Firesetting Arrests Reduce Future Intentional Fires

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Humans are responsible for about 90 percent of wildfire ignitions, through unattended campfires, debris burning, discarded cigarettes, or intentional arson. Photo by Matt Howard via Unsplash.

New research by the USDA Forest Service explores how law enforcement efforts might impact future incidents of arson.

“We found very little documented research on whether arrests, as a distinct measure of law enforcement efforts, are linked to reductions in the occurrence of intentional fires or whether such efforts have broader impacts across space and time,” says Jeff Prestemon, the study’s lead author and project leader for the Forest Economics and Policy research unit.

Prestemon and his co-authors evaluated whether arrests of intentional illegal firesetters in the region of Galicia, in northwestern Spain, lead to movements in or reductions of future fires. Their results were published in the International Journal of Wildland Fire.

Galicia was chosen because it’s a region where intentional wildfires are the dominant wildfire cause attribution. It’s also a region with a large enough number of intentional wildfires — half of Spain’s — and associated arrests to permit statistical identification of spatiotemporal effects of arrests.

“If someone is arrested, does this merely push other firesetters to new locations, or does the arrest result in perceived higher risks for being caught, thereby disincentivizing additional firesetting across a broader spatial domain?” asks Prestemon.

Prestemon and his co-authors examined municipality-level data from 1999 to 2014 to develop daily spatial and temporal ignition count models of for intentional, illegal wildfires on agricultural and non-agricultural lands.

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Climate change is projected to increase the severity and extent of wildfires, increasing the need to deal with human-ignited wildfires. Photo by Kari Greer, USFS.

The analysis dataset included information about arrests, the election cycle, seasonal and daily indicators, meteorological factors, and additional socioeconomic variables like average income and unemployment rate.

The research team found evidence that arrests reduce future intentional illegal fires across space in subsequent time periods and that arrests lead to overall reductions in intentional illegal wildfires.

The reductions are significant – the number of intentionally ignited wildfires declines for at least 18 months, and the reduction benefit is spread over 750 square miles around the site of the arrest.

Understanding how law enforcement efforts affect the timing and locations of future  illegal firesetting is critical to enacting effective policies and designing more effective law enforcement strategies aimed at reducing the occurrence of intentionally ignited wildfires that destroy property, damage resources, and harm individuals.

The article was chosen as the journal’s “Editor’s Choice” in its June 2019 issue.

“Highlighting of our research by selection as the Editor’s Choice is a wonderful honor for me and my coauthors,” adds Prestemon. “The journal appreciates the long-running collaboration by the four of us that has sought to understand better how arsonists and other illegal firesetters are affected by law enforcement and society. We are thrilled to be able to share the knowledge we have gained.”

Read the full text of the article.

For more information, email Jeff Prestemon at jeff.prestemon@usda.gov.

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