Forest Management 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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 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 …

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 …

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 …

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 …

Investigating Tribal Co-Management Of Caifornia’S Public Lands, Zachary Joseph Erickson

Cal Poly Humboldt theses and projects

Collaborative management with Indigenous groups is becoming increasingly common as many Indigenous communities continue to assert their inherent rights to self-determination. Due to the removal from and dispossession of lands, tribes often rely on access to public properties for various uses including ceremonies and gathering of culturally important plants. Some believe that the absence of indigenous involvement has also led to a decline in both the quality and abundance of culturally important resources, as well as limited the intergenerational transfer of traditional ecological knowledge, or TEK. There is increasing momentum toward re-engaging tribes as stewards of their ancestral lands through …

Physical Characteristics And Fine Roots Within Duff Mounds Of Old-Growth Sugar And Jeffrey Pine In A Fire-Excluded Sierran Mixed-Conifer Forest, Jules Bartley

Cal Poly Humboldt theses and projects

Fire exclusion has profoundly impacted frequent fire forests in western North America, disrupting fundamental ecological processes while leaving large, old pine trees vulnerable to drought, insects and disease, and fire. Forest managers want to increase the pace and scale of prescribed burning, yet heavy accumulations of organic material (duff mounds) at the bases of large pines can smolder for prolonged periods, damaging the cambium or consuming fine roots occupying the O horizon and/or upper mineral soil horizons. Increased duff mound depth is associated with greater mortality risk during prescribed fire, yet the biotic and abiotic drivers of duff mound accumulation …

Assessing The Recovery Of Forest Understory Vegetation After Clearcut Logging Across A 445-Year Chronosequence, Molly Smith Metok

Cal Poly Humboldt theses and projects

The conversion of natural forested lands to managed forests has reduced the amount of older, structurally diverse forests worldwide. In conifer forests of the Pacific Northwest (USA) – where the understory plant communities comprise only 1% of forest biomass but represent 90% of the plant species richness – the long-term impacts of timber harvesting are not fully understood. I used a chronosequence of forests in southwestern Oregon that ranged from 25 to 445 years of age to compare changes in plant communities in logged (i.e., managed) stands with that of stands in late succession and old growth conditions. The chronosequence …

Carnivore And Ungulate Occurrence In A Fire-Prone Region, Sara J. Moriarty-Graves

Cal Poly Humboldt theses and projects

Increasing fire size and severity in the western United States causes changes to ecosystems, species’ habitat use, and interspecific interactions. Wide-ranging carnivore and ungulate mammalian species and their interactions may be influenced by an increase in fire activity in northern California. Depending on the fire characteristics, ungulates may benefit from burned habitat due to an increase in forage availability, while carnivore species may be differentially impacted, but ultimately driven by bottom-up processes from a shift in prey availability. I used a three-step approach to estimate the single-species occupancy of four large mammal species: mountain lion (Puma concolor), coyote …

Establishing A Market Capacity And Economic Baseline For Forest Biomass Utilization In The Southern Cascade And Northern Sierra Nevada Mountain Range, California, Clarke Stevenson

Cal Poly Humboldt theses and projects

Attempts to address wildfire risk and forest resilience have increased substantially over the last 20 years with specific interest in removing excess vegetation from stands, commonly referred to as “forest biomass”. However, the market capacity for and the economics of biomass utilization have been a limiting factor to achieving statewide goals for forest health and fire resilience. This thesis looks at the Southern Cascade and Northern Sierra Nevada biomass supply chain to benchmark current market capacity for biomass utilization through mapping and harvest record analysis. It also calculates the net revenue of biomass mobilization based on costs developed from a …

Knobcone Pine Response To Shading From Competing Chaparral Shrubs Following Stand-Replacing Wildfire, Sean T. Lindley

Cal Poly Humboldt theses and projects

In northern California, fire regimes are shifting towards more frequent and larger severe wildfire. There is growing concern that this shift poses a threat to biodiversity in the form of cover type change at the landscape scale, resulting in the extirpation of some species in favor of +AD617:AD649well-adapted ones. In northern California, mature serotinous conifers, such as knobcone pine (Pinus attenuata), and resprouting shrub species easily regenerate in severe patches of any size. There is no general consensus regarding the effects of shrub competition on conifer recruitment; conifer response varies with shade tolerance and other abiotic factors. Knobcone …

Investigating Seed Maturation And Mortality: A Mechanism For Post-Fire Regeneration In Non-Serotinous Conifers, Madeleine A. Lopez

Cal Poly Humboldt theses and projects

Climate warming and associated dry conditions are contributing to increased fire frequency, severity, and size, for many regions in western North America. These changes in fire activity have prompted concern over the long-term persistence of some conifer species, specifically those not adapted to withstand high-severity fire. However, regeneration of non-serotinous conifer species is possible if the timing of fire occurs following seed maturation, and within a heat range that seeds can withstand, in a regenerative mechanism termed “facultative serotiny.” To address this mechanism, I determined the timing of conifer seed maturation using viability testing for four California conifer species: ponderosa …

Data Repository For "North American Porcupine Distribution In The Pacific Northwest And Evaluation Of A Non-Invasive Monitoring Technique", Cara L. Appel, Katie M. Moriarty, Sean M. Matthews, David S. Green, Stacy Anderson, Evan King, J Scott Yaeger, Jeremy Brown, Claire Bortot, Tim Bean

Research Data Sets

North American Porcupines (Erethizon dorsatum) have a broad geographic distribution across much of the continent, but recent evidence suggests that their populations may be declining in some areas, including the Pacific Northwest. Estimating baseline historical and contemporary distributions of Porcupines is necessary for initiating monitoring efforts and, if necessary, informing strategic conservation actions. We compiled 1905 occurrence records of Porcupines in Washington, Oregon, and northern California from 1908 to 2018. Using maximum entropy modeling (Maxent), we created historical and contemporary distribution models based on Porcupine records from 1981–2010 and 2012–2018, respectively, to match the temporal scale of available …

Recreation, Vegetation Management, And Disease Impact Sympatric Carnivore Activity In California's East Bay Parks, Leigh J. Douglas

Cal Poly Humboldt theses and projects

East Bay Regional Park District designated over 1000 ha of protected wildland-urban interface habitat in the hills of California’s East Bay Area for invasive tree removal to reduce fire risk and restore native habitat over a 10-year period starting in 2016. From June to November 2019, 36 camera traps were deployed using a stratified two-pronged detection approach of surveying recreation and wildlife trails to assess the impact of vegetation management on the spatiotemporal distribution of sympatric carnivore species while accounting for potential impacts of human activity and proximity to development. The sampling effort resulted in 5,191 cumulative trap nights, 2,739 …

Post-Fire Effects In Chaparral And Oak Ecosystems Of Northern California, Abigail M. Jones

Cal Poly Humboldt theses and projects

The issue of wildfires, hazard fuels management, and post-fire tree mortality has become an increasingly common topic in the western United States. This thesis is composed of two studies, with the first study, Chapter 1, examining fuel treatment effectiveness and the second study, Chapter 2, striving to characterize post-fire mortality in oaks.

Prior to wildfire, fuel reduction projects may take place to decrease the likelihood of high severity fire around human infrastructure and communities. Within California’s chaparral ecosystems, common treatment types include hand-thinning, prescribed burning, mechanical mastication, and mechanical mastication followed with prescribed burning. Because chaparral has a longer historical …

Conifer Encroachment And Removal In A Northern California Oak Woodland: Influences On Ecosystem Physiology And Biodiversity, Gabriel S. Goff

Cal Poly Humboldt theses and projects

Oregon white oak (Quercus garryana) woodlands across their range are becoming increasingly threatened by encroaching Douglas-fir encroachment (Pseudotsuga menziesii) as a result of fire exclusion. Using water potential (Ψ), stomatal conductance (g_s), xylem water stable isotopes (dD), and three metrics of biodiversity, this study investigates the effects of conifer encroachment and removal at the ecosystem-scale. The study was set in an Oregon white oak woodland in northern California and compared three levels of encroachment before and after conifer removal. Findings indicate that heavily encroached stands have the least amount of water stress and gas …

Comparison Of Low-Cost Commercial Unpiloted Digital Aerial Photogrammetry To Airborne Laser Scanning Across Multiple Forest Types In California, James Edward Lamping

Cal Poly Humboldt theses and projects

Science-based forest management requires quantitative information about forest attributes traditionally collected via sampled field plots in a forest inventory program. Remote sensing tools, such as active three-dimensional (3D) Light Detection and Ranging (lidar), are increasingly utilized to supplement and even replace field-based forest inventories. However, lidar remains cost prohibitive for smaller areas and repeat measurement, often limiting its use to single acquisitions of large contiguous areas. Recent advancements in unpiloted aerial systems (UAS), digital aerial photogrammetry (DAP) and high precision global positioning systems (HPGPS) have the potential to provide low-cost time and place flexible 3D data to support forest inventory …