DOI: 10.5061/dryad.0rxwdbs47
title: Data from: Reduced fire severity offers near-term buffer to climate-driven declines in conifer resilience across the western United States

description: The combination of increasing fire-caused tree mortality and warmer, drier
 post-fire conditions is making forests in the western United States (West)
 vulnerable to ecological transformation. Yet, the relative importance of
 and interactions between these drivers of forest change remain unresolved,
 particularly over upcoming decades. Here we assess how the interactive
 impacts of changing climate and wildfire activity influenced conifer
 regeneration after 334 wildfires, using a novel dataset of post-fire
 conifer regeneration from 10,230 field plots. Our findings highlight
 declining regeneration capacity across the West over the past four decades
 for the eight dominant conifer species studied. Post-fire regeneration is
 sensitive to high-severity fire, which limits seed availability, and
 post-fire climate, which influences seedling establishment and survival.
 In the near-term, projected differences in recruitment probability between
 low- and high-severity fire scenarios were larger than projected impacts
 of climate change for most species, suggesting that reductions in fire
 severity, and resultant impacts on seed availability, could partially
 offset expected climate-driven declines in post-fire regeneration. Across
 40–42% of the study area, we project post-fire conifer regeneration to be
 likely following low-severity but not high-severity fire under future
 climate scenarios (2031–2050). However, increasingly warm, dry climate
 conditions are projected to eventually outweigh the influence of fire
 severity and seed availability. The percent of the study area considered
 unlikely to experience conifer regeneration, regardless of fire severity,
 increased from 5% in 1981–2000 to 26–31% by mid-century, highlighting a
 limited time window over which management actions that reduce fire
 severity may effectively support post-fire conifer regeneration.
description: This archive includes field data and various spatial datasets
 used in Davis et al. (2023).  Individual datasets in
 the Dryad archive include the following: 1) Field data.
 This data includes post-fire regeneration density for eight conifer
 species from the western US that were surveyed in plots 2–30 years
 following fire. Predictors that were used in the manuscript "Reduced
 fire severity offers near-term buffer to climate-driven declines in
 conifer resilience across the western United States" are included
 with each plot including climate data, fire severity, heat insolation load
 index, surrounding tree cover, and distance to nearest live seed source.
 The dataset is a compilation of many datasets. The field methods performed
 to collect the data varied by dataset/study and are described in detail in
 each individual study. For a list of the publications that produced each
 individual dataset please see the supplemental information Table S1 from
 Davis et al. 2023, the provided .csv file called
 "data_dryad_contributor_key.csv" or the definitions for each of
 the values of the contributor id column in the metadata. 
 2) Statistical models. The final models for recruitment
 probability for each species and for all species combined are included as
 .rds files.  3) Projections of recruitment probability
 made with the final models for 10-years post-fire under four climate
 scenarios (1981–2000, 2001–2020, 2031–2050 RCP 4.5, 2031–2050 RCP 8.5) and
 two fire severity scenarios (low severity: 10 m to a seed source, 30%
 surrounding live tree cover within 300-m radius of plot, relativized burn
 ratio (RBR) of 100; high severity: 150 m to a seed source, 10% surrounding
 live tree cover within 300-m radius of plot, RBR of 400). Plot size in
 projections is set to 100 m<sup>2</sup> so the projections can
 be interpreted as the probability of at least one seedling regenerating by
 10 years post-fire in a 100 m<sup>2</sup> plot under the given
 climate and fire severity scenario, which is equivalent to a density of
 100 trees ha<sup>-1</sup> or around 40 trees
 acre<sup>-1</sup>. Please note that the threshold probability
 at which recruitment is considered likely varies between species due to
 differences in the models. Therefore when interpreting the probabilities
 it is not appropriate to compare raw probabilities between species. It is
 best to interpret the probabilities in light of the provided threshold
 probabilities above which recruitment is most likely.