Theses and Dissertations at Montana State University (MSU)
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Item Initial effects of low-tech restoration of wet meadows in sagebrush steppe(Montana State University - Bozeman, College of Letters & Science, 2022) Sutton, Thomas Anderson; Chairperson, Graduate Committee: Andrea Litt; This is a manuscript style paper that includes co-authored chapters.In semi-arid environments, wet meadows are important sources of late-season palatable vegetation for many wildlife species; these areas often support higher coverage and diversity of plants relative to surrounding upland environments. In the sagebrush steppe of southwest Montana, wet meadows are fed by melting snowpack. Due to climate change and land use practices, the duration and amount of moisture wet meadows receive is declining. To mitigate these changes, low-tech restoration structures, such as primitive rock dams, have been installed in six different drainages across southwest Montana. Similar structures have been studied in Colorado, where they found immediate increases in plant productivity. We used these structures within an experimental framework to compare soil moisture, vegetation structure, and vegetation composition (Chapter Two), as well as known food resources (both plants and arthropods) for sage grouse chicks and nesting sage thrashers, Brewer's sparrows, and vesper sparrows (Chapter Three) one and two years after restoration. We measured soil moisture and plant canopy coverage, as well as food resources for the focal birds during the summers of 2021 and 2022. We did not detect differences between treated and control areas in soil moisture, vegetation structure, or vegetation composition during any sampling period; however, many of our estimates for vegetation structure and composition were higher in treated than control areas two years after treatment. We also did not detect differences in plant or arthropod food resources for sage grouse chicks, nesting sage thrashers, or nesting Brewer's sparrows during any sampling period. We did find higher coverage of known plant foods for vesper sparrows in treated areas, compared to controls, during September, two years after treatment; this increase was mainly driven by Kentucky bluegrass. Given the cold climate of our study sites, more time may be needed before we can detect changes resulting from the restoration structures. Even if these low-tech solutions do not provide a 'cure-all' for wet meadow restoration, changes in climate and land-use practices emphasize the continued need to find effective and practical tools to restore wet meadows in arid landscapes.Item Integrating cover crop mixtures in the northern Great Plains: an ecological assessment on crop productivity, biodiversity, and temperature and moisture conditions(Montana State University - Bozeman, College of Agriculture, 2020) DuPre, Mary Ellyn; Chairperson, Graduate Committee: Fabian D. Menalled and Tim F. SeipelCropping systems can impact crop productivity and functioning of biodiversity in the Northern Great Plains, a region heavily reliant on low diversity crop rotations and off-farm inputs, and a region predicted to experience warmer and drier climate scenarios by mid-century. In three complementary studies, I compared the impacts of cover crop mixtures and termination methods on crop productivity and three forms of the associated biodiversity (weeds, soil fungi, and ground beetles), under varying temperature and soil moisture conditions. First, I assessed the impacts of the presence (cover crops and fallow) and composition (cover crop mixtures) of cover crops, termination methods (herbicide, cattle-grazing, and haying), as a function of temperature and soil moisture conditions on crop yields, and weed communities. A 5-species, early-spring mixture generated cooler temperatures, produced more biomass, and suppressed weed biomass under warmer and drier conditions, compared to summer fallow and the 7-species, mid-spring mixture. However, lower soil moisture and subsequent reduced grain yields following the mixtures, especially under warmer and drier conditions, suggests that continuously rotating wheat with mixtures may not be the optimal method to diversify small-grain cropping systems. Second, I assessed the impacts of the presence and composition of cover crops, termination methods and temperature and soil moisture conditions on fungal communities. The early-season cover crop mixture reduced plant pathogen abundance and enhanced AM fungal richness in both the soil and subsequent wheat root crop. The enhancement of beneficial fungi and fewer plant pathogens may be a proxy to better support ecosystem services through the use of cover crop mixtures. Third, I compared ground beetle communities among cover crops treatments and termination methods. Ground beetle activity density was not impacted by termination methods and was greatest in the early-season mixture at the beginning of the growing season and in summer fallow at the end of the growing season, while the mid-season mixture peaked in the middle. Ground beetle diversity peaked in the middle and differed in community composition earlier in the growing season. These results indicate that cover crop mixtures can act as an ecological filter to ground beetle communities to better support pest regulation. Overall, these studies indicate that cover crop mixtures can support crop productivity and the associated biodiversity with changes to temperature and soil moisture, although, with agronomic and ecological trade-offs.Item Long term multispecies cover crops in semi-arid Montana: soil response and aboveground biomass(Montana State University - Bozeman, College of Agriculture, 2020) D'Agati, Kristen Mary; Chairperson, Graduate Committee: Catherine A. Zabinski; Perry Miller (co-chair); Perry R. Miller, Clain A. Jones and Catherine Zabinski were co-authors of the article, 'Soil biological effects of herbicide-terminated multi-species cover crop mixes, in semi-arid Montana' which is contained within this thesis.; Catherine Zabinski, Clain A. Jones and Perry R. Miller were co-authors of the article, 'Aboveground biomass quality and quantity of long-term multispecies cover crop mixes, in the semi-arid Montana' which is contained within this thesis.; Maryse Bourgault, Perry R. Miller, Clain A. Jones and Catherine Zabinski were co-authors of the article, 'Soil biological response to spraying, grazing, or haying of long-term multispecies cover crops in semi-arid Montana' which is contained within this thesis.Low and variable annual precipitation (250-350 mm) make management strategies that conserve soil moisture imperative for wheat producers in semi-arid Montana. A wheat-fallow rotation was historically the most common dryland cropping system in semi-arid Montana, due to its ability to conserve soil water; however, summer fallow has negative environmental impacts (Campbell et al., 1991). There is interest to incorporate cover crops into a rotation as a partial replacement for summer fallow to enhance soil quality. An eight-yr study explored the effect of cover crops on biological soil properties through aboveground biomass inputs of four plant functional groups: brassica (BC), fibrous root (FR), tap root (TR), and nitrogen fixers (NF) grown as two-species mixes, six-species mixes (three functional groups), a full eight-species mix, and two controls--chemical fallow and sole pea. Cover crops grew for about 60 days, were terminated with glyphosate, then soil samples were taken nine months after termination at wheat seeding. The only difference in biological parameters based on functional group was that mycorrhizal colonization in wheat was higher following FR than BC at one site. Potentially mineralizable nitrogen (PMN) was 1.6-1.7 times higher and microbial biomass was 1.4 times higher in soils from cover crop treatments relative to fallow at one of two sites. PMN was 1.2-1.3 times higher in soils from six-species mixes than two-species mixes at both sites, and six-species mixes produced 1.4 times more biomass at one site. Nitrogen fixers had the lowest C:N ratio of the functional groups at both sites, while FR had the highest at one site. In a second study of cover crop termination, cover crops were grown about 90 days and terminated with one of three strategies: chemically, grazing, or haying. Soils were sampled nine months after termination at the time of wheat seeding. Few enzyme differences and no PMN differences or meaningful patterns were discovered among termination strategies. Minimal differences in biological parameters, even when shoot biomass was removed, may mean grazing or haying could improve net revenue without detracting from soil health. In semi-arid annual systems, water limitations may be the main concern with growing cover crops.Item An acoustic emission and hygrothermal aging study of fiber reinforced polymer composites(Montana State University - Bozeman, College of Engineering, 2019) Newhouse, Kai Jeffrey; Chairperson, Graduate Committee: David A. MillerFiber reinforced polymer matrix composites are a premier choice for offshore wind turbines and Marine Hydro-Kinetic Devices, which operate in harsh and isolated marine environments. These factors combined with decades long target service life make imperative the understanding of damage mechanisms and the environmental effects thereof. Acoustic emission monitoring is a research technology that uses specialized sensors to detect transient elastic waves in a material which originate from damage sources. Waveform parameters have been correlated with different damage mechanisms in fibrous composites. A diverse set of fiber-matrix combinations configured into a variety of layups totaling more than 30 laminates were mechanically tested in quasi-static uniaxial tension while monitoring acoustic emission. A subset of these materials was aged prior to testing in an artificial marine environment by soaking in a water bath of simulated seawater at 50 degrees Celsius. Various acoustic emission waveform parameters were investigated with respect to expected damage between layups and possible material-based differences. Among the conditioned material set, mechanical changes from moisture absorption shows mixed levels of degradation among different material systems. Moduli were generally unaffected with a few minor decreases. Strengths were reduced by as much as 41%, and failure strains fell as much as 47%. From acoustic emission investigation, good correlation is found between Fast Fourier Transform peak spectral frequency bands and expected damage mechanisms between layups. Material based peak frequency differences are found exclusively in interphase failures (de-bond and fiber pullout). Layup-based correlations in conjunction with elastic wave theory were used to put forth new frequency band ranges associated with damage types.Item Soil temperature and soil moisture characteristics for several habitat types of Montana and Idaho(Montana State University - Bozeman, College of Agriculture, 1996) Sirucek, DeanItem Interrelationships of precipitation, soil moisture and spring wheat production in northern Montana(Montana State University - Bozeman, College of Agriculture, 1954) Aasheim, Torlief S.Item Water relations in highly calcareous very gravelly soils(Montana State University - Bozeman, College of Agriculture, 1978) McLean, Daniel LyleItem Sprinkler irrigation system design model and application(Montana State University - Bozeman, College of Agriculture, 1977) ElHanbali, Usaid Izzat SulimanItem The influence of different soil types, treatments, and soil properties on the efficiency of water storage(Montana State University - Bozeman, College of Agriculture, 1959) Choriki, Raymond T.Item The contact angle between water and soil materials(Montana State University - Bozeman, College of Agriculture, 1962) Cawlfield, George E.