First Advisor

Geoffrey Duh

Term of Graduation

Spring 2023

Date of Publication

7-25-2023

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Geography

Department

Geography

Language

English

Subjects

Western redcedar -- Habitat -- Mathematical models, Western redcedar -- Climatic factors -- Pacific Northwest, Geographic information systems, Dieback

DOI

10.15760/etd.3592

Physical Description

1 online resource (viii, 95, vi-xix pages)

Abstract

Climate change is a real phenomenon that is exacerbating existing natural processes and developing into a new normal for the planet. This change may be devastating for Pacific Northwest populations of Western Red Cedar (WRC) west of the Cascade Mountain range in the states of Oregon and Washington. WRC is a valuable tree species for reasons both economic and cultural. Dieback among WRC is following an accelerating trend. Since dieback is usually followed by tree mortality, understanding its causes and distribution is beneficial to the overall success of the species going into the future.

Through the use of ESRI's ArcGIS Pro software, I created a series of Multi-criteria Evaluation models based on Christine Buhl et al’s thresholds for climate predictor variables of WRC dieback. I tested each MCE score for spatial autocorrelation and statistically significant clustering in order to provide more confident results that could be applied by forest managers and other stakeholders. I used the R Statistical Software to further analyze my results and identify any meaningful differences within the data between the present and five different futures using Cohen's Kappa. Additionally, I included a pair of case studies focusing on two WRC watersheds and their respective indigenous, natural resource, and environmental characteristics to broaden the scope of WRC experiences.

I found that a warming climate was likely to cause a decrease in many areas' suitability as WRC habitat. Low latitude and low elevation sites had a greater likelihood of this decrease. Results suggested that elevation had a more observable influence on the predictor climate variables than did latitude. The potential loss or scarcity of WRC in the future will have negative impacts on many different people groups in the Pacific Northwest. Northerly and, especially, higher elevation sites within the study area should be prioritized by forest managers and commercial timber companies for prolonged stability in Western Red Cedar populations.

Rights

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

Persistent Identifier

https://archives.pdx.edu/ds/psu/40591

Download

Share

COinS