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Investigating Within-Canopy Variation Of Functional Traits And Cellular Structure Of Sugar Maple (Acer Saccharum) Leaves, Adam P. Coble

Dissertations, Master's Theses and Master's Reports - Open

Patterns of increasing leaf mass per area (LMA), area-based leaf nitrogen (N_area), and carbon isotope composition (δ13C) with increasing height in the canopy have been attributed to light gradients or hydraulic limitation in tall trees. Theoretical optimal distributions of LMA and N_area that scale with light maximize canopy photosynthesis; however, sub-optimal distributions are often observed due to hydraulic constraints on leaf development. Using observational, experimental, and modeling approaches, we investigated the response of leaf functional traits (LMA, density, thickness, and leaf nitrogen), leaf carbon isotope composition (δ13C), and cellular structure to light availability, height, and leaf water …

The Influence Of Diet Composition, Plant Defensive Chemicals, And Winter Severity On The Nutritional Condition Of A Freeranging, Generalist Herbivore, Grace L. Parikh

Dissertations, Master's Theses and Master's Reports - Open

Herbivory requires animals to manage intake of toxic phytochemicals. Detoxification and excretion of these chemicals prevents toxicity, but is energetically expensive. I investigated the relationship between investment in detoxification and nutritional condition for moose on Isle Royale National Park (Alces alces) during winter, using urinary indices from urine samples collected in snow. The ratio of urinary urea nitrogen:creatinine is an indicator of nutritional condition, and the ratio of glucuronic acid:creatinine is an indicator of investment in detoxification. Nutritional condition declined with greater investment in detoxification. An alternative means of managing defensive chemical intake is to diversify the diet. Microhistological …

Interactive Effects Of Climate Change And Fungal Communities On The Decomposition Of Wood-Derived Carbon In Forest Soils, Samantha L. Mosier

Dissertations, Master's Theses and Master's Reports - Open

Soils are the largest sinks of carbon in terrestrial ecosystems. Soil organic carbon is important for ecosystem balance as it supplies plants with nutrients, maintains soil structure, and helps control the exchange of CO₂ with the atmosphere. The processes in which wood carbon is stabilized and destabilized in forest soils is still not understood completely. This study attempts to measure early wood decomposition by different fungal communities (inoculation with pure colonies of brown or white rot, or the original microbial community) under various interacting treatments: wood quality (wood from +CO₂, +CO₂+O₃, or ambient …

Translocation And Telemetry Tracking Of Lake Sturgeon In The Menominee River, Mi / Wi, Jeremy G. Olach

Dissertations, Master's Theses and Master's Reports - Open

The Menominee River is a Michigan-Wisconsin boundary water historically traversed by lake sturgeon (Acipenser fulvescens), but now contains fragmented populations between hydroelectric dams. Though fish passage is currently being implemented on the lower dams, it is unclear whether sturgeon given access to historic spawning grounds would use them. In 2012 and 2013, a total of 15 pre-spawning sturgeon were captured, implanted with sonic transmitters and translocated upstream over two hydroelectric dams to the stretch below the historic spawning site of Sturgeon Falls. Sturgeon were then tracked via five stationary receivers from April 2012 until August 2013, and with …

Biogeochemical Cycling In Lake Superior Tributaries: Seasonality, Quantity And Quality Of Export, Ashley Anne Coble

Dissertations, Master's Theses and Master's Reports - Open

Seasonal and spatial variability in environmental factors may affect dissolved organic matter composition and nutrient transformation and retention in streams. The objective of this research was to quantify and describe seasonality, quantity, and quality of nutrient processing and export of ammonium (NH₄), soluble reactive phosphate (SRP), and dissolved organic carbon (DOC) into Lake Superior through intensive study in a small 1st order watershed coupled with snapshot measurements across 12 tributaries that varied in size, location, and wetland coverage. Our results suggest biodegradable C is exported from a small headwater stream year-round and that DOC mineralization rates can be …

Ecophysiological Responses Of Sugar Maple Roots To Climatic Conditions, Mickey Philip Jarvi

Dissertations, Master's Theses and Master's Reports - Open

The severity of future climate change resulting from anthropogenic alteration of the global C cycle will depend in part on feedbacks between atmospheric greenhouse gases and forest ecosystem carbon balance, but how these two systems will interact is not entirely understood. Forests are both major sinks and sources for atmospheric CO₂ through the processes of photosynthesis and ecosystem respiration. The balance between these two processes could be altered if autotrophic respiration were to increase exponentially with temperature as climate warms. Root respiration, and especially fineroot respiration (<1 mm diameter), is a major contributor to total ecosystem C exchange. A study to assess long-term responses of root respiration to warmer soil conditions was conducted at the SMART (sugar maple altered rainfall and temperature) experiment located in Alberta, MI at the Michigan Technological University’s Ford Center and Forest. It was found that acclimation of fine-root respiration in this system was not due to an insufficient supply of carbohydrates from photosynthesis (substrate limitation), but was the result of adenylate control. As a result, fine root respiration was constrained to levels needed to perform work required of the fine roots (e.g. nutrient acquisition). Acclimation also occurred for roots 1-2 mm in diameter at the 0-10 cm soil depth, but not in any roots larger than 2 mm or in roots of any size at deeper soil depths. As a result, at the ecosystem level, total root system respiration was 60% greater in warmed soil than in unwarmed soil. The studies in experimentally warmed sugar maple forests were complemented by an examination of fine-root respiration and root biomass at sixteen sugar maple forests located across a latitudinal gradient across sugar maple’s native range, spanning approximately 10°C of mean annual temperature. Sugar maple in the southern, warmer sites had lower root N, lower specific fine-root respiration at a given temperature, and less fine-root biomass than that from the northern cooler regions. Fine root respiration at ambient soil temperature actually decreased from north to south, despite a nearly 10°C increase in soil temperature. However, within sites respiration measured across three sample dates did increase with temperature. The next big question is whether these adjustments that exist across sugar maple’s range are plastic responses to l local climate or result from genotypic differences among populations in different locations. If the former is true, all sugar maple would be capable of acclimation, reduction in root biomass, and/or reduction in root N as mechanisms for dealing with climatic warming, and sugar maple would have a large capacity to adjust to future climate change. The latter would suggest that predicted rates of climatic warming could have negative impacts on this important species across its entire current range. The lack of changes in fine root biomass and root N concentration at the SMART study location after four plus years of soil warming support the possibility that differences along the latitudinal transect are largely the result of inherent genetic differences among population.

Climate Anomalies And Primary Production In Lake Superior, Marcel L. Dijkstra

Dissertations, Master's Theses and Master's Reports - Open

This dissertation supports the modeling of primary production in Lake Superior by offering site specific kinetics and algorithms developed from lab experiments performed on the natural phytoplankton assemblage of Lake Superior. Functions, developed for temperature, light and nutrient conditions and the maximum specific rate of primary production, were incorporated in a 1D specific primary production model and confirmed to published in-situ measured rates of primary production.

An extensive data set (supporting model calibration and confirmation), with a fine spatiotemporal resolution, was developed from field measurements taken bi-weekly during the sampling seasons of 2011, 2012 and 2014; considered to be meteorologically …

Big Manistee River Tributaries As Potential Arctic Grayling Habitat, Brian M. Danhoff

Dissertations, Master's Theses and Master's Reports - Open

The Big Manistee River was one of the most well known Michigan rivers to historically support a population of Arctic grayling (Thymallus arctics). Overfishing, competition with introduced fish, and habitat loss due to logging are believed to have caused their decline and ultimate extirpation from the Big Manistee River around 1900 and from the State of Michigan by 1936. Grayling are a species of great cultural importance to Little River Band of Ottawa Indian tribal heritage and although past attempts to reintroduce Arctic grayling have been unsuccessful, a continued interest in their return led to the assessment of environmental conditions …

Impacts Of Climate Change On Soil Microorganisms In Northern Hardwood Forests, Carley Jane Kratz

Dissertations, Master's Theses and Master's Reports - Open

As global climate continues to change, it becomes more important to understand possible feedbacks from soils to the climate system. This dissertation focuses on soil microbial community responses to climate change factors in northern hardwood forests. Two soil warming experiments at Harvard Forest in Massachusetts, and a climate change manipulation experiment with both elevated temperature and increased moisture inputs in Michigan were sampled. The hyphal in-growth bag method was to understand how soil fungal biomass and respiration respond to climate change factors. Our results from phospholipid fatty acid (PLFA) analyses suggest that the hyphal in-growth bag method allows relatively pure …

Using Indicators Of Biotic Integrity For Assessment Of Stream Condition, Stephanie A. Ogren

Dissertations, Master's Theses and Master's Reports - Open

Multiple indices of biotic integrity and biological condition gradient models have been developed and validated to assess ecological integrity in the Laurentian Great Lakes Region. With multiple groups such as Tribal, Federal, and State agencies as well as scientists and local watershed management or river-focused volunteer groups collecting data for bioassessment it is important that we determine the comparability of data and the effectiveness of indices applied to these data for assessment of natural systems. We evaluated the applicability of macroinvertebrate and fish community indices for assessing site integrity. Site quality (i.e., habitat condition) could be classified differently depending on …

Analysis Of Populus Tremuloides Clonal Variation And Delineation In The Ottawa National Forest, Kristina N. Flesher

Dissertations, Master's Theses and Master's Reports - Open

The technique of delineating Populus tremuloides (Michx.) clonal colonies based on morphology and phenology has been utilized in many studies and forestry applications since the 1950s. Recently, the availability and robustness of molecular markers has challenged the validity of such approaches for accurate clonal identification. However, genetically sampling an entire stand is largely impractical or impossible. For that reason, it is often necessary to delineate putative genet boundaries for a more selective approach when genetically analyzing a clonal population. Here I re-evaluated the usefulness of phenotypic delineation by: (1) genetically identifying clonal colonies using nuclear microsatellite markers, (2) assessing phenotypic …

Investigating The Impacts Of Streambed Habitat Heterogeneity On Ecosystem Structure And Processes Using Basic And Applied Perspectives, James C. Olson

Dissertations, Master's Theses and Master's Reports - Open

Stream restoration often focuses on increasing habitat heterogeneity to reverse ecosystem degradation. However, the connection between heterogeneity and ecosystem structure and processes is poorly understood. We looked to investigate this interaction from both applied and basic science perspectives. For the applied study, we examined two culvert replacements designed to mimic natural stream channels, to see if they were better at maintaining ecosystem processes within as well as upstream and downstream of culverts compared to non-replaced culverts. We measured three ecosystem processes (nutrient uptake, hydrologic characteristics, and coarse particulate organic matter retention) and found that stream simulation culvert restoration improved organic …

Ionic Liquid Extraction Unveils Previously Occluded Humicbound Iron In Peat Porewater, Timothy J. Veverica

Dissertations, Master's Theses and Master's Reports - Open

Extracellular iron reduction has been suggested as a candidate metabolic pathway that may explain a large proportion of carbon respiration in temperate peatlands. However, the o-phenanthroline colorimetric method commonly employed to quantitate iron and partition between redox species is known to be unreliable in the presence of humic and fulvic acids, both of which represent a considerable proportion of peatland dissolved organic matter. We propose ionic liquid extraction as a more accurate iron quantitation and redox speciation method in humic-rich peat porewater. We evaluated both o-phenanthroline and ionic liquid extraction in four distinct peatland systems spanning a gradient of physico-chemical …

Exploring Changes In Detrital Flocculent Layer Dynamics Due To Shifts In Macrophyte Communities In The Northern Everglades, Erin Leigh Mckenney

Dissertations, Master's Theses and Master's Reports - Open

A shift in plant communities of the Water Conservation Areas (WCAs) within the Everglades has been linked to changes in hydrology and high levels of nutrient loading from surrounding agicultural areas. This has resulted in the encroachment of dense cattail stands (Typha domingensis) into areas that had previously been a ridge and slough landscape populated primarily by native sawgrass (Cladium jamaicense). In order to study ecological management solutions in this area, WCA-2A was broken into study plots; several of which became open water areas through the application of herbicide and burning regimens. The open water areas …

Beyond Roots Alone: Novel Methodologies For Analyzing Complex Soil And Minirhizotron Imagery Using Image Processing And Gis Tools, Justina A. Silva

Dissertations, Master's Theses and Master's Reports - Open

Quantifying belowground dynamics is critical to our understanding of plant and ecosystem function and belowground carbon cycling, yet currently available tools for complex belowground image analyses are insufficient. We introduce novel techniques combining digital image processing tools and geographic information systems (GIS) analysis to permit semi-automated analysis of complex root and soil dynamics. We illustrate methodologies with imagery from microcosms, minirhizotrons, and a rhizotron, in upland and peatland soils. We provide guidelines for correct image capture, a method that automatically stitches together numerous minirhizotron images into one seamless image, and image analysis using image segmentation and classification in SPRING or …

Influence Of Vegetation Removal And Altering Water Levels On Co2 Flux Rates Of A Northern Bog, Laura M. Matkala

Dissertations, Master's Theses and Master's Reports - Open

Boreal peatlands contain approximately one third of the global soil carbon and are considered net sinks of atmospheric CO2. Water level position is one of the main regulators of CO2 fluxes in northern peatlands because it controls both the thickness of the aerobic layer in peat and plant communities. However, little is known about the role of different plant functional groups and their possible interaction with changing water level in boreal peatlands with regard to CO2 cycling. Climate change may also accelerate changes in hydrological conditions, changing both aerobic conditions and plant communities. To help answer these questions, this study …

The Effects Of Black Locust (Robinia Pseudoacacia L.) On Understory Vegetation And Soils In A Northern Hardwood Forest, Keri A. Deneau

Dissertations, Master's Theses and Master's Reports - Open

No abstract provided.

Carbon In The Peatlands In The Great Lakes Region, Cassandra A. Ott

Dissertations, Master's Theses and Master's Reports - Open

Peatlands cover only ~3% of the global land area, but store ~30% of the worlds' soil carbon. There are many different peat types that store different amounts of carbon. Most inventories of carbon storage in northern peatlands have been conducted in the expansive Sphagnum dominated peatlands. Although, northern white cedar peatlands (NW cedar, Thuja occidentalis L.) are also one of the most common peatland types in the Great Lakes Region, occupying more than 2 million hectares. NW cedar swamps are understudied, due in part to the difficulties in collection methods. General lack of rapid and consistent sampling methods has also …

Plant-Mediated Effects On Microbial Diversity In Mesocosms Of An Oligotrophic Bog, Karl J. Romanowicz Iv

Dissertations, Master's Theses and Master's Reports - Open

Globally, peatlands occupy a small portion of terrestrial land area but contain up to one-third of all soil organic carbon. This carbon pool is vulnerable to increased decomposition under projected climate change scenarios but little is known about how plant functional groups will influence microbial communities responsible for regulating carbon cycling processes. Here we examined initial shifts in microbial community structure within two sampling depths under plant functional group manipulations in mesocosms of an oligotrophic bog. Microbial community composition for bacteria and archaea was characterized using targeted 16S rRNA Illumina gene sequencing. We found statistically distinct spatial patterns between the …

Spatial And Temporal Patterns In Ungulate-Ecosystem Interactions, Bryan D. Murray

Dissertations, Master's Theses and Master's Reports - Open

Ungulates are important components of a variety of ecosystems worldwide. This dissertation integrates aspects of ungulate and forest ecology to increase our understanding of how they work together in ways that are of interest to natural resource managers, educators, and those who are simply curious about nature. Although animal ecology and ecosystem ecology are often studied separately, one of the general goals of this dissertation is to examine how they interact across spatial and temporal scales. Forest ecosystems are heterogeneous across a range of scales. Spatial and temporal habitat use patterns of forest ungulates tend to be congregated in patches …

Interactive Controls Of Water Table Position And Plant Functional Types On Peat Porewater Character In Northern Bog Ecosystems: Implications For Carbon Cycling Dynamics, Aleta L. Daniels

Dissertations, Master's Theses and Master's Reports - Open

Northern wetlands, and particularly peatlands, have been shown to store around 30% of the world's soil carbon and thus play a significant role in the carbon cycle of our planet. Changes in climate are altering peatland hydrology and vegetation communities. These changes are possibly resulting in declines in the ability of peatlands to sequester carbon because losses through carbon oxidation and mineralization are likely to increase relative to C inputs from net primary production in a warmer, drier climate. However, the consequences of interactive effects of altered hydrology and vegetation on carbon storage are not well understood. This research evaluated …

Evaluation And Monitoring Of Ash (Fraxinus Spp.) Tolerant To Long-Term Emerald Ash Borer (Agrilus Planipennis [Coleoptera: Buprestidae]) Exposure, Kathryn G. Hietala

Dissertations, Master's Theses and Master's Reports - Open

Invasive insects that successfully establish in introduced areas can significantly alter natural communities. These pests require specific establishment criteria (e.g. host suitability) that, when known, can help quantify potential damage to infested areas. Emerald ash borer (Agrilus planipennis [Coleoptera: Buprestidae]) is an invasive phloem-feeding pest which is responsible for the death of millions of ash trees (Fraxinus spp. L.). Over 200 surviving ash trees were previously identified in the Huron-Clinton Metroparks located in southeast Michigan. Trees were assessed over a four year period and a hierarchical cluster analysis was performed on dieback, vigor, and presence of signs and …

Predator-Prey: Interactions Between The Spiny Waterflea (Bythotrephes Longimanus) And Pumpkinseed Sunfish (Lepomis Gibbosus), Jaime F. Leduc

Dissertations, Master's Theses and Master's Reports - Open

Small pumpkinseed sunfish ( Lepomis gibbosus), were found to be capable of removing the spine of Bythotrephes longimanus, an invasive cladoceran. Because fish consumption may be important in the dispersal or control of Bythotrephes, aquarium feeding experiments were conducted to 1) establish if the spine removal behavior of the pumpkinseeds was locally unique; 2) quantify how frequently pumpkinseeds exhibit the behavior; 3) determine if pumpkinseed handle Bythotrephes more quickly than other species of fish; and 4) verify if Bythotrephes' resting eggs pass through the digestive systems of pumpkinseeds in viable condition. The experiments revealed that pumpkinseeds (45-70 mm TL) from …

Nitrogen Deposition Effects On Production And Decomposition Of Coarse Woody Debris, Bethany Jeanne Lyons

Dissertations, Master's Theses and Master's Reports - Open

Atmospheric nitrogen deposition has the potential to impact forest productivity, microbial associations, nutrient cycling, decomposition and stand dynamics. However, among the least studied aspects of these processes are the production and decomposition of dead woody biomass, or coarse woody debris (CWD). Coarse woody debris is made up of dead woody material on the ground called down dead wood (DDW) and dead standing trees which are often referred to as snags. Observed reductions in decomposition of CWD have been linked to substrate quality and microbial communities. If the decomposition effect is ubiquitous among litter types, CWD density, C:N, and biomass are …

Effects Of Chemical Deicers On Amphibian Communites, Meagan Leigh Harless

Dissertations, Master's Theses and Master's Reports - Open

Roads and highways present a unique challenge to wildlife as they exhibit substantial impacts on the surrounding ecosystem through the interruption of a number of ecological processes. With new roads added to the national highway system every year, an understanding of these impacts is required for effective mitigation of potential environmental impacts. A major contributor to these negative effects is the deposition of chemicals used in winter deicing activities to nearby surface waters. These chemicals often vary in composition and may affect freshwater species differently. The negative impacts of widespread deposition of sodium chloride (NaCl) have prompted a search for …