• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 666
  • 59
  • 46
  • 40
  • 38
  • 36
  • 26
  • 13
  • 8
  • 8
  • 8
  • 8
  • 8
  • 8
  • 5
  • Tagged with
  • 1162
  • 287
  • 187
  • 181
  • 181
  • 178
  • 177
  • 151
  • 133
  • 90
  • 90
  • 78
  • 78
  • 71
  • 67
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
691

Strategic environmental assessment design for wetland assessment and conservation policy development in an urban planning context

2015 June 1900 (has links)
This research advances Strategic Environmental Assessment (SEA) design and methodology for wetland assessment and policy development within an urban planning context. The thesis is a ‘manuscript-style’ and consists of three manuscripts, which collectively contribute to the overarching research purpose. The first manuscript presents and demonstrates a spatial framework for the application of SEA in the context of land use change analysis for urban wetland environment. The study aims to meet the needs for a proactive framework to assess and protect wetland areas more efficiently, and advance urban planning and development design. The proposed framework, adopting Geographic Information System and Remote Sensing approaches, presents a temporal evaluation of wetland change and sustainability assessment based on landscape indicator analysis. The results show that despite the recent extremely wet period in the Canadian prairie region, land use change contributed to increasing threats to wetland sustainability in the developing urban environment of the city of Saskatoon from 1985 to 2011. The second manuscript presents a scenario-based approach to SEA for wetland trends analysis and land use and land cover (LUC) modeling. Alternative future LUC was simulated using remote sensing data and city planning documentation using a Markov chain technique. Two alternatives were developed for LUC change and threats to urban wetland sustainability: a zero alternative that simulated trends in urban development and wetland conservation under a business as usual scenario, in the absence of prescribed planning and zoning actions; and an alternative focused on implementation of current urban development plans, which simulated future LUC to account for prescribed wetland conservation strategies. Results show no improvement in future wetland conditions under Saskatoon’s planned growth and wetland conservation scenario versus the business as usual scenario. Results also indicate that a blanket wetland conservation strategy for the city may not be sufficient to overcome the historic trend of urban wetland loss; and that spatially distributed conservation rates, based on individual wetland water catchment LUC differences, may be more effective in terms of wetland conservation. The results also demonstrate the challenges to applied SEA in a rapidly changing urban context, where data are often sparse and inconsistent across the urban region, and provides potential solutions through LUC classification and prediction tools to help overcome data limitations to support land use planning decisions for wetland conservation. The third manuscript presents an analytical approach to SEA, bridging strategic level assessment with operational planning and implementation. An expert-based strategic assessment framework was developed and applied to assess the potential implications of alternative wetland conservation policy targets on urban planning goals, and to identify a preferred conservation policy target. Site-specific algorithms, based on wetland area and wetland sustainability, were used to prioritize wetlands for conservation to meet policy targets within urban planning units. Results indicate a preferred wetland conservation policy target beyond which higher targets provided no additional benefit to urban development goals. The use of different implementation strategies, based on wetland area versus wetland sustainability, provides operational guidance and choice for planners to meet policy objectives within neighborhood planning units, but those choices have implications for local land use and wetland sustainability. Overall, the research contributes to the following aspects of SEA design and methodology: i) scoping processes to define the spatial and temporal context for SEA; ii) baseline assessment for analysis of environmental conditions and changes across space and/or over time; iii) methods to support the identification and evaluation of potential impacts of strategic alternatives; and iv) structured and systematic, quantitative assessment and decision-support tools for SEA that bridge strategic-level assessment with operational planning and implementation.
692

Distribution and environmental associations throughout southwestern Manitoba and southeastern Saskatchewan for the cattail species Typha latifolia, and T. angustifolia, and for the hybrid, T. x glauca

Wasko, Jennifer 23 April 2014 (has links)
Cattails (Typha spp.) are invasive and tend to decrease the biodiversity and area of open water of marshes, particularly where the natural hydrological cycles have been altered, as in Delta Marsh, Manitoba. Understanding the distribution of T. latifolia L., T. angustifolia L., their hybrid, T. x glauca Godr., and the environmental variables associated with their habitats, may give valuable insight for managing cattails. The distribution of these cattail species and hybrid were surveyed in 2011 in prairie pothole and roadside ditch marshes across southwestern Manitoba and southeastern Saskatchewan. Plants were identified by analysis of microscopic leaf-lamina margin characteristics. T. x glauca was most widespread, followed by T. latifolia, whereas T. angustifolia was rare and only found as far west as central Manitoba. Current understanding of the correlations between cattail invasions and their environment is conflicting and largely based on lacustrine wetland studies. A generalized linear model was developed. The model explained approximately 40% of the variation in T. x glauca distribution in the prairie potholes and ditches. The model included the environmental variables of sediment Olsen-P, sediment nitrate-N, water pH, litter depth, surrounding land use, and the interaction between Olsen-P and nitrate-N. Olsen-P was the most important of these variables, because its removal from the model significantly reduced the residual deviance of the model (P=0.05). In a survey of 13 transects throughout Delta Marsh in 2009, hybrid cattail, T. x glauca, was dominant, T. angustifolia was rare, and T. latifolia was absent. ANOVA linear regression (P=0.05) revealed that above-ground biomass was correlated with mean cattail ramet height, cattail ramet density, and standing litter biomass. Cattail ramet density was negatively correlated with sampling date and positively correlated with standing litter biomass. Mean cattail height was correlated with fallen litter biomass. One-way ANOVA (P=0.05) revealed that fallen litter biomass was lowest in quadrats closer to the open water, and mean cattail height was greatest at the quadrats closest to the open water. While mean cattail height differed depending on whether the cattail stand was a hybrid monoculture or a mixed stand of T. x glauca and T. angustifolia, no other cattail population variables were correlated with stand type. As revealed by one-way ANOVA (P=0.05), water conductivity, sediment texture, total-N, nitrate-N, Olsen-P, and organic-C were not important variables in the distributions of T. x glauca or T. angustifolia at Delta Marsh. Therefore, managing the nutrient levels at Delta Marsh would not likely be important for limiting the distribution of the cattails at this marsh. However, reducing the P concentration in pothole and ditch marshes may limit cattails in those environments.
693

Modelling the likelihood of wetland occurrence in KwaZulu-Natal, South Africa : a Bayesian approach.

Hiestermann, Jens. 05 September 2014 (has links)
Global trends of transformation and loss of wetlands to other land uses has deleterious effects on surrounding ecosystems, and there is a resultant increasing need for improved mapping of wetlands. This is because wetland conservation and management depends on accurate spatial representation of these systems. Current approaches to mapping wetlands through the classification of satellite imagery typically under-represent actual wetland area, and the importance of ancillary data in improving the accuracy in mapping wetlands is recognized. This study uses likelihood estimates of wetland occurrence in KwaZulu-Natal (KZN), South Africa, using a number of environmental surrogate predictors (such as slope, rainfall, soil properties etc.). Using statistical information from a set of mutually independent environmental variables in known wetland areas, conditional probabilities were derived through a Bayesian network (BN) from which a raster layer of wetland probability was created. The layer represents the likelihood of wetlands occurring in a specific area according to the statistical conditional probability of the wetland determinants. Probability values of 80% and greater also accounted for approximately 6% of the KZN area (5 520 km²), which is substantially more than the previously documented wetland area in KZN (4% of the KZN area or 4 200 km²). Using an independent test dataset, Receiver Operating Characteristic (ROC) curves with the Area Under Curve (AUC) analysis verified that the final model output predicted wetland area well (AUC 0.853). Based on visual comparisons between the probability layer and ground verified wetland systems, it was shown that high wetland probability areas in the final output correlated well with previously highlighted major wetland and wetland-rich areas in KZN. Assessment of the final probability values indicated that the higher the probability values, the higher the accuracy in predicting wetland occurrence in a landscape setting, irrespective of the wetland area. It was concluded that the layer derived from predictor layers in a BN has the potential to improve the accuracy of the KZN wetland layer by serving as valuable ancillary data. Application of the final probability layer could extend into the development of updated spatial freshwater conservation plans, potentially predicting the historical wetland extents, and as input into the land cover classification process. Keywords: ancillary data, Bayesian network, GIS, modelling, probability, wetland mapping. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.
694

Experimental manipulation of connectivity and common carp: the effects on native fish, water-column invertebrates, and amphibians in Delta Marsh, Manitoba

Parks, Candace R. 05 April 2006 (has links)
Common carp (Cyprinus carpio) have been hypothesized to contribute to declines in aquatic macrophytes, waterfowl, and water clarity in Delta Marsh, an 18,500 ha freshwater coastal wetland on Lake Manitoba, Canada. Ten ponds (1-13 ha) were chosen for a two-year experimental manipulation study. Following a year of baseline monitoring, manipulations were conducted in 2002. To facilitate access by carp into isolated ponds, channels were blasted from the main marsh into two ponds. Meanwhile, to restrict or exclude carp access into ponds, channels were either screened or diked to four ponds. Two connected and two isolated ponds functioned as controls. Although common carp were the original subject of the study, it became apparent that hydrological connection to the surrounding marsh had a paramount importance on the abundance and diversity of the fish, amphibian and water-column invertebrate communities. Connectivity, or lack of connectivity, played an important role in the distribution of the fish community, and subsequently the composition and abundance of water-column invertebrates and amphibians. Ponds with direct connection had diverse, mixed-species fish assemblages, with fewer invertebrates and amphibians. Ponds with restricted connections had fish communities composed of tolerant small-sized species and increased abundance of invertebrates and amphibians. Ponds that lacked connection could freeze and lose all fish, and had higher numbers of invertebrates and amphibians. An absence of adult common carp may have been responsible for increased amphibian numbers in the screened ponds, however more study is needed. Confounding impacts of fluctuating water levels made it impossible to implicate common carp for most changes observed within ponds in Delta Marsh.
695

Determining the potential for wetland construction within a linear park setting

Flaugh, Dianne L. January 1991 (has links)
The purpose of this creative project was to outline the concept of Wetland Incentive Zones and to develop a site masterplan based on this concept. Meant as an alternative to large single-site wetland banks, Wetland Incentive Zones would be linear areas of land where wetland construction and preservation efforts would be concentrated. The linear structure would distribute the benefits associated with wetlands through a greater area than would a typical wetland bank. If linked together, the zones would form a network of recreational greenways and function as a travel corridor for wildlife. Participating zone landowners would benefit from tax abatements on wetland acreage and other incentive programs. The public would benefit from the preservation and construction of wetlands and the zone's recreational and educational elements.The masterplan was developed to direct wetland site development opportunities and public recreation and educational functions within a 3200 acre study site located in Allen County, Indiana. This site masterplan identified areas suitable for wetland construction, investigated their potential as wildlife habitat, and the wetland condition likely to be supported. The development plan for the site was focused on the use of an abandoned railroad line as a trail system for public recreation and educational use. / Department of Landscape Architecture
696

A watershed approach to decrease flooding of Pipe creek in Alexandria, Indiana

Zapf, Jeff January 1996 (has links)
This project explores one method of controlling flooding of Pipe Creek in Alexandria, Indiana. The method used is one of placing wetlands and grass filters within one subwatershed of Pipe Creek to reduce peak discharge and the time to peak discharge. A computer program called Sedimot II was used to determine the peak discharge for the Thurston Ditch subwatershed of Pipe Creek. Both 10 and 50 year 24 hour storms were studied. Following the construction of base line hydrographs for both storm events, four examples of wetland and grass filter placement were shown for the watershed. Hydrographs were then produced for all four alternatives for both 10 and 50 year storms. Recommendations were then made on how these examples could be used in the rest of the Pipe Creek watershed to further reduce the potential for flooding in Alexandria. / Department of Landscape Architecture
697

Experimental manipulation of connectivity and common carp: the effects on native fish, water-column invertebrates, and amphibians in Delta Marsh, Manitoba

Parks, Candace R. 05 April 2006 (has links)
Common carp (Cyprinus carpio) have been hypothesized to contribute to declines in aquatic macrophytes, waterfowl, and water clarity in Delta Marsh, an 18,500 ha freshwater coastal wetland on Lake Manitoba, Canada. Ten ponds (1-13 ha) were chosen for a two-year experimental manipulation study. Following a year of baseline monitoring, manipulations were conducted in 2002. To facilitate access by carp into isolated ponds, channels were blasted from the main marsh into two ponds. Meanwhile, to restrict or exclude carp access into ponds, channels were either screened or diked to four ponds. Two connected and two isolated ponds functioned as controls. Although common carp were the original subject of the study, it became apparent that hydrological connection to the surrounding marsh had a paramount importance on the abundance and diversity of the fish, amphibian and water-column invertebrate communities. Connectivity, or lack of connectivity, played an important role in the distribution of the fish community, and subsequently the composition and abundance of water-column invertebrates and amphibians. Ponds with direct connection had diverse, mixed-species fish assemblages, with fewer invertebrates and amphibians. Ponds with restricted connections had fish communities composed of tolerant small-sized species and increased abundance of invertebrates and amphibians. Ponds that lacked connection could freeze and lose all fish, and had higher numbers of invertebrates and amphibians. An absence of adult common carp may have been responsible for increased amphibian numbers in the screened ponds, however more study is needed. Confounding impacts of fluctuating water levels made it impossible to implicate common carp for most changes observed within ponds in Delta Marsh.
698

Can Landscape Composition Predict Movement Patterns and Site Occupancy by Blanding's Turtles?: A Multiple Scale Study in Québec, Canada

Fortin, Gabrielle 07 December 2012 (has links)
As habitat loss and fragmentation are major causes of decline in animal species, studying habitat requirements in these species is a key component of their recovery. I investigated the relationship between landscape composition and habitat use of Blanding’s turtles, Emydoidea blandingii, a freshwater turtle threatened by habitat loss and road mortality on most of its Canadian range. In 2010, I conducted a radio-telemetry survey of 44 Blanding’s turtles in southern Québec, Canada, and modelled their home range size from land cover proportions measured at many spatial scales. I also used data from a visual survey conducted in 2008 and 2009 to model wetland occupancy of the species at the landscape scale. Home range size of the Blanding’s turtle was significantly correlated to landscape composition, and the proportions of agriculture, open water and anthropogenic lands had the strongest relationships with home range size. However, those relationships were weak and the models were unable to predict home range size accurately. At the landscape scale, land cover and road density poorly predicted probability of occurrence, and Blanding’s turtles occupied wetlands in both disturbed and natural sites. Management of the species should focus on protecting sites of occurrence with high wetland density, low road density, and sufficient suitable habitat to cover their seasonal movement patterns.
699

The Effects of the Glyphosate-based Herbicide WeatherMax on Sexual Differentiation and Growth in the Wood Frog (Lithobates sylvaticus)

Robertson, Courtney 20 February 2013 (has links)
Glyphosate-based herbicides are the dominant pesticide on the market and are utilized worldwide in both the agricultural and forestry industries. Their prevalence comes at a time when concern over the potential effects of pesticide application in amphibian spawning grounds is growing. The primary goal of this thesis was to determine if the glyphosate-based herbicide WeatherMax® has the potential to disrupt sexual differentiation and growth in the wood frog (Lithobates sylvaticus) in a pulse exposure at the predicted maximal environmental concentration (PMEC) of 2.88 mg acid equivalent per liter. This was carried out in laboratory, mesocosm and in-situ field exposures, in an attempt to determine how a potential disruption might vary between experimental environments. In this study, tadpoles from three split-wetlands targeted at the PMEC for WeatherMax were found to display no significant change in survival or growth, however gene expression of several genes involved in steroidogenesis during sexual differentiation (cyp19, cyp17, star, foxl2) were found to be affected. The effects on these genes appeared to be dependant on the exposure concentration of WeatherMax in each wetland, which varied even though all three wetlands were meant to target the PMEC. The wetland that was measured as having the highest herbicide concentration (PMEC 13) was found to have a female biased sex ratio. The results found in the field varied from those found in the more artificial exposures. In the laboratory the PMEC of WeatherMax experienced complete mortality, whereas in the mesocosms survival was not significantly affected. Sex ratios were unaffected in the laboratory, however at the PMEC there was a significant male bias in the mesocosms. The discrepancies in the results obtained from the different exposure types highlights the importance of real world exposures. That the same concentration that caused complete mortality in the laboratory caused sublethal effects in the field is of importance as it denotes that these endpoints may not be easily investigated in these synthetic exposures. This project is a part of the Long Term Experimental Wetlands Area (LEWA) and contributes to the body of information amassed therein on the impact of a glyphosate-based herbicide on amphibians in a wetland ecosystem.
700

Habitat suitability of the yellow rail in south-central Manitoba

Martin, Kristen 21 September 2012 (has links)
Little is known about the distribution and habitat suitability of yellow rails (Coturnicops noveboracensis) throughout their breeding range. Yellow rail and vegetation surveys were conducted at 80 wetlands in south-central Manitoba in 2010-2011 to evaluate the effectiveness of repeat-visit, call-broadcast night surveys for detecting this species and habitat associations of this species at the 3-km landscape, patch, and plot scales. Yellow rails were detected at 44% of the study wetlands. Yellow rail detection was imperfect (0.63 in each year), but call-broadcast increased the number of yellow rails detected. Future yellow rail survey efforts should employ call-broadcast and at least three surveys per survey point. Yellow rail presence was positively influenced by the amount of marsh/fen in the landscape and the proportion of rushes at the study wetlands. These characteristics should be considered when identifying potential yellow rail habitat in south-central Manitoba.

Page generated in 0.0434 seconds