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Mortality predispositions of conifers across western USA
Author(s) -
Wang Wenzhi,
English Nathan B.,
Grossiord Charlotte,
Gessler Arthur,
Das Adrian J.,
Stephenson Nathan L.,
Baisan Christopher H.,
Allen Craig D.,
McDowell Nate G.
Publication year - 2021
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16864
Subject(s) - δ13c , biology , ecology , dendrochronology , mortality rate , demography , stable isotope ratio , paleontology , physics , quantum mechanics , sociology
Summary 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 ( δ 13 C and δ 18 O, 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, δ 13 C, and δ 18 O. 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.