The Science Behind Wildfire Prevention

New GTR Summarizes State of Knowledge

Most wildfires are started by people, either accidentally or intentionally. Photo by NOAA.
Most wildfires are started by people, either accidentally or intentionally. Photo by NOAA.

According to the U.S. Forest Service National Climate Assessment now being finalized, by 2050 the area burned each year by severe wildfires will rise to 20 million acres nationwide, at least double of what it is now. Because many of those future fires are likely to burn under severe fire conditions, preventing people from starting fires in the wrong places at the wrong time will become even more important.

Forest Service Southern Research Station (SRS) researchers, experts from state, other federal, and tribal land management agencies as well as representatives from the law enforcement community recently published a review of the science of and recommendations for modeling wildfire occurrences. Based on original work done for the National Cohesive Wildland Fire Management Strategy, the new general technical report Wildfire Ignitions: A Review of the Science and Recommendations for Empirical Modeling summarizes the state of knowledge about the underlying causes of major wildfires and the role of education and law enforcement in preventing them.

“In this report, we describe a model that shows how wildfire ignitions are produced and and how they can be affected by management,” says Jeff Prestemon, lead author of the report and project leader of the SRS Forest Economics and Policy unit. “Tools developed based on the models we present could improve the ability of land managers to respond to emerging and ongoing wildfire threats.”

Wildfires result from a combination of ignition source, fuels, and conditions that allow flames to spread. Fires either start naturally, primarily from lightning, or are started by humans, either accidentally or intentionally. There’s not much land managers can do to prevent ignitions from natural causes like lightning, but they do have a few key options—wildfire prevention education, fuels management, and law enforcement—for dealing with human-caused ignitions.

The authors present a model that visualizes how wildfire ignitions are both produced and prevented; the model in turn serves as the groundwork for further statistical modeling that managers could use to predict wildfire occurrences at different spatial scales through different periods of time.  The authors discuss biophysical factors that affect ignition—temperature, humidity, precipitation, and others—but devote most of the discussion to research on patterns of human-caused wildfires and the few studies published on the effects of wildfire prevention.

“Evidence shows that human-caused wildfires do cluster around places where there are more people and machines and where it can easily spread,” says Prestemon. In short time frames, human-caused fires cluster in regular, predictable patterns associated with work, leisure, and time of year.  Research also shows that some human-caused fires cluster spatially and temporally,  which may be explained by serial and copycat behavior by arsonists.

The report concludes with 15 specific recommendations for modeling wildfire ignitions and prevention based on the scientific studies covered. Though presently very challenging to develop, tools that could provide wildfire hotspot models, especially for fires ignited by people, could help both land managers and law enforcement personnel in a future with more fire on the landscape.

Access the full text of the General Technical Report.

For more information, email Jeff Prestemon at jprestemon@fs.fed

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