In South Africa, the loss of wetlands and their associated benefits has been considerable. A need was identified for a system that, using available information, would assist in achieving a balance between local, mainly short-term benefits to individuals and spatially wider and longer term benefits to society. Such a system, termed WETLAND-USE, was developed with the philosophy that:(l) wetlands have been well demonstrated to supply several indirect benefits to society (e.g. water quality enhancement); (2) the impact on these benefits can be described on a qualitative basis using field indicators that characterize the wetland and the disturbance associated with a particular land-use; (3) this information can be communicated to wetland users, which will contribute to achieving a desired balance, provided there is an enabling organizational environment and due consideration is taken of the socio-economic and organizational factors affecting wetland management. The primary conceptual framework underlying WETLAND-USE was the pressure-state-perceptions-policy framework, which depicts: the mode of use (i.e. the pressure); how this affects the state of the system (including its underlying processes and the goods and services it delivers); which in turn shape the perceptions that ultimately determine the policy pertaining to further use. This cycle is repeated at a range of organizational levels from local to national and takes place within a particular socioeconomic context. WETLAND-USE, which was designed for use by fieldworkers, and built using a rule-based, expert system approach, has two main parts, dealing largely with biophysical and social aspects respectively. Part 1, which guides the collection of data relating to the state of the wetland, assists in: (1) predicting the likely impacts of disturbances associated with a proposed land-use (the pressure) on the wetland state, and (2) providing ongoing management guidelines for particular land-uses. Part 2 assists in: (1) describing the social, land tenure and policy contexts of the wetland; and (2) establishing and maintaining organizational arrangements, local policy and management objectives and goals. Several discrete investigations were required for the development and refinement of WETLAND-USE, which was done in an iterative fashion. Initial discrete investigations fed into the development of a prototype system which was refined through evaluation using a questionnaire survey and further discrete investigations. The revised system was re-evaluated using a fieldworkshop approach and, based on the performance of the system in the field, it was revised further to produce the final system. In the two initial discrete studies, protocols were developed for characterizing key physical determinants of wetland functioning, notably: (1) degree of wetness, one of the primary functional determinants, described in the field using readily identifiable soil morphological indicators (e.g. matrix chroma and mottles) and (2) landform setting, which strongly influences local flow patterns and lateral exchange of water and water-borne materials. Graminoid plant species composition and functional groups (defined in terms of photosynthetic pathway) were then described in relation to the above physical determinants, together with rainfall, temperature and soil texture, within wetlands spanning a wide altitudinal range. This revealed that degree of wetness and altitude had the strongest influence over the vegetation parameters examined. An investigation into incorporating cumulative impacts into wetland decision making revealed that consideration should be given to: wetland loss in relation to ecoregions and catchments, and the relation of change in wetland extent, spatial configuration and context respectively to wetland function. Current conservation initiatives in KwaZulu-Natal were shown to account poorly for cumulative impacts on wetlands. Rules of thumb for making such considerations, given severe data limitations, were developed with reference to the high turn-over of species along the altitudinal gradient observed in the vegetation study. The "rules" were than applied to a case-study, the upper Mgeni catchment, as part of an initiative to engage a diversity of stakeholders in wetland information gathering and use. This resulted in the selection of priority wetlands in the catchment and an examination of the extent to which integration had been achieved vertically (across hierarchical levels) and horizontally (across organizations within particular hierarchical levels). In order to broaden the range of land-uses accounted for by the WETLAND-USE prototype, it was applied to a communally used wetland, Mbongolwane, and found to account poorly for the traditional cultivation and vegetation harvesting practices encountered. WETLAND-USE was modified to include a greater diversity of land-use types as well as enhancing its capacity to allow assessments to be conducted using the system's general criteria, thereby making WETLAND-USE more robust. In enhancing the capacity of WETLAND-USE to account for the social and organizational dimension of wetland management, the involvement of local and outside organizations in influencing wetland resource use in five sites was examined in relation to predefined frameworks. The sites, Mandlazini wetland, Mbongolwane wetland, Blood River vlei, Ntabamhlope vlei and Wakkerstroom vlei were chosen to represent a diversity of social contexts and management authorities. This revealed that in communally used areas in particular, a wide range of organizations are involved to varying degrees in influencing the use of different wetland resources. The level to which the local organizational environment contributed to sustainable use varied greatly among wetlands, but in all cases had important deficiencies: (1) self-governing resource-management organizations were largely lacking and in communal areas were weakening under contemporary conditions; and (2) although a formal management system was in place in two of the five wetlands, it was largely absent in the remaining three. There has been little involvement from extension services in facilitating local policy development and in promoting alternative land-uses which have less pressure on the state of the wetland. Local wetland management policy and collaboration among land-owners in wetlands under multiple separate ownership such as Blood River vlei was identified as being particularly poor. The evaluations of WETLAND-USE revealed that, in relation to the underlying philosophy of the thesis, WETLAND-USE had been improved through field application and incorporation of the findings of the discrete investigations. Nevertheless, important limitations of the study were highlighted, including: its high level of reliance on expert opinion in the face of a paucity of empirical data relating to the functioning of local wetlands and their attendant benefits (and how these are affected by anthropogenic disturbances), and a particularly shallow representation of socio-economic factors. The identification of these limitations was useful in highlighting key areas for further research. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1999.

Anthropogenic disruptions in the form of hydrological alterations, such as dam construction and the associated water diversions are a cause of much upheaval to local and regional ecosystems. Lake 626 within the Experimental Lakes Area of north-west Ontario, along with its downstream wetlands, 626A and 626B are one such system. Construction of a dam at the L626 inflow has completely restricted water flow, reducing and reshaping the watershed, increasing water retention time, and decreasing outflow into the wetlands. This study investigates the state of each wetland through physical and geochemical characterization during the first year following the diversion. Previous studies have found that hydrological diversions in wetlands can lower water table levels, altering soil chemistry and producing a shift in floral and faunal communities. Ultimate consequences involve significant loss of wetland area through conversion to upland habitat. This provides a model for climatic warming scenarios, wherein sustained drought conditions can produce the same result. Boreal wetlands are surprising fragile ecosystems that store massive quantities of carbon and are at risk of releasing it in such situations. One study showed that an extended summer drought in an otherwise average year with above average precipitation produced losses of 90 g C/m2 over the course of the year. Maintenance of reduced-flow in wetlands 626A and 626B is expected to convert the system into a carbon source and reduce overall wetland area. Radiocarbon dating has revealed that following deglaciation, both 626A and 626B basins were open water wetlands, depositing limnic peat for about 3200 and 1300 years respectively. Each site then transitioned into open sedge dominated fen – 626B to the present and 626A until about 2.5 ka BP when Sphagnum began to develop. Wetland 626B is decidedly an open shrub/sedge fen, supporting Myrica gale, Chamaedaphne calyculata and Carex rostrata / lasiocarpa communities. Wetland 626A is a bog/fen complex, sharing similar communities in the fen areas, but housing a large, centrally located bog of shrub species overlying Sphagnum hummocks. Tritium values in 626A were similar to cosmic background levels, indicating that recharge of basal pore water has not occurred in at least 60 years. Tritium in 626B was much higher, suggesting a substantial difference in hydrology or peat hydraulic conductivity between the basins. Measurement of DOC profiles showed high concentrations in near-surface water, reaching over 80 mg/L, and dropping to about 20 mg/L at maximum depths. An opposite trend was seen for DIC and CH4 profiles which increased concentration with depth (25 – 70 mg/L DIC; 75 – 700 μmol/L CH4). Isotopically however, 13C signatures from basal DIC were more positive while signatures from CH4 were typically more negative (-6 ‰ to +4 ‰ DIC; -57 ‰ to -73 ‰ CH4). Breakdown of DOC by LC-OCD showed high concentrations of humic substances and low molecular weight neutrals. The origin of humic substances in surface water became more pedogenic with increasing distance from the L626 outflow, indicating the influence of decaying wetland vegetation on the DOC of adjacent water. A comparison between contemporary and future characterization of boreal peatlands under drought-like conditions will provide a better understanding of the impacts suffered by wetlands during hydrological alterations. The high sensitivity of wetlands to changing hydrology should also provide a measure for gauging the effects of long term climate warming. This will assist in the development of environmental policies to better govern both the establishment of water diversions and the multitude of other practices leading to climate change.

This study examined the responses of algae and invertebrates to a single application of nutrients in a series of experimental wetland enclosures in the Interlake Region of Manitoba during 1989 and 1990. Water, sediment and vegetation chemistry were also monitored. The 3 fertilization treatments were: dissolved inorganic high (6200 $ mu$g/l N, 420 $ mu$g/l P), dissolved inorganic low (3200 $ mu$g/l N, 210 $ mu$g/l P) and organic high (alfalfa: 6200 $ mu$g/l N, 420 $ mu$g/l P). / Dissolved nutrients in the high and low treatments were quickly depleted from the system but dissolved N increased in the alfalfa treatment as decomposition progressed. No changes in sediment or vegetation chemistry were detected. Phytoplankton biomass increased in all the fertilized enclosures while epiphytic periphyton exhibited only minor responses. Epipelon biomass increased in the alfalfa treatment and metaphyton standing crops were extensive in the high treatment enclosures. / In the alfalfa treatment, high microbial respiration rapidly decreased dissolved oxygen concentrations which negatively affected invertebrates. This trend reversed as oxygen levels increased. Dominant nektonic and benthic herbivores-detritivores increased in the high and alfalfa treatment enclosures. Orthocladiinae emergence increased in the high and alfalfa treatments while Chironominae and Tanypodinae increased in the alfalfa treatment. Responses by algae and invertebrate communities to the fertilization treatments were minimal during 1990. Annual single pulse fertilization has the potential to increase the productivity of Interlake wetlands.

Movement of growth faults, a type of normal fault which is formed during sedimentation and is characterized by having greater vertical thickness on the downthrown fault side, on barrier islands contributes to wetland losses. The opening objective of this study was to quantify land cover change within a Matagorda, Texas wetland that results from sea level rise and elevation change over time due to coastal faulting. The closing objective of this study was to simulate land cover conversion as a function of relative sea level rise (RSLR) within the wetland and to compare and contrast the impact of specific rates of both fault-induced elevation change and predicted International Panel on Climate Change (IPCC) sea level rise projections. To accomplish these objectives a time series of aerial images was classified using automated unsupervised classification and hand digitization. After classification, total wetland losses on both the upthrown and downthrown sides of the fault were evaluated as a function of spatial distance from the fault plane. This classified product was draped over a digital elevation model (DEM) layer to evaluate elevations of land cover classes and model potential future outcomes based on RSLR. Classification results show that while wetland loss occurred on both sides of the fault, losses were far more extensive on the downthrown side. It was concluded that this vertical fault movement impacts wetland losses, especially on the downthrown side. Modeling results show that rapid water level rise can force wetland land cover class conversion regardless of whether this relative rise is caused by vertical fault displacement or eustatic sea level rise, resulting in the destruction of vital wetland areas. Current recorded conditions of sea level rise along the Texas Gulf Coast leave a grim outlook for regions similar to this study area.

Includes bibliography. / 2 v. : ill., maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis analyses the aquatic macrophyte vegetation of remnant wetlands in the South East of South Australia and of Bool Lagoon in particular. The study describes the diversity of aquatic vegetation in 11 remnant and ephemeral wetlands in the South East using a multivariate approach of classification and ordination of vegetation quadrats. The second section of the study characterises the seasonal pattern of fluctuation through a numerical description of water regime. The third section is a consideration of the population demography of Typha domingensis and Phragmites australis in relation to flooding frequency at Bool Lagoon. The final section of the study considers the influence of flooding frequency on the distribution of some important components of the vegetation of Bool Lagoon. / Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1997?

Thesis (Ph. D.)--University of Western Sydney, Hawkesbury, 1996. / Includes bibliographical references (p. 511-557).

Thesis (Ph.D.) -- Dept. of Botany, University of Adelaide, 1993. / Bibliography: leaves 103-120.

Thesis (M.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 142-146). Also available in electronic format on the Internet.

Thesis (Ph.D.)--Mississippi State University. Department of Biological Sciences. / Title from title screen. Includes bibliographical references.

Thesis (diplôme d'archiviste paléographe)--École nationale des chartes, Paris, 2002 and Thesis (Ph. D.)--Université Paris IV Sorbonne, 2004. / Includes bibliographical references (p. [519]-522) and indexes.