Modeling fire susceptibility in west central Alberta, Canada Jennifer L. Beverly *, Emily P.K. Herd, J.C. Ross Conner Canadian Forest Service, Northern Forestry Centre, 5320-122 Street, Edmonton AB T6H 3S5, Canada 1. Introduction The composition and configuration of landscape vegetation types in northern forest ecosystems can influence wildfire susceptibility. Stands characterized by different species and age classes will have different fuel complexes and structures that will either support or restrict the spread of fire from adjacent stands. Homogenous fuel, weather, and topographic conditions across an area are generally associated with larger, more uniform fires because continuous areas become simultaneously receptive to fire ignition and spread (Turner and Romme, 1994; Delong, 1998; Ryan, 2002). In the Boreal and Foothills natural regions of Alberta, large but infrequent high-intensity fires are characteristic (Tym- stra et al., 2005). These fires kill the majority of the trees and over long periods and large spatial scales, produce a diverse mix of landscape patches that differ by age and cover type. Dominant tree species in these ecosystems can be divided into two groups—the conifer fuels that fires select for, such as white spruce (Picea glauca), black spruce (Picea mariana), and lodgepole pine (Pinus contorta) and the deciduous fuels, such as aspen (Populus tremuloides), that limit or arrest fire ignition and spread (Cumming, 2001; Krawchuk et al., 2006). Because the fires characteristic of these areas can affect large areas over short periods, they can pose a sudden and significant threat to forest resources, forest-based communities, and the industries and economic activity associated with both. Fire suppression has reduced area burned in northern forest ecosys- tems (Cumming, 2005; DeWilde and Chapin, 2006; Martell and Sun, 2008) and there are concerns that effective suppression over long time periods in these ecosystems may potentially contribute to increasing fuel continuity that could result in some fires reaching sizes that would otherwise have been constrained by the landscape mosaic. The mechanisms of this process are summarized by Chapin et al. (2008) for black spruce forests in boreal Alaska, where the moisture content of deciduous early post-fire succes- sional species are thought to create fuel breaks between adjacent Forest Ecology and Management 258 (2009) 1465–1478 ARTICLE INFO Article history: Received 5 February 2009 Received in revised form 29 June 2009 Accepted 30 June 2009 Keywords: Fuels treatment Fuel management Fire behavior Landscape simulation Burn-P3 Prometheus Fire growth model Forest management Fire risk Spatial scale ABSTRACT Strategic modification of forest vegetation has become increasingly popular as one of the few preemptive activities that land managers can undertake to reduce the likelihood that an area will be burned by a wildfire. Directed use of prescribed fire or harvest planning can lead to changes in the type and arrangement of forest vegetation across the landscape that, in turn, may reduce fire susceptibility across large areas. While among the few variables that fire managers can influence, fuel conditions are only one of many factors that determine fire susceptibility. Variations in weather and topography, in combination with fuels, determine which areas are more likely to burn under a given fire regime. An understanding of these combined factors is necessary to identify high fire susceptibility areas for prioritizing and evaluating strategic fuel management activities, as well as informing other fire management activities, such as community protection planning and strategic level allocation of fire suppression resources across a management area. We used repeated fire growth simulations, automated in the Burn-P3 landscape-fire simulation model, to assess spatial variations in fire susceptibility across a 2.4 million ha study area in the province of Alberta, Canada. The results were used to develop a Fire Susceptibility Index (FSI). Multivariate statistical analyses were used to identify the key factors that determine variation in FSI across the study area and to describe the spatial scale at which these variables influence fire susceptibility at a given location. A fuel management scenario was used to assess the impact of prescribed fire treatments on FSI. Results indicated that modeled fire susceptibility was strongly influenced by fuel composition, fuel arrangement, and topography. The likelihood of high or extreme FSI values at a given location was strongly associated with the percent of conifer forest within a 2-km radius, and with elevation and ignition patterns within a 5-km radius. Results indicated that prescribed fire treatments can be effective at reducing forest fire susceptibility in community protection zones and that simulation modeling is an effective means of evaluating spatial variation in landscape fire susceptibility. Crown Copyright ß 2009 Published by Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +1 780 430 3848. E-mail address: jbeverly@nrcan.gc.ca (J.L. Beverly). Contents lists available at ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco 0378-1127/$ – see front matter . Crown Copyright ß 2009 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.foreco.2009.06.052