title: Areas of Agreement and Disagreement Regarding Ponderosa Pine and Mixed Conifer Forest Fire Regimes: A Dialogue with Stevens et al.
abstract: In a recent PLOS ONE paper, we conducted an evidence-based analysis of current versus historical fire regimes and concluded that traditionally defined reference conditions of low-severity fire regimes for ponderosa pine (Pinus ponderosa) and mixed-conifer forests were incomplete, missing considerable variability in forest structure and fire regimes. Stevens et al. (this issue) agree that high-severity fire was a component of these forests, but disagree that one of the several sources of evidence, stand age from a large number of forest inventory and analysis (FIA) plots across the western USA, support our findings that severe fire played more than a minor role ecologically in these forests. Here we highlight areas of agreement and disagreement about past fire, and analyze the methods Stevens et al. used to assess the FIA stand-age data. We found a major problem with a calculation they used to conclude that the FIA data were not useful for evaluating fire regimes. Their calculation, as well as a narrowing of the definition of high-severity fire from the one we used, leads to a large underestimate of conditions consistent with historical high-severity fire. The FIA stand age data do have limitations but they are consistent with other landscape-inference data sources in supporting a broader paradigm about historical variability of fire in ponderosa and mixed-conifer forests than had been traditionally recognized, as described in our previous PLOS paper.
authors.affiliation: Earth Research Institute, University of California Santa Barbara, Santa Barbara, California, United States of America.|Environmental Studies Department, Southern Oregon University, Ashland, Oregon, United States of America.
authors.forename: Dennis C
authors.initials: DC
authors.lastname: Odion
authors.affiliation: Earth Island Institute, Berkeley, California, United States of America.
authors.forename: Chad T
authors.initials: CT
authors.lastname: Hanson
authors.affiliation: Program in Ecology and Department of Geography, University of Wyoming, Laramie, Wyoming, United States of America.
authors.forename: William L
authors.initials: WL
authors.lastname: Baker
authors.affiliation: Geos Institute, Ashland, Oregon, United States of America.
authors.forename: Dominick A
authors.initials: DA
authors.lastname: DellaSala
authors.affiliation: Program in Ecology and Department of Geography, University of Wyoming, Laramie, Wyoming, United States of America.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Williams
mesh_terms: D004190:Disasters; D004463:Ecology; D017753:Ecosystem; D005390:Fires; D016468:Forestry / Q000379:methods*; D065928:Forests; D041604:Pinus ponderosa / Q000502:physiology*; D015203:Reproducibility of Results; D064028:Tracheophyta / Q000502:physiology*; D014197:Trees