Mortality predispositions of conifers across western USA

New Phytologist
By: , and 



  • Conifer mortality rates are increasing in western North America, but the physiological mechanisms underlying this trend are not well understood.
  • We examined tree‐ring‐based radial growth along with stable carbon (C) and oxygen (O) isotope composition (δ13C and δ18O, respectively) of dying and surviving conifers at eight old‐growth forest sites across a strong moisture gradient in the western USA to retrospectively investigate mortality predispositions.
  • Compared with surviving trees, lower growth of dying trees was detected at least one decade before mortality at seven of the eight sites. Intrinsic water‐use efficiency increased over time in both dying and surviving trees, with a weaker increase in dying trees at five of the eight sites.
  • C starvation was a strong correlate of conifer mortality based on a conceptual model incorporating growth, δ13C, and δ18O. However, this approach does not capture processes that occur in the final months of survival. Ultimately, C starvation may lead to increased mortality vulnerability, but hydraulic failure or biotic attack may dominate the process during the end stages of mortality in these conifers.

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Publication type Article
Publication Subtype Journal Article
Title Mortality predispositions of conifers across western USA
Series title New Phytologist
DOI 10.1111/nph.16864
Volume 229
Issue 2
Year Published 2021
Language English
Publisher Wiley
Contributing office(s) Fort Collins Science Center, Western Ecological Research Center
Description 14 p.
First page 831
Last page 844
Country United States
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