Sponsor
Portland State University. Department of Biology
First Advisor
Daniel Ballhorn
Term of Graduation
Spring 2024
Date of Publication
6-18-2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (Ph.D.) in Biology
Department
Biology
Language
English
DOI
10.15760/etd.3775
Physical Description
1 online resource (viii, 196 pages)
Abstract
In the context of rapid global climate change, understanding the resilience of local tree species is essential for fostering effective environmental stewardship and community hopefulness. Oregon white oak (Quercus garryana), an emblematic species in the Pacific Northwest, has faced significant habitat loss and degradation since settler colonization. However, it also exhibits a predicted resilience to climate change, potentially leading to a range shift and expansion. Species resilience refers to the capacity of a species to persist and adapt in the face of rapid global climate change. Beyond vulnerability assessments and niche models, we know little about this species' ability to adapt at varying timescales. This dissertation addresses these gaps in scientific knowledge of climate change impacts on Oregon white oak. It specifically addresses the species' overall adaptive capacity, phenotypic plasticity, and drivers of regeneration in its now highly urbanized environment. I address these gaps while recognizing that integrating Indigenous Traditional Ecological and Cultural Knowledge (ITECK) and respectful collaboration by land managers is key to the species' adaptive management.
My dissertation begins with a trait-based range-wide adaptive capacity assessment of Oregon white oak that integrates historical management narratives. The assessment reveals the species' vulnerabilities and strengths in adapting to climate change, emphasizing important traits related to evolutionary potential and how they can aid in species adaptation.
To further our understanding of how this species can adapt at shorter timescales, I explore what is known about plant phenotypic plasticity in a changing climate and present results on a climate factorial experiment conducted with Oregon white oak seedlings. These results are contextualized for land managers to help further our understanding of how phenotypic plasticity may be used and understood in a changing climate for plant materials selection.
Further, I delve into drivers of oak regeneration in high conservation priority urban and fragmented habitats within the Portland metro region. This field study identified landscape, community, and climate-level variables influencing the different age classes of oaks, providing insights for restoration and management decisions. The findings underscore the significance of habitat quality, connectivity, and community structure in supporting oak demography.
Bridging gaps in knowledge and emphasizing what Indigenous Peoples have shared about climate adaptation, this dissertation contributes to a comprehensive understanding of Oregon white oak's resilience. I end by emphasizing the necessity of collaborative approaches between Indigenous knowledge holders and Western scientists for effective climate adaptation strategies and increasing ecosystem resilience.
This dissertation aims to encourage local land managers to integrate climate adaptation and to make space for Indigenous people to practice ITECK as part of land management practices. To do this, Western land managers and scientists will have to overcome barriers of epistemology and embrace interdisciplinary work along with new ways of approaching restoration. Although this dissertation focuses on a single tree species, the study of Q. garryana resilience in the face of global climate change represents a crucial step in our regional understanding of climate adaptation and mitigation. Oregon white oak is beloved by many, and its climate resilience can be a symbol of hope for people to embrace climate adaptation strategies in times of ecological uncertainty.
Rights
© 2024 Jess Rose Nettle Shamek
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/42256
Recommended Citation
Shamek, Jess Rose Nettle, "Assessing the Climate Resilience of Quercus garryana in the Portland Metro Region" (2024). Dissertations and Theses. Paper 6643.
https://doi.org/10.15760/etd.3775