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Novel Fire And Herbivory Regime Impacts On Forest Regeneration And Plant Community Assembly, Devri A. Tanner

Theses and Dissertations

Human activities are increasing the occurrence of megafires that have the potential to alter the ecology of forest ecosystems. The objective of this study was to understand the impact of a 610 km2 megafire on patterns of forest regeneration and herbivory of three forest types (aspen/fir, oak/maple, and pinyon/juniper) within the burn scar. Sapling density, meristem removal, and height were measured across a transect network spanning the area of the burn scar over three years from 2019-2021. The network consisted of 17 burned/unburned transect pairs in adjacent burned/unburned forest stands (6 aspen/fir, 5 oak/maple, and 6 pinyon/juniper). Species that regenerated …

The Effects Of Prescribed Fire On Ant Community Composition In A Temperate Deciduous Forest., Emma Jones

College of Arts & Sciences Senior Honors Theses

Prescribed fire is a tool commonly used in land management to decrease wildfire frequency and promote plant diversity. However, the effects of prescribed fire on invertebrate communities, especially those within temperate deciduous forest, are poorly understood. I measured the response of epigeic ant communities in mixed mesophytic forest in Berea, Kentucky following prescribed burning. I used pitfall traps to repeatedly sample epigeic ants in replicate burned and unburned plots for up to 21 months postburn following two separate (2021 and 2022) prescribed fires. Ant species richness was similar between treatments (burn vs. control) and by burn year. Ant community composition …

Disruption Of Play Behavior Influences Development Of Caution In Juvenile Ground Squirrels, William Ryan

Master's Theses

Play behavior is ubiquitous among young mammals and has a variety of important influences on early development. I evaluated possible influences of social play behavior on the development of temperament in juvenile Belding’s ground squirrels (Urocitellus beldingi), using the caution/boldness spectrum as a measure of temperament. I disrupted the play behavior of juvenile U. beldingi by walking toward juveniles at play until the play interactions stopped. I used undisrupted juveniles and juveniles whose non-play behavior was disrupted at regular intervals as controls. Caution was measured with behavioral tests during which a human intruder walked toward a squirrel and recorded the …

Response Of Running Buffalo Clover (Trifolium Stoloniferum Muhl Ex. A. Eaton) To Herbaceous Competition And Transplanting In Monongahela National Forest, Ruben E. Sabella

Graduate Theses, Dissertations, and Problem Reports

Running buffalo clover (RBC) is a rare perennial plant that grows throughout the American Midwest and the Appalachian Mountains. It requires disturbed forests to establish and proliferate. It has been suggested that, in the past, these conditions were created by buffalo; now logging operations maintain RBC populations. However, forest managers have been looking for ways to create suitable habitat for RBC that do not involve harvesting practices. This could help create new populations in areas that cannot be logged. Once established, competing vegetation might influence RBC abundance and flowering. This study seeks to quantify this influence by measuring the vegetation …

Patterns, Mechanisms, And Characterization Of Carbon Cycling Stability Following Partial Forest Disturbance, Kayla C. Mathes

Theses and Dissertations

Among the most essential questions in the era of climate change is how the forest carbon (C) cycle will respond to an increase in the extent of biotic disturbances from insects and pathogens. While research has focused on stand-replacing disturbance regimes, less is known about C cycling stability following partial disturbances that produce gradients of disturbance severity. Belowground C cycling responses to disturbance are especially poorly understood, even though temperate forest soils contain up to 50% of total ecosystem C and soil respiration (R_s) accounts for more than half of temperate forest C loss. Interpreting trends and mechanisms …

Disturbance Ecology Of The Sonadora River Rock Pool Insect Assemblage At Luquillo Experimental Forest, Puerto Rico, Patrick Gilkey

Master's Theses

Freshwater rock pools can serve as habitat for aquatic insects. Flash-flooding can have profound effects on insect communities in streams and rivers, but these effects have not been studied on freshwater rock pools. The goal of this thesis was to describe ecological patterns of the Sonadora River rock pool insect community at the Luquillo Experiment Forrest, Puerto Rico, specifically in response to intense flash-flooding, and then perform experiments to elucidate possible processes to explain those patterns. The rock pools contained primarily three taxa of Dipteran (true-fly) larvae, in order of decreasing abundance, 1) a newly discovered species of ceratopogonid (biting …

Fire And Periodical Cicadas: Impacts On Soil Nutrients And Understory Plant Germination, Andrea Gamache

Master of Science in Integrative Biology Theses

Purpose

A compound disturbance, composed of a prescribed fire and a periodical cicada emergence, occurred in northern Georgia in the summer of 2021. Independently these disturbances have substantial effects on the surrounding ecosystems. This study investigated the collective impact on soil composition and seed germination.

Methods

Through the soil analysis of cicada turrets, burned soil, and unburned soil, we hope to understand the composition of each soil type. Additionally, a 2 x 2 factorial study was performed with those same samples, providing insight into the impact on seed germination these disturbances have. The two factors were between burned and unburned …

Grassland Bird Responses To Bison And Prescribed Fire Disturbances At Nachusa Grasslands And Kankakee Sands, Antonio Del Valle

Graduate Research Theses & Dissertations

Grazing from native herbivores such as bison (Bison bison), in combination with prescribed fire, are applied to tallgrass prairies by managers to recreate important disturbance patterns in this ecosystem. Bird communities may be indirectly impacted by these disturbances through their direct impact on plants that provides critical breeding habitat for grassland birds. The objectives of this research are to determine the impacts that bison and prescribed fire have on grassland breeding birds in two tallgrass prairie preserves, Kankakee Sands and Nachusa Grasslands. Birds, vegetation structure, and bison activity were surveyed systematically at these two preserves in 2020 and 2021. Prescribed …

The Impacts Of Maple Syrup Production On The Herbaceous Layer In Appalachian Hardwood Forests, Logan Scott Ferguson

Graduate Theses, Dissertations, and Problem Reports

Vegetation data were collected from eight maple syrup farms (sugarbushes) and eight undeveloped maple-dominated sites to examine potential differences in understory plant communities due to disturbance effects. Understory plants were identified to the species level and percent cover of aboveground leaf-area for each species was estimated within 600 total quadrats. Overstory data and environmental data were collected to help determine if they had any effect on herbaceous-layer plant communities. Species richness, Shannon diversity, and Pielou’s evenness were calculated, with the analysis showing no significant differences between the site types. The absolute cover of plant functional groups was also compared between …

Factors Influencing Brook Trout Population Dynamics And Resilience In Central Appalachian Headwater Streams, Christopher W. Schwinghamer

Graduate Theses, Dissertations, and Problem Reports

Central Appalachia has a unique history of human perturbation due largely to its historical economic reliance on extractive industry and timber harvest. Legacy impacts from these historic disturbances along with contemporary stressors in the form of continued industry, changing climates, altered land use, habitat fragmentation, and introduced species can present great threats to the region’s aquatic ecosystems. Brook Trout Salvelinus fontinalis are a species that has recreational and economic importance to the communities of central Appalachia but declines in size and abundance have been observed. Given the disturbances that threaten Brook Trout populations, understanding how their populations will respond to …

Anthropogenic Disturbance Regimes Impact The Microbial And Chemical Composition Of Soils And Sediments Across Ecosystems, Gregory D. Martin

Graduate Theses, Dissertations, and Problem Reports

Human activities have led to profound changes in the climate and environment, fundamentally changing global carbon and nitrogen cycles. Ongoing conversion of wildland for human use and the intensification of agricultural systems have dire consequences for biodiversity and the ecosystem services that support society. While natural disturbance regimes are important for the long-term maintenance of native biodiversity and ecosystem function, many disturbances are becoming increasingly frequent due to anthropogenic activities. Increasing the frequency, intensity, or duration of disturbances can prevent ecosystems from returning to their previous equilibria. Disturbance-induced changes to the local environment shape microbial communities, which in turn govern …

Coupled Structure-Function Responses To Disturbance: High Structural Complexity Resistance Supports Primary Production Resistance, Kerstin M. Niedermaier

Theses and Dissertations

The capacity of forests to resist structural change and retain material legacies–the biotic and abiotic resources that persist through disturbance–is crucial to sustaining ecosystem functioning after disturbance. However, the role of forest structure as both a material legacy and feature supporting carbon (C) cycling stability following disturbance has not been widely investigated. We used a large-scale disturbance manipulation to ask whether LiDAR-derived canopy structures as material legacies drive 3-year responses of NPP to a range of disturbance severity levels. As part of the Forest Resilience Threshold Experiment (FoRTE) in northern Michigan, USA we simulated phloem-disrupting disturbances at a range of …

Understanding The Interaction Between Habitat Use Of Feral Horses And The Abundance Of Greater Sage-Grouse In The Great Basin, Mikiah R. Carver

Theses and Dissertations

Environmental impacts of feral horses (Equus caballus) are a subject of conservation concern and controversial national policy. In North America, feral horses are considered an invasive species where they impact rangelands of the arid and semi-arid western United States. The greater sage-grouse (Centrocercus urophasianus) is a native sagebrush obligate bird species that relies on sagebrush habitats to sustain viable population levels. Recent literature suggests that feral horse presence can have a notable effect on the fitness of native and sagebrush obligate species throughout the arid and semi-arid western United States. The purpose of this thesis was to assess the potential …

The Impacts Of Disturbance On Submerged Aquatic Macrophytes Populations Of The Jemez Mountains, New Mexico, Virginia F. Thompson

Biology ETDs

This dissertation investigates the effects of disturbance (a catastrophic forest fire and decadal-level multi-day flood) on populations of submerged aquatic macrophytes (SAMs) in the streams and rivers of the Jemez Mountains of northern New Mexico, USA. Research conducted and reported in this dissertation addresses the following research questions: 1.) What factors influence the presence or absence of SAMs in Jemez Mountain streams? 2.) How does disturbance (catastrophic wildfire and decadal-level flood) change the amount of aboveground SAM biomass? and 3.) How does that disturbance change the nutrient content (%C, %N, %P) and nutrient stoichiometry of SAMs? These disturbance events had …

Food-Web And Functional Trait Community Structure Of Predator Assemblages In Pine Forests Under Different Management Regimes, Connor Adams

Electronic Theses and Dissertations

Anthropogenic activities can alter natural disturbance regimes in ecosystems, and thereby affect the structure and function of biological diversity. As many of the world’s ecosystems are degraded beyond natural recovery, well-defined restoration goals are necessary to maintain the ecological processes that provide valuable ecosystem services. Utilizing taxonomic, functional, and food-web approaches, I investigated the impacts of forest management practices in structuring predator communities in two pine forest systems of eastern Texas. The results of this study indicate that the increased frequency of forest management practices such as prescribed fires and thinning operations encourages predator diversity while increasing functional and trophic …

Increasing The Frequency Of Periodic Spatial Disturbance Decreases Surface Attachment Protein Expression In Staphylococcus Aureus, Ivana M. Barraza

All HCAS Student Capstones, Theses, and Dissertations

Staphylococcus aureus is an opportunistic pathogen that can cause a variety of acute and chronic illnesses. The severity of these illnesses such as sepsis, necrotizing pneumonia, and toxic shock syndrome is measured through the virulence that S. aureus inflicts on its host. Methicillin-resistant S. aureus (MRSA) is commonly associated with secondary infections and is challenging to treat given the limited selection of antibiotics that are effective against it. Accordingly, novel approaches to reduce S. aureus pathogenicity are required. S. aureus regulates pathogenesis through a cell-to-cell communication system referred to as quorum sensing. Effective communication determines the production of two broad …

Successional Changes In Carbon Storage Are Sustained In A Temperate Forest Across Different Initiating Disturbances, Cameron Clay

Theses and Dissertations

Managing forests for carbon (C) sequestration requires an understanding of how disturbance history shapes C pools and fluxes over successional time. At the University of Michigan Biological Station, we examined how two stand establishing disturbances influenced C pools and fluxes over 100+ years of succession, comparing these secondary forests with “legacy” late-successional stands encompassing ages and compositions that would be present in the absence of region-wide stand-replacing disturbance. Our work utilized measurements taken between 2014 and 2020 from separate experimental forest chronosequences initiated following clear-cut harvesting only or clear-cut harvesting and fire, along with three >130-yr-old late successional stands comprising …

Does Invasion Science Encompass The Invaded Range? A Comparison Of The Geographies Of Invasion Science Versus Management In The U.S., Lara Munro

Masters Theses

Biases in invasion science lead to a taxonomic focus on plants, particularly a subset of well-studied plants, and a geographic focus on invasions in Europe and North America. Geographic biases could also cause some branches of invasion science to focus on a subset of environmental conditions in the invaded range, potentially leading to an incomplete understanding of the ecology and management of plant invasions. While broader, country-level geographic biases are well known, it is unclear whether these biases extend to a finer scale and thus affect research within the invaded range. This study assessed whether research sites for ten well-studied …

Characterizing Patterns In Texas Gulf Coast Beach Dune Plant Species Composition, Cody Foster

Electronic Theses and Dissertations

Regional vegetation patterns of Texas beach plant communities were analyzed using cluster analysis, ANOSIM, SIMPER, NMDS, and ISA for fives zones representing the foredune complex of twenty Gulf Coast beaches. ANOVA revealed that zones differ in terms of percent bare sand, percent vegetative cover, and species richness. Cluster Analysis, ANOSIM, and SIMPER results indicate that Texas beaches can be divided into northern and southern regions based on differences in species composition of plant communities. Indicator Species Analysis (ISA) indicates that northern beaches are characterized by the presence of Rayjacksonia phyllocephala, Ambrosia Strophostyles, Ambrosia psilostachya, and Panicum amarum …

Influences Of Forest Edges On The Growth And Health Of Old-Growth Coast Redwood Forests, Cody R. Dangerfield

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Coast redwood (Sequoia sempervirens) is the tallest species in the world, frequently attaining heights greater than 300 ft. The unique characteristics of the redwoods has led to the establishment of several preservation areas including national and state parks. However, abrupt forests edges created by previous logging and landcover changes has left the remaining stands exposed to elevated temperature, sunlight, and wind intensities, thereby making redwoods along the forest edge more susceptible to windthrow and drought stress. Despite the rarity of old-growth coast redwood forests and their ecological and cultural significance, very few studies have investigated how forests edges …

Disturbance, Defense And Fitness In Silverleaf Nightshade (Solanum Elaeagnifolium) In Their Native Range In South Texas, Jesus Chavana

Theses and Dissertations

The role of human disturbance in accelerating weed growth is well understood. While most of these studies have focused on soil mediated disturbance, mowing is also a management practice that could impact weed traits. Using silver leaf nightshade (Solanum elaeagnifolium), a noxious and invasive weed, we asked whether continuous mowing affects growth and plant defense traits. We found that mowed plants produced significantly less fruits, had lower total seed fitness, but had higher seed mass, and germinated significantly faster. When three common herbivores were allowed to feed on the seedlings; tobacco hornworm (Manduca sexta), a generalist Solanaceae caterpillar gained more …

Improving Rangeland Seedling Recruitment Using Fungicide Seed Coatings And Golden Eagle Reproductive Success In Relation To Explosive Military Tests And Trainings, Benjamin William Hoose

Theses and Dissertations

The objective of the first chapter of this thesis was to determine whether fungicide seed coatings constitute an effective strategy for increasing seedling recruitment in restoration scenarios in the Intermountain West. We tested a mixture of four fungicides that address potential fungal pathogens to bluebunch wheatgrass, a dominant bunchgrass that is commonly used in restoration. Across two sites and three years, we found that the fungicide seed coating increased emergence in five of the six sites and years, with an average increase of 59.1% over the control. There was a strong interaction (P < 0.001) between the effects of fungicide treatment, the year and the site on emergence. This interaction was likely related to the effects of the hydrothermal microsite environment on disease severity. Further research is necessary to fully understand the conditions under which fungicide seed coatings are most likely to be effective. The objectives the second chapter of this thesis were to 1) estimate the effects of golden eagle nest proximity to explosive disturbances on reproductive success given other relevant habitat variables (e.g. indices of topography and vegetation), and 2) determine the relative importance of nest proximity to explosive disturbances as a predictor of golden eagle reproductive success compared to other relevant habitat variables. Reproductive success data were collected from nesting territories within and surrounding land controlled and managed by the US Department of Defense. We fit the reproductive survey data using generalized linear mixed-effects models comprised of unique, hypothesis-based sets of habitat variables. We compared the models using AICc-based model selection processes. Given the best approximating model, we found no evidence that the likelihood of reproductive success was affected by nest proximity to explosive disturbances (P = 0.460). We further found nest proximity to explosive disturbances consistently ranked in the bottom 50% of relative variable importance. These results may indicate golden eagle tolerance or habituation to explosive military tests and trainings. Although the two chapters of this thesis are disjointed, they are loosely unified by the ecological importance of disturbance, invasive species, and restoration within the Great Basin ecoregion.

Impact Of Disturbance Regimes On Community And Landscape Biodiversity In Atlantic Coastal Pine Barren Ecoregion Streams, Sean T. Mccanty

Graduate Doctoral Dissertations

Streams are dynamic systems shaped by geographic location, hydrology, riparian vegetation, and in-stream habitat. Furthermore, ecosystem disturbance plays a major role in structuring stream communities and ecosystem processes. Disturbances include natural occurrences, such as flooding, drought, and fire events and anthropogenic disturbances such as land use changes, damming, and pollution. Agricultural use acts as a press disturbance regime, homogenizing the surrounding landscape and simplifying in-stream habitat, leaving legacy effects after farming ceases. Active restoration is intended to ameliorate these effects by reintroducing variation, with the goal of shifting the ecosystem into a more diverse and natural state. The act of …

Disruption Of Pyoverdine Synthesis In Pseudomonas Aeruginosa Through Periodic Disturbance Of Biofilm Structure, Rebecca J. Quinn

All HCAS Student Capstones, Theses, and Dissertations

Infections due to bacteria were once easily treated using antibiotics. However, the effective shelf life of antibiotics is diminishing due to the rise and spread of antibiotic resistant bacteria. Accordingly, novel approaches to treating infections are required. Pseudomonas aeruginosa is a multi-drug resistant, biofilm forming opportunistic pathogen. A determinant of P. aeruginosa’s pathogenicity is pyoverdine, a siderophore that is used to sequester iron from the environment. After being produced by a bacterium, pyoverdine is secreted into the environment where it complexes with iron. The pyoverdine-iron complex is then returned to the bacteria through diffusion, where it drives the synthesis of …

Biogeochemical Cycling Of Nutrients And Carbon In Subtropical Wetlands, Lauren N. Griffiths

USF Tampa Graduate Theses and Dissertations

As human development intensifies, ecosystems around the word are being exponentially destroyed and degraded. Wetlands have the capacity to mitigate some of the possible problems by retaining nutrients and carbon, keeping them from harming downstream ecosystems or being released into the atmosphere. This project focuses on the processes that make wetlands successful by studying two unique ecosystems: 1) a created urban stormwater treatment wetland and 2) mangrove wetlands in Florida and Puerto Rico that were affected by hurricanes in 2017.

The first phase of this study investigates the role of sedimentation and vegetative and algal uptake of nutrients to retain …

Characterizing The Impacts Of The Invasive Hemlock Woolly Adelgid On The Forest Structure Of New England, Peter Brehm Boucher

Graduate Doctoral Dissertations

Climate change is raising winter temperatures in the Northeastern United States, both expanding the range of an invasive pest, the hemlock woolly adelgid (HWA; Adelges tsugae), and threatening the survival of its host species, eastern hemlock (Tsuga canadensis). As a foundation species, hemlock trees underlie a distinct network of ecological, biogeochemical, and structural systems that will likely disappear as the HWA infestation spreads northward. Remote sensing can offer new perspectives on this regional transition, recording the progressive loss of an ecological foundation species and the transition of evergreen hemlock forest to mixed deciduous forest over the course of the infestation. …

Sclerocactus Wrightiae (Cactaceace): An Evaluation Of The Impacts Associated With Cattle Grazing And The Use Of Remote Sensing To Assess Cactus Detectability, Thomas Hathaway Bates

Theses and Dissertations

The Wright fishhook cactus (Sclerocactus wrightiae L.D. Benson) is an endangered cactus species endemic to south-central Utah. Since its listing in 1979 by the U.S. Fish and Wildife Service, the potential impacts of soil disturbance by cattle have become a central focus of management policies and monitoring efforts. However, little to no empirical data has been collected to substantiate the hypothesis that soil disturbance by cattle has direct or indirect negative effects on Wright fishhook cactus growth or reproduction. Over the years, the Bureau of Land Mangement (BLM) and Capitol Reef National Park (CRNP) have invested significant resources documenting cactus …

Evaluation Of Space Use And Movement By Wild Turkey (Meleagris Gallopavo) During Extreme Climatic Disturbances And Annual Phenological States, David J. Moscicki

LSU Master's Theses

Space use is driven by both intrinsic and extrinsic factors across space and time. Meaning a species demography and habitat requirements may vary across landscapes. Recent studies on wild turkeys (Meleagris gallopavo spp., hereafter turkey) have shown both direct and indirect demographic impacts of climatically driven events on turkey populations. Similarly, there is an abundance of information documenting turkey demographic parameters and space use, but few studies have addressed breeding phenology in great detail. We evaluated the impact on space use and movement patterns of Eastern wild turkeys (M. g. silvestris; n = 20) and Rio Grande wild …

The Role Of Fire And A Fire-Free Interval In The Restoration Of Upland Oak Communities On The Cumberland Plateau, Kentucky, Jordan Winkenbach

Theses and Dissertations--Forestry and Natural Resources

The decline of upland oak (Quercus spp.) communities in our eastern forests has been attributed to the loss of periodic disturbance after decades of fire suppression. As land managers have begun to reintroduce fire, effects on oak regeneration and species composition have varied widely, making it apparent that our understanding of how fire can aid in oak forest management needs refinement. Restoring upland oak communities requires decreasing stand density and opening of the canopy to release shade-intolerant oaks in the understory. This necessitates an extended fire-free interval to allow these oaks to be recruited into larger size classes and …

Plant-Pollinator Associations In An Eastern Serpentine Savannah And The Effects Of Overbrowsing, Allyson Richins

Theses and Dissertations

Chapter 1: Native plant response to deer overbrowsing in a serpentine savannah

Plants are particularly vulnerable to physical disturbance in low productivity areas, due to a high cost of replacing lost plant tissue. In the eastern United States, serpentine grasslands are fragmented ecosystems with high concentrations of rare endemic plant species, low concentrations of soil nutrients, and uncontrolled deer overpopulation. This study assessed functional responses of native angiosperms in a rare eastern serpentine savannah to selective deer browsing. Plant count, flower count, floral area, vegetative area, and plant height of 10 serpentine plant species were compared inside and outside of …