Forest Sciences Commons^™

Exploring The Relationship Between Tree Dbh And Lichen Cover On Coast Redwood, Grace M. Personeus, Sierra Gittleman, Alisa A. Zarattini

IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt

We investigated the relationship between Diameter at Breast Height (DBH) and lichen cover on coast redwood (Sequoia sempervirens) to see if larger trees had higher percentages of cover. We measured cover using 10 cover classes on the southeastern and southwestern sides of trees in a secondary growth forest. We found a significant relationship between DBH and cover, yet no significant difference between the two sides measured. We suggest that further research with a larger sample size and more varied age classes will provide further insight into the relationship.

Factors Influencing Tree Vigor And Structural Failure Along Powerline Corridors In Northern California: A Multi-Species Analysis, David Justin Dorval

Cal Poly Humboldt theses and projects

Tree failures (e.g., stem breakage, uprooting, or branch drop) can pose significant risks to public safety, particularly along powerline corridors for the risk of power outages and wildfire ignitions. In California, tree-related powerline failures have led to severe ecological and human costs in recent years. Despite extensive research on tree failure in urban environments and post-disturbance contexts, comparatively little empirical work has examined where powerlines intersect largely unmanaged stands. This study evaluates tree failure trends across multiple forest types in Northern California by examining how tree-level characteristics influence recent growth and failure occurrence in regionally dominant tree species. Specifically, the …

Early Successional Response To Stream Daylighting In Redwood National And State Parks, Orick, California, Rylee Rawson

Cal Poly Humboldt theses and projects

In-channel stream restoration projects can act as both disturbance and recovery mechanisms, disrupting existing conditions to reestablish the hydrologic and ecological processes that sustain stream ecosystems. These interventions initiate successional trajectories in which channel form and biological communities reorganize over time. In Redwood National and State Parks (California, USA), the Redwoods Rising initiative restores buried headwater channels by recontouring legacy logging roads and daylighting streams buried by Humboldt crossings. Using the National Park Service Klamath Network wadable stream monitoring protocol, I evaluated nine restored reaches spanning one to five years post-restoration, alongside old-growth reference reaches and available pre-treatment data. I …

Forest Management Options For The Wildland Urban Interface: Comparative Analysis Of Stand Development, Economics, And Forest Carbon Over 100 Years In Sierra Nevada Ponderosa Pine, Kassandra A. Mcdaniel

Cal Poly Humboldt theses and projects

This thesis presents a simulation study of various forest stand treatments and their long-term effects on ponderosa pine-dominated forests in the Sierra Nevada Mountain Range of the western USA. The goal was to create recommendations for forest management in the wildland urban interface (WUI) of the Tahoe National Forest and other locations with similar conditions. This study simulates current United States Forest Service (USFS) - Truckee Ranger District silvicultural treatment alternatives repeated over a 100-year period using the USFS Forest Vegetation Simulator (FVS). Proposed treatment alternatives include restoration, resilience, transition, conservation, and no management. Treatments are to be compared in …

Regeneration And Fuel Loading With Varying Overstory Retention In Redwood Stands 10 Years After Transformation To Multiaged Management, Jud Fisher

Cal Poly Humboldt theses and projects

Forest managers using retention forestry in western forests need information on regeneration dynamics and fuel development to design stands that are both productive and fire resilient. This study analyzes 10-year remeasurement data from the Redwood Multiaged Experiment in Jackson Demonstration State Forest, California, comparing regeneration and fuel responses across group selection (GS), aggregated (HA), and dispersed (LD, HD) retention treatments. Target relative density (RD) of the residual stand was zero in GS, 13% in LD, and 21% in HA and HD. Measurements included sprout growth and size of redwood and tanoak, seedling and sprout density, and surface fuel loading.

Redwood …

Ectomycorrhizal Fungi Associated With Pinus Species Of California's Northwestern Coast, Monika Audrey Richardson

Cal Poly Humboldt theses and projects

Ectomycorrhizal (ECM) fungi are vital for increasing host plant uptake of nutrients and stress tolerance within ECM forest ecosystems. The species assemblage of ECM fungi can vary locally in response to numerous biotic and abiotic environmental factors. In California’s northwestern coast the occurrence of three Pinus species, along with a disjunction between populations of Pinus muricata in Mendocino and Humboldt Counties, offer a unique opportunity to investigate the spatial and host effects on pine-associated ECM fungi. Ectomycorrhizal fungal community structure was quantified from host tree roots and sequenced sporocarps occurring at the same sites to create a project specific ITS …

Mount Rainier National Park: Tales, Trails, & Auto Tours, Jerry Rohde, Gisela Rohde, Larry Eifert

Archives & Reprint Series (imprint)

Re-release of the 1996 book on exploring Mount Rainier National Park. We are very pleased that you are about to read a reprint of our book, but 1996 was a long time ago, and many things have changed since then. While the human and natural history accounts are still accurate, some trail and road descriptions, along with park phone numbers and park facilities, are no longer valid. Before hiking any of the trails we describe in this book, please check with one of the park visitor centers for current information.

Following The Water: Tree Water Sources In Coastal Northern California Forests, Kaitlyn Briggs

Cal Poly Humboldt theses and projects

Increasing drought intensity and declining summer water availability in Mediterranean- climate forests raise concerns about forest resilience and streamflow persistence. This study evaluated how tree water sources vary with hillslope position, season, species, and watershed context across three coastal northern California forests. Stable isotopes of hydrogen (δD) and oxygen (δ18O), soil moisture time series, linear mixed-effects models, and site-specific Bayesian mixing models (MixSIAR) were used to estimate proportional contributions of shallow soil, deep soil, stream-associated, and fog water to tree xylem water. Across sites, xylem water isotopic signatures overlapped primarily with soil water, indicating dominant reliance on subsurface sources, while …

Relational Approaches To Fire Resilience: Designing A Living Shaded Fuel Break With Indigenous Knowledge Systems, Natalee Nicole Lopes

Cal Poly Humboldt theses and projects

Escalating wildfire severity across California reflects not only changing climatic conditions but also the cumulative impacts of colonial land management systems that have disrupted Indigenous fire stewardship and altered forest structure and function. This project examines how wildfire mitigation infrastructure, specifically linear fuel treatments, such as fuel breaks, can be reimagined through Indigenous relational frameworks of care-based land stewardship. Grounded in Happy Camp (Athithúfvuunupma), California, within the ancestral homelands of the Karuk Tribe along the mid-Klamath River, this research is carried out in collaboration with Karuk knowledge holders, centering Indigenous knowledge systems and priorities.

Using a mixed-methods approach that integrates …

Effects Of Conifer Encroachment On Oregon White Oak Crown Structure And Nonvascular Epiphyte Communities, Courtney Jonell Copper

Cal Poly Humboldt theses and projects

Oregon white oak (Quercus garryana, QUGA) is an ecologically and culturally important broadleaf tree species native to northern California and the Pacific Northwest. Fire suppression and subsequent encroachment by Douglas-fir (Pseudotsuga menziesii, PSME) and other conifers have made QUGA woodlands among the most threatened habitat types in the region. This study examines the influence of conifer encroachment on QUGA crown structure and nonvascular epiphyte (NVE) communities using ground- and crown-based sampling techniques.

Twenty-four trees were sampled across four sites in northern California along a gradient of conifer encroachment that was quantified as PSME basal area (BA). A …

Long-Term Relationships Between Tree Growth And Climate In The Trinity Alps Wilderness, Klamath Mountains, California, Usa, Emma R. Knepp

Cal Poly Humboldt theses and projects

The Trinity Alps Wilderness is a unique setting for evaluating late-Holocene climate variability because former glaciers occupied comparatively low elevations in a region influenced by both coastal and interior climate patterns. Tree-ring chronologies were developed from four conifer species—Shasta red fir (Abies magnifica var. shastensis), western white pine (Pinus monticola), Brewer’s spruce (Picea breweriana), and mountain hemlock (Tsuga mertensiana)—sampled at high elevations (1950 - 2300 m) near Emerald and Grizzly Lakes in the Trinity Alps Wilderness in northern California. The final chronologies included 12 Shasta red fir trees, 12 western white pine …

Baker Cypress (Hesperocyparis Bakeri) In A Changing Fire Landscape: Characterizing Fire Refugia And Guiding Post-Fire Reforestation, Olivia Lorraine Moskowitz

Cal Poly Humboldt theses and projects

Increasing wildfire frequency threatens serotinous, fire-obligate species that depend on sufficient fire-free intervals to develop seed banks for reproduction. These species require fire intense enough to trigger seed release and create favorable substrate and light levels for regeneration, yet consecutive fires that reburn populations before they reach maturity can cause local population contraction or extirpation. Understanding the environmental drivers of natural regeneration and mature tree survival, as well as when and how active reforestation should supplement natural recovery, is critical for managing fire-adapted species under altered fire regimes.

This thesis uses Baker cypress (Hesperocyparis bakeri [Jeps.] Bartel), a rare …

Solvent Extracts Of Pulvigera Papillosa (Orthotrichaceae) Show No Antimicrobial Properties In Disk Diffusion Tests, Ryan A. Solorzano, Justin Paulin, Grayson Prater, Michael Lanier

Humboldt Journal of Microbiology

Abstract As antibiotic-resistant bacteria become more prevalent, the search for novel forms of antibiotics in the natural world has become an increasingly worthwhile endeavor. Many mosses have been found to contain antimicrobial properties, including those in the family Orthotrichaceae. Pulvigera papillosa, an Orthotrichaceous moss native to California, has thus far not been investigated to determine whether it contains antimicrobial properties. Extraction techniques using polar and nonpolar solvents have proven to be effective in extracting the secondary metabolites that allow mosses to defend themselves against a hostile microbial world. This study takes a preliminary look into the antimicrobial properties of P. …

The Isolation And Dna Extraction Of Phytophthora From Four Wildland Soil Types In Northern California, Humboldt County, Angelina Lasko, Christopher Lee, David S. Baston, Susan E. Marshall

Creative Publications and Manuals

Phytophthora species are of global importance (Sinclair and Lyon, 2005). For most Phytophthora species, the natural mechanism of how these pathogens travel and spread long distances is not fully understood. They are have been shown to travel by air, water, nursery stock, and via inadvertent human transport. The purpose of this study was to identify the presence of Phytophthora species in four different Northern California forest/wildland soil types. Soils from Franciscan complex parent material (riparian, mixed conifer, and oak woodland), and serpentine parent material (mixed conifer) were sampled in Humboldt County (Fig 1). Phytophthora and other pathogens were baited from …

Assessing Understory Along The Elk River (Hikshari') In Headwaters Forest Reserve, Humboldt County, California, Julie R. Meyers, Aliyah M. Ingram, Caleb N. Larkin, Joshua L. Carpenter

Environmental Science & Management Senior Capstones

Northern California’s extensive logging history and lack of forest management has altered old-growth coast redwood (Sequoia sempervirens) forests, leaving dense, homogenous second and third-growth forest stands. This has led to the use of modern restoration techniques such as variable density thinning (VDT) which aims to rehabilitate old-growth forest conditions by improving stand heterogeneity and light availability for understory species. Our study was done in Headwaters Forest Reserve (HFR) along the Elk River (Hikshari’) Trail in Humboldt County, California. Initially, the project was supervised by the Bureau of Land Management (BLM) Arcata Field Office. However, the 2025 U.S. government …

Six Rivers National Forest Hazardous Fuels And Fire Management Project 2025 Orleans Complex Fire Effects From 9/13/25 - 9/14/25, James L. Parr, Nosheen Maung, Darby J. Lewis, Javier E. Margarito, Giancarlo Golloti

Environmental Science & Management Senior Capstones

The 2025 Orleans Complex affected the Klamath National Priority Landscape, designated by Congress as a priority to reduce fuel load and mitigate wildfire risk near rural, at-risk communities. To address the threat of large destructive wildfires, the 2023 Six Rivers Hazardous Fuels and Fire Management Project identified desired ecological conditions, using the right type of fire at the right time and place.

An Assessment Of The California Logging Workforce, Kendra Jean Gerstenberg

Cal Poly Humboldt theses and projects

There is limited literature describing the capacity and capabilities of the logging workforce in California. This study examines the logging workforce in California to quantify the number of logging crews, assess demographic diversity, and evaluate capacity and capabilities. The target population was California Licensed Timber Operators (LTOs) who have the legal right to harvest timber. A survey was developed and distributed to LTOs on the CAL FIRE database. Surveys were also distributed at regional logging conferences or collected by phone. Data were analyzed using Statistical Package for the Social Sciences (SPSS) and emergent coding for follow-up interviews was conducted. There …

An Evaluation Of Fuel Model Accuracy And Multi-Scale Mitigation Strategies In The Wildland-Urban Interface Of Southern Humboldt County, Julia I. Cavalli

Cal Poly Humboldt theses and projects

Strategic placement of fuel treatments is critical for mitigating wildfire risk and reducing potential structure losses in wildland-urban interface (WUI) communities. As wildfire activity accelerates across the western United States, the need to identify high-impact fuel treatment locations grows increasingly urgent. Concurrently, housing development in the WUI is expanding, intensifying the exposure of homes and infrastructure to wildfire threats. In response, many communities are looking to mitigate the likelihood and severity of losses during wildfire events. The success of these efforts depends, in part, on robust data to support strategic placement of effective treatments that reduce fuel availability.

This study …

Can We Help Coast Redwood Adapt To Climate Change? A Provenance Study On Genetic Variation And Climate Transfer Distance, Aidan J. Murphy

Cal Poly Humboldt theses and projects

The climate is changing more rapidly than many species can adapt or migrate. Coast redwood (Sequoia sempervirens) is a unique, long-lived conifer and remains California’s most valuable and economically important timber species. The species is threatened in its natural range due to anthropogenic climate change and human activity. Redwood favors asexual reproduction which restricts its ability to migrate naturally. The consequences of asexual reproduction when faced with a rapidly changing climate may make some form of assisted migration necessary for long-lived organisms like redwood.

This study evaluates drivers of variation in redwood growth and the influence of climate …

Effects Of Experimental Structural Retention Position And Aggregation On Avian Communities In Managed Forests Of The Pacific Northwest, U.S., Aidan M. Healey

Cal Poly Humboldt theses and projects

Managed forest lands in Oregon and Washington produce wood products and host diverse bird communities, though standing dead snags are often limited. State forest practices rules governing forest harvest dictate retention of a minimum number of trees when forests are clearcut harvested. However, little research has explored how the slope position and aggregation of retention, and the supplemental inclusion of mechanically created snags, affects use of these forest units by wildlife, especially highly mobile taxa such as birds. I used an avian point count sampling approach, within a replicate-block experiment dictating unit-level slope position, aggregation, and snag retention treatments, to …

Modeling Forest Stewardship In Goukdi’N: An Assessment Of Carbon, Wildlife Habitat, And Fire Resilience In A University Forest, Benjamin Stock

Cal Poly Humboldt theses and projects

This thesis presents a forest management plan for Goukdi’n (also known as the Jacoby Creek Forest University Tract), a coast redwood–tanoak–Douglas-fir forest within the ancestral homelands of the Wiyot Tribe. This project addresses the need for a forest stewardship approach that supports ecological resilience, cultural values, and long-term forest health in a landscape shaped by industrial logging, fire exclusion, and decades of under-management. To evaluate potential management pathways, forest growth modeling was conducted using the USFS Forest Vegetation Simulator (FVS) to compare three management prescriptions focused on carbon storage, fire resilience, and structural heterogeneity and a no-action alternative. Model outputs …

Assessing The Potential For Bigleaf Maple Syrup Production In Humboldt County, Ca, David A. Reinhart, Juan A. Ramos-Cool, Liam H. Richardson

Undergraduate Scholarship

The bigleaf maple (Acer macrophyllum, Pursh) is the largest maple of the Pacific Northwest. While it has generally been treated as a nuisance in timber harvesting operations, a small amount of research has been conducted on its sugaring ability in Oregon, Washington, and British Columbia. This research has yet to reach further south in the species' range. This study aims to help a California landowner understand which maple trees on his property produce the most maple sap, to gauge what environmental factors contribute to maple sap production, and to find greater implications for the production of maple sap …

Sense Of Place In Natural Resource Recreation And Tourism: An Evaluation And Assessment Of Research Findings.

The International Journal of Ecopsychology (IJE)

No abstract provided.

Longevity Of Prescribed Fire Effectiveness In Mixed-Evergreen Forests Of The Klamath Mountains, Kaily M. Fineran

Cal Poly Humboldt theses and projects

Prescribed fire is a common management tool used across the western United States to create wildfire-resilient ecosystems and communities. The Klamath Mountains of northern California, USA has experienced numerous, large wildfires in recent years. This is due in part to a combination of highly flammable fuels, uncharacteristic weather events, and high fuel accumulations as a result of fire exclusion and forest management practices. Within the last decade, local land management organizations and the Karuk Tribe have begun re-introducing prescribed fire in low elevation, mixed evergreen forests. While the long-term effects of fuel treatments are not well-known, these efforts provided a …

Post-Fire Persistance Of Sequoia Semperviens In A Secondary Forest: Examining Drivers Of Basal Resprouting Response, Jackson T. Carrasco

Cal Poly Humboldt theses and projects

Historically frequent-fire forest ecosystems are now facing increased size, frequency, and severity of fires attributed to climate change, intensive forest management, and fire exclusion. Understanding post-fire resilience in forest ecosystems is critical amidst escalating challenges posed by recent increases in fire activity. This study examined the basal resprouting response of coast redwood (Sequoia sempervirens) in a secondary forest two years after the CZU Lightning Complex fire on the central coast of California. Robust allometric equations were developed to quantify redwood resprout biomass and leaf area, revealing strong explanatory power for biomass equations (R² > 0.85). Probability of …

Satellite-Based Phenology And Climate Anomaly Analysis In Evaluating The Response Of Puerto Rico And The U.S. Virgin Islands Tropical Forests To The 2015-2016 Drought, Sean Fleming

Cal Poly Humboldt theses and projects

The health and overall resilience of tropical forest ecosystems are closely tied to the timing of phenological events. One must consider how forests react to significant climate anomalies to forecast the possible effects of climate change. This research study utilized U.S. Forest Service Forest Inventory Analysis (FIA) plot-level data and Landsat satellite data together to determine if these datasets are valuable techniques to understand the impacts of the 2015-2016 drought on Puerto Rico and the U.S. Virgin Islands (PRVI). I did remote sensing analysis on PRVI to produce repaired and near cloud-free satellite imagery, producing dozens of phenometrics of all …

Determining The Quality And Quantity Of California Sitka Spruce (Picea Sitchensis) On Private Commercial Timberland For Use In Domestic Acoustic Steel-String Guitars, Ryan Eugene Cooper

Undergraduate Scholarship

Development of additional revenue streams for timber products with relatively low profitability is an important step in securing future economic success for the forestry sector in Humboldt county. Utilization of California Sitka spruce (Picea sitchensis) for use in domestic acoustic steel-string guitar manufacturing may provide exactly that. Determining the quality and quantity of California Sitka spruce is the logical first step in achieving this.

Quality was determined from tree core samples gathered at sites on Green Diamond Resource Company’s (GDRco) California timberlands and the Arcata Community Forest (ACF) with high basal area of Sitka spruce. Rings Per Inch …

Environmental Implications Of Modern Food Production: An Analysis For The Conscious Consumer, Jessica T. Coming

Cal Poly Humboldt theses and projects

This project explores the pathways by which agriculture affects the environment and determines which foods have the greatest climate, water, and land impacts. Agricultural effects on the environment are extensive, from loss of habitat and declines in regional biodiversity to disruption of global nutrient cycles and climate change. Global food production accounts for 26-34% of annual anthropogenic greenhouse gas emissions, makes up 38-46% of habitable land, and is responsible for 70% of freshwater extraction. The effect of agriculture on the environment is most significantly dictated by what type of food is being produced. Animal-based food products consistently have the highest …

Assessing Understory Vegetation Response And Fuel Load Levels Following Silvicultural Treatments In Headwaters Forest Reserve, Humboldt County, California, Kyle James Railton, Madison Tatar

Undergraduate Scholarship

Old growth forests are important for ecological resilience, especially in temperate rainforest ecosystems. There are presently 3,000 acres of old growth forest within the 7,472 acres of the Headwaters Forest Reserve (HFR) in Humboldt County, California. Remaining acres were subjected to unsustainable logging practices, such as clearcutting, that resulted in a severely overstocked second-growth forest. The Bureau of Land Management (BLM) created a management plan for the reserve to restore previously harvested areas to their historic condition. The goal for the BLM is to accelerate growth rates of residual forests, to align them on a trajectory of achieving old-growth forest …

Factors Contributing To Legacy Hardwood Mortality Following Prescribed Fire, Heather D. Rickard

Cal Poly Humboldt theses and projects

Interruption of Indigenous stewardship has resulted in hardwood decline along what is now known as the middle Klamath River in northern California related to adverse effects to Tribal food sovereignty and community wellbeing. The survivors of a “legacy” of Indigenous stewardship are highly valued by the Karuk and neighboring Tribes for a myriad of culturally beneficial ecological associations and sources of traditional staple foods. Prescribed fire, following a century of fire exclusion, has resulted in unanticipated mortality of legacy tanoak (Notholithocarpus densiflorus), California black oak (Quercus kelloggii), and madrone (Arbutus menziesii), warranting further investigation. …