Forestry

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Managing disturbance in the longleaf pine ecosystem: effects of managed fire regime characteristics on fire hazard and community ecology at multiple spatial scales
(2026-04-20) Cronan, James Breswter; Alvarado-Celestino, Ernesto
Conservation lands within the range of longleaf pine (Pinus palustris) are valuable because they protect remnants of an ecosystem with globally high measures of biological diversity. The longleaf pine ecosystem is adapted to frequent, low-intensity fire, however, naturally occurring fire no longer burns with sufficient frequency to maintain the ecological structure and function necessary to sustain high levels of biological diversity. To compensate, aggressive prescribed fire programs are necessary. The fragmented nature of this ecosystem combined with the difficulty, complexity, and expense of applying regular prescribed fire in a densely populated landscape raises numerous management challenges. The research presented in this dissertation addresses many of the knowledge gaps confronting land managers using prescribed fire in longleaf pine ecosystems. The focus here is to provide information that describes how changes in the fire regime affect understory vegetation from the perspective of both fire hazard and community ecology: the two main management objectives for prescribed burning in longleaf pine forests. Research addressing these objectives is presented in three chapters. First, in Chapter 3 I examined the effects of season-of-burn on shrub and herbaceous fuel layers and predicted fire behavior on frequently burned mesic pine flatwoods in northern Florida. Compared to single dormant season burns, single growing season burns caused no changes to live understory fuels and had no detectable effect on fire behavior. Shrub coverage and predicted fire behavior were, however, significantly different between two geographic regions sampled. Additionally, shrub height was significantly affected by fire temperature. Predicted fire behavior was strongly correlated with measures of the litter and herb strata. Results from this study suggest that land managers should not initially expect large changes in understory fuel properties or potential fire behavior related to a shift from dormant to growing season prescribed burning, and that geographic location and fire intensity can have significant effects on live fuels and potential fire behavior. Second, in Chapter 4 I evaluated the effects of frequent prescribed fire and forest structure on understory composition in mesic longleaf pine flatwoods. To do this, understory biomass and forest structure were measured in 22 stands of longleaf pine that were burned regularly for at least 20 years. Constrained multivariate ordination and boundary line regression were used to test whether explanatory variables (i.e., fire history and forest structure) affected understory biomass, grouped by genera and plant functional groups. Fire frequency, as measured by the mean fire interval (MFI) and coarse woody debris biomass had marginally significant effects on understory composition. These variables, though uncorrelated, weakly aligned with the first Principal Components axis where sites were arranged along a compositional gradient from typical understory shrubs and wiregrass (Aristida beyrichiana) to sites characterized by vines and understory hardwoods. Boundary line regression showed a significant negative relationship between forb abundance and MFI; however, this relationship did not extend to graminoids. Boundary line regression did not show any significant effects of MFI on measures of woody plant biomass. Season-of-burn had no significant effects on understory plants in the constrained ordination or boundary line regression. These results suggest that other environmental factors and fire regime characteristics that are more favorable to fire sensitive species would be necessary to significantly influence understory vegetation dynamics. Third, in Chapter 5 I used the Fuelbed Dynamics Model (FDM), a landscape-succession model I developed that incorporates fire and other disturbances, to simulate changes in fuels at Eglin Air Force Base (Eglin) in northwestern Florida for 50-year time periods under four scenarios of prescribed burning. The simulation outputs quantified the effect of different levels of prescribed burning on fire hazard across the longleaf pine-dominated landscape at Eglin where prescribed fire is the primary method used to manage vegetation and mitigate fire hazard. If the rate of prescribed burning is insufficient to maintain a low fire hazard landscape, Eglin’s forests could pose substantial wildfire risk to the base’s infrastructure, surrounding wildland urban interface communities, and longleaf pine communities. Simulations indicated that fire hazard for surface and canopy fuels would rise under reduced prescribed fire scenarios (20k and 30k ha yr-1), would remain relatively unchanged at the baseline level of burning (40k ha yr-1), and decline if prescribed burning was increased to 50k ha yr-1. The MFI and overstory cover data suggest that fire hazard would ultimately decrease towards the end of the simulation for reduced burn scenarios over a substantial portion of Eglin relative to baseline and increased burn scenarios as forest mesophication favored fire impeding species in management units were fire was excluded and longleaf pine was replaced by broadleaf species and sand pine (Pinus clausa).
Pollution and parasitism in coyotes of the Puget Sound region
(2026-02-05) Hentati, Yasmine; Prugh, Laura R; Schell, Christopher J
Urban ecosystems are complex social-ecological systems where wildlife are exposed to a mosaic of interacting stressors, including habitat fragmentation, novel food resources, and persistent environmental contaminants. However, urban ecology studies often overlook a crucial hidden player: parasites, which can reflect effects of anthropogenic stressors in their hosts and serve as bioindicators for contamination. While parasites impact their hosts’ health, and their hosts’ health is impacted by the environment, few urban wildlife studies consider how the environment in turn impacts parasites. Coyotes (Canis latrans), as mesocarnivores that inhabit a range of urban-rural gradients across North America, provide a unique lens through which to examine these ecological and physiological dynamics. In my dissertation, I sought to determine how human-driven environmental pressures shape wildlife and parasite populations in the Puget Sound region, Washington State, USA, using coyotes as a model species. In Chapter 1, I examined how environmental contamination contributes to the structure of mammalian diversity and mesocarnivore activity across the Seattle-Tacoma metropolitan region. This chapter integrated spatial contaminant data with camera trap surveys and revealed that, while environmental contamination has an overall negative impact on mammal communities, responses are species-specific: coyote detections were negatively affected by environmental contamination, while detections of raccoons and opossums were not. In Chapter 2, I further identify connections between the environment and wildlife by investigating contamination at an organismal scale. Using salvaged coyote carcasses, I quantified trace metal concentrations in tissues of coyotes and their gastrointestinal helminth parasites, finding that parasites bioaccumulate metals at higher concentrations than their hosts and revealing a potential silver lining of parasite infection. In Chapter 3, I applied morphological and molecular techniques to coyote carcasses and field-collected scats and discovered the zoonotic cestode Echinococcus multilocularis in coyotes across western Washington state — the first record of this parasite in a wild host in the region. These findings highlight the crucial gaps in and public health relevance of our understanding of wildlife parasite distributions. In Chapter 4, I modeled the ecological drivers of distribution of E. multilocularis as well as two other gastrointestinal parasites, Taenia pisiformis and strongylid hookworms, in coyotes. I showed that both individual coyote diet and urbanization influence parasite distribution, but that the strength and direction of these influences depended on parasite species traits. This dissertation elucidates the impacts of environmental contamination on urban wildlife, advances understanding of parasite ecology in human-altered systems, and positions coyotes as sentinels for environmental contamination and zoonotic disease.
Living on Winter’s Edge: Snow Ecology of Large Mammals in Northern Ecosystems
(2026-02-05) Sullender, Benjamin Knight; Prugh, Laura R
Climate change is rapidly reshaping snowpacks around the world, with dramatic impacts on wildlife. My dissertation explored the role of snow in shaping predator–prey relationships and movement ecology, focusing on large mammals in the northern United States of America and Canada. Chapter 2 used winter fieldwork to quantify how specific snow properties influence the sink depths of tracks made by predators (bobcats, cougars, coyotes, and wolves) and their sympatric ungulate prey (caribou, deer, moose). Using generalized additive models, breakpoint regression, and animal morphology, I found that near-surface snow density is the most significant predictor of sink depth, with different thresholds for predators and prey. I identified "danger zones" where snow conditions impede ungulates’ movement more than predators, providing a framework to predict the impacts of climate-driven snow changes on predator–prey dynamics. Chapter 3 applied an entirely different methodological approach to investigate whether these danger zones factor into apex predator habitat selection. Using GPS collar data for cougars, wolves, mule deer, and white-tailed deer, I found that snow depth and density significantly affect predator movement, with predators selecting for areas with either shallow or with deep, dense snow. Kill-site investigations for cougar-killed deer indicated similar snow preferences. In Chapter 4, I examined winter movements from an ungulate perspective, using GPS collared data from five moose populations across their entire latitudinal range. I found that, even in winter, high temperatures cause moose to adjust behavioral patterns and alter habitat selection, potentially forgoing foraging opportunities in favor of thermal refuge. These changes were most dramatic in southern moose and may be a contributing factor to recent moose range contraction along their southern margins. Finally, Chapter 5 integrated physically based snow modeling with climate projections to predict how changing snowpacks will alter predator–prey interactions. I focused on two apex predators, cougars and wolves, and their primary prey, mule deer and white-tailed deer, under two mid-century climate change scenarios (SSP2-4.5 and SSP5-8.5). My results showed significant declines in snow-mediated advantages for predators, with a reduction in both the duration and extent of snowpack conditions that favor predator movement (as identified in Chapter 3). These changes are expected to have disproportionate impacts on apex predators, potentially leading to shifts in predator home ranges, prey densities, and ecosystem dynamics. Collectively, these chapters underscore the profound effects of climate-driven changes in snowpack dynamics on large carnivore and ungulate behavior, with potential for significant shifts in predator–prey interactions across the Northern Hemisphere.
Many Small Stepping Stones Improve Habitat Connectivity for the Endangered Taylor's Checkerspot Butterfly (Euphydryas editha taylori)
(2025-10-02) Crossway, Fern; Lawler, Joshua J.
Habitat fragmentation is a major driver of wildlife population decline globally, and the loss and fragmentation of grassland ecosystems has resulted in the reduction of functional connectivity for many specialist butterflies. These species are highly dependent on connected habitat patches for maintaining genetic diversity and protecting populations from extreme events such as drought or fire. The Taylor's checkerspot, an endangered Pacific Northwest endemic species, has experienced declines in local population abundance across their geographical range due to the loss of grasslands. This loss has been caused by the increasing spread of invasive species, conifer encroachment, the loss of historical fire regimes, and human activities. To support the conservation goals for this species, I developed a movement model and conducted a connectivity analysis to determine how patch size, quantity, and placement influence dispersal probabilities across a portion of the butterfly's range. Because this species is short lived with a limited flight period, movement over multiple generations may be necessary for colonizing new patches. To account for this, I quantified dispersal potential over 100 generations using a Markov chain approach. Over 100 generations, many small stepping stones produced the highest dispersal probabilities when compared to the addition of fewer, larger patches. The placement and number of these patches differed in their ability to improve immigration versus emigration rates. After 100 years, randomized patch placement supported higher immigration probabilities while randomized and least-cost-path patch placement supported similar emigration probabilities, providing managers with flexibility when selecting sites, which may alleviate budgetary limitations or land-use conflicts. This is especially important in highly developed areas where options for restoring habitat are likely to be limited to small, opportunistically acquired patches.
Resilience and Adaptation to Climate Change Among Organic Farmers in the United States: A Mixed Methods Investigation
(2025-10-02) Vernik, Masha; Shah, Sameer H.
Farmers around the world are adapting to less predictable seasons and more frequent extreme weather events. This challenge is no less for organic farmers, who contribute to social well-being and ecological regeneration through their food production practices. This thesis employs a mixed-methods approach to explore resilience and perceived adaptive capacity to climate change among organic farmers in western Washington and the United States, more broadly. Chapter 2 uses qualitative methods to explore the relationship between climate resilience and crop diversity among organic vegetable farmers in western Washington. Findings contribute to academic debates around diversity and climate resilience by offering (i) a grounded perspective of how diversity confers socio-ecological resilience by those who enact it; (ii) an explanation for how climate interacts with social contexts to shape diversity; and (iii) an analysis of the limits of diversification and benefits of specialization to confer resilience. Chapter 3 uses Bayesian structural equation modeling to assess the relationship between land access and perceived adaptive capacity to climate change among certified organic farmers in the United States. Beyond the specific associations reported, the Chapter signals how Bayesian approaches can integrate qualitative and quantitative analyses, while accounting for uncertainty inherent in complex socio-ecological systems.
Novel production of lignocellulosic nanofibrils with diverse physical and chemical characteristics from wheat straw
(2025-10-02) Sidhu, Abhi; Bura, Renata
As the demand for sustainable materials grows, lignocellulosic nanofibrils (LCNFs) have gained attention for their abundance, renewability, and promising properties. However, widespread commercialization remains limited by unsustainable production methods, high costs, and the narrow functionality of currently available nanocellulose, which often lacks tunable properties. Existing LCNF production techniques frequently rely on expensive feedstocks, hazardous chemicals, or lack clarity on how process modifications affect material properties, making it difficult to tailor products for specific applications. This research addresses these challenges by developing process conditions to produce LCNFs with diverse physical and chemical properties from wheat straw. Seven fractionation treatments were conducted, varying sodium hydroxide (7.5–15%), hydrogen peroxide (0–7.5%), and temperature (50–95 °C), followed by chemical composition analysis. Two treatments were oxidized with 7.5% peracetic acid, while three others were oxidized at both 7.5% and 30%. Resulting samples were cast into films and thoroughly characterized using FTIR, conductometric titrations, SEM, XRD, UV–vis spectroscopy, TGA, contact angle measurements, and tensile testing. Lowering fractionation parameters (temperature and chemical charge) increased hemicellulose and lignin retention, enhancing yields and producing LCNFs with smaller diameters, semi-crystalline structure, low UV transmittance, moderate thermal and mechanical properties, and low wettability. Residual lignin content correlated with several properties: higher lignin led to less uniform fibrils, reduced optical transparency, increased UV absorption and haze, and lower thermal mass loss. Mechanical strength and elastic modulus declined with lignin content, except in samples treated with 30% PAA. Lignin also decreased surface hydrophilicity. Additionally, charge demand and mechanical performance were dictated not only on lignin content but also on whether lignin was primarily removed during fractionation or oxidation. This work contributes to sustainable material development by offering an adaptable platform for producing LCNFs with tunable properties suitable for a wide range of end-use applications.
Beyond Prediction: Climate Change Adaptation, Science & Technology Studies (STS), and Transformational Change
(2025-10-02) Wettstein, August; Shah, Sameer H
Climate change adaptation is a priority for researchers, policymakers, and the public. Adaptation practices, however, have largely failed to keep pace with climate change risks and deliver the systemic changes required to reduce vulnerability. Critical scholarship has focused on conventional planning and decision-making processes to explain the inadequate and inequitable outcomes of adaptation. This thesis applies Science and Technology Studies (STS) theories as a complementary means of explaining such outcomes. Chapter 1 introduces the stakes of adaptation, the concerns brought by critical adaptation scholars, and the potential benefits of STS for advancing adaptation practice. Chapter 2 identifies four themes in STS through a literature review: representations, boundaries, politics and participation, and the future. These demonstrate how STS can enrich adaptation studies' explanations for why insufficient adaptation persists. Chapter 3 presents a case study that applies STS concepts to explain the structure and outcomes of a participatory adaptation planning initiative in Washington State's North Olympic Peninsula region. Key findings, drawn from twenty-six interviews with planning organizers and participants and an analysis of planning documents, illustrate how adaptation's meaning in practice was tied to its creation in broader social and institutional settings. The thesis synthesizes how STS can both benefit critical adaptation studies and advance the broader mission of effective adaptation.
Assessing the effects of fertilization on Douglas-fir growth responses and edaphic variables in the Pacific Northwest
(2025-10-02) Zhang, Xingyue; Turnblom, Eric; Johnson, Brittany
Douglas-fir (Pseudotsuga menziesii var. menziesii.) is an important commercial tree species in the coastal Pacific Northwest (PNW), and its biomass is also regarded as a significant forest carbon (C) sink. Productivity of Douglas-fir varies regionally due to nutrient availability (especially nitrogen). Nitrogen (N) fertilization can improve Douglas-fir productivity, but knowledge gaps remain in the mechanisms affecting growth response to fertilization, as well as in the effects of this management practice to the soil nutrient condition itself in the long term due to the complex interactions between environmental variables. This study leveraged a paired-tree fertilization study to examine the growth response of Douglas-fir to soil nutrient availability and fertilization, plus the effects of the fertilization on the edaphic variables ten to thirteen years after the N input. The objectives of this study were to 1) Predict Douglas-fir growth responses after N fertilization in the PNW; 2) Examine changes in soil nutrient availability ten to thirteen years after fertilization. In this study, N fertilization was applied across 15 sampled Douglas-fir installations throughout coastal Oregon and Washington State, and basal area and ring area responses to the fertilization were analyzed along with the initial and current soil macronutrient levels measured with Probes. Results of this study show that 1) multiple factors affect the long-term response of Douglas-fir growth to one-time N fertilization; 2) the levels of soil cation availability and surface C:N ratio affect response extent; 3) the level of initial N content determines the responding patterns; 4) N fertilization has limited long-term effect on soil nutrient availability; 5) stand-level understanding of edaphic and geoclimatic conditions should contribute to better outcomes of N fertilization in the PNW. Our findings provide critical references for accurately assessing the long-term effects of N fertilization on Douglas-fir productivity and the ecosystem services of plantation forests such as carbon sequestration.
A Life Cycle Assessment of Glued Laminated Timber (Glulam) Production in Indonesia
(2025-10-02) Hariadi, Karisha Shahnaz; Ganguly, Indroneil
The building construction sector is one of the most carbon-intensive industries, contributing nearly 40% of global energy-related CO2 emissions. In tropical countries, rapid urbanization and economic growth amplify this impact, highlighting the need to reduce both operational and embodied carbon. While mass timber is gaining traction as a low-carbon solution in temperate regions, its potential in tropical areas remains underexplored. As the country of this case study, Indonesia offers a unique opportunity to harness the environmental benefits of mass timber due to its abundant wood resources, strong wood industry, and supportive climate policies. However, challenges such as land use change remain a major concern. This research aims to document the mass timber supply chain and perform a cradle-to-gate LCA of glued laminated timber (glulam) produced in Indonesia, with the consideration of land use and land use change (LULUC). The results demonstrate the potential of glulam produced in Indonesia to contribute positively to climate change mitigation. The production of 1 m3 of glulam in Indonesia results in 523.26 kg CO2 eq. of fossil emissions, while 914.11 kg CO2 eq. of biogenic carbon is stored. Thus, the overall product's carbon balance is -390.85 kg CO2 eq. Two land use change scenarios were considered to reflect conditions where logs are harvested from forest lands that have undergone conversion. One scenario was conversion from primary to secondary dryland forest, representing forest degradation, while the other was conversion from dry shrubs to secondary dryland forest, representing forest gains. For the forest gain scenario, the product's overall climate impact becomes -426.75 kg CO₂ eq. In contrast, forest degradation raises it to 821.48 kg CO₂ eq. The forest degradation scenario takes away the biogenic carbon sequestration credit while still accounting for all the biogenic and fossil emissions throughout the product's life, resulting in a significantly higher climate impact. This highlights the importance of sourcing wood from sustainably managed forests to claim the carbon benefits of wood products.
Impacts of Invasive Species on Tropical Seabird Populations on Tetiaroa Atoll, French Polynesia
(2025-08-01) Hallock, Eve McKinley; Converse, Sarah J; Gardner, Beth
Seabird populations provide crucial ecological services to their environments, yet their populations are declining globally due to invasive species, climate change, habitat loss and degradation, over-fishing, and pollution. Although they are keystone species and bio-indicators of coral island health, tropical seabirds remain understudied. Their reproductive success is influenced by an array of biotic and abiotic factors, particularly in coral island (atoll) ecosystems where low-lying nesting habitats are vulnerable to anthropogenic and environmental disturbances. In Chapter 1, we modeled daily nest survival of Brown Boobies (Sula leucogaster) on Tetiaroa Atoll, Society Islands, French Polynesia, using a Bayesian framework. We analyzed data from 903 nests monitored between 2021 and 2024 across three motus (islets) that differed in exposure to invasive rats before and during a rat-eradication effort. Our daily nest survival model included motu-specific intercepts, a before-after-control-impact design to assess effects of rat suppression, and covariates representing ocean swell height, El NiÃ±o-Southern Oscillation conditions, colonial nest density, and an avian disease outbreak event. We found no evidence that rat presence negatively affected daily nest survival, which may indicate that rats are less of a threat to Brown Booby reproduction when compared to other seabird species. Higher ocean swells were associated with lower daily nest survival probability, while positive Southern Oscillation Index values, indicative of La NiÃ±a conditions, were associated with higher daily nest survival probabilities. These findings suggest that oceanic variability, rather than rat presence, was the dominant driver of nest success during the study period, suggesting the importance of accounting for risks posed by a changing climate and rising sea levels when developing seabird conservation strategies on atolls. In Chapter 2, we investigated terrestrial habitat associations of four seabird species on Tetiaroa, the Red-footed Booby (Sula sula), Brown Noddy (Anous stolidus), Black Noddy (Anous minutus), and White Tern (Gygis alba). We conducted 824 avian point counts with multiple observers at 110 sites between 2022 and 2024. A variety of vegetation variables were measured at each site, including the abundance of mature native broadleaf trees and previously cultivated coconut palm (Cocos nucifera), which is considered invasive and may be harmful to atoll ecosystem functioning. We fit species-specific N-mixture models to the avian point count data, using a zero-inflation Poisson distribution to model abundance, and habitat variables in both the zero-inflated and abundance components. Estimated Red-footed Booby abundance was higher in areas closer to the shoreline, with greater amounts of the coastal shrub, Heliotropium arboretum, and native broadleaf trees including Pisonia grandis, and in areas with more open space in the herbaceous layer. Abundance was lower with greater amounts of invasive Cocos nucifera trees. We found Brown Noddy estimated abundance was lower in areas with greater amounts of Pandanus tectorius trees. Estimates of Black Noddy abundance and probability of White Tern presence were higher with greater amounts of native broadleaf trees. Our findings provide information on habitat associations of these seabird species, which can be used to inform terrestrial restoration projects on Tetiaroa and other atolls.
Cryptic Carbon: Improving Wetland Representation and Soil Carbon Characterization across Forested Landscapes
(2025-08-01) Stewart, Anthony; Moskal, Ludmila M; Butman, David E
Inland freshwater wetlands disproportionately contain soil organic carbon (SOC), storing greater than 30% of the total global pool but only cover 6% of the land surface. However, many of these wetlands, especially in the Pacific Northwest, are hidden under forest canopy and excluded from maps of wetland extent, estimates of landscape SOC stock, and under-evaluated in broader soil science. Chapter 1 shows that implementing a new wetland mapping tool, the wetland intrinsic potential (WIP) tool, to identify hidden “cryptic” wetlands can improve estimates of landscape SOC stocks and identifies approximately 5-fold wetland SOC stock than previous estimates. Chapter 2 describes how the WIP wetland identification can be applied in models across regional scales, producing consistently higher landscape and wetland SOC measurements. This shows that the patterns of landscape soil moisture regimes with WIP is significant driver of SOC stock but not mineral soil SOC% across regional scales with climatic variation. Chapter 3 further investigates the mineral associations with soil organic matter (MAOM) and evaluates the SOC stability in forested wetlands and uplands finding that forested wetlands have lower MAOM SOC content (MAOM-C) compared to dry uplands but the radiocarbon dating of the MAOM-C (MAOM-∆14C) in forested wetlands was much older. The results suggest that landscape class, Fe, pH and SOC% are drivers of the MAOM-C and MAOM-∆14C. Overall this dissertation reveals new insights into the spatial distribution of inland freshwater wetlands and wetland SOC as well as how well this SOC is preserved.
A Multi-Scale Approach to Forest Restoration: Endophytes, Environmental Gradients, and Seedling Performance in the Pacific Northwest
(2025-08-01) Aghai, Matthew Mehdi; Ettl, Gregory J
Pacific Northwest (PNW) forests face growing pressures from legacy management practices, wildfire, and drought intensified by climate change. This dissertation reframes forest restoration as an investment in critical infrastructure, arguing that the long-term public benefits of resilient forests warrant sustained, incentive-backed support for the science and practice of their stewardship. To provide an evidence-based blueprint for such investment, this work uses a multi-scale approach, employing factorial experiments to evaluate seedling performance from the micro-scale (the phytobiome) to the meso-scale (forest structural conditions following silvicultural intervention), aiming to improve artificial regeneration and strengthen forest resilience. Chapter 1 synthesizes literature on resilience science, plant holobionts, and gap-based silviculture, identifying three knowledge gaps for species endemic to the PNW: (1) the performance of endophyte-inoculated seedlings under key abiotic stressors like drought and nutrient limitation, (2) species-specific physiological and morphological thresholds along light and moisture gradients, and (3) strategies for integrating these factors into adaptive management. Chapter 2 addresses the micro-scale by testing multi-strain bacterial and fungal consortia as bioinoculants for Pseudotsuga menziesii and Thuja plicata. Bioinoculation raised T. plicata survival by up to 80% under the driest regime, enhanced root development, and stabilized key physiological indicators. The findings show that these empirically selected consortia can improve seedling performance on water-limited sites. Chapter 3 presents the meso-scale, reporting on a 1,080-seedling experiment that simulated the light and moisture gradients found in canopy gaps. Light availability was the dominant driver of seedling performance. Notably, moderate canopy retention (~40% shade) maximized the Dickson Quality Index, a key measure of seedling vigor, in six of twelve species, including shade-tolerant taxa like Tsuga heterophylla and pioneers like Larix occidentalis. These results challenge traditional shade-tolerance rankings for artificially regenerated seedlings and support the use of partial-retention silviculture. Collectively, these results demonstrate the potential of integrating micro- and meso-scale interventions: (1) bioinoculation of seedlings enhances their drought fitness, while (2) partial overstory retention creates a more favorable establishment environment than open conditions. These findings expand the toolkit for artificial regeneration, opening new possibilities for utilizing a wider range of silvicultural prescriptions and species mixtures. This research provides a practical basis for the "critical infrastructure" framework by showing that while ecologically superior, these restoration strategies are often less economically efficient than traditional methods. Unless the risk reward balance changes and industrial forest managers begin to adopt more costly investments in rebuilding forested landscapes, we are unlikely to see large scale integration of these approaches. Therefore, justifying investments in these practices through subsidies or other financial incentives (new economies based on valuing forests for carbon or their biodiversity and therefore deriving new more expansive revenue streams) is essential for securing long-term societal benefits, such as reducing the regional reforestation backlog, maintaining biodiversity, and ensuring the continued flow of ecosystem services that support rural economies.
Habitat Assessment of the Rare and At-Risk Species Umtanum Desert Buckwheat (Eriogonum codium) for Increased Successes with Assisted Migration
(2025-08-01) Kahn-Abrams, Maya D.; Bakker, Jonathan; Johnson, Brittany
“Edaphic islands” are comprised of unique or challenging soil habitats and host 15-20% of global floral taxa including numerous rare and endangered species. These communities in general, and small populations of edaphic endemic species in particular, are at increasing risk from climate change related stress, threats from invasion by generalist non-native species, and exposure to novel anthropogenic disturbances, including altered fire intervals. The rare and endangered Umtanum Desert Buckwheat (Eriogonum codium) is a slow growing, long-lived perennial plant highly restricted to a 1.9 acre discontinuous band in the shrub-steppe of Hanford Reach Nuclear Facility (Department of Defense). Little is known about the habitat characteristics of its single population or whether its extremely limited distribution is due to the presence of unique soil properties at this location. Previous work has theorized E. codium may require specific edaphic conditions and/or low inter-species competition. The single population is in decline and outplanting efforts undertaken at nearby locations with similar site and soil conditions have largely failed. Assisted migration could enable otherwise impossible translocations of this species outside its native site, greatly reducing its risk of decline, genetic loss, and extinction. In 2020, the Washington Natural Heritage Program (WNHP) developed a habitat suitability model for E. codium which identified 115 acres of likely habitat, and seedlings were planted at five sites across two locations in 2020 and 2021. The intent of this study is to inform management strategies for the assisted migration of E. codium and determine the effects of outplanting locations and site selection on outplanted seedling success. To do so, this study characterizes E. codium’s current habitat and compares these habitat characteristics to past, current, and potential future assisted migration locations at two different spatial scales. In Chapter 1, site, soil, and vegetation habitat characteristics were measured at the single location where E. codium occurs (Native Site). Differences in E. codium site occupancy, abundance, and between the five remaining subpopulations and sampling transects was used to characterize E. codium’s associated habitat type and responses to a range of biotic and abiotic habitat variables. Inter-species competition was found to be an important factor shaping E. codium habitat. Site and soil characteristics, such as heat load, rock and bareground cover, and the abundance of fine and very fine gravel grades, were found to interact and form spatially heterogenous microhabitats and vegetation community dynamics directly impacting E. codium’s growth and survival. Cluster analysis of vegetation functional group composition identified six distinct vegetation habitat types delineating three perennial graminoid community types, each associated with either high, medium, or low abundance of E. codium. Site, soil and vegetation characteristics were compared between these “optimal” E. codium habitat groups to elucidate E. codium’s ability to occupy a range of microhabitat conditions. These results are explored as a means to theorize on E. codium’s evolutionary ecology and the role of microhabitat differences on its current confinement to the edge of Umtanum Ridge. In Chapter 2, site, soil and vegetation habitat characteristics were measured at past, present, and potential assisted migration locations, and compared to characteristics at the Native Site. Badger Mountain is considered a highly suitable past assisted migration location where seedlings were outplanted in 2020. Snow Mountain is considered a moderately suitable assisted migration location where seedlings were outplanted at three sites in 2020 and 2021, with additional trails ongoing at the time of this study. Gingko Petrified Forest State Park is considered a highly suitable assisted migration location, although no seedlings have been outplanted there to date. Site-level habitat characteristics at Gingko State Park and Snow Mountain were compared to those at the Native Site to evaluate the accuracy of the WNHP habitat model at the spatial scale utilized by managers when selecting assisted migration sites. Gingko State Park shared more habitat similarities with the Native Site than Snow Mountain did, consistent with the output from the WNHP habitat suitability model. However, similarity to the Native Site was quite different between the three Snow Mountain sites which was not reflected in the model. These results suggest that the habitat model may not be useful at selecting assisted migration sites at spatial scales finer than landscape level, or distinguishing highly suitable and moderately suitable habitats when they co-occur within a given location. Overlaps between the range of values at the Native Site and at assisted migration sites indicate the existence of potentially suitable microhabitats at fine spatial scales. Targeting these microhabitats for seedling establishment may be important for assisted migration. To assess this, differences in site, soil and vegetation characteristics around outplanted seedlings (transect-scale) were related to seedling survival rates and to habitat characteristics at the Native Site (high, medium, and low optimal habitat groups from Chapter 1). Overall seedling survival was very low, possibly due to differences in soil characteristics from the Native Site, and/or increased inter-species competition with forbs, annual graminoids, and especially other woody shrubs including more widely adapted Eriogonum species. However, heterogeneity in microhabitat niches at very fine spatial scales may have allowed for very limited seedling establishment (14% at Badger Mountain, 3% at Snow Mountain) and should continue to be the focus of future studies.
Physiological Constraints of Assisted Migration of Coast Redwoods (Sequoia Sempervirens) to Washington’s Western Cascade Region
(2025-08-01) Oliva, Beatriz; Ettl, Gregory
There is broad interest in moving the iconic Sequoia sempervirens (D. Don) Endl. to western Washington to assist in the climate pressured species’ habitat shift northward as well as provide cultural, ecological, carbon, and timber value. This research investigates the ecophysiological constraints of young redwoods in comparison with native species, Pseudotsuga menziesii (Mirb.) Franco and Thuja plicata (Donn.) through testing of S. sempervirens cultivars under controlled greenhouse drought conditions and across a soil moisture gradient in a field study outside of its native range. In the drought trial, measurement of photosynthetic capacity (Fv/Fm) as a stress metric, water potential, growth investments and survival show that S. sempervirens had similar or better drought response than native P. menziesii and consistently better than T. plicata. S. sempervirens cultivars showed similar levels of drought response, surviving almost 2 months of drought conditions, though a select few cultivars had early stress and mortality in the drought. In field conditions, S. sempervirens had a lower mortality rate (23% post establishment) than native, but nursery stock affected, P. menziesii (27.97% post establishment). A majority (10/16) of S. sempervirens cultivars also showed similar levels of vigor, while the remaining 6/16 demonstrated significantly lower vigor 10 months after planting. S. sempervirens cultivar performance in the greenhouse and field trial differ enough to suggest that greenhouse drought tolerance is not a predictor of successful S. sempervirens cultivar selection in Washington field conditions (p=0.342). While there is much left to understand about S. sempervirens ecophysiological limitations, assisted migration of S. sempervirens to western cascade region of Washington could be a feasible strategy to provide ecological and economic security to Washington forests.
Quantifying the effects of wildfire reintroduction on native pollinators in ponderosa pine forests of the Pacific Northwest
(2025-08-01) Maust, Autumn; Tobin, Patrick C.
Pollinators are an essential component of ecosystem function, and declining bee populations are a global conservation concern. Despite this importance, there is a lack of understanding regarding the distribution and demography of native bee species across western North American landscapes. Furthermore, the effects of disturbance on these essential fauna are understudied. Fire is a major driver of biodiversity and structural integrity in fire prone ecosystems. Over the last century, historical wildfire regimes have shifted due to climate change, exclusion of Indigenous fire stewards, and land management philosophies. As a result of these pressures, forests have experienced increases in fuel buildup that threatens dry forest resilience across western North America. In these post-fire landscapes, pollination is critical for vegetation recovery and ecosystem health. Pollinators are critical for successful angiosperm reproduction, food security, and ecosystem resilience. Because pollination services can vary by species and across spatial and temporal scales, land managers and ecologists seek to understand the spatial and temporal effects of fire reintroduction on native bee communities. An increased understanding of the effects of fire on pollinators can inform conservation management and ecosystem restoration. In this dissertation, I used field based and molecular methods to evaluate the effects of fire reintroduction on bee community composition across a temporal range of 1-9 years post-fire, and in an unburned control, in the Okanogan-Wenatchee National Forest in Washington, USA. In Chapter 1, I quantified native bee richness at nine forested plots using blue vane and pan traps, and determined that native bee genus richness was driven by the interaction between burn severity and burn age. Study areas that had been recently burned at higher severities had higher bee genus richness values. Furthermore, the proportion of above ground nesting bees in landscapes 1-8 years post-fire were greatest at sites that burned with moderate fire severity and had more available nesting habitat. In Chapter 2, I highlighted shifts in foraging resources for pollinator communities in post-fire landscapes based on DNA metabarcoding of pollen collected in blue vane and pan traps. The findings suggest that herbaceous perennials such as Achillea millefolium, Lupinus spp., and Phacelia hastata are important floral resources for post-fire pollinator communities. Burn age and burn severity were important drivers of plant-pollinator network richness, and plant species richness increased with burn age and burn severity. This work is the first to use pollen suspended in trap solutions to quantify floral resources for insect pollinators and highlights the utility of trap byproducts to provide insightful ecological information. In Chapter 3, I evaluated changes in pollinator demography to provide insights for bee community health following disturbance by wildfire. By deploying nesting materials across three burned landscapes and one unburned control, I quantified native wood-cavity-nesting bee reproductive success for two exemplar pollinator species: Osmia lignaria propinqua and Osmia kincaidii. The results suggest that burn age is the main driver of wood-cavity-nesting bee oviposition. Furthermore, DNA metabarcoding of pollen from nest boxes revealed herbaceous perennials such as Phacelia hastata and Epilobium brachycarpum to be important floral resources for wood-cavity-nesting pollinators. Finally, in Chapter 4, I documented new records of Melissodes nigracauda LaBerge, Dufourea dilatipes Bohart, Atoposmia abjecta abjecta Cresson, Coelioxys funerarius Smith, Dianthidium cressonii Dalla Torre, Dianthidium singulare Cresson, Osmia cyaneonitens Cockerell, and Stelis heronae Sheffield. These eight new records supplement the ~565 bee species previously documented in Washington state. Collectively, I assessed the effects of wildfire in ponderosa pine forests on native pollinator community composition, wood-cavity-nesting bee reproductive success, and plant-pollinator networks. These findings highlight the importance of fire reintroduction for native pollinator conservation in dry forest landscapes.
Post-fire carbon, fuels, and vegetation dynamics in wet temperate forests: implications for future fire and management in the Pacific Northwest
(2025-08-01) Morris, Jenna; Harvey, Brian J
Forecasting ecosystem dynamics under warming climate and increasing fire activity is a critical priority for contemporary ecology and ecosystem management. However, fundamental understanding of fire effects is missing in ecosystems where fire is infrequent, including wet temperate forests west of the Cascade Range crest in Washington and northern Oregon, USA (“northwestern Cascadia”). In this dissertation, I combined empirical and simulation insights from recent fires in northwestern Cascadia to address research priorities for anticipating the effects of large infrequent fires on future forest dynamics. First, I characterized initial (2–5 years) post-fire aboveground biomass in long-term monitoring plots within five fires to explore the relative influence of pre-fire stand age and burn severity on two important post-fire disturbance legacies: carbon and fuel profiles. I found that pre-fire stand age drove total legacy amounts while burn severity modified legacy condition. Regardless of burn severity, most biomass present pre-fire persisted following fire. These findings suggest that, when burned, older stands may have greater potential than younger stands to support several ecosystem functions, due to more abundant and complex disturbance legacies. Next, I characterized the relative importance of bottom-up and top-down drivers on short-interval reburn potential. I used the Fire and Fuels Extension to the Forest Vegetation Simulator to model potential fire behavior and effects in each field plot under two fire weather scenarios. I found that initial fuel variability influenced some aspects of potential fire behavior and effects in reburns under moderate fire weather conditions. However, extreme fire weather is likely to override these effects and result in stand-replacing fire effects regardless of differences in initial fuel variability among stands. Microclimate responding to differences in stand structure buffered potential fire behavior and effects, particularly in unburned stands, but did not change overall patterns. These findings suggest the dominance of top-down drivers on influencing short-interval reburn potential in wet temperate forests. Finally, I examined potential tradeoffs for managing post-fire forest trajectories, specifically focusing on early-seral conditions, tree regeneration, and fuel profiles. I initialized each high severity field plot in the individual-based landscape model, iLand, and simulated 80 years of stand development under two future climate scenarios. I found that pre-fire stand age had lasting effects on forest recovery following stand-replacing fire, with older stands having longer persistence of early-seral conditions, more abundant and diverse live tree regeneration, and greater canopy and surface fuel loads. Post-fire trajectories were similar under both warming and current future climate scenarios. These findings suggest that post-fire recovery may be more robust in older stands, and negative effects of warming are unlikely through the end of the century in the absence of additional disturbance. Further, common post-fire management interventions present likely tradeoffs for post-fire forest structure and function. Collectively, this work builds understanding of the drivers and consequences of fire in forests shaped by long intervals between severe disturbances. Exploring the immediate and future effects of fire on ecosystem functions, disturbance interactions, and management outcomes supports our ability to manage post-fire recovery trajectories in some of the world’s highest biomass forests.
Understanding the Effects of Human Recreation on Wildlife from Fieldwork to Management Decisions
(2025-05-12) Todd Zaragoza, Marcela; Gardner, Beth
Interest in outdoor recreation is increasing across natural landscapes, benefiting people and communities, but posing challenges for wildlife and land managers. This thesis examines recreation and wildlife management through field-based research on wildlife responses to recreation and an exploration of how scientific research informs management decisions. In Chapter 1, we examined the impacts of recreation on wildlife using camera trap data from 113 stations across eight Washington State Parks in the wildland-urban interface (WUI) — critical ecological zones where recreation-wildlife dynamics remain understudied. Using dynamic occupancy models and temporal activity analyses, we found that recreation influences species detection probabilities and activity patterns. Raccoons, bobcats, and cougars were more likely to be detected at stations with high recreation, while black bears, elk, black-tailed deer, and coyotes had higher detection probabilities at stations with low recreation. Temporal shifts were evident among coyotes and deer, which had significant differences in their activity patterns, showing increased diurnal activity in off-trail areas. To understand how field-based studies inform recreation and wildlife management, Chapter 2 examines the role of science in decision-making. We conducted semi-structured interviews with 14 land managers from local, state, and federal agencies in Washington, using thematic analysis grounded in the Theory of Planned Behavior. While managers expressed positive attitudes toward science-based decision-making, structural constraints, resource limitations, and communication gaps were barriers to research integration. In contrast, partnerships and accessible science were key facilitators, with tribal and local community pressures shaping management priorities. As outdoor recreation expands, maintaining spatial and temporal refuges for wildlife and strengthening the integration of science into management decisions will be essential for balancing wildlife conservation with sustainable recreation access.
Space use and temporal relationships among western spotted skunks (Spilogale gracilis) and two competing mesocarnivores on the Olympic Peninsula of Washington
(2025-05-12) Hubl, Dylan; Wirsing, Aaron J.
Among sympatric carnivores, acts of interference competition range in intensity from the threat of attack to interspecific killing (IK). If IK is a regular outcome of encounters between two carnivores, the subordinate species may be forced to avoid the other in space and/or time. Carnivores are at the greatest risk of becoming victims of IK if they are 2–4 times smaller than their potential attacker. Thus, the spatial distributions and activity patterns of small carnivores may be dictated by the presence of larger competitors. However, many species rely on constitutive defenses—those that are always present and provide continuous protection—to reduce the risk of mortality during encounters with predators, and thus small, but constitutively defended, carnivores such as skunks may not respond to the threat of IK through spatial or temporal avoidance. To explore the hypothesis that the risk of predation and IK by larger competitors is mitigated by constitutive defenses, we used multispecies occupancy models and detection/non-detection data from baited camera stations and collocated hair snares to test for pairwise interaction effects on the space use of western spotted skunks (Spilogale gracilis), coyotes (Canis latrans), and bobcats (Felis rufus) on the Olympic Peninsula of Washington, USA. Use of a multispecies occupancy model simultaneously allowed us to examine the spatial relationship between coyotes and bobcats and thus we also tested a secondary hypothesis that the slight body size disparity between the coyotes and bobcats and high dietary overlap between the two species promotes IK, which is dominated by coyotes. We also used timestamp data taken from camera detections to analyze the temporal overlap of daily activity patterns of all three species. We found no evidence of spatial or temporal avoidance among the three focal species. Our best supported occupancy model indicated that these species use space independently of one another, and we found high levels of temporal overlap among all three species. Our findings suggest that neither western spotted skunks nor bobcats fall victim to IK at a great enough rate to promote avoidance of their respective potential attacker(s). The decision to engage in IK is influenced by many risk and reward factors and the constitutive defense of western spotted skunks is likely a strong deterrent. Likewise, bobcats may be too formidable of an opponent— armed with sharp claws in addition to teeth—for coyotes to attack with regularity.
Evaluating Uncrewed Vehicle Systems (UVS) for Regulatory Monitoring of Compensatory Mitigation Sites
(2025-05-12) Munoz, Jocelyn; Bakker, Jonathan D.
In wetland resource management, drones, also known as uncrewed vehicle systems, offer unique advantages for monitoring and ensuring regulatory compliance at wetland mitigation sites. However, before introducing drone monitoring to evaluate performance standards on these sites, agencies need to understand the fundamental processes of working with drone-derived data, how these data compare to that collected via traditional field methods, and the respective advantages and disadvantages of drone-based monitoring. This study evaluated two critical components of the classification process: classification method and machine learning algorithm. I assessed overall accuracy and woody vegetation class accuracy at six mitigation sites in western Washington. These sites encompassed wetland, buffer, and riparian zones, and ranged in age from 3 to 10 years. Results from four classification trials indicated that object-based classifications consistently outperformed pixel-based approaches. The choice of machine learning algorithms, whether support vector machines or random trees, had no significant impact on accuracy metrics. I then compared woody cover measurements from drone- and field-derived data and analyzed results at the mitigation zone and sample plot scales. At the zone scale, I represented drone cover as the percentage of woody cover across the entire zone and field cover as the average woody cover of all plots. At the plot scale, I expressed drone cover as the percentage of woody cover within each plot, and field cover as the raw data collected in each plot. Differences in mean woody cover estimates between methods ranged from marginally significant to significant at the zone and plot scales. While correlations were significantly positive at the zone scale, they were weaker and more variable at the plot scale. These findings suggest that drone methods underestimate woody cover, and further refinement is needed to improve agreement between methods at the plot level. This study highlights the potential for drones to help site managers meet monitoring demands, particularly when resources are limited. A key drawback is the upfront time investment required to learn processing and analysis techniques. Overall, these findings contribute to developing guidelines for government agencies to adopt drone-based monitoring using off-the-shelf equipment and user-friendly methods that prioritize practical implementation, affordability, and accessibility.
Estimating Forest metrics in interior Alaska with terrestrial Lidar.
(2025-05-12) Deininger, Rachel; Moskal, L. Monika
This thesis contains multiple research documents, including a report for the Forest Service, a detailed field guide, a metadata document, and a research proposal. Boreal forests make up a third of global forested area and play a vital role in global carbon storage, but their vulnerability to climate change necessitates improved methods for monitoring. We need accurate models of forest structure to understand how boreal forests will respond to climate change. Lidar remote sensing shows potential to fulfil this need by providing fine-scale models of individual trees. study assesses the application of Terrestrial Laser Scanning (TLS) to estimate Above Ground Biomass (AGB) in Alaska's boreal forests, focusing on its performance compared to traditional Forest Inventory and Analysis (FIA) methods. TLS, using the FARO Focus S360 scanner, detected significantly more trees than FIA, especially smaller trees that FIA does not measure due to its diameter threshold. These differences in stem count are most pronounced in black spruce and mixed forests. Trees from the segmented TLS point clouds were matched with FIA manually measured trees. The matched trees were used to train a Random Forest model to predict tree species. With predicted species for all TLS detected trees, a species specific allometric equation to predict biomass was employed on an individual tree level. Statistical tests, including Kruskal-Wallis and Dunn's post-hoc tests, revealed that forest type and species composition significantly influenced errors in TLS-derived metrics, with deciduous forests showing the lowest variability in biomass estimates. Due to its ability to capture smaller trees, TLS identifies a greater amount of biomass, particularly in black spruce forests. The findings highlight TLS's potential to improve biomass estimates but also emphasize the need for careful calibration and species-specific adjustments. Future work should focus on integrating TLS with airborne and mobile Lidar technologies to scale forest structure assessments across broader landscapes. The field guide in Appendix A. provides a framework for conducting terrestrial and mobile laser scans in forest inventory in Alaska's boreal forests. By standardizing data collection and analysis protocols, this field guide aims to support the U.S. Forest Service's Forest Inventory and Analysis (FIA) program and advance the use of Lidar for assessing forest structure, carbon dynamics, and resilience in boreal ecosystems. The metadata document in Appendix B. provides detailed descriptions of data collected during field campaigns in Alaskan. These datasets are the product of this study, containing details of tree structural metrics such as diameter at breast height (DBH), height, projected area, and alpha volume, calculated from TLS, as well as derived attributes like biomass, proximity, and species predictions. The research proposal in Appendix C., funded by the Gloria Barron Wilderness Society Scholarship, addresses the need for monitoring forest state changes in Alaskan wilderness areas. The study plans to integrate aerial laser scanning (ALS) and mobile laser scanning (MLS), to develop a scalable method for quantifying forest structural complexity and monitoring ecological trajectories in boreal forests.

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