DOI: 10.5061/dryad.cz8w9gj1b
title: Data from: A trait-based approach to assessing resistance and resilience to wildfire in two iconic North American conifers

description: Ongoing changes in fire activity have the potential to drive widespread
 shifts in Earth’s vegetation. Plant traits and vital rates can be
 indicators of the ability of individuals to survive fire (resistance) and
 populations to persist (resilience) following fire and provide a
 method to assess vulnerability to fire-driven vegetation shifts.
 In 15 study sites spanning climatic gradients in the southern Rocky
 Mountains, U.S.A., we quantified variation in key traits and vital rates
 of two co-occurring, widely-distributed conifers (Pinus ponderosa Douglas
 ex. P. Lawson & C. Lawson and Pseudotsuga menziesii (Mirb.)
 Franco). We used mixed models to explain inter- and intraspecific
 variation in tree growth, survival, bark thickness, and seed cone
 production, as a function of species, tree life stage (i.e., diameter,
 height, and age), average climate, local competition, and site conditions.
 P. ponderosa was predicted to survive low-severity fire at a 23% earlier
 age than P. menziesii. P. ponderosa had thicker bark and more rapid
 juvenile height growth, traits conferring greater fire resistance. In
 contrast, P. menziesii was predicted to produce seed cones at a 28%
 earlier age than P. ponderosa. For both species, larger individuals were
 more likely to survive fire and to produce cones. For P. ponderosa, cone
 production increased where average actual evapotranspiration (AET) was
 higher and local competition was lower. More frequent cone production on
 productive sites with higher AET is an important and underappreciated
 mechanism that may help to explain greater resilience to fire in these
 areas. Synthesis:  Our analyses indicated that many plant traits
 and vital rates related to fire differed between P. ponderosa and P.
 menziesii, with trade-offs between investment in traits that promote
 individual defence to fire and those that promote recolonization of
 disturbed sites. Future changes in fire activity will act as a filter
 throughout North American forests, with our findings providing insight
 into which individuals and populations of two iconic species are most
 vulnerable to future change and offering a framework for future inquiry in
 other forests facing an uncertain future.
description: Datasets included in the final archive file are stored within the
 following subfolders. Brief descriptions are included below, but more
 detailed descriptions are provided in .docx files within each
 subfolder. 1) "AET and CWD": This folder
 includes two c. 250m climate grids used in the study. These data were
 clipped to bounds of the Southern Rocky Mountains Ecoregion (EPA Level III
 Ecoregion #21). Each dataset was initially calculated at 4km using the
 water balance equations of Dobrowski et al. (2013) and spatially
 downscaled using GIDS interpolation (Flint and Flint 2012). For a further
 description of processing, see Rodman et al. (2020; Global Ecology and
 Biogeography). AET is total actual evapotranspiration (evaporation
 constrained by moisture availability) for the calendar year. CWD is total
 climatic water deficit (unmet evaporative demand of the atmosphere) for
 the calendar year. All units are in mm/year in an average year in the
 1981-2010 period. These data were extracted to field plot locations and
 used in statistical models 2)
 "Fires_SpatialData": Contains a raster grid of Landsat-derived
 fire severity (Relative differenced Normalized Burn Ratio following Miller
 and Thode, 2007) clipped to the perimeters of the 15 studied wildfires, as
 well as a shape file of perimeters of each fire, obtained from the
 Monitoring Trends in Burn Severity program (Eidenshink et al.
 2007) 3) "Post-Fire Seedling Data": Includes
 three individual .csv files that contain much of the field data describing
 juveniles in "burned plots" included in this study. Briefly,
 these data include post-fire seedling abundances of coniferous tree
 species throughout each of 15 studied fires, site-level variables such as
 fire severity (percent basal area mortality), ground cover, forest
 structure, as well as the age, height, and bark thickness of individual
 juveniles of Pinus ponderosa, Pseudotsuga menziesii, and a few other
 species. For additional information on field collection protocol and data
 processing, see Rodman et al. (2020, J. Ecology).  4)
 "Resistance": Contains two individual .csv files with
 descriptions of trees that survived or died during each of the 15 fire
 events. Plot information within these data correspond to .csv files in
 "Post-Fire Seedling Data." For additional information on field
 collection protocol and data processing, see Rodman et al. (2020, J.
 Ecology) 5) "Ring Widths": Includes raw and
 processed ring width data from scans of increment cores, processed using
 WinDendro software. Data is primarily for Pinus ponderosa and is at 17
 individual stands in southern Colorado and northern New Mexico, USA. For
 additional information on field collection protocol and data processing,
 see Rodman et al. (2020, J. Ecology) 6) "Trees and
 Cone Scars": Includes one .csv that describes tree-level variables
 related to tree size, cone production, bark thickness, and other traits
 related to wildfire. All surveyed trees in this .csv were in stands that
 were unburned or burned at low severity. For additional information on
 field collection protocol and data processing, see Rodman et al. (2020, J.
 Ecology)
description: See "Rodman_J_Ecol_2020.html" in data archive for
 examples of use. See "README.txt" and metadata within the
 compressed archive files for usage notes. We encourage the user to contact
 the corresponding author (Kyle Rodman, Kyle.Rodman@colorado.edu) with any
 additional questions regarding data usage.