Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 40-46). Also available on the World Wide Web.

Thesis (M.Sc.)--College of William and Mary. / Vita. Includes bibliographical references.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Includes bibliographical references (p. 49.

Thesis (M.S.)--Oregon State University, 1993. / Typescript (photocopy). Includes bibliographical references (leaves 118-122). Also available online.

The landscapes of British Columbia, prominently modified by glaciation, present many large and varied wetlands. These wetlands have not been well delineated nor classified although they are being rapidly modified for residential, agricultural and industrial developments. Some federal and provincial agencies are currently undertaking inventory and classification based largely on soil profile characteristics. To complement these efforts, particularly for management purposes, this study was undertaken in which predominantly plant-mediated processes were examined. The investigations were limited to the maritime marshes of south western British Columbia with study sites located in the Pitt, Brunswick and Iona marshes. Estimates of productivity were obtained from single and sequential harvesting of the aerial vegetation. Peak standing crops varied between species and between sites. Species differences were attributed to plant characteristics such as photosynthetic canopy development and shoot configuration. Peak standing crops were also related to environmental variables such as climate, water regime, salinity and substrate nutrient status. Data from sequential harvesting revealed that most emergents experienced a rapid growth in the spring and early summer declining with the onset of cold weather in the fall. Time of peak production differed markedly between species depending on presence or absence of overwintered photosynthetic shoots, time of shoot emergence and seasonal shoot mortality rates. Studies of belowground organs showed that roots and rhizomes may comprise up to 85 percent of the total phytomass of emergent vegetation emphasizing the importance of this fraction in wetland functions and processes. The main routes of disposition of the emergents were identified as the grazing route, accumulation route and the detrital route. Grazing was relatively unimportant in the marshes. Any grazing of the living vegetation was carried out largely by gastropods, earthworms, insects and resident and migrant waterfowl. Minimal grazing of the marsh vegetation appeared to be related to unfavourable wetland conditions, high levels of structural constituents and low levels of nitrogen in the plants. Quality of the vegetation declined sharply with age. Low ash levels and high phenolic content were also implicated in the minimal grazing of the Pitt marsh vegetation. Total energy content appeared to be unimportant in this regard. Organic matter accumulation was a distinct feature of the marshes studied. There was more organic matter accumulation in the Pitt than in the Brunswick marsh. Accumulation also seemed to be more uniform over large areas in the Pitt marsh than in the tidal marshes. Data from old growth samples indicated that a large portion of the phytomass produced in the marshes enters the detrital pathway via decomposition. Factors affecting decomposition rates were discerned largely from litter bag trials and in vitro decomposition studies. Fragmentation of litter by physical forces generally preceded biological degradation. Such comminution was more marked in the Fraser delta marshes where tidal and freshet activities are predominant. Temperature was a significant factor affecting disappearance rates. The rates were generally lower in the "cooler" Pitt marsh than in the "warmer" Brunswick marsh. Low soil temperatures together with low oxygen tensions were responsible for the relatively low decomposition rates in buried litter samples. Decomposition rates also reflected the chemical composition of the emergent vegetation. Less fibrous species such as Carex lyngbyei were more readily degraded than more fibrous species such as Carex sitchensis. Leaching of readily degradable plant materials occurred in significant quantities both in living and dead vegetation. Leaching losses in living shoots averaged 64 mg/g leaf dry matter in 4 days. Variations in stomatal number, shape and distribution were implicated in the possible mechanisms controlling leaching losses in living emergent vegetation. In dead shoots, dry weight losses of up to 50 percent were recorded over a four month period. Such losses were attributed mainly to leaching. High initial losses in the litter bag and in vitro decomposition trials were also suggestive of leaching. / Land and Food Systems, Faculty of / Graduate

Arbuscular mycorrhizal fungi, colonizing over 80% of all plants, were long thought absent in wetlands; however, recent studies have shown many wetland plants harbor arbuscular mycorrhizae (AM) and dark septate endophytes (DSE). Wetland services such as biodiversity, shoreline stabilization, water purification, flood control, etc. have been estimated to have a global value of $14.9 trillion. Recognition of these vital services is accompanied by growing concern for their vulnerability and continued loss, which has resulted in an increased need to understand wetland plant communities and mycorrhizal symbiosis. Factors regulating AM and DSE colonization need to be better understood to predict plant community response and ultimately wetland functioning when confronting natural and human induced stressors. This study focused on the effects of water quality, hydrology, sedimentation, and hurricanes on AM and DSE colonization in three wetland species (Taxodium distichum, Panicum hemitomon, and Typhal domingensis) and plant communities of coastal wetlands in Southeast Louisiana and effects of an antimicrobial biocide, triclosan (TCS), on AM (Glomus intraradices) spore germination, hyphal growth, hyphal branching, and colonization in fresh water wetland plants (Eclipta prostrata, Hibiscus laevis, and Sesbania herbacea) from bottom land hardwood forest in north central Texas. The former, mesocosm studies simulating coastal marsh vegetation ran for five years. In the latter studies, AM spores and wetland plants were exposed to 0 g/L, 0.4 g/L, and 4.0 g/L TCS concentrations in static renewal and flow through exposures for 21 and 30 days, respectively. AM and DSE colonization was significantly affected by individual and interactions of four independent variables in mesocosm experiments. Similarly, spore germination, hyphal growth, hyphal branching, and AM colonization in selected wetland plants were significantly lowered by exposure to the TCS at environmentally relevant concentrations. However, levels of effects were plant species and fungal propagules specific. My results showed that natural and human induced alterations in environmental factors and chemical contaminants can significantly impact levels of mycorrhizal spore germination, colonization, and spore density in coastal and freshwater wetland plants. The resulting impacts on plant community structure and ecosystem function require further study.

No description available.

Theses (M.S.)--Marshall University, 2005. / Title from document title page. Includes abstract. Document formatted into pages: contains ix, 111 p. Bibliography: p. 103-106.

Bibliography : leaves [34]-[40]

<p>Mine tailings can be rich in sulphide minerals and may form acid mine drainage (AMD) through reaction with atmospheric oxygen and water. AMD contains elevated levels of metals and arsenic (As) that could be harmful to animals and plants. An oxygen-consuming layer of organic material and plants on top of water-covered tailings would probably reduce oxygen penetration into the tailings and thus reduce the formation of AMD. However, wetland plants have the ability to release oxygen through the roots and could thereby increase the solubility of metals and As. These elements are released into the drainage water, taken up and accumulated in the plant roots, or translocated to the shoots. </p><p>The aim was to examine the effects of plant establishment on water-covered mine tailings by answering following questions: A) Is plant establishment on water-covered mine tailings possible? B) What are the metal and As uptake and translocation properties of these plants? C) How do plants affect metal and As release from mine tailings, and which are the mechanisms involved?</p><p><i>Carex rostrata Stokes, Eriophorum angustifolium</i> Honck., <i>E. scheuchzeri</i> Hoppe, <i>Phragmites australis</i> (Cav.) Steud., <i>Salix phylicifolia</i> L. and <i>S. borealis</i> Fr. were used as test plants. Influences of plants on the release of As, Cd, Cu, Pb, Zn and in some cases Fe in the drainage water, and plant element uptake were studied in greenhouse experiments and in the field. </p><p>The results obtained demonstrate that plant establishment are possible on water-covered unweathered mine tailings, and a suitable amendment was found to be sewage sludge. On acidic, weathered tailings, a pH increasing substance such as ashes should be added to improve plant establishment. The metal and As concentrations of the plant tissue were found to be generally higher in roots than in shoots. The uptake was dependent on the metal and As concentrations of the tailings and the release of organic acids from plant roots may have influenced the uptake. The metal release from tailings into the drainage water caused by<i> E. angustifolium </i>was found to depend greatly on the age and chemical properties of the tailings. However, no effects of <i>E. angustifolium </i>on As release was found. Water from old sulphide-, metal- and As-rich tailings with low buffering capacity were positively affected by <i>E. angustifolium </i>by causing higher pH and lower metal concentrations. In tailings with relatively low sulphide, metal and As contents combined with a low buffering capacity, plants had the opposite impact, i.e. a reduction in pH and elevated metal levels of the drainage water. The total release of metal and As from the tailings, i.e. drainage water together with the contents in shoots and roots, was found to be similar for <i>C. rostrata</i>, <i>E. angustifolium </i>and <i>P. australis</i>, except for Fe and As, where the release was highest for <i>P. australis</i>. The differences in metal and As release from mine tailings were mainly found to be due to the release of O₂from the roots, which changes the redox potential. Release of organic acids from the roots slightly decreased the pH, although did not have any particular influence on the release of metal and As. </p><p>In conclusion, as shown here, phytostabilisation may be a successful technique for remediation of mine tailings with high element and sulphide levels, and low buffering capacity.</p>