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Mortality predispositions of conifers across Western USA

journal contribution
posted on 20.04.2021, 03:42 by Wenzhi Wang, Nathanael Brooks-English, Charlotte Grossiord, Arthur Gessler, Adrian J Das, Nathan L Stephenson, Christopher H Baisan, Craig D Allen, Nate G McDowell
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 incor- porating 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.

History

Volume

229

Issue

2

Start Page

831

End Page

844

Number of Pages

14

eISSN

1469-8137

ISSN

0028-646X

Location

England

Publisher

Wiley

Language

en

Peer Reviewed

Yes

Open Access

No

Acceptance Date

03/08/2020

External Author Affiliations

US Geological Survey, University of Arizona, US Geological Survey, Pacific Northwest National Laboratory, USA; Swiss Federal Institute for Forest, Snow and Landscape WSL, Switzerland

Era Eligible

Yes

Medium

Print-Electronic

Journal

New Phytologist

Article Number

nph.16864