Fuel treatments and landform modify landscape patterns of burn severity in an extreme fire event.

Under a rapidly warming climate, a critical management issue in semiarid forests of western North America is how to increase forest resilience to wildfire. We evaluated relationships between fuel reduction treatments and burn severity in the 2006 Tripod Complex fires, which burned over 70,000 ha of mixed-conifer forests in the North Cascades range of Washington State and involved 387 past harvest and fuel treatment units. A secondary objective was to investigate other drivers of burn severity including landform, weather, vegetation characteristics, and a recent mountain pine beetle outbreak. We used sequential autoregression (SAR) to evaluate drivers of burn severity, represented by the relative differenced Normalized Burn Ratio index, in two study areas that are centered on early progressions of the wildfire complex. Significant predictor variables include treatment type, landform (elevation), fire weather (minimum relative humidity and maximum temperature), and vegetation characteristics, including canopy closure, cover type, and mountain pine beetle attack. Recent mountain pine beetle damage was a statistically significant predictor variable with red and mixed classes of beetle attack associated with higher burn severity. Treatment age and size were only weakly correlated with burn severity and may be partly explained by the lack of treatments older than 30 years and the low rates of fuel succession in these semiarid forests. Even during extreme weather, fuel conditions and landform strongly influenced patterns of burn severity. Fuel treatments that included recent prescribed burning of surface fuels were particularly effective at mitigating burn severity. Although surface and canopy fuel treatments are unlikely to substantially reduce the area burned in regional fire years, recent research, including this study, suggests that they can be an effective management strategy for increasing forest landscape resilience to wildfires.

[1]  B. Quayle,et al.  A Project for Monitoring Trends in Burn Severity , 2007 .

[2]  Paulo M. Fernandes,et al.  A review of prescribed burning effectiveness in fire hazard reduction , 2003 .

[3]  J. Littell,et al.  Climatic Water Balance and Regional Fire Years in the Pacific Northwest, USA: Linking Regional Climate and Fire at Landscape Scales , 2011 .

[4]  Robert E. Keane,et al.  Objectives and considerations for wildland fuel treatment in forested ecosystems of the interior western United States , 2008 .

[5]  M. Turner,et al.  Do mountain pine beetle outbreaks change the probability of active crown fire in lodgepole pine forests , 2011 .

[6]  Donald McKenzie,et al.  How Robust Are Burn Severity Indices When Applied in a New Region? Evaluation of Alternate Field-Based and Remote-Sensing Methods , 2012, Remote. Sens..

[7]  P. Fulé,et al.  Do thinning and/or burning treatments in western USA ponderosa or Jeffrey pine-dominated forests help restore natural fire behavior? , 2012 .

[8]  W. Cohen,et al.  Estimating the age and structure of forests in a multi-ownership landscape of western Oregon, U.S.A. , 1995 .

[9]  T. Spies,et al.  Vegetation and weather explain variation in crown damage within a large mixed-severity wildfire. , 2009 .

[10]  N. Coops,et al.  Estimating burn severity from Landsat dNBR and RdNBR indices across western Canada. , 2010 .

[11]  S. Stephens,et al.  Stand-replacing patches within a ‘mixed severity’ fire regime: quantitative characterization using recent fires in a long-established natural fire area , 2010, Landscape Ecology.

[12]  J. Hicke,et al.  Effects of bark beetle-caused tree mortality on wildfire , 2012 .

[13]  T. Swetnam,et al.  Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity , 2006, Science.

[14]  Susan J. Prichard,et al.  Fuel treatments reduce the severity of wildfire effects in dry mixed conifer forest, Washington, USA , 2010 .

[15]  Max A. Moritz,et al.  SPATIOTEMPORAL ANALYSIS OF CONTROLS ON SHRUBLAND FIRE REGIMES: AGE DEPENDENCY AND FIRE HAZARD , 2003 .

[16]  P. Fulé,et al.  Pre-wildfire fuel treatments affect long-term ponderosa pine forest dynamics , 2007 .

[17]  D. Peterson,et al.  Surface fuel treatments in young, regenerating stands affect wildfire severity in a mixed conifer forest, eastside Cascade Range, Washington, USA , 2012 .

[18]  H. Akaike.  A new look at the statistical model identification , 1974 .

[19]  Matthias M. Boer,et al.  Long-term impacts of prescribed burning on regional extent and incidence of wildfires : evidence from 50 years of active fire management in SW Australian forests , 2009 .

[20]  Jay D. Miller,et al.  Mapping forest post-fire canopy consumption in several overstory types using multi-temporal Landsat TM and ETM data , 2002 .

[21]  W. Jolly,et al.  Do mountain pine beetle outbreaks change the probability of active crown fire in lodgepole pine forests? Comment. , 2012, Ecology.

[22]  Garry D. Peterson.  Contagious Disturbance, Ecological Memory, and the Emergence of Landscape Pattern , 2002, Ecosystems.

[23]  J. Régnière,et al.  Climate Change and Bark Beetles of the Western United States and Canada: Direct and Indirect Effects , 2010 .

[24]  Dominik Kulakowski,et al.  Effect of prior disturbances on the extent and severity of wildfire in Colorado subalpine forests. , 2007, Ecology.

[25]  Carl N. Skinner,et al.  Basic principles of forest fuel reduction treatments , 2005 .

[26]  Sandra L. Haire,et al.  Effects of landscape patterns of fire severity on regenerating ponderosa pine forests (Pinus ponderosa) in New Mexico and Arizona, USA , 2010, Landscape Ecology.

[27]  Myoung-Soo Won,et al.  Relationship between landscape structure and burn severity at the landscape and class levels in Samchuck, South Korea , 2009 .

[28]  Michael Battaglia,et al.  Can prescribed fire be used to maintain fuel treatment effectiveness over time in Black Hills ponderosa pine forests , 2008 .

[29]  S. Stephens,et al.  Fuel treatment longevity in a Sierra Nevada mixed conifer forest , 2012 .

[30]  P. Hessburg,et al.  Restoring forest resilience: From reference spatial patterns to silvicultural prescriptions and monitoring , 2013 .

[31]  M. Turner,et al.  Landscape dynamics in crown fire ecosystems , 1994, Landscape Ecology.

[32]  D. Kulakowski,et al.  The influence of mountain pine beetle outbreaks and drought on severe wildfires in northwestern Colorado and southern Wyoming: A look at the past century , 2011 .

[33]  J. Agee.  Fire Ecology of Pacific Northwest Forests , 1993 .

[34]  Russell A. Parsons,et al.  Numerical Simulation of Crown Fire Hazard Immediately after Bark Beetle-Caused Mortality in Lodgepole Pine Forests , 2012 .

[35]  E. Johnson,et al.  The Relative Importance of Fuels and Weather on Fire Behavior in Subalpine Forests , 1995 .

[36]  M. Finney.  Design of Regular Landscape Fuel Treatment Patterns for Modifying Fire Growth and Behavior , 2001, Forest Science.

[37]  Jay D. Miller,et al.  Quantifying burn severity in a heterogeneous landscape with a relative version of the delta Normalized Burn Ratio (dNBR) , 2007 .

[38]  A. Weaver,et al.  Detecting the effect of climate change on Canadian forest fires , 2004 .

[39]  Robert A. Norheim,et al.  Forest ecosystems, disturbance, and climatic change in Washington State, USA , 2010 .

[40]  P. Hessburg,et al.  Dry forests and wildland fires of the inland Northwest USA: Contrasting the landscape ecology of the pre-settlement and modern eras , 2005 .

[41]  W. Keeton,et al.  Disturbances and structural development of natural forest ecosystems with silvicultural implications, using Douglas-fir forests as an example , 2002 .

[42]  飯塚 寛,et al.  Aspect transformation in site productivity research , 1967 .

[43]  Michael C Wimberly,et al.  Assessing fuel treatment effectiveness using satellite imagery and spatial statistics. , 2009, Ecological applications : a publication of the Ecological Society of America.

[44]  Jon E. Keeley,et al.  Ecological effects of large fires on US landscapes: benefit or catastrophe? , 2008, International Journal of Wildland Fire.

[45]  Richard Field,et al.  Spatial patterns of woody plant and bird diversity: functional relationships or environmental effects? , 2008 .

[46]  Charles W. McHugh,et al.  Stand- and landscape-level effects of prescribed burning on two Arizona wildfires , 2005 .

[47]  Frederick W. Smith,et al.  Influence of topography and forest structure on patterns of mixed severity fire in ponderosa pine forests of the South Dakota Black Hills, USA , 2006 .

[48]  S. Stephens,et al.  The Effects of Forest Fuel-Reduction Treatments in the United States , 2012 .

[49]  P. Morgan,et al.  Multi-season climate synchronized forest fires throughout the 20th century, northern Rockies, U.S.A. , 2008, Ecology.

[50]  Joseph W. Sherlock,et al.  Calibration and validation of the relative differenced Normalized Burn Ratio (RdNBR) to three measures of fire severity in the Sierra Nevada and Klamath Mountains, California, USA , 2009 .

[51]  Christof Bigler,et al.  MULTIPLE DISTURBANCE INTERACTIONS AND DROUGHT INFLUENCE FIRE SEVERITY IN ROCKY MOUNTAIN SUBALPINE FORESTS , 2005 .

[52]  C. A. Cansler.  Drivers of burn severity in the northern Cascade Range, Washington, USA , 2011 .

[53]  Z. Gedalof,et al.  ATMOSPHERIC, CLIMATIC, AND ECOLOGICAL CONTROLS ON EXTREME WILDFIRE YEARS IN THE NORTHWESTERN UNITED STATES , 2005 .

[54]  F van Langevelde,et al.  Spatial autocorrelation and the scaling of species-environment relationships. , 2010, Ecology.

[55]  M. Cochrane,et al.  Do mountain pine beetle outbreaks change the probability of active crown fire in lodgepole pine forests? Comment. , 2012, Ecology.

[56]  W. D. Kissling,et al.  Spatial autocorrelation and the selection of simultaneous autoregressive models , 2007 .

[57]  Donald McKenzie,et al.  Climatic Change, Wildfire, and Conservation , 2004 .

[58]  A. Latimer,et al.  Fuel treatment effectiveness in California yellow pine and mixed conifer forests , 2012 .

[59]  N. Mantua,et al.  Climate drivers of regionally synchronous fires in the inland Northwest (1651-1900) , 2008 .

[60]  R. Haining.  Spatial Data Analysis in the Social and Environmental Sciences , 1990 .

[61]  P. Moorcroft,et al.  The Influence of Previous Mountain Pine Beetle (Dendroctonus ponderosae) Activity on the 1988 Yellowstone Fires , 2006, Ecosystems.

[62]  Nicholas C. Coops,et al.  Estimating the probability of mountain pine beetle red-attack damage , 2006 .

[63]  M. Newcomer,et al.  Burn Severity Assessment in the Okanogan-Wenatchee Forest Using NASA Satellite Missions , 2008 .

[64]  Luca Vogt.  Statistics For Spatial Data , 2016 .

[65]  D. Peterson,et al.  Climate and wildfire area burned in western U.S. ecoprovinces, 1916-2003. , 2009, Ecological applications : a publication of the Ecological Society of America.

[66]  Jay D. Miller,et al.  Trends in Wildfire Severity: 1984 to 2010 in the Sierra Nevada, Modoc Plateau, and Southern Cascades, California, USA , 2012, Fire Ecology.

[67]  M. Moritz,et al.  Native Fire Regimes and Landscape Resilience , 2011 .

[68]  David S. Pilliod,et al.  Pattern and process of prescribed fires influence effectiveness at reducing wildfire severity in dry coniferous forests , 2012 .

[69]  R Core Team,et al.  R: A language and environment for statistical computing. , 2014 .

[70]  E. Knapp,et al.  Trends and causes of severity, size, and number of fires in northwestern California, USA. , 2012, Ecological applications : a publication of the Ecological Society of America.

[71]  Michael A. Wulder,et al.  Sensitivity of the thematic mapper enhanced wetness difference index to detect mountain pine beetle red-attack damage , 2003 .

[72]  M. Flannigan,et al.  Future Area Burned in Canada , 2005 .

[73]  Colin M Beale,et al.  Regression analysis of spatial data. , 2010, Ecology letters.

[74]  Carl H. Key,et al.  Ecological and Sampling Constraints on Defining Landscape Fire Severity , 2006 .

[75]  S. Stephens,et al.  Spatial patterns of large natural fires in Sierra Nevada wilderness areas , 2007, Landscape Ecology.