great factors which govern the distribution and character of forest growth” (Pinchot, 1899). Early in the 20th century, even loggers and silviculturists were suggesting that fire was not always a “risk” to their stewardship objectives. In a bold article written in 1910 for the magazine Sunset, the California timberman George Hoxie stated that “We must count on fire to help in the practical forestry … the practice invites the aid of fire as a servant [otherwise] it will surely be a master in very short time” (Hoxie, 1910). And Harold Weaver, a 1940s-era silviculturist in northeastern Washington, noted the negative impacts of fire exclusion on management of ponderosa pine when he wrote, “This [fire policy] has brought about changes in ecological conditions which were not fully anticipated, and some of which seem to threaten sound management and protection of ponderosa pine forests” (Weaver, 1943).

The language we use to characterize resource management and, particularly, fire management appears to have become less concise over time. Perhaps, the diverse constituency expecting policy solutions to their perceived fire dilemma can only be acquiesced by holistic, all-inclusive language evolved through lumping, rather than splitting. For example, in 1998 the General Accounting Office (GAO) presented to Congress a comprehensive assessment of the wildfire threat to western national forests, but the final language used in the testimony seems to be couched largely in emotional terms driven by societal values, rather than ecological considerations:

“In 1995, the [Forest Service] agency estimated that 39 million acres … are now at risk of large, uncontrollable, catastrophic fires” (GAO, 1998).

It is noted that, during the period of the GAO investigation leading to their 1998 report, the term catastrophic was regularly used by both the GAO and the Forest Service.

In his keynote address to the conference titled “Risk assessment for decision-making related to uncharacteristic wildfire”, Forest Service Chief Dale Bosworth challenged us to facilitate the public understanding of the relative risks of wildland fire, and he provided three suggestions towards meeting this goal: (1) take the uncertainties into account; (2) weigh the risks without paralysis; and (3) translate into language the public understands. Unfortunately, we are sometimes so anxious to provide understandable language that we homogenize the information to the point that it loses any real value. For example, in the 1998 GAO testimony, the Forest Service and the GAO use common, understandable terms—large, uncontrollable, catastrophic—but at the price of losing any scientific basis for applying those terms to decision-making. On the positive side of these observations, we have recently made considerable progress in improving our language. The term “uncharacteristic” is now (fortunately!) the currency for describing fire processes occurring outside their biophysical baseline conditions. I note and commend the pervasive use of this term in the presentations and papers associated with this conference. Consider the likely possibility that a large, uncontrollable fire might well have catastrophic socio-economic consequences, yet could be well within the range of scientifically acceptable (characteristic) ecological consequences.

Further, I present various common interpretations of a number of fire-related terms and, where possible, suggest standardization based on a convergence of respected opinions. These terms include hazard, risk, characteristic (or not), and severity. Finally, I present a continuum of time and space within which the terms risk and severity can be considered. In this context, I will demonstrate numerous inconsistencies (and ambiguities) to the notion of an “all-risk” approach for wildland fire management.