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Title: Temperature response surfaces for mortality risk of tree species with future drought

Abstract

Widespread, high levels of tree mortality, termed forest die-off, associated with drought and rising temperatures, are disrupting forests worldwide. Drought will likely become more frequent with climate change, but even without more frequent drought, higher temperatures can exacerbate tree water stress. The temperature sensitivity of drought-induced mortality of tree species has been evaluated experimentally for only single-step changes in temperature (ambient compared to ambient + increase) rather than as a response surface (multiple levels of temperature increase), which constrains our ability to relate changes in the driver with the biological response. Here we show that time-to-mortality during drought for seedlings of two western United States tree species, Pinus edulis (Engelm.) and Pinus ponderosa (Douglas ex C. Lawson), declined in continuous proportion with increasing temperature spanning a 7.7 °C increase. Although P. edulis outlived P . ponderosa at all temperatures, both species had similar relative declines in time-to-mortality as temperature increased (5.2% per °C for P. edulis; 5.8% per °C for P. ponderosa). When combined with the non-linear frequency distribution of drought duration—many more short droughts than long droughts—these findings point to a progressive increase in mortality events with global change due to warming alone and independent of additional changes inmore » future drought frequency distributions. As such, dire future forest recruitment patterns are projected assuming the calculated 7-9 seedling mortality events per species by 2100 under business-as-usual warming occurs, congruent with additional vulnerability predicted for adult trees from stressors like pathogens and pests. Our progressive projection for increased mortality events was driven primarily by the non-linear shape of the drought duration frequency distribution, a common climate feature of drought-affected regions. These results illustrate profound benefits for reducing emissions of carbon to the atmosphere from anthropogenic sources and slowing warming as rapidly as possible to maximize forest persistence.« less

Authors:
ORCiD logo; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1422306
Report Number(s):
PNNL-SA-130379
Journal ID: ISSN 1748-9326
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Research Letters; Journal Volume: 12; Journal Issue: 11
Country of Publication:
United States
Language:
English
Subject:
drought; tree mortality; Pinus edulis; Pinus ponderosa; temperature; tree die-off; climate change ecology

Citation Formats

Adams, Henry D., Barron-Gafford, Greg A., Minor, Rebecca L., Gardea, Alfonso A., Bentley, Lisa Patrick, Law, Darin J., Breshears, David D., McDowell, Nate G., and Huxman, Travis E. Temperature response surfaces for mortality risk of tree species with future drought. United States: N. p., 2017. Web. doi:10.1088/1748-9326/aa93be.
Adams, Henry D., Barron-Gafford, Greg A., Minor, Rebecca L., Gardea, Alfonso A., Bentley, Lisa Patrick, Law, Darin J., Breshears, David D., McDowell, Nate G., & Huxman, Travis E. Temperature response surfaces for mortality risk of tree species with future drought. United States. doi:10.1088/1748-9326/aa93be.
Adams, Henry D., Barron-Gafford, Greg A., Minor, Rebecca L., Gardea, Alfonso A., Bentley, Lisa Patrick, Law, Darin J., Breshears, David D., McDowell, Nate G., and Huxman, Travis E. Wed . "Temperature response surfaces for mortality risk of tree species with future drought". United States. doi:10.1088/1748-9326/aa93be.
@article{osti_1422306,
title = {Temperature response surfaces for mortality risk of tree species with future drought},
author = {Adams, Henry D. and Barron-Gafford, Greg A. and Minor, Rebecca L. and Gardea, Alfonso A. and Bentley, Lisa Patrick and Law, Darin J. and Breshears, David D. and McDowell, Nate G. and Huxman, Travis E.},
abstractNote = {Widespread, high levels of tree mortality, termed forest die-off, associated with drought and rising temperatures, are disrupting forests worldwide. Drought will likely become more frequent with climate change, but even without more frequent drought, higher temperatures can exacerbate tree water stress. The temperature sensitivity of drought-induced mortality of tree species has been evaluated experimentally for only single-step changes in temperature (ambient compared to ambient + increase) rather than as a response surface (multiple levels of temperature increase), which constrains our ability to relate changes in the driver with the biological response. Here we show that time-to-mortality during drought for seedlings of two western United States tree species, Pinus edulis (Engelm.) and Pinus ponderosa (Douglas ex C. Lawson), declined in continuous proportion with increasing temperature spanning a 7.7 °C increase. Although P. edulis outlived P. ponderosa at all temperatures, both species had similar relative declines in time-to-mortality as temperature increased (5.2% per °C for P. edulis; 5.8% per °C for P. ponderosa). When combined with the non-linear frequency distribution of drought duration—many more short droughts than long droughts—these findings point to a progressive increase in mortality events with global change due to warming alone and independent of additional changes in future drought frequency distributions. As such, dire future forest recruitment patterns are projected assuming the calculated 7-9 seedling mortality events per species by 2100 under business-as-usual warming occurs, congruent with additional vulnerability predicted for adult trees from stressors like pathogens and pests. Our progressive projection for increased mortality events was driven primarily by the non-linear shape of the drought duration frequency distribution, a common climate feature of drought-affected regions. These results illustrate profound benefits for reducing emissions of carbon to the atmosphere from anthropogenic sources and slowing warming as rapidly as possible to maximize forest persistence.},
doi = {10.1088/1748-9326/aa93be},
journal = {Environmental Research Letters},
number = 11,
volume = 12,
place = {United States},
year = {Wed Nov 01 00:00:00 EDT 2017},
month = {Wed Nov 01 00:00:00 EDT 2017}
}