Congressional Research Service

CRS Report RL30755
Forest Fire / Wildfire Protection

•Historical Background
•Concerns and Problems
•Fuel Management
•Fire Control
•Wildfire Effects
•Roles and Responsibilities
•Current Issues
•References

CRS Report RS21544 Wildfire Protection Funding

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Order Code RL30755

Forest Fire/Wildfire Protection

Updated February 14, 2005

Wildfire Effects

Wildfires cause damages, killing some plants and occasionally animals. [52] Firefighters have been injured or killed, and structures can be damaged or destroyed. The loss of plants can heighten the risk of significant erosion and landslides. Some observers have reported soil “glassification,” where the silica in the soils has been melted and fused, forming an impermeable layer in the soil; however, research has yet to document the extent, frequency, and duration of this condition, and the soil and burning conditions under which it occurs. Others have noted that “Even the most intense forest fire will rarely have a direct heating effect on the soil at depths below 7 to 10 cm [centimeters].” [53]

Damages are almost certainly greater from stand replacement fires than from surface fires. Stand replacement fires burn more fuel, and thus burn hotter (more intensely) than surface fires. Stand replacement fires kill many plants in the burned area, making natural recovery slower and increasing the potential for erosion and landslides. Also, because they burn hotter, stand replacement fires are generally more difficult to suppress, raising risks to firefighters and to structures. Finally, stand replacement fires generate substantial quantities of smoke, which can directly affect people’s health and well-being.

Wildfires, especially conflagrations, can also have significant local economic effects, both short-term and long-term, with larger fires generally having greater and longer-term impacts. Wildfires, and even extreme fire danger, may directly curtail recreation and tourism in and near the fires. Extensive fire damage to trees can significantly alter the timber supply, both through a short-term glut from timber salvage and a longer-term decline while the trees regrow. Water supplies can be degraded by post-fire erosion and stream sedimentation, but the volume flowing from the burned area may increase. If an area’s aesthetics are impaired, local property values can decline. However, federal fire management includes substantial expenditures, and fire-fighting jobs are considered financially desirable in many [54] areas.

Ecological damages from fires are more difficult to determine, and may well be overstated, for several reasons. First, burned areas look devastated immediately following the fire, even when recovery is likely; for example, conifers with as much as 60% of the crown scorched are likely to survive. [55] Second, even the most intense stand replacement fires do not burn 100% of the biomass within the burn’s perimeter

— fires are patchy. For example, in the 1988 fires in Yellowstone, nearly 30% of the area within the fire perimeters was unburned, and another 15%-20% burned lightly (a surface fire); 50%-55% of the area burned as a stand replacement fire. [56] Finally, traditional damage appraisals apply a standard value-per-acre for all acres burned to estimate losses, but the values have not been determined by the on-site resource changes that resulted from the fires.

Emergency rehabilitation is common following large fires. This is typically justified by the need for controlling erosion and preventing landslides, and may be particularly important for fire lines (dug to mineral soil) that go up steep slopes and could become gullies or ravines without treatment. Sometimes, the rehabilitation includes salvaging dead and damaged trees, because the wood’s quality and value deteriorate following the fire. Emergency rehabilitation often involves seeding the sites with fast-growing grasses. While helpful for erosion control, such efforts might inhibit natural restoration if the grasses are not native species or if they inhibit tree seed germination or seedling survival.

Finally, as mentioned above, wildfires can also generate benefits. Many plants regrow quickly following wildfires, because fire converts organic matter to available mineral nutrients. Some plant species, such as aspen and especially many native perennial grasses, also regrow from root systems that are rarely damaged by wildfire. Other plant species, such as lodgepole pine and jack pine, have evolved to depend on stand replacement fires for their regeneration; fire is required to open their cones and spread their seeds. One author identified research reporting various significant ecosystems threatened by fire exclusion — including aspen, whitebark pine, and Ponderosa pine (western montane ecosystems), longleaf pine, pitch pine, and oak savannah (southern and eastern ecosystems), and the tallgrass prairie. [57] Other researchers found that, of the 146 rare, threatened, or endangered plants in the coterminous 48 states for which there is conclusive information on fire effects, 135 species (92%) benefit from fire or are found in fire-adapted ecosystems. [58]

Animals, as well as plants, can benefit from fire. Some individual animals may be killed, especially by catastrophic fires, but populations and communities are rarely threatened. Many species are attracted to burned areas following fires — some even during or immediately after the fire. Species can be attracted by the newly available minerals or the reduced vegetation allowing them to see and catch prey. Others are attracted in the weeks to months (even a few years) following, to the new plant growth (including fresh and available seeds and berries), for insects and other prey, or for habitat (e.g., snags for woodpeckers and other cavity nesters). A few may be highly dependent on fire; the endangered Kirtland’s warbler, for example, only nests under young jack pine that was regenerated by fire, because only fire-regenerated jack pine stands are dense enough to protect the nestlings from predators.

In summary, many of the ecological benefits of wildfire that have become more widely recognized over the past 30 years are generally associated with light surface fires in frequent-fire ecosystems. This is clearly one of the justifications given for fuel treatments. Damage is likely to be greater from stand replacement fires, especially in frequent-fire ecosystems, but even crown fires produce benefits in some situations (e.g., for the jack pine regeneration needed for successful Kirtland’s warbler nesting).

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Footnotes

52 For a thorough discussion of these effects, see L. Jack Lyon, Mark H. Huff, Robert G. Hooper, Edmund S. Telfer, David Scott Schreiner, and Jane Kapler Smith, Wildland Fire in Ecosystems: Effects of Fire on Fauna, Gen. Tech. Rept. RMRS-GTR-42-vol. 1 (Ogden, UT: USDA Forest Service, Jan. 2000). Hereafter referred to as Lyon, et al., Effects of Fire on Fauna.

53 Craig Chandler, Phillip Cheney, Philip Thomas, Louis Traberd, and Dave Williams, Fire In Forestry. Volume I: Forest Fire Behavior and Effects (New York, NY: John Wiley & Sons, 1983), p. 173.

54 Nelson, A Burning Issue, pp. 37-38.

55 See Ross W. Gorte, Fire Effects Appraisal: The Wisconsin DNR Example, Ph.D. dissertation (East Lansing, MI: Michigan State Univ., June 1981).

56 See Lyon, et al., Effects of Fire on Fauna, p. 44.

57 Leenhouts, “Assessment of Biomass Burning.”

58 Amy Hessl and Susan Spackman, Effects of Fire on Threatened and Endangered Plants: An Annotated Bibliography, Information and Technical Report 2 (Fort Collins, CO: U.S. Dept. of the Interior, National Biological Service, n.d.).

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