Geography Commons^™

Identifying The Drivers Behind The Decline Of Douglas-Fir And True Fir Species In Sw Oregon, Alexander Bryant Bentley

Dissertations and Theses

Increased levels of Pseudotsuga menziesii (DF) and Abies species (TF) decline throughout dry forests in the Klamath Mountains and Western Cascades ecoregions have been recorded in recent years, with preliminary evidence suggesting that factors influenced by changing climatic conditions and encroachment from fire suppression policies are primarily to blame. Yet, the physiological and environmental mechanisms of drought-driven tree decline are poorly understood across biophysical and spatial gradients. Given the complex relations that drive decline, determining the degree of influence of specific drivers is difficult, creating unique challenges for modern forest management. To elucidate the most important factors driving DF and …

Sunrise At The Salton Sea: Environmental Justice, Land Use Change, And Hydrosocial Dynamics Of Solar Energy Transitions In The Imperial Valley, California, Dustin Mulvaney, James J. A. Blair, Alida Cantor

Geography Faculty Publications and Presentations

California's Imperial Valley, with lithium-rich geothermal brines, extensive flat agricultural fields with abundant desert sunshine, and access to transmission lines, is a leading case to explore interconnected themes around just energy transitions. Despite being the poorest county in California and one of the smallest, Imperial already provides 15% of the state’s solar electricity, and the region as a whole represents on the order of 25% of the state’s electric power capacity. This paper brings to light frictions over solar energy development that have emerged over the history of solar power development in the southern Salton Sea region. It describes the …

Convergence Research For Microplastic Pollution At The Watershed Scale, Heejun Chang, Elise F. Granek, Amanda Gannon, Jordyn M. Wolfand, Janice Brahney

Geography Faculty Publications and Presentations

Microplastics are found in Earth’s atmosphere, lithosphere, hydrosphere, pedosphere, and ecosphere. While there is a growing interest and need to solve this grand challenge in both the academic and policy realms, few have engaged with academics, policymakers, and community partners to co-identify the problem, co-design research, and co-produce knowledge in tackling this issue. Using a convergence research framework, we investigated the perception of microplastic pollution among different end users, delivered educational materials to K-12 teachers and practitioners, and identified key sampling points for assessing environmental microplastic concentrations in the Columbia River Basin, United States. Three community partner workshops identified regional …

Synthesis Of Publications On The Anomalous June 2021 Heat Wave In The Pacific Northwest Of The United States And Canada, Erica Fleishman, David E. Rupp, Paul C. Loikith, Karin A. Bumbaco, Larry W. O'Neill

Geography Faculty Publications and Presentations

We synthesized more than 70 articles, most peer reviewed, that addressed the heat wave that occurred across the Pacific Northwest of the United States and Canada in late June 2021, breaking hundreds of daily and all-time daily maximum temperature records across the region. A persistent, extraordinarily strong ridge of high pressure was a primary driver of the heat wave. Contributing mechanisms were moisture originating in the tropical western Pacific Ocean, high solar radiation, low pressure offshore, large-scale subsidence over land, and unusually dry soils. Climate change contributed to the heat wave’s magnitude by increasing mean temperature, although it is unclear …

Effects Of Climate Change On Stream Temperature And Salmonid Habitats In A Cascades River Basin, Michael Krochta, Kara Anlauf-Dunn, Dave Bugni, Heejun Chang

Geography Faculty Publications and Presentations

Rising stream temperatures pose significant challenges to aquatic ecosystems, particularly for coldwater-adapted organisms like salmonids. This study examines the effects of climate change on stream temperatures and salmonid habitats in the Clackamas River Basin, Oregon, USA. Using spatial stream network models and CMIP6 climate projections under SSP2-4.5 and SSP5-8.5 scenarios, we project mid- (2045-2074) and late-century (2075-2100) stream temperature changes. These projections are then integrated with thermal tolerances and intrinsic habitat metrics to assess future habitat suitability for key species, including steelhead, coho, Chinook, and bull trout. Stream temperature trends from 1991 to 2023 reveal basin-wide warming, with high-elevation tributaries …

Post-Fire Delayed Tree Mortality In Mesic Coniferous Forests Reduces Fire Refugia And Seed Sources, Alec S. Dyer, Sebastian Busby, Cody Evers, Matthew Reilly, Aaron Zuspan, Andres Holz

Geography Faculty Publications and Presentations

Context Ecological functions provided by fire refugia are critical for supporting conifer forest resiliency under increased fire activity across the western United States. The spatial distribution and persistence of fire refugia over time are uncertain as fire-injured trees continue to die over subsequent years post-fire. Objectives We examined how post-fire delayed tree mortality affects the spatial distribution and attributes of fire refugia at patch and landscape scales following high-severity wildfires. Methods To explore changes in fire refugia patch size, isolation, and fragmentation over time, we used high-resolution satellite imagery (3 m pixel size) following high-severity fires in Oregon’s western Cascades …

Disaster Vulnerability Hotspots In The Portland Metro-Region: Converging Indices For Equitable Resilience, Idowu Ajibade, Matthew Walter, Jason Sauer, Aswatha Raghunathasami, James M. Done, Paul Loikith, Chris Lower, Heejun Chang, Arun Pallathadka, Mae E. Sowards, Ming Ge

Geography Faculty Publications and Presentations

As climate-related extreme events intensify across the globe, governments, practitioners, and communities have focused on reducing vulnerability and building resilience. However, debates persist about the validity, differences, and similarities between social vulnerability and resilience indices. This study combines the Social Vulnerability Index (SoVI) (26 indicators) and the Baseline Resilience Indicators for Communities (BRIC) (52 indicators) to assess the Portland Metro region using ACS (2016–2020) and 2020 Census data. Through hotspot analysis, Pearson’s correlation, and linear regression, we identify key drivers as well as areas of convergence and divergence between the two indices. Results show a strong overlap between SoVI and …

Towards An Explicit Understanding Of Network Governance In Urban Forestry Management: A Case Study Of Portland (Or), Usa, Quadri Olatunbosun Taiwo, Vivek Shandas

Geography Faculty Publications and Presentations

As the climate continues to warm, and municipal leaders look for cost-effective and timely approaches to urban sustainability, one increasingly sought-out approach is the use of tree canopy to cool neighborhoods. Despite widespread efforts to expand tree canopy in cities, an overwhelming body of evidence suggests that urban green space is declining across the U.S., yet little is known about the factors that propel these changes. Understanding the institutional and governance systems can help identify the opportunities for slow consistent declines. Using social network analysis (SNA) metrics, we examined stakeholder roles in power structures and decision-making processes within Portland, Oregon’s …

A Case For Change: Flood Risk Management And Green Infrastructure, Heejun Chang, Arun Pallathadka

Geography Faculty Publications and Presentations

With climate change, changing demographics, and the historical legacy of aging infrastructure, many cities are facing challenges in urban flood risk management. We propose potential opportunities and synergies of collaborative urban flood risk management using green infrastructure to achieve social, ecological, and technological benefits.

Advancing Methods For Comparative Urban Research: A City-Centric Protocol And Longitudinal Dataset For Us Metropolitan Statistical Areas, Jason R. Jurjevich, Katie Meehan, Nicholas M. J. W. Chun, Greg Schrock

Urban Studies and Planning Faculty Publications and Presentations

Comparative urban research in the USA has an unacknowledged data and methodological problem at the metropolitan scale, rooted in geographic and definitional boundary changes of urban areas across time. In this article, we introduce a new spatial dataset, decision criteria, and methodological protocol for longitudinal and comparative research with US metropolitan statistical areas (MSAs)—known as ‘metros’—in a way that centers a ‘city-centric’ approach to comparison while significantly reducing spatial error and bias. First, we review gaps and limitations of existing approaches and identify three major but previously unacknowledged sources of error, including a new source of bias we call ‘spanning …

Urban Beavers At The Crossroads: How Ecological Knowledge, Sociodemographic, And Spatial Context Shape Public Perception And Coexistence Preferences, Matthew Guziejka

Dissertations and Theses

Urban beavers demonstrate synurbization by adapting to urban environments, offering ecological benefits such as biodiversity enhancement and flood mitigation, while also occasionally conflicting with infrastructure. This study examines how ecological knowledge, sociodemographics, and spatial context influence public perceptions and management preferences for urban beavers in the Tualatin River watershed, Oregon.

A voluntary survey of 176 participants from peri-urban areas assessed demographic characteristics, ecological knowledge, and attitudes toward management approaches. Spatial factors, such as proximity to watercourses and green spaces, were also analyzed. Logistic regression analyses were used to explore relationships between these factors and management preferences. Political orientation was significantly …

Accessible Bike Map Design: A Review And Critique Of Portland’S Bike Maps, Zachary Cheyney

Geography Masters Research Papers

Urban bike maps can serve as key tools for route planning and navigation for prospective cyclists, providing both general information (such as landmarks and natural features) and cycling specific information (such as bike lane infrastructure types and cycling amenities). Despite this, there is little professional guidance or academic research on best practices for bike map design. Potential guidance should consider the full range of potential cyclists, including disabled cyclists who have often been left out of cycling policy discussions. In this paper, I begin by discussing 3 case studies on participatory mapping methodologies with disabled participants in order to generate …

Towards A Global Understanding Of Tree Mortality, Andres Holz, International Tree Mortality Network

Geography Faculty Publications and Presentations

Rates of tree mortality are increasing globally, with implications for forests and climate. Yet, how and why these trends vary globally remain unknown. Developing a comprehensive assessment of global tree mortality will require systematically integrating data from ground-based long-term forest monitoring with large-scale remote sensing. We surveyed the metadata from 466 865 forest monitoring plots across 89 countries and five continents using questionnaires and discuss the potential to use these to estimate tree mortality trends globally. Our survey shows that the area monitored has increased steadily since 1960, but we also identify many regions with limited ground-based information on tree …

Patagonia's Late Holocene Lake Sediments Reveal No Major Black Carbon Sources For Antarctica, Sandra O. Brugger, David B. Mcwethy, Nathan Chellman, Oliver Heiri, Kyla Sara Zaret, Joseph R. Mcconnell, Andres Holz, Joseph R. Mcconnell

Geography Faculty Publications and Presentations

Black carbon from biomass and fossil fuel burning is an important aerosol in the climate system. Understanding its historical variation is crucial to constrain current anthropogenic and wildfire impacts on the atmosphere. Patagonia was proposed previously as a major source region for the late 13th century black carbon increase observed in an ice core from the northern Antarctic Peninsula but not in continental Antarctic ice cores. Here, we reconstruct regional black carbon trends using high-resolution measurements of refractory black carbon (rBC) in two Patagonian lake-sediment cores spanning the last two millennia and compare the results with other records of fire …

Pumped Storage Hydropower In The United States: Emerging Importance, Environmental And Social Impacts, And Critical Considerations, Surabhi Karambelkar, Alida Cantor, Thien-Kim Bui, Bethani Turley, Maryalice Fischer, Shannon Ames

Geography Faculty Publications and Presentations

Pumped storage hydropower is a widely used, long-duration energy storage system that sits squarely at the water-energy nexus. Bold decarbonization goals have propelled a rapid resurgence of interest in pumped storage hydropower in the US, given its ability to provide bulk energy storage, manage grid reliability, and support increasing integration of variable renewable energy sources. Drawing on published research from both technical and social science perspectives, this paper provides an overview of pumped storage hydropower technology, the project development pipeline, potential social and environmental impacts, including a comparison of open-loop and closed-loop design configurations, and critical considerations for project development. …

Predicting Post-Wildfire Stream Temperature And Turbidity: A Machine Learning Approach In Western Us Watersheds, Junjie Chen, Heejun Chang

Geography Faculty Publications and Presentations

Wildfires significantly impact water quality in the Western United States, posing challenges for water resource management. However, limited research quantifies post-wildfire stream temperature and turbidity changes across diverse climatic zones. This study addresses this gap by using Random Forest (RF) and Support Vector Regression (SVR) models to predict post-wildfire stream temperature and turbidity based on climate, streamflow, and fire data from the Clackamas and Russian River Watersheds. We selected Random Forest (RF) and Support Vector Regression (SVR) because they handle non-linear, high-dimensional data, balance accuracy with efficiency, and capture complex post-wildfire stream temperature and turbidity dynamics with minimal assumptions. The …

Explaining The 2022 Record Low Great Salt Lake Volume, Siiri Bigalke, Paul C. Loikith, Nicholas Siler

Geography Faculty Publications and Presentations

The Great Salt Lake reached the lowest water volume in its entire 170+ year record in 2022. To explain this record low we develop and apply a lake mass‐balance model and perform four simulations: one where all input and output variables are fixed to their mid‐20th century average resulting in an equilibrium lake volume, and three others where one of the input variables (precipitation or streamflow) or the output variable (evaporation) follows observations while the other two are fixed to their mid‐20th century average. Results show anomalously low streamflow accounting for the largest proportion of the lake volume departure from …

Tree-Equity And Environmental Justice Discourses Among Urban Forestry Professionals In Portland: Current Impacts And Future Implications, Axcelle Deone Bell

Dissertations and Theses

Urban tree equity is critical for addressing environmental justice and mitigating the effects of climate change in cities. This study investigates how professionals in Portland's urban forestry sector conceptualize and implement tree equity, focusing on equity and justice discourses. Through 27 semi-structured interviews with 29 professionals from government agencies and NGOs, I examine how these discourses shape decisions regarding tree planting, distribution, and maintenance, particularly in underserved communities. The analysis draws on political ecology, systems dynamics, and structuration theory to explore the systemic barriers perpetuating inequities in tree canopy distribution. The findings reveal tensions between different approaches to equity, such …

Unseen Connections: A Storymap Exploring Case Studies In Water-Energy Transitions And Environmental Justice, Alida Cantor, Elizabeth Bartholomew, Kate Berry, James Blair, Dustin Mulvaney, Nancee Hunter

Geography Faculty Publications and Presentations

Climate change is one of the most important challenges in the world today. Communities and decision makers at many levels, from local to international, are working to ensure that energy, water, and other societal infrastructures can transition and adapt to address climate change (IPCC, 2023). One major mitigation strategy involves the decarbonization of energy systems (Rockström et al. 2017). Despite wide recognition of the need to decarbonize globally, renewable energy infrastructures and technologies are often locally controversial, involving claims of environmental injustice and disputes over land and water (Cantor, Turley, and Maxfield 2023; Jerez, Garcés, and Torres 2021; Turley et …

Thermal Regimes Of Beaver-Impacted Stream Reaches In The Tualatin River Basin, Oregon, United States, Miles Mayer, Heejun Chang

Geography Faculty Publications and Presentations

As beavers are increasingly used in stream restoration, interest in their potential to mitigate stream degradation has grown. However, the impacts of beaver dams on stream temperature remain inconsistent across studies, often due to differences in spatial scale and methodology. We investigated summer thermal regimes at multiple spatial scales in three beaver-impacted streams within the Tualatin River Basin, Oregon, using fiber-optic distributed temperature sensing. Substantial variability in thermal regimes was observed among the three stream reaches and around individual beaver dams within each reach. This variability was primarily influenced by geomorphic changes in stream depth associated with beaver dams and …

Collaborative Governance And Hydrosocial Territorialization: Reaching Consensus On Salmon Restoration Goals In The Columbia River Basin, Thien-Kim Bui, Rebecca Mclain

Geography Faculty Publications and Presentations

Across the Cascadia bioregion, salmon and steelhead are ecological and cultural keystone species that contribute to and illustrate riverine health. Due to complex social, economic, and ecological relations over the past 150 years, many Columbia River Basin salmon and steelhead populations are now listed as threatened or endangered in the United States. This research uses the 2017–2020 Columbia Basin Partnership Task Force as a case study to understand how this collaborative governance effort of sovereign entities and nonsovereign stakeholders navigated competing water claims to reach consensus on aspirational qualitative and quantitative goals for salmon and steelhead restoration. Using semistructured interviews …

Map Marker Accuracy: Evaluating Spatial Data Quality In A Simplified Mapping Survey, Christopher Sean Ghormley

Masters in GIS Practicum Reports

Collecting spatial information using maps is a recurring need in research and policy (Evers, 2020; Gottwald et al., 2016; Hitchins, 2018; Tang & Liu, 2016). Survey participants frequently abandon map-based surveys at the first mapping task (Poplin, 2015). In his survey of wildfire risk management personnel, Evers (2020) applied a simplified web-mapping interface that uses circles as the sole input geometry for all spatial representations. The current project examines an updated version of this web map. An anonymous survey gathered data from participants who completed six mapping exercises within Portland, Oregon, and provided feedback on the survey experience. A working …

The Geography Of Rock Glaciers In The American West, Allison Reese Trcka, Andrew G. Fountain, Bryce Allen Glenn

Geology Faculty Publications and Presentations

Rock glaciers are relatively common in conterminous United States west of the 100° meridian, yet their distribution and number are not well known. Using aerial and satellite imagery, we inventoried the population of rock glaciers, yielding 2,257 rock glaciers totaling 234.28 km² with an area of uncertainty of 7 percent. Of these, 1,561 (155.44 km²) are considered intact (moving) and 696 (76.84 km²) relict. Based on published estimates of ice content, total water-equivalent volume is roughly 2.52 km³. Rock glacier elevations increase from the northwest (Washington) to the southeast (Colorado), following a spatial …

Scale-Dependent Effects Of Urban Canopy Cover, Canopy Volume, And Impervious Surfaces On Near-Surface Air Temperature In A Mid-Sized City, Carson Ralls, Anne Y. Polyakov, Vivek Shandas

Geography Faculty Publications and Presentations

Cities are significantly warmer than their surrounding rural environments. Known as the ‘urban heat island effect’, it can affect the health of urban residents and lead to increased energy use, public health impacts, and damage to infrastructure. Although this effect is extensively researched, less is known about how landscape characteristics within cities affect local temperature variation. This study examined how tree canopy cover, canopy volume, and impervious surface cover affect daytime near-surface air temperature, and how these effects vary between different scales of analysis (10, 30, 60, 90 m radii), ranging from approximate street corridor to city block size. Temperature …

Foreign Funding Of U.S. Higher Education Relates To Sanctioning Of Scholars And Antisemitism, Michael Bass, Alexander Reid Ross, Ben Wolfson, Joel Finkelstein, Sonia Yanovsky, Danit Finkelstein, Sean T. Stevens, Nathan Honeycutt, Pamela Paresky, Ayal Feinberg, Multiple Additional Authors

Geography Faculty Publications and Presentations

We examined relations between foreign funding of U.S. colleges and universities and campus political developments. Seven studies investigated associations between foreign funding and campus liberal democratic norms, specifically, deterioration of free speech and academic freedom, and presence of antisemitism. Study I found that 349 colleges and universities received a total of almost $18 billion from foreign sources between 2014 and 2019. Study II examined relationships of foreign funding to campus deplatforming of speakers and punitive actions for speech protected by academic freedom. Main results were: 1. overall foreign funding was not strongly related to campus speech outcomes; 2. higher levels …

Impacts Of A Short-Interval Severe Fire On Forest Structure And Regeneration In A Temperate Andean Araucaria-Nothofagus Forest, Paola Arroyo-Vargas, Sebastian Busby, Thomas T. Veblen, Mauro E. Gonzalez, Andres Holz

Geography Faculty Publications and Presentations

Background:

Warmer climate conditions are altering fire regimes globally, eroding the capacity of forest ecosystems to resist and recover from natural disturbances like wildfire. Severe and rapidly repeated wildfires are promoting tree regeneration failure of obligate-seeders and/or fire-sensitive species in temperate forests of the Southern Hemisphere. We collected post-fire field data to evaluate whether forest structure and tree regeneration responses varied between two Andean forest study areas dominated by the threatened Gondwanan conifer Araucaria araucana and Nothofagus species (southern beeches) — one area burned once, the other reburned after 13 years.

Results:

Tree mortality was high across species after a …

The Water-Climate Nexus: Intersections Across Sectors, Thushara Gunda, Alida A. Cantor, Emily Grubert, Angela R. Harris, Yolanda J. Mcdonald

Geography Faculty Publications and Presentations

Water security and climate change are important priorities for communities and regions worldwide. The intersections between water and climate change extend across many environmental and human activities. This Primer is intended as an introduction, grounded in examples, for students and others considering the interactions between climate, water, and society. In this Primer, we summarize key intersections between water and climate across four sectors: environment; drinking water, sanitation, and hygiene; food and agriculture; and energy. We begin with an overview of the fundamental water dynamics within each of these four sectors, and then discuss how climate change is impacting water and …

Climate Hazards And Human Migration: Literature Review, Anna Ivanova, Deepti Singh, Pronoy Rai, Claire Richards, Hugo Vasconcelos, Michael Goldsby

International & Global Studies Faculty Publications and Presentations

Human populations are migrating as a result of climate change. We conducted a systematic literature review examining the relationship between several climate hazards and migration flows. We reviewed 58 empirical studies between 2010 and 2023 that examined current and future migration related to acute and long-term climate hazards. The results indicate that the relationship between climate hazards and migration is diverse and depends on a range of socio-economic factors. Droughts and rising temperatures have a major impact on both international and domestic migration. Our review also reveals that multiple climate hazards collectively tend to intensify domestic migration toward urban areas, …

Post-Wildfire Water Quality Dynamics: A Multiscale Examination And Predictive Modeling Of Stream Temperature And Turbidity In Western U.S. Watersheds, Junjie Chen

Dissertations and Theses

Wildfires, exacerbated by climate change and human activities, pose significant threats to water-related ecosystem services in forested watersheds. This dissertation investigates the multifaceted impacts of wildfires on stream temperature and turbidity, two critical water quality parameters essential for maintaining aquatic ecosystem health and human water uses. By integrating a comprehensive literature review, empirical data analysis, and advanced machine learning techniques, this research provides a nuanced understanding of how wildfires affect hydrological processes across various temporal and spatial scales.

The findings reveal significant regional variability and the complex interplay between climatic, geographic, and anthropogenic factors. For instance, the literature review highlights …

Exploration Of Large-Scale Vegetation Transition In Wet Ecosystems: A Comparison Of Conifer Seedling Abundance Across Burned Vs. Unburned Forest-Peatland Ecotones In Western Patagonia, Kyla Zaret, Andres Holz

Geography Faculty Publications and Presentations

Altered fire regimes, combined with a warmer and drier climate, have been eroding the resilience of temperate rainforests and peatlands worldwide and leading to alternative post-fire vegetation communities. Chronic anthropogenic burning of temperate rainforests at the forest-peatland ecotone in western Patagonia appears to have shifted vegetation communities in poorly-drained sites from forests dominated by the threatened conifer, Pilgerodendron uviferum, to peat-accumulating wetlands covered by Sphagnum mosses. We collected and modeled post-reburn field data using ordinations and hierarchical Bayesian regressions to examine mechanisms through which P. uviferum forests may recover following fire or become locked into alternative development pathways by comparing …