Life Sciences Commons^™

Evaluating Immaturity Risk In Young Stands Of The Serotinous Knobcone Pine (Pinus Attenuata), Katherine Marlin

Cal Poly Humboldt theses and projects

As wildfire becomes increasingly frequent, many plant populations risk local extirpation if fire recurs too soon, a problem dubbed “immaturity risk”. We studied the regeneration of a serotinous conifer species, knobcone pine (Pinus attenuata), as a function of the time between high-severity fires (6-79 years). We evaluated age, cone production, and regeneration at two burned sites in northern California, the Ranch Fire (2018) in Mendocino National Forest, and the Carr Fire (2018) in Whiskeytown National Recreation Area. We found an average of 30.5 filled seeds in closed, brown cones (42% viability of filled seeds). The bulk of the …

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 …

Understory Dynamics Across 62-Years Of A Northern Hardwood Management Gradient Study, Heidi Harmala

Dissertations, Master's Theses and Master's Reports

Northern hardwood selection silviculture relies on the perpetuation of natural regeneration. However, many researchers and forest managers have concerns about deficiencies in regeneration and the associated ingrowth and recruitment of advance regeneration under single-tree selection. Given the differences of management application in the Great Lakes region, long-term studies and datasets are critical to understanding of how these systems function and change. Using the Cutting Methods Study, in the Western Upper Peninsula of Michigan, these concerns were investigated with a multi-decadal dataset, for understory tree species composition and density, diversity, recruitment, and age-diameter relationships across management methods. In response to the …

Regional Impacts Of Invasive Species And Climate Change On Black Ash Wetlands, Joseph Shannon

Dissertations, Master's Theses and Master's Reports

For more than a decade intensive research on the ecohydrology of black ash wetland ecosystems has been performed to understand these systems before they are drastically altered by the invasive species, emerald ash borer (EAB). In that time there has been little research aimed at the scale and persistence of the alterations. Three distinct but related research articles will be presented to demonstrate a method for moderate resolution mapping of black ash across its entire range, understand the relative impacts of EAB and climate change on probable future wetland conditions, and develop an experimental and modeling approach to quantify and …

Wildlife Forage Recovery Following Boreal Wildfire, Alexis Jorgensen, Jennifer Baltzer

Theses and Dissertations (Comprehensive)

Climate change is altering the boreal wildfire regime through increases in the extent and severity of burning and reductions in fire return intervals. These changes can alter the regeneration trajectory of canopy species and ground vegetation, with implications for wildlife habitat. There is some uncertainty about the timelines of when different animal species will use burned areas as their preferred forage taxa recover following fire, and how such recovery is mediated by environmental factors. Here, we aim to address these knowledge gaps through the following questions: 1) What are the main forage types consumed by boreal wildlife and how much …

Insect Community Associated With Black Cherry (Prunus Serotina) In The Allegheny National Forest, Craig James Larcenaire

Graduate Theses, Dissertations, and Problem Reports

Black cherry (Prunus serotina Ehrh.) is valuable species managed for its economic and ecologic benefits. This species grows best in the environment of the Allegheny Plateau region in northwestern Pennsylvania. Land managers on the Allegheny National Forest (ANF) have been managing black cherry for a variety of goals and purposes. Over the last few decades, the land managers have noticed a decline in the natural regeneration of black cherry in the forest. Because the black cherry flowers are self-incompatible and require animal pollinators to transfer the pollen from one tree to another one hypothesis for this decline could be …

Southern Pine Beetle-Specific Rna Interference Demonstrates No Effects On Nontarget Insects, Hannah Marie Hollowell

Theses and Dissertations--Entomology

The endemic southern pine beetle (SPB), Dendroctonus frontalis Zimmermann, is a highly destructive bark beetle that has devastated coniferous forests of the southern United States for decades. Traditional management strategies have been unable to respond effectively to largescale SPB outbreaks, prompting exploration of novel techniques including RNA interference (RNAi). Double-stranded RNAs (dsRNAs) are effective at triggering gene silencing and inducing mortality in SPB, but determining delivery methods and demonstrating specificity of the treatments is necessary before this technology may progress to deployment.

I evaluated three SPB-specific dsRNAs on model nontarget insects to assess potential lethal effects, sublethal effects such as …

Three Essays On “Energy , Environment, And Developmental Economics”, Bolarinwa Ajanaku

Graduate Theses, Dissertations, and Problem Reports

This dissertation examines topics related to renewable energy development and investment planning, energy markets, environment degradation and economic development. The substantial ecological costs of deforestation are well known and considered globally important due to biodiversity loss, land degradation, soil erosion, and contributions to climate change. The first essay focuses upon understanding the tradeoff between development and deforestation in Africa. In the second essay, spatial analysis and Geographic Information System (GIS) are applied to determine potential locations for wind farms development in the state of West Virginia. Lastly, the third essay examines the role of wind power penetration on wholesale electricity …

The Role Of Tree Species, The Herb Layer, And Watershed Characteristics On Nitrogen Cycling In A Central Appalachian Hardwood Forest, Sian E. Eisenhut

Graduate Theses, Dissertations, and Problem Reports

Little is known about the forest herbaceous layer’s contributions to nitrogen (N) cycling under varying levels of N deposition, at different stages of forest succession, in watersheds with different aspects, and under different tree species. The objectives of this study were to quantify nitrogen reductase activity (NRA) of two tree species, red maple and sugar maple, and surrounding common herb-layer species at the tissue (foliage, roots) and plot level and to assess how these species affect the concentrations of nitrate, ammonium, and organic N in soil water collected in lysimeters beneath these trees. Different watersheds located at the Fernow Experimental …

Sula Study Revisited: 20-Year Post-Fire Regeneration In The Southern Bitterroot Valley, Montana., Luke Alan Rymniak

Graduate Student Theses, Dissertations, & Professional Papers

In the summer of 2000, a number of large fires burned in the southern Bitterroot Valley near Sula, Montana. Research was conducted in 2001 and 2003 in the fire-affected areas of the French Basin and Larid Creek areas in order to investigate the effects of environmental variables, fire severity, and post-fire management on vegetation regeneration. In 2020 these areas were remeasured to understand trends over time by evaluating the impact of these same factors 20 years post fire. The results showed that the effects of environmental variables, fire severity, and post-fire management on vegetation regeneration were varied. The most influential …

Forest Development And Regeneration Dynamics In The Context Of Global Change And Associated Adaptation Strategies, Peter Clark

Graduate College Dissertations and Theses

Over the past century, forested ecosystems in northeastern North America have undergone significant changes characterized by the recovery from intensive land use and impacts from the introduction of invasive insects and disease. These changes, coupled with emerging threats posed by a changing climate present challenges to the maintenance and conservation of biodiversity, ecological functions, and delivery of critical forest ecosystem services. While management strategies to increase forest resilience and mitigate impacts from climate change have been broadly proposed, there are nascent empirical evaluations of their effectiveness. To address this uncertainty, this dissertation couples field manipulations with long-term measurements to examine …

Informing Adaptation Strategies For Northeastern Pitch Pine Barrens In The Context Of Mesophication And Southern Pine Beetle Impacts, Elizabeth-Ann Jamison

Graduate College Dissertations and Theses

Forest pests, the most significant agent of disturbance in forested ecosystems of North America, are highly sensitive to climate change. Southern pine beetle (SPB) is a highly destructive pine forest pest that is expanding its historic range in the southeastern US to affect the globally rare northeastern pitch pine barrens as winter temperatures warm. By generating high levels of mortality in canopy pitch pine, SPB is accelerating the ongoing conversion of fire-dependent pine barrens to mesophilic forests. We aimed to support the adaptive management of pine barrens ecosystems in the context of these two threats by (1) assessing stand conditions …

Soil Microbial Nitrogen-Transforming Genes Influenced By Tree Species And Fertilization In An Appalachian Hardwood Forest, Emma G. Fox-Fogle

Graduate Theses, Dissertations, and Problem Reports

Many forest ecosystems have been receiving elevated nitrogen (N) deposition due to human activity. Increased ecosystem N threatens soil fertility, water and air quality, and modifies the soil microbially-mediated N cycle in complex ways. The current study investigates how the abundance of key functional N cycling genes within soil bacteria is altered by N deposition and further mediated by different dominant tree species at the Fernow Experimental Forest, WV. Soils were analyzed from two watersheds, where watershed 3 (WS 3) has been receiving experimental applications of N fertilizer that are 2x historic ambient N deposition and 5x the current ambient …

The Impacts Of Asian Longhorned Beetle On Forests In Southern New England, Olivia Fay Box

Graduate College Dissertations and Theses

Over the past several decades, the United States has been experiencing an influx of nonnative pests due to increased globalization, and many of these pests have the potential to permanently alter the composition, structure, and function of forests. Asian longhorned beetle (ALB) is an invasive pest that came into Worcester county, MA in 2008, where the first instance of this species invading both urban and natural forested areas was documented. Within the quarantine area for this novel invasion, 30,000 trees were removed over the course of 10 years as part of management efforts focused on harvesting all host species, primarily …

Analyzing Safety Audits To Improve Logging Safety Performance, George Daniel Nolan Jr

Graduate Theses, Dissertations, and Problem Reports

This study examines logging safety audits to determine how different variables, and differing amounts of time between audits, affect the outcome of safety score performance. To collect the data for this study a three-page paper audit was used that examined five areas of the logging site which include: Personal protective equipment (PPE), general, felling, mobile equipment and, landing and loading.

The study analyzed 3 aspects of the audit which were the total score and the sub-categories of PPE and felling since they were the two heaviest weighted sections. The analysis only included audits that had a 5 percent or greater …