Forest Fuels Management

Forest Fuels Management

The Need for Expanded Wildland Fuel Management in California

A Position of the California Society of American Foresters

This Position Statement was not renewed after its initial 5-year duration; therefore, the Statement has been archived. 


Large, high-intensity wildfires pose a major threat to the sustained production of goods and amenities in California’s forests, woodlands, and brushlands. In fiscal year 1993-1994, total wildfire suppression costs and related losses in California exceeded $1.2 billion (California Board of Forestry 1996). The Northern California Society of American Foresters recommends expanded and strategic management of vegetation density, composition, and structure to reduce the risk of unacceptable wildfire losses.

Issue Statement

California faces a critical need for wildland fire hazard reduction at a time when the state’s collective will and wherewithal to implement the needed fuel treatments are highly limited. Perhaps the greatest impediments to increased support for fuel management are the pervasive public misperceptions that wildfire is necessarily bad and that healthy, productive forests can be sustained without being managed. Some environmental organizations oppose all forms of forest management and suspect that any management involving tree removal constitutes resource exploitation. Many nonindustrial landowners and residents of forest intermix areas fail to implement needed fuel treatments because they view such management as conflicting with their preservationist values or are simply reluctant to invest in land improvements. Land management agencies such as the U.S. Forest Service have undergone repeated reductions in their land management budgets and related output targets. The wildfire suppression divisions of these agencies sometimes regard fuel management programs as being in competition with their own programs for funding. Air quality management agencies sometimes oppose the use of prescribed fire for fuel management because of its short-term environmental impacts.


Wildland fire hazards have increased substantially in California as a consequence of historical fire suppression and past timber harvesting practices. Fire suppression costs and economic and environmental damages associated with catastrophic wildfires have increased over the past two decades and are likely to continue increasing unless management activities designed to reduce fuel hazards are implemented on an unprecedented scale. Increased effort and cooperation to reduce wildfire hazards are needed on the part of a wide range of affected parties including industrial and nonindustrial timberland owners, residents of wildland intermix and urban-wildland interface areas, local governments in forest communities, state and federal land management agencies, and the agencies that regulate forest management activities. Foresters and other resource professionals must commit to working together to reduce wildfire hazards through extensive and strategic application of a wide range of fuel management techniques. These techniques include management-ignited fire, prescribed natural fire, precommercial thinning, and treatment of slash from timber harvesting. A key to expanded implementation of fuel management is the development of stable markets for products into which biomass materials generated by fuel treatments can be converted.

Changes in Fire Regime, Forest Structure, and Fire Hazard

Fire is among the most important forces shaping the California’s forest and rangeland ecosystems. Fire was historically a principal mechanism by which the nutrients contained in wood fuels were recycled. Due to the extensive and successful application of fire suppression during this century, rates of biomass recycling have declined and fuels have accumulated throughout most wildlands. As a result, although wildland landscapes typically burn much less frequently than prehistorically, wildfires apparently burn larger contiguous areas at higher intensities and with greater environmental damage than during the presettlement period (McKelvey et al. 1996).

Over the past century, fire exclusion and selective logging of large conifers have resulted in extensive forested areas dominated by dense stands of relatively small trees of shade-tolerant and fire-sensitive species, such as white firs and incense-cedars. The result has been a large increase in the volume and continuity of live and dead wood fuels near the forest floor that provide a fuel ladder connecting surface fuels with the forest canopy (McKelvey et al. 1996). Fire exclusion has also allowed chaparral to invade and dominate many foothill woodlands. Risks of large, severe fires have increased accordingly. While fuel conditions have become increasingly hazardous, human populations and property values potentially endangered by fire have also increased, primarily in the lower and middle elevations of the Sierra Nevada. At a regional scale, Sierran forest ecosystems are believed to be outside the historical range of variability regarding fire frequency and severity, forest structure, and landscape mosaic (distribution of vegetation patches) (Skinner and Chang 1996).

Widespread in the Sierra Nevada are unthinned stands featuring dense understories that provide the horizontal and vertical continuity of fuels that fires need to move from the ground surface to the forest canopy. Excessive competition for water and sunlight in unthinned stands often weakens or kills trees, thus increasing fuel loads and potential fire severity and rate of spread (Weatherspoon 1996). Fuel conditions in much of the Sierra Nevada support the potential for large, severe fires (Sapsis et al. 1996).

Selective timber harvesting may temporarily increase fire hazard unless postharvest slash treatments (e.g, piling and burning) are implemented (Weatherspoon 1996, van Wagtendonk 1996). The California Forest Practice Rules, which apply on all private timberland in California, currently require only minimal slash treatments (e.g., lopping of branches and tops) only in a highly limited area (within 50-100 feet of publicly accessible roads and 100-200 feet of structures maintained for human habitation) (14 CCR 917.2). Many landowners, however, go beyond these regulations by implementing combinations of silvicultural and slash treatments that leave harvested areas in a relatively fire-safe condition.

Environmental Consequences

Catastrophic fire is detrimental to watershed function and water quality. By killing vegetation, burning the organic matter in litter and soil, and forming impervious soil layers, severe fires accelerate runoff from the watershed. More water is discharged in a shorter time period, peak flows are greater (contributing to increased flood hazards), and summer and fall streamflows are lower than in less disturbed watersheds. Bare soils and increased runoff cause greater detachment and transport of soil particles. With reduced infiltration, saturated soil conditions and shallow debris flows become more prevalent. Sediment yields increase markedly, particularly where riparian vegetation is burned (Kattelmann 1996). Besides the direct effects of catastrophic fires, ground disturbance related to fire suppression and postfire activities (e.g., salvage logging) also may adversely affects water quality. Although total water yield may increase for several years following a fire in response to decreased transpiration and leaf interception, the value of the increased yield is limited in that it occurs during peak flows.

Historical changes in montane fire regimes have had diverse effects on wildlife and biodiversity. Fire suppression has led to extensive replacement of highly-productive forest openings containing herbs and shrubs by dense stands of trees, which typically have relatively low productivity for wildlife. High fuel hazards also threaten the key elements (e.g., large trees, snags, and downed logs) of the Sierra Nevada’s remaining late-successional habitat (Graber 1996).

Smoke from wildfires causes the most extensive locally-generated impacts on air quality in the Sierra Nevada. For example, the 1992 Cleveland fire in the Eldorado National Forest generated approximately as much smoke in one day as typically results from that national forest’s prescribed fire program during an entire year. Because of their infrequency, however, major fires have a smaller overall impact on Sierran air quality than smoke from wood burning in urban enclaves such as Mammoth Lakes, Truckee, and South Lake Tahoe (Cahill et al. 1996).

Social Consequences

Wildfire hazards pose increasing risks to human life and health, property, natural resources, and firefighter safety in California. Populations will continue to increase in wildland areas at risk of catastrophic fire, especially in the central Sierra Nevada and in Riverside, San Bernardino, and San Diego Counties. Human-caused ignitions generally increase with population. Losses of many types of assets to wildfire damage are expected to accelerate (California Board of Forestry 1996).

Historical land-use changes in the upper watersheds make infeasible a return to the prehistoric fire regime, where cycles of typically light fires ranged in average length from 8-26 years, depending on vegetation type and climate (McKelvey et al. 1996). Not only are structures, infrastructure, and managed forests at risk of fire damage too extensive to permit burning at the presettlement rate, but regulatory constraints and the social costs of fire and its effects (e.g., low air quality) also prohibit burning at pre-European scales. Although fire will remain an essential element of these wildland ecosystems, it must be controlled and used in conjunction with other techniques to reduce fuel loads to levels consistent with maintaining healthy forests (McKelvey et al. 1996).

Mechanical fuel management techniques can reduce fire hazard. A recent simulation study of the behavior of fires immediately following harvesting found that prescribed burning, harvesting of biomass fuel followed by prescribed burning, and sanitation-salvage or group-selection harvests with slash and landscape fuel treatments produced fuel structures that minimized average fireline intensities, heat per unit area, rate of spread, area burned, and scorch heights (Elliott-Fisk et al. 1997). In contrast, sanitation-salvage or group-selection harvests without slash treatment or with lopping and scattering of slash result initially in more extreme fire behavior than in untreated areas. The latter treatments probably result in less severe fires relative to untreated stands, however, after sufficient time has passed to allow the slash to decompose.

Prescribed fire is also an effective tool for managing fuels (McKelvey et al. 1996). It includes prescribed ignited fires (fires intentionally set to burn a planned area at a planned intensity) and prescribed natural fires. In many forested areas, however, fuel structures are currently too hazardous to safely attempt prescribed ignitions without pretreating the stand mechanically.

Prescribed natural fires are fires resulting from unplanned ignitions (caused by either lightning or humans) in areas for which prescribed natural fire plans have been adopted specifying conditions under which such fires will be allowed to burn. Prescribed natural fire planning represents an important opportunity to have wildfire help meet management objectives, rather than be in conflict with their achievement, particularly in relatively remote or isolated areas where the public safety hazards and air-quality effects of fires are minor.

From a practical perspective, perhaps the most important requirement for successful fuel management programs is a viable market for small trees and other biomass materials removed from wildlands. Products into which such material could potentially be converted include pulp chips, panel products (e.g., particle board), biomass energy fuel, ethanol, and lumber. A major limitation on the marketability of biomass materials is their high handling costs. Recent innovations in logging equipment (e.g., the processor-forwarder combination) could substantially increase the feasibility of marketing such materials, which, in turn, would enable fuel treatments to be accomplished much more extensively.

The U.S. Departments of the Interior and Agriculture (1995) recently recommended a shift from their traditional focus on fire suppression and control to comprehensive fire management, taking into consideration the essential role of fire in forest ecosystems. Similarly, the California Department of Forestry and Fire Protection (California Board of Forestry 1996) recently began implementing a prefire management initiative involving planning for hazard reduction at the multicounty level throughout the state.


  • Increased efforts along a broad front are needed to control wildland fire hazards in California. The Northern California Society of American Foresters recommends that the following actions be implemented:
  • Increasing public awareness of the need for expanded fuel management and of the dire consequences of the absence of vegetation management in most human-populated wildland landscapes in California.
  • Constructing and maintaining strategically designed and located, large-scale networks of fuel reduction zones through extensive public-private sector coordination.
  • Preparing fuel management plans at the local or subregional level that identify treatments to be applied, priorities and schedules for their application, and adequate means to implement the treatments.
  • Streamlining project-level environmental compliance for fuel management involving limited commercial timber harvesting through preparation of county-wide program timberland environmental impact reports.
  • Expanding the use of mechanized harvesting for fuel reduction, both as stand-alone treatments and in combination with prescribed ignitions.
  • Expanding and stabilizing markets for biomass materials removed from wildlands.
  • Increasing recognition by the state legislature and by federal, state, and local air quality agencies that fuel management (particularly biomass harvesting) reduces air pollution by utilizing material that would otherwise be burned by wildfire.
  • Increasing recognition on the part of air quality agencies of the qualitative differences between airborne particulates resulting from burning of wildland vegetation and those resulting from other sources.
  • Expanding the application of prescribed natural fire where it can be used safely and effectively (e.g., in relatively remote areas).
  • Increasing resource allocations for fuel management, while maintaining fire suppression capabilities.
  • Recognizing the public benefits of fuel management by providing incentives (e.g., state income tax credits) to encourage private investment in fuel management.
  • Providing increased job opportunities and training in fuel management, including cross-training of fire suppression specialists.
  • Establishing additional service forestry positions to provide fuel management assistance to landowners in high fire-hazard areas.
  • Assessing changes in fire hazard resulting from timber operations as part of forest management planning and timber harvest planning.
  • Evaluating current requirements for slash disposal following timber harvesting and implementing more effective practices if needed under specified conditions.
  • Developing a consistent, comprehensive system for recording of key information on fire events and having such a system be adopted by the U.S. Forest Service, California Department of Forestry and Fire Protection, U.S. Bureau of Land Management, U.S. National Park Service, and other major wildfire suppression agencies.
  • Refining analytical tools (e.g., landscape-level models of fire behavior) to facilitate identification of effective fuel management regimes and cost-effective strategies to implement them.

Literature Cited

Cahill. T.A., J.J. Carroll, D. Campbell, and T.E. Gill. 1996. Air quality. In: Status of the Sierra Nevada. Vol. II. Assessments and scientific Basis for Management Options. Wildland Resources Center Report No. 37. University of California, Davis. Davis, CA.

California Board of Forestry. 1996. California fire plan – a framework for minimizing costs and losses from wildland fires. Sacramento, CA.

Graber, D.M. 1996. Status of terrestrial vertebrates. In: Status of the Sierra Nevada. Vol. II. Assessments and scientific Basis for Management Options. Wildland Resources Center Report No. 37. University of California, Davis. Davis, CA.

Kattelmann, R. 1996. Hydrology and water resources. In: Status of the Sierra Nevada. Vol. II. Assessments and scientific Basis for Management Options. Wildland Resources Center Report No. 37. University of California, Davis. Davis, CA.

McKelvey, K.S., C.N. Skinner, C.Chang, D.C. Erman, S.J. Husari, D.J. Parsons, J.W. van Wagtendonk. 1996. In: Status of the Sierra Nevada. Vol. II. Assessments and scientific Basis for Management Options. Wildland Resources Center Report No. 37. University of California, Davis. Davis, CA.

Sapsis, D., B. Bahro, J. Gabriel, R. Jones, and G. Greenwood. 1996. An assessment of current risks, fuels, and potential fire behavior in the Sierra Nevada. In: Status of the Sierra Nevada. Vol. III. Assessments and scientific Basis for Management Options. Wildland Resources Center Report No. 37. University of California, Davis. Davis, CA.

Skinner, C.N. and C. Chang. 1996. Fire regimes, past and present. In: Status of the Sierra Nevada. Vol. II. Assessments, Commissioned Reports, and Background Information. Wildland Resources Center Report No. 38. University of California, Davis. Davis, CA.

U.S. Department of the Interior and U.S. Department of Agriculture. 1995. Federal wildland fire management – policy and program review. Final report. National Intreragency Fire Center. Boise, ID.

Van Wagtendonk, J.W. 1996. Use of a deterministic fire growth model to test fuel treatments. In: Status of the Sierra Nevada. Vol. II. Assessments and scientific Basis for Management Options. Wildland Resources Center Report No. 37. University of California, Davis. Davis, CA.

Weatherspoon, C.P. 1996. Fire-silviculture relationships in Sierra forests. In: Status of the Sierra Nevada. Vol. II. Assessments and scientific Basis for Management Options. Wildland Resources Center Report No. 37. University of California, Davis. Davis, CA.


The Northern California Society of American Foresters, with about 1,000 members, is a unit of the Society of American Foresters, with about 19,000 members. The Society was established in 1900 by Gifford Pinchot and six other pioneer foresters. It is the national organization representing all aspects of the forestry profession in the United States, including public and private practitioners, researchers, administrators, educators, and forestry students.

The mission of the Society is to advance the science, technology, teaching, and practice of professional forestry in America; to enhance the competency of its members; to establish professional excellence; and to use the knowledge, skills, and conservation ethic of the profession to ensure the continued health and use of forest ecosystems and the present and future availability of forest resources to benefit society.

The Society is the accreditation authority for professional forestry education in the United States. Its periodicals include the Journal of Forestry, Forest Science, The Forestry Source, Western Journal of Applied Forestry, Southern Journal of Applied Forestry, Northern Journal of Applied Forestry, and the annual Proceedings of the Society of American Foresters national convention.