MS Title: Wildfires and climate change push low-elevation forests across a critical climate threshold for tree regeneration MS Authors: Kimberley T. Davis, Solomon Z. Dobrowski, Philip E. Higuera, Zachary A. Holden, Thomas T. Veblen, Monica T. Rother, Sean A. Parks, Anna Sala, Marco P. Maneta MS Journal: PNAS **FILES' NAMES AND CONTENTS** Davis_et_al_climate_timeseries.csv - Annual maximum surface temperature, soil mositure of the driest month, spring soil moisture, mean summer vapor pressure deficit, AET, PET, and climateic water deficit for each site. Davis_et_al_recruitment_plot_data.csv - Annual recruitment and site information for each site. **FILES' STRUCTURES AND UNITS OF MEASUREMENTS** Davis_et_al_climate_timeseries.csv The file is a comma delimited file. Column headings are in the following order and format: site - Name of the site. year - Year of the climate conditions that follow. tskin_max - Maximum land surface temperature (degrees Celsius) occuring in each year. vwc_mean_driestM - Mean soil moisture (volumetric water content) in the driest month of the growing season (March-October) in the top 10 cm of the soil. vwc_mean345 - Mean soil moisture (volumetric water content) in the spring (March-May) in the top 10 cm of the soil. vpd_mean678 - Mean vapor pressure deficit (kPa) of the summer (June-August). aet - Annual actual evapotranspiration (mm). pet - Annual potential evapotranspiration (mm). def - Annual climatic water deficit (mm). Davis_et_al_recruitment_plot_data.csv The file is a comma delimited file. Column headings are in the following order and format: site - Name of the site. Each site contained one belt transect that was 60 m long and varied in width from 2-40 m depending on juvenile tree density. year - Year in which recruitment occurred and which climate data are for. species - Species of tree that recruitment density refers to. Either PIPO (ponderosa pine, Pinus ponderosa) or PSME (Douglas-fir, Pseudotsuga menziesii). region - Region that the study site was located in. CA - northern California, CO - Colorado's Front Range, NR - Northern Rockies (Idaho and Montana), or SW - Southwest Mountains (Arizona and New Mexico). fire_year - Year that the fire in which the sample site is located occurred. sample_year - Year that site was sampled. time_since_fire - Time between the fire year and the year of recruitment ("pith_year"). count - Number of trees of the given species that recruited in the given "pith_year" at the given site. Note that sampled belt transect area differed at each site depending on regeneration density so these raw counts need to be adjusted for transect area. proportion - Proportion of all the regeneration of the given species at the given site that occurred in the given "pith_year." density - Annual recruitment density (trees/m^2) of the given species at the given site that occurred in the given "pith_year." This is the count divided by the transect area for the given species. fire - Name of the fire in which the site was located. Long_WGS84 - Longitude of the site (decimal degrees; datum WGS1984). Lat_WGS84 - Latitude of the site (decimal degrees; datum WGS1984). fire_severity - Fire severity class assigned to the site by the Monitoring Trends in Burn Severity database. transect_areaPSME - Area (m^2) of the belt transect that was used to destructively sample Douglas-fir (PSME) juveniles for aging. transect_areaPIPO - Area (m^2) of the belt transect that was used to destructively sample ponderosa pine (PIPO) juveniles for aging. aspect - Aspect of the site (degrees) recorded in the field with a compass. slope - Slope of the site (%) recorded in the field with a clinometer. dist_PIPO_seed_source - Distance (m) to the nearest mature (cone-bearing) ponderosa pine (PIPO) individual measured with a laser range finder. dist_PSME_seed_source - Distance (m) to the nearest mature (cone-bearing) Douglas-fir (PSME) individual measured with a laser range finder. mean_litter_cover - Mean percent litter cover in the three 3x2 m subplots that were sampled along the center of the transect (at 0, 30, 57 m). mean_shrub_cover - Mean percent shrub cover in the three 3x2 m subplots that were sampled along the center of the transect (at 0, 30, 57 m). mean_grass_cover - Mean percent grass cover in the three 3x2 m subplots that were sampled along the center of the transect (at 0, 30, 57 m). mean_forb_cover - Mean percent forb cover in the three 3x2 m subplots that were sampled along the center of the transect (at 0, 30, 57 m). PIPO_taken - Number of ponderosa pine juveniles destructively sampled and brought back to the lab for aging. PSME_taken - Number of Douglas-fir juveniles destructively sampled and brought back to the lab for aging. tree_mortality - Estimated tree moratlity (%) recorded in the field to verify that sites burned at moderate to high severity. dnbr - Fire severity (differenced normalized burn ratio) extracted for the 30x30 m cell in which the transect fell from the Monitoring Trends in Burn Severity database. Where the transect crossed two cells with different dNBR values they were averaged. cv_group - The name of the fire, used to group folds for cross validation in gbm.step (boosted regression tree models). In cases where none of the plots within a fire had recruitment above our annual recruitment thresholds that fire was included with the most similar (climatically and geographically) fire to it for the purposes of cross validation. def30 - 30-year mean (1980-2009) annual climatic water deficit (mm) from Dobrowski et al. 2013. **DATA QUESTIONS** Questions about data can be addressed to Kimberley Davis (kimberley.davis@umontana.edu).