A Century of Wildland Fire Research Contributions to Long-term Approaches for Wildland Fire Management: Proceedings of a Workshop (2017) / Chapter Skim
Currently Skimming:
4 Understanding Fire: State of the Science and Research Priorities
4 Understanding Fire: State of the Science and Research Priorities
Pages 39-58
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 39... ...
LANDSCAPES Meg A Krawchuk, Oregon State University Krawchuk said fire ecology covers a great number of ideas about natural and human fire history and fire effects on the environment, species, ecosystems, and landscapes.
|
From page 40... ...
For instance, frequent surface fires in FIGURE 4-1 Historical fire regimes in the conterminous United States. NOTE: Fire Regime Group I: burn frequency 0–35 years, burn severity generally low, replacing less than 25 percent of the dominant overstory vegetation, can include mixed-severity fires that replace up to 75 percent of the overstory; Fire Regime Group II: burn frequency 0–35 years, burn severity high, replacing greater than 75 percent of the dominant overstory vegetation; Fire Regime Group III: burn frequency 35–200 years, burn severity generally mixed, can also include low-severity fires; Fire Regime Group IV: burn frequency 35–200 years, burn severity high, leading to replacement; Fire Regime Group V: burn frequency more than 200 years, burn severity varies but leads to replacement.
|
From page 41... ...
Figure 4-3 illustrates the relationship between fire regimes and the biotic membership within those ecosystems; the safe operating space for fire regimes and biota is where the fire regime adaptive traits match quite well with the characteristics of the box of fire regime. Krawchuk concluded by asking: Are humans leaving safe operating space for ecosystems to respond to fire as they have done historically within a given fire regime?
|
From page 42... ...
Forest Service Missoula Fires Sciences Laboratory Finney's overview of fire prediction and mapping began with the following observations about wildland fire in the United States: • Ninety-five percent of the area burned in the United States (including Alaska) each year stems from only 3 percent of the 80,000 fires that occur each year; the other 97 percent of fires are suppressed.
|
From page 43... ...
All fires under the jurisdiction of the federal government are entered into this system. It provides access to models, data, and decision frameworks and generates fire growth projections, fire behavior calculations, and probabilistic predictions that can be overlaid with values at risk.
|
From page 44... ...
The physical and empirical models do not resolve the physical processes that produce fire spread and behavior. Finney cited examples from a couple of papers to illustrate his point that understanding the processes involved in fire behavior and spread is still a scientific challenge (Clark et al., 2003; Sullivan, 2009)
|
From page 45... ...
Allen pointed to the "grassification" of the American West as an example. Bare inner spaces between perennial plants and woody plants in western desert areas are filling in with nonnative grasses, which causes change in fire behavior that the local flora and ecosystems are not adapted to.1 nother example is the drought- and heat-induced stress on conifers and the associated A insect outbreaks that have caused immense mortality in western North American forests in 1 See also Balch's discussion of cheatgrass in the Great Basin in Chapter 3.
|
From page 46... ...
the last 20 years. There are debates and ongoing research about how much stress and insect pressure actually changes fire hazard and fire behavior, but regardless, millions of hectares in western North America are facing these conditions.
|
From page 47... ...
Photo A courtesy of Jeff Dube, U.S. Forest Service.
|
From page 48... ...
Some forests are adapted to high-severity, infrequent fire -- for example, crown fires in Rocky Mountain lodgepole pine -- while other forests are adapted to frequent fire and can handle these disturbances within a desired range. The type of fire regime needs to be considered when fuel treatments are undertaken.
|
From page 49... ...
Another example of fire regime change is evident from historical data in the central Sierra Nevada in California. In 1911, there were 19 trees per acre in an inventoried area that included parts of the Stanislaus National Forest and Yosemite National Park; in 2013, the density had increased to 224 trees per acre (Collins et al., 2015)
|
From page 50... ...
Prescribed burning management has to be done continually rather than as a one-time occurrence. Experiments involving fuel treatment demonstrate that, if ladder fuels and surface fuels can be reduced, fire hazards and fire effects can be lessened in frequent-fire adapted forests.
|
From page 51... ...
B, site in 2003, after a prescribed fire. C, site in 2008, just before a second prescribed fire.
|
From page 52... ...
B, site in 2003, after mechanical thinning followed by a prescribed fire. C, site in 2008.
|
From page 53... ...
Photo courtesy of Scott Stephens. A B FIGURE 4-12 Vegetation change from fire use in the Illilouette Creek basin in Yosemite National Park.
|
From page 54... ...
With regard to the Clean Air Act requirement that Class 1 airsheds never have impeded visibility and the public health reasons in the act for limiting smoke, Stephens admitted that there is no way to have a fire-sustainable future without smoke in the air. From his point of view, this dilemma is why a congressional act prioritizing forest resilience is needed as a prime objective of federal policy; such an act may need to supersede other policies, including those carried out under the Endangered Species Act, the Clean Water Act, and the Clean Air Act, to ensure the long-term viability of forest ecosystems.
|
From page 55... ...
He agreed that the social and political issues were critical when it comes to forest resilience. Land managers, including the Forest Service and National Park Service, are trying to help forests become more resilient and they need to be empowered to continue to find solutions.
|
From page 56... ...
It is incumbent upon the fire behavior sciences to figure out how fire spreads so remote-sensing data can be used and more accurate tools can be developed for the many dimensions of fire management, including mitigation. This knowledge would help close the gap in understanding with regard to how fuels are related to fire behavior.
|
From page 57... ...
How does slope affect wildland fire spread? Are the effects of slope different from those of wind?
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.