Browsing Plant Science & Landscape Architecture Theses and Dissertations by Subject "Agriculture, Forestry and Wildlife"
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- ItemAssessing evapotranspiration rates of a Mid-Atlantic red maple riparian wetland using sap flow sensors.(2005-04-13) Renz, Jennifer Theresa; Momen, Bahram; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Riparian forests are unique due to increased exposure of trees to winds and radiation and the subsequent effects on the quality and quantity of water discharge from the system. Since "edge effects" can enhance evapotranspiration (ET) of exposed trees, ET rates of a first-order red maple riparian wetland were assessed with thermal dissipation probes during the 2002 growing season to address: a) if edge trees transpire more water daily than interior trees, b) correlations among sap flow rates and energy balance-derived estimates, c) variations in ecosystem ET estimates based on 6 scaling variables, and d) diurnal correlations between maximum sap flow rates and streamflow losses. Results from this study indicate that: a) edge trees transpire more water daily than interior trees during early summer, b) choice of scaling variable affects estimation of ecosystem ET rates, and c) maximum sap flow rates correlate with streamflow losses diurnally under specific environmental conditions.
- ItemChemotherapeutic Treatment Options to Manage Xylella fastidiosa in Shade Trees(2005-12-13) DeStefano, Darren Albert; Sullivan, Joseph; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Xylella fastidiosa is a fastidious, xylem-limited, broad spectrum, bacterial plant pathogen native to the Americas, causing substantial economic losses to the viticulture, citrus, and shade tree industries. In shade trees the disease is manifested as a chronic late season leaf scorch largely confined to urban areas of southeastern North America. Proposed treatments include antibiotics and growth regulators. Recently paclobutrazol, a diastereomeric triazole with fungistatic and growth regulation properties has been associated with symptom remission. Investigation into direct interaction of paclobutrazol with X. fastidiosa show no significant reduction in growth at the manufacturers recommended dosage of 20 µg ml-1; however significant reductions in growth were observed at a dosage of 200 µg ml-1. Therefore high levels of paclobutrazol may have a direct effect on X. fastidiosa while other plant physiological effects induced by paclobutrazol merit investigation for association in symptom mitigation of X. fastidiosa.
- ItemEffects of nitrogen and calcium on photosynthesis and metabolic activity in Acer saccharum in the Catskill Mountains(2008-03-31) Behling, Shawna Joy; Sullivan, Joseph H; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Catskill Mountains in southern New York have received some of the most acidic rainfall in the country for the past 50 years. Acid deposition on these thin soils may deplete the concentration of calcium and other essential ions in the soil solution and mobilize other ions that can be harmful to sugar maple (Acer saccharum) rooting systems. The effects of fertilizers on the metabolism and photosynthesis rates of sugar maple are of great interest to both farmers and ecologists. In this study, 12 plots in a 60-year-old sugar maple dominated forest were treated with no fertilizer, nitrogen, calcium, or nitrogen and calcium together. Photosynthesis was measured with a LiCor 6400. Metabolic heat rate was measured with a MC-DSC calorimeter. While some sampling periods showed significant responses to some treatments, the study as a whole suggests the addition of calcium and/or nitrogen had minimal effects on photosynthesis or metabolism.
- ItemThe Establishment and Persistence of American Ginseng (Panax quinquefolius L.) in Maryland Forests.(2005-05-26) Slak, David; McIntosh, Marla; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)American ginseng (Panax quinquefolius L.) is a profitable non-timber forest product with the potential of improving the sustainability of Maryland forests. In order to determine factors affecting Maryland ginseng production, ginseng seeds and roots were planted in forests in Eastern, Central, and Western Maryland in plots amended with no treatment, lime, or gypsum. The response variables measured included soil nutrients and ginseng persisence and establishment. In general, soil lime treatments improved establishment at the Eastern but not the Central or Western sites. The gypsum soil treatments did not significantly affect populations. Establishment of American ginseng grown from seed ranked by site was Western>Central>Eastern. Conversely, root establishment was best at the Eastern site. Across sites, soil pH, Ca, Mg, and K were positively correlated with establishment and persistence. Thus, American ginseng was grown throughout Maryland and ginseng production was enhanced by lime addition at the Eastern site.
- ItemTHE INFLUENCE OF LAND-USE, ENVIRONMENT, AND SOCIOECONOMIC FACTORS ON TREE SPECIES DISTRIBUTION IN BALTIMORE, MARYLAND.(2009) Mead, Kimberley Ellen; Sullivan, Joseph H.; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)With the exponential growth in human population and rapid increase in global urbanization, understanding changes in community dynamics and structure in human dominated landscapes is essential, yet, rarely studied. To determine what factors account for tree species composition and distribution in an urban setting, data from the 1999 UFORE Model vegetation survey of Baltimore, Maryland was analyzed. There was a diverse arboreal population found, comprised primarily of species native to the area. Detrended correspondence analysis did not show a clear pattern of species assemblages based on land-use, possibly indicating a homogenization of conditions across the urban environment. In canonical correspondence analyses, species distribution could not be explained by socioeconomic factors, however, there was a significant relationship of tree species assemblages and the physical environment, specifically with percent impervious surface cover. The amount of variance accounted for was small indicating that other factors may be involved in determining tree species distribution.
- ItemUtilizing Hybrid Poplar Trees to Phytoremediate Soils with Excess Phosphorus(2005-09-01) Neal, Amy; McIntosh, Marla S; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Phytoremediation, using plants to remove soil pollutants, has been suggested as a method to remove P from over-enriched soils. This research investigated the potential of utilizing hybrid poplar trees to remove excess P from soils associated with long-term poultry manure application. Hybrid poplar clones were planted in Snow Hill, MD, on three fields differing in previous poultry manure applications with Mehlich-3 soil-test P levels of 261, 478, and 982 mg P kg-1. During this two year study, soil P decreased on fields planted with hybrid poplar; the magnitude of the reduction was positively associated with initial soil-test P. Plant tissue P concentrations increased with soil P concentration. However, factors other than plant uptake were hypothesized to contribute to the soil-test P reductions. Results suggest that hybrid poplars have the potential to phytoremediate soils with excess P but that soil chemistry also impacts the fate of available P in the soil.