Ability of seedlings to survive heat and drought portends future demographic challenges for five southwestern US conifers

Climate change and disturbance are altering forests and the rates and locations of tree regeneration. We examined seedling survival of five southwestern United States (US) conifer species found in warmer and drier woodlands (Pinus edulis, P. ponderosa) and cooler and wetter subalpine forests (Pseudotsuga menziesii, Abies concolor, and Picea engelmanii) under hot and dry conditions in incubators. We constructed models that explained 53% to 76% of the species-specific survival variability, then applied these to recent climate (1980-2019) and projected climate (1980-2099) for the southwestern US. We found that lower elevations within species’ range would have low survival under projected climate and that range contraction would be greatest for species that currently occupy warm-dry conditions. These results demonstrate that empirically derived physiological limitations can be used to identify where species composition or vegetation type change are likely to occur in the southwest US., We obtained 135 one growth year old seedlings of each species (675 seedlings total) from the New Mexico State University John T. Harrington Forestry Research Center in Mora, NM between April 2020 and September 2021. Seedlings were grown from locally sourced seeds from mature trees in northern New Mexico to ensure that they represented local adaptation to conditions. Seedlings were grown in a greenhouse in 10 cm containers at staggered intervals to ensure that they were of similar age and size when they were placed in the incubators.
We transplanted seedlings into 22 cm deep pots (volume: 590 cm3) with well-drained soil (2 parts sphagnum moss, 1.5 parts vermiculate, 1.5 parts sand) brought to field capacity following transplanting. We allowed soil moisture to draw down to the treatment level, measuring soil moisture gravimetrically. Once soil moisture matched the treatment condition, we randomly assigned seedlings to one of two Percival Model E-36L1 incubators. We intended to use 15 seed..., Application: R/Rstudio
Package List: 'dplyr','ggpubr','hexbin','raster','sp','','terra','Survival','brms','car','cowplot','curl','ggplot2','grid','gtable','lubridate','readr','reshape2','sf'
'sjPlot','stringr','surrosurv','tidybayes','tidyr','wesanderson','broom','geomtextpath', # Ability of seedlings to survive heat and drought portends future range contractions for five southwestern US conifers

This readme file was generated on 2023-01-03 by Joseph L Crockett

## Author/Principal Investigator Information

Name: Joseph L. Crockett

Institution: University of New Mexico

Address: Department of Biology, University of New Mexico, MSC03 2020, Albuquerque, NM 87131-0001, United States

Email:

## Associate or Co-investigator Contact Information

Name: Matthew D. Hurteau

Institution:University of New Mexico

Address: Department of Biology, University of New Mexico, MSC03 2020, Albuquerque, NM 87131-0001, United States

Email:

## Date of data collection: April 2020 - September 2021

## Geographic location of data collection: New Mexico, CA

Information about funding sources that supported the collection of the data:

This work was supported by the Interagency Carbon Cycle Science program Grant No. 2017-67004-26486/ project accession no. 1012226 from the USDA Nat...