WWETAC Projects

Project Title: Case studies on risk analysis for fuel treatment planning

Status: Ongoing

Principal Investigators: Nicole Vaillant, WWETAC; Alan Ager, WWETAC; Mark Finney, USDA Forest Service, Rocky Mountain Research Station, Missoula, MT

E-mail Contact: Nicole Vaillant, nvaillant[at]fs.fed.us

Key Issues: Large investments in wildland fuel reduction projects are being made on federal lands in many regions within the United States in an ongoing effort by land management agencies to control human and ecological losses from catastrophic wildfire.  The implementation of these projects continues to challenge planners as they attempt to reduce fuels over extensive areas while addressing multiple and often conflicting federal planning regulations, management objectives, public expectations, and finite budgets.  Policies, constraints, and regulations that restrict treatment location, type, and total area treated, can significantly degrade the performance of a landscape fuel treatment strategy. For instance, focusing treatments in and around highly valued areas, such as the wildland urban interface (WUI), is less efficient and perhaps not compatible with landscape restoration goals to change large fire behavior. The long term compatibility of these divergent management objectives to protect relatively small WUI’s while also meeting large landscape forest restoration goals is not well understood. In fact, there are few case studies that examine the effect of alternative landscape fuel treatment strategies on fire behavior and fire effects.

Study Objectives and Goals: This work concerns the application of risk analysis for project planning.  Specifically, case studies are being completed to demonstrate the operational application and interpretation of risk analysis tools and models.  The methods combine formal risk analyses with wildfire simulation methods and provide a framework to quantitatively measure performance of the fuel treatments with risk based measures.  

General Description: Two case studies have been completed, one on the Mt. Emily wildland-urban interface, Wallowa Whitman National Forest, the other on the Five Buttes planning area, Deschutes National Forest.  The former study analyzed treatment strategies on a typical WUI in Eastern Oregon and determined the potential loss of large trees when fuel treatments were intended to reduce risk to structures rather than to reduce fire risk to large trees and old growth stands. The latter study examined the effects of different treatment intensities (area treated) on wildfire risk to Northern spotted owl habitat.

expected owl habitat loss graph

Expected loss (probability of owl habitat loss) with increasing area treated on the Five Buttes planning area

Both studies revealed spatial variation in burn probability and intensity that is useful for prioritizing fuels treatments to protect specific human and ecological values. Risk scatter plots and burn probability were developed as a decision tool for to evaluate risk, prioritize treatments, and measure the potential treatment effects (below). The methods employed here demonstrated a quantitative approach to risk assessment using existing models that are widely used within the USDA Forest Service and other public land management agencies in the US.

burn probability map

Burn probability and wildfire flow paths for the Five Buttes planning area  

flame length and burn probability scatter plotsExpected flame length and burn probability scatter plots for residential structures on the Mt Emily WUI. Two alternatives were analyzed: stand density (SDEN), which treated overstocked stands outside the WUI; and residential density (RDEN) which treated around structures. Treatment alternatives were 20% and 66% of the study area. The graph on the left shows a significant reduction in risk to structures when treatments are located outside the WUI.

Deliverables and Citations:

Ager, A.A, Vaillant, N.M., Finney, M.A. 2010. A comparison of landscape fuel treatment strategies to mitigate wildland fire risk in the urban interface and preserve old forest structure. Forest Ecology and Management 259:1556-1570

Ager, A.; Finney, M., Kerns, B.; Maffei, H. 2007.  Modeling wildfire risk to late successional forest reserves in the Pacific Northwest, USA.  Forest Ecology and Management 246:45-56.

Ager, A.; McMahan, A.; Barrett, J.; McHugh, C. 2007. A simulation study of forest restoration and fuels treatments on a wildland-urban interface. Landscape and Urban Planning 80:292-300.

Ager, A.A., Finney, M.A. McMahan, D.  2006 A wildfire risk modeling system for evaluating landscape fuel treatment strategies.  In: Andrews, P.L., Butler, B.W. (comp.),  Fuels Management-How to Measure Success.  USDA Forest Service, Rocky Mountain Research Station Proceedings RMRS-P-41. p 149-162.

Project ID: FY09AA68