DOI: 10.5061/dryad.gt22vt4
title: Data from: Impacts of growing-season climate on tree growth and post-fire regeneration in ponderosa pine and Douglas-fir forests

description: We studied the impacts of climate variability on low-elevation forests in
 the U.S. northern Rocky Mountains by quantifying how post-fire tree
 regeneration and radial growth varied with growing-season climate. We
 reconstructed post-fire regeneration and radial growth rates of Pinus
 ponderosa and Pseudotsuga menziesii at 33 sites
 that burned between 1992 and 2007, by aging seedlings at the root-shoot
 boundary. We also measured radial growth in adult trees from 12 additional
 sites that burned between 1900 and 1990. To quantify the relationship
 between climate and regeneration, we characterized seasonal climate
 before, during, and after recruitment pulses using superposed epoch
 analysis. To quantify growth sensitivity to climate, we performed moving
 regression analysis for each species and for juvenile and adult life
 stages. Climatic conditions favoring regeneration and tree growth differed
 between species. Water deficit and temperature were significantly lower
 than average during recruitment pulses of ponderosa pine, suggesting that
 germination-year climate limits regeneration. Growing degree days were
 significantly higher than average during years with Douglas-fir
 recruitment pulses, but water deficit was significantly lower one year
 following pulses, suggesting moisture sensitivity in two-year-old
 seedlings. Growth was also sensitive to water deficit, but effects varied
 between life stages, species, and through time, with juvenile ponderosa
 pine growth more sensitive to climate than adult growth and juvenile
 Douglas-fir growth. Increasing water deficit corresponded with reduced
 adult growth of both species. Increases in maximum temperature and water
 deficit corresponded with increases in juvenile growth of both species in
 the early 20th century but strong reductions in growth for juvenile
 ponderosa pine in recent decades. Changing sensitivity of growth to
 climate suggests that increased temperature and water deficit may be
 pushing these species towards the edge of their climatic tolerances. Our
 study demonstrates increased vulnerability of dry mixed-conifer forests to
 post-fire regeneration failures and decreased growth as temperatures and
 drought increase. Shifts towards unfavorable conditions for regeneration
 and juvenile growth may alter the composition and resilience of
 low-elevation forests to future climate and fire activity.
description: Hankin_et_al_2019_Ecosphere_DataThis archive includes regeneration, ring width, and climate data needed to reproduce the results presented in Hankin et al. (2019). The archived script and data should be extracted to the same directory to run the script for analysis. The archive contains six .csv files. Methods for the collection of these data are described in Hankin et al. (2018).Hankin_et_al_2019_Ecosphere_CodeThis archive includes the R script to reproduce the results presented in Hankin et al. (2019). The archived script and data should be extracted to the same directory to run the script for analysis.