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Alternative title

Dendroclimatology of Alaska yellow cedar (Callitropsis nootkatensis) in the West Cascades

Date Permissions Signed

8-17-2019

Date of Award

Summer 2019

Document Type

Masters Thesis

Department or Program Affiliation

Huxley College of Environmental Science

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Bunn, Andrew Goddard

Second Advisor

Helfield, James M.

Third Advisor

Mitchell, Robert J. (Geologist)

Abstract

Subalpine tree growth in the Washington Cascades is often limited by both growing season temperatures and persistence of the winter snowpack, making paleoclimate inferences on temperature alone difficult. Here I expand on three yellow cedar chronologies on the west slopes of the North Cascades and build chronologies for two co-dominant species at one of the sites. I used the VIC hydrologic model to include biologically relevant proxies for water stress, including evapotranspiration deficit, and snow cover in a climate-growth analysis. The co-dominant species, specifically mountain hemlock, showed a climate response reminiscent of a high-elevation, energy-limited environment with an interaction between temperature and winter snow persistence. The first PC of the yellow cedar chronologies showed a strong relationship with growing season minimum temperature (R$^2=0.49$), and I did not find a strong correlation with any water stress variables. A temperature reconstruction built with a simple linear model is skillful throughout much of western Washington (CE > 0.35) and is consistent with other global and hemispheric reconstructions at low frequencies, differing at the decadal or shorter time scale. This suggests that yellow cedar at these sites may be a useful single-species proxy for temperature on the Pacific slopes of the North Cascades. Having this proxy would be helpful for understanding regional temperature add climate variability as well as adding spatial resolution to global reconstructions that are currently lacking the maritime influence on temperature in the Pacific Northwest.

Type

Text

Keywords

Yellow cedar, VIC, temperature reconstruction, mountain hemlock, pacific silver fir, Washington Cascades

Publisher

Western Washington University

OCLC Number

1112497051

Subject – LCSH

Dendroclimatology--North Cascades (B.C. and Wash.); Callitropsis nootkatensis--North Cascades (B.C. and Wash.); Dendrochronology--North Cascades (B.C. and Wash.); Paleoclimatology--Holocene

Geographic Coverage

North Cascades (B.C. and Wash.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

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