Historical, Observed, and Modeled Wildfire Severity in Montane Forests of the Colorado Front Range

Rosemary L. Sherriff, Rutherford V. Platt, Thomas T. Veblen, Tania L. Schoennagel, Meredith H. Gartner, Ben Bond-Lamberty
2014 PLoS ONE  
Large recent fires in the western U.S. have contributed to a perception that fire exclusion has caused an unprecedented occurrence of uncharacteristically severe fires, particularly in lower elevation dry pine forests. In the absence of long-term fire severity records, it is unknown how short-term trends compare to fire severity prior to 20 th century fire exclusion. This study compares historical (i.e. pre-1920) fire severity with observed modern fire severity and modeled potential fire
more » ... r across 564,413 ha of montane forests of the Colorado Front Range. We used forest structure and tree-ring fire history to characterize fire severity at 232 sites and then modeled historical fire-severity across the entire study area using biophysical variables. Eighteen (7.8%) sites were characterized by low-severity fires and 214 (92.2%) by mixed-severity fires (i.e. including moderate-or high-severity fires). Difference in area of historical versus observed low-severity fire within nine recent (post-1999) large fire perimeters was greatest in lower montane forests. Only 16% of the study area recorded a shift from historical low severity to a higher potential for crown fire today. An historical fire regime of more frequent and low-severity fires at low elevations (,2260 m) supports a convergence of management goals of ecological restoration and fire hazard mitigation in those habitats. In contrast, at higher elevations mixed-severity fires were predominant historically and continue to be so today. Thinning treatments at higher elevations of the montane zone will not return the fire regime to an historic low-severity regime, and are of questionable effectiveness in preventing severe wildfires. Based on present-day fuels, predicted fire behavior under extreme fire weather continues to indicate a mixed-severity fire regime throughout most of the montane forest zone. Recent large wildfires in the Front Range are not fundamentally different from similar events that occurred historically under extreme weather conditions. Citation: Sherriff RL, Platt RV, Veblen TT, Schoennagel TL, Gartner MH (2014) Historical, Observed, and Modeled Wildfire Severity in Montane Forests of the Colorado Front Range. PLoS ONE 9(9): e106971. Data Availability: The authors confirm that, for approved reasons, some access restrictions apply to the data underlying the findings. Landscape-level datasets used in this study are publically available and specified in the manuscript and supplementary table -Table S1 (LANDFIRE cover type and fuels; DEM; instrumental climate data; fire behavior models; fuel models, MTBS fire severity maps). All landscape-level maps that were developed in this paper (historical fire severity, observed fire severity, modeled potential fire behavior) can be either downloaded (MTBS observed fire severity maps) or recreated using the publically available datasets described above with the modeling criteria specified in the manuscript. In addition, 232 sites were used from existing datasets (141 sites) and newly sampled datasets (91 sites). Data for 44 stand-level sites (Veblen et al. 2000) are already publically available through NOAA's International Multiproxy Paleofire Database (IMPD; http://www.ncdc.noaa.gov/paleo/impd/) and the remaining 76 stand-level sites (fire-scar and tree age data) will be input into the IMPD over the next month (expected by August 31). The site-level data can be accessed through the IMPD by author/investigator (Schoennagel, Sherriff, and Veblen) with the publication source. The remaining 112 plot-level sites were assessed from field observations where only a small number of trees (,10 trees/site) were sampled to estimate tree establishment patterns and we tallied information about fire history and forest structure (as described in the manuscript).
doi:10.1371/journal.pone.0106971 pmid:25251103 pmcid:PMC4175072 fatcat:3omzzra34bcypmldcwl3kdyj2y