Forest Sciences Commons^™

Carbon Dioxide Emissions From Deadwood In Forests Of The Northeastern United States, Zoe Read

Electronic Theses and Dissertations

As the climate changes, understanding the sources and sinks of greenhouse gases such as carbon dioxide (CO₂) is increasingly important. However, several components of the carbon cycle within forests remain poorly understood. For example, knowledge gaps exist in our understanding of CO₂ emissions from coarse woody material (CWM; logs and stumps), including how emissions change over time, how they are influenced by environmental variables, and how they compare to soil and ecosystem-level CO₂ emissions.

To fill these knowledge gaps, we examined CO₂ emissions from CWM at three sites. We sampled 18 red spruce (Picea …

Vegetation And Nutritional Changes Over 20 Years Of White-Tailed Deer Exclusion, Gabrielle Nicole Ripa

Theses and Dissertations

Knowledge of the impacts of white-tailed deer (Odocoileus virginianus; hereafter deer) as dominant herbivores throughout the Southeastern United States of America is lacking. To address this, three paired experimental units of exclosures and controls were constructed in 2000 on three Wildlife Management Areas across Mississippi within the ecoregions of the Upper Coastal Plain, Lower Coastal Plain, and the Mississippi Alluvial Valley. Vegetation was sampled in the summers of 2000, 2005, and 2021 including vegetation structure, canopy coverage, basal area, and species composition. Additionally, in 2005 and 2021, biomass was sampled to determine potential impacts on nutritional carrying capacity. Among the …

Assessing Priority Bird Response To Open Pine Management In Eastern Mississippi, Holly Marie Todaro

Theses and Dissertations

Fire suppression, combined with lack of forest thinning and short-rotation, monodominant management, has drastically altered the landscape in the southeastern U.S., leading to the loss of open pine ecosystems and associated avian species. Management of open pine ecosystems is a common practice; yet, there remains uncertainty regarding how vegetation structure impacts priority species. Using empirical data, I assessed changes in species abundance and associated vegetation characteristics before and after management. I also sought to identify vegetation characteristics that influence home range establishment and microhabitat selection of Bachman’s Sparrows. Priority species were negatively associated with hardwood midstory and abundance per site …

Plant Community Responses To Interactive Anthropogenic Disturbances Along A Natural-Wildland-Urban Gradient And Undergraduate Students’ Attitudes Toward Disturbances, Mali M. Hubert

Doctoral Dissertations

Anthropogenic disturbances are defined as any change caused by human activity that alters biodiversity. Wildfire and urbanization disturbances are among the most influential on the landscape because of their individual and interactive properties. Areas deemed wildland-urban interfaces (WUI; area where environment intermingles with human-built structures) are increasing near protected lands because of human population growth and movement, which often facilitates fire ignitions by humans. Houses that are adjacent to or overlap with wildland vegetation can complicate protection of urban development and wildlands from fires. The expansion of the WUI due to population growth will exacerbate fire risk, which can ultimately …

Assessing The Long-Term Effects Of Natural Disturbance-Based Silvicultural On The Avian Assemblage At The Acadian Forest Ecosystem Research Program, Carl Pohlman

Electronic Theses and Dissertations

Active forest management alters the resources available to forest-obligate species. Large-scale intensive management practices where timber production is the primary objective can lead to notable ecological changes in forest ecosystems. A key concept of ecological forestry is to design forest management activities to emulate natural disturbance regimes as a way to maintain the ecological integrity of forests. The Acadian Forest Ecosystem Research Program (AFERP) was undertaken as an experimental demonstration of management reflective of the region’s disturbance regime, which typically produces small canopy gaps. AFERP includes nine research areas assigned to three silvicultural treatments: unharvested control, small gap (expanding-group selection …

Spatiotemporal Factors Affecting The Occupancy And Phenology Of A Declining Songbird (Bachman's Sparrow - Peucaea Aestivalis) At The Western Extent Of Its Range, Liam G. Wolff

Electronic Theses and Dissertations

The Bachman’s Sparrow (Peucaea aestivalis) is a declining songbird that occurs throughout the southeastern United States. Bachman’s Sparrow is a Species of Greatest Conservation Need in Texas, but information crucial to management efforts, such as factors affecting their detectability and occupancy, is lacking. I investigated the predictors of Bachman’s Sparrow occupancy and phenology in Texas using detections from autonomous recording units coupled with site characteristics and weather data. My results indicate that Bachman’s Sparrow occupancy is associated with increasing herbaceous ground cover and decreasing basal area, distance to the nearest source population, and basal area when canopy height …

The Role Of Leaf Decomposition In Macroinvertebrate Colonization, Bethany Mabel Lian Schorr, Kevin Geedey

Independent Research Projects

Decomposition plays an important ecological role in carbon and nutrient cycling that supply food and energy resources to food webs. This study investigates the potential role that leaf decomposition of different leaf species may play in macroinvertebrate assemblages in upper Midwest streams. We hypothesized that the different decomposition rates experienced with different leaf species and in different streams would have an effect on invertebrate colonization due to the variance in nutrient availability. Due to altered fire regimes and other influences, forests are experiencing declines in fire-adapted, heliophytic species such as oaks and compositional shifts toward shade-tolerant, mesophytic species such as …

Mark-Recapture Study And Habitat Assessment For The Northern Metalmark Butterfly, Calephelis Borealis (Lepidoptera: Riodinidae), Weston J. Henry, Kristian S. Omland, Henry Frye, Wagner L. David

EEB Articles

Background: The northern metalmark (Calephelis borealis), is an exceedingly local, globally rare butterfly that is declining across the Midwestern and Northeastern USA. The principal stressors driving colony losses include afforestation and invasive plants that crowd out its larval hostplant (Packera ovata) and nectar resources.

Aims/Methods: To better understand its declines and guide restoration efforts, we 1) performed a mark-recapture study in Connecticut to document population trends where we were actively managing vegetation; 2) conducted a range-wide survey for evidence of phylogeographic structure, using cytochrome oxidase (CO1); 3) investigated abundance determinants of its larval foodplant, Packera ovata …

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 …

Advancing Forest Structure-Function Relationships: Linking Above- And Belowground Structure To Soil Respiration, Laura J. Hickey

Theses and Dissertations

Variation in the soil-to-atmosphere C flux, or soil respiration (Rs), is influenced by a suite of biotic and abiotic factors, including soil temperature, soil moisture, and root biomass. However, whether canopy structure is tied to soil respiration through its simultaneous influence over these drivers is not known. We assessed relationships between measures of above- and belowground vegetation density and complexity, and evaluated whether Rs is linked to remotely sensed canopy structure through pathways mediated by established biotic and abiotic mechanisms. Our results revealed that, at stand-scale, canopy rugosity–a measure of complexity–and vegetation area index were coupled to soil respiration through …

A Comparison Of Wildfire Adaptive Traits In Juvenile Conifers Of The Northern Rockies, Andie Sonnen

Undergraduate Theses, Professional Papers, and Capstone Artifacts

Wildfire is an importance disturbance that continues to shape the ecosystems of the northern Rockies through varying patterns of frequency and intensity. Due to historical fire suppression and the hotter and drier conditions brought upon by anthropogenic climate change, wildfire frequency and intensity is increasing. These increases will alter vegetation structure and composition, but the degree to which is unknown.

Individual plant traits can offer insight into how these vegetation communities will shift, especially the particular traits that reduce fire-related mortality. To survive wildfires, juvenile northern conifers employ two strategies: increasing their bark thickness and increasing their crown height. To …

Effects Of Dissimilar Silvicultural Techniques On Small Mammal Communities In Michigan's Upper Peninsula, Breanna R. Gusick

Dissertations, Master's Theses and Master's Reports

Small mammal populations, and predators reliant upon them as food resources, are often challenged by conflicting objectives of timber production and maintenance of quality habitat. With over 70% of the landscape forested, and nearly one-third of the land privately owned, Michigan’s Upper Peninsula (UP) is a matrix of independent management strategies. To assess the effects of various silvicultural regeneration methods on small mammal populations in the Upper Peninsula, we trapped small mammals in experimental silviculture plots, whereby treatments varied by regeneration method (amount of residual canopy cover) and site preparation (i.e., control, tip-up, and scarification), and deer exclosures. We used …

Invasive Earthworms In The Crown Of The Continent System And Implications For Land Management, Meghan Elizabeth Scott

Graduate Student Theses, Dissertations, & Professional Papers

The United States contains invasive earthworms originating from Europe and Asia; the majority are European lumbricids. Direct introduction occurs primarily through human activity and, once established, earthworm populations are difficult to address. When exotic earthworms engage in bioturbation, they negatively alter subterranean food webs and nutrient cycling by disrupting soil layering systems. The most prominent form of physical alteration is the change and removal of the topmost organic layer. This disruption is associated with altered nitrogen and carbon cycling, as well as altered forest floor plant communities.

The Crown of the Continent ecosystem is located in southwestern Alberta, southeastern British …

Changes In Plant Community Composition, Structure, And Function In Response To Permafrost Thaw, Katherine Standen

Theses and Dissertations (Comprehensive)

Air temperature is increasing at three or more times the global average in high latitudes, causing widespread permafrost thaw across the boreal biome. Since the boreal biome stores 30-40% of global terrestrial carbon (C), of which about 30-45% is found in permafrost soils, this temperature increase could cause a large efflux of C to the atmosphere. Climate warming and permafrost thaw are also expected to alter plant community composition and productivity and, given the link between plant functional traits and ecosystem C fluxes, may alter overall ecosystem function. Across the boreal biome of western Canada, we know surprisingly little about …