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  • 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.
11

Perception of scale and scale effects in the landscape, with specific reference to wind turbines in Scotland

Stanton, Caroline Mary January 2016 (has links)
Perception of scale is important to our activity within a space and to our experience of a landscape. This presents a problem if people cannot predict or convey the scale effects of large structures proposed in a landscape, as has been the case for recent wind turbine proposals in Scotland. To address this problem, this research explored how people perceive scale and scale effects in a landscape. It took wind turbines as an example structure and analysed how different scales of windfarm create different scale effects in different landscapes, as well as how to best assess and communicate these effects. The research applied three methods to address the research questions: Landscape and Visual Impact Assessment (LVIA), which is a standard, structured process applied by professional landscape architects; experiential landscape assessment, which included semi-structured interviews with local people in addition to site assessment; and public attitude and preference study, which included Adaptive Choice-Based Conjoint analysis (ACBC). These different methods allowed the research questions to be explored in different ways, while overlapping in some aspects and providing triangulation. The research findings revealed that our perception of scale and scale effects in a landscape is influenced by numerous attributes and depends on how these are experienced together. Building upon the theoretical background, an important difference between visual scale and spatial scale was highlighted, as well as alternative ways in which scale references are made. Throughout the research, the need for clear communication was emphasised and the findings included identifying the specific words that people use to describe scale effects in the most discriminating way. This research supported other studies in finding that consultation with local people (professionals and the public) was vital to understand in sufficient depth how a landscape was perceived, experienced and valued. In addition, the innovative development of Conjoint Analysis demonstrated how this method can reveal how people judge the relative importance of different attributes that influence landscape and visual effects and, by doing so, offer new possibilities as a tool in landscape research. Building upon the general findings concerning scale, specific findings regarding the scale effects of windfarms included: greater influence of the proximity of a windfarm than size or numbers of wind turbines; greater importance for being in private and/or fixed locations that offer a sense of refuge compared to public locations and/or when moving; the importance of collective effects perceived and experienced by a community; the importance of perceived spatial separation between a viewer and a windfarm (affecting sensitivity to scale effects within open settings); and differences in how people judge the importance of horizontal scale effects compared to vertical scale effects. The research findings contribute to the knowledge and understanding of people’s perception of scale and scale effects in a landscape and they counter some common assumptions and current practice in landscape architecture. They can be applied in practice and policy to help assess scale effects, convey more clearly to people the type of scale effects and how these will affect them, and minimise the adverse scale effects of windfarms through siting and design. The thesis also identifies how to build upon these findings in the future, including recommendations for additional research, new approaches to assessment (including the use of prompt lists) and thresholds for acceptability of scale effects.
12

Effects of local and landscape scale factors on ant diversity and biocontrol of the coffee berry borer in Colombia

Escobar-Ramírez, Selene 10 July 2018 (has links)
No description available.
13

Freshwater Aquatic and Terrestrial Microbial Community Functional Responses to Chronic Nutrient Limited Environments

Kirchner, Nicole M. 21 September 2016 (has links)
No description available.
14

Conservation and ecology of wetland birds in Africa

Donaldson, Lynda January 2017 (has links)
Conservation managers worldwide are increasingly faced with the challenges of managing and protecting fragmented landscapes, largely as a consequence of human activities. Over recent decades, ecological theory has made a significant contribution to the development of landscape-scale conservation and practice. However, recommendations accounting for what is practically achievable in the modern-day landscape are currently lacking, while criteria for conservation planning and prioritisation continue to neglect the role of habitat networks at the required spatial scale for the long-term persistence of biodiversity. In this thesis, I test and apply ideas surrounding the complexities of managing and conserving species in a landscape context, using a suite of bird species endemic to papyrus (Cyperus papyrus) swamps in East and Central Africa as a model system. In the face of large-scale habitat loss and degradation, practical measures that account for the fragmented nature of this system, the needs of multiple specialist species, and the reliance on this habitat by local people, are urgently required. I first review the concepts originating from reserve design theory to provide a decision-making framework for those involved in landscape-scale conservation amid 21st century challenges to biodiversity, highlighting the key principles to be considered for informed choices to be made. Second, I show that the needs of local people can be compatible with conservation planning in the tropics, and may play an important part in maintaining habitat quality for species residing in historically disturbed landscapes. Third, I develop a novel framework to make an explicit link between metapopulation dynamics and conservation planning. Despite differences in the patch-level dynamics of individual species, areas of habitat where populations of multiple species are resistant to extinction, and resilient because of high chances of (re)colonization can be identified, highlighting where resources could be invested to ensure species have the capacity to respond to future change. Finally, I simulate the metapopulation dynamics of the papyrus-endemic birds to demonstrate that the optimal conservation strategy for the long-term persistence of all species residing in a network depends on the characteristics of individual species, and the total area that can be protected. Overall, this thesis develops and tests the ecological theory used in spatial conservation planning, emphasising the importance of habitat disturbance and interspecific ecological differences for the effective management of habitat networks. The results increase the evidence base for the conservation of wetland birds in Africa, as well as for species residing in fragmented landscapes more generally.
15

Landscape scale measurement and monitoring of biodiversity in the Australian rangelands.

Clarke, Kenneth David January 2008 (has links)
It is becoming increasingly important to monitor biodiversity in the extensive Australian rangelands; currently however, there is no method capable of achieving this goal. There are two potential sources of relevant data that cover the Australian rangelands, and from which measures of biodiversity might be extracted: traditional field-based methods such as quadrat surveys have collected flora and fauna species data throughout the rangelands, but at fine scale; satellite remote sensing collects biologically relevant, spatially comprehensive data. The goal of this thesis was to provide the spatially comprehensive measure of biodiversity required for informed management of the Australian rangelands. The study specifically focused on the Stony Plains in the South Australian rangelands. To that end the thesis aimed to develop indices capable of measuring and/or monitoring biodiversity from vegetation quadrat survey data and remotely sensed data. The term biodiversity is so all-encompassing that direct measurement is not possible; therefore it is necessary to measure surrogates instead. Total perennial vegetation species richness (y-diversity) is a sound surrogate of biodiversity: the category of species is well defined, species richness is measurable, and there is evidence that vegetation species richness co-varies with the species richness of other taxonomic groups in relation to the same environmental variables. At least two broad scale conventional vegetation surveys are conducted in the study region; the Biological Survey of South Australia; and the South Australian Pastoral Lease Assessment. Prior to the extraction of biodiversity data the quality of the BSSA, the best biodiversity survey, was evaluated. Analysis revealed that false-negative errors were common, and that even highly detectable vegetation species had detection probabilities significantly less than one. Without some form of correction for detectability, the species diversity recorded by either vegetation survey must be treated with caution. Informed by the identification of false-negative errors, a method was developed to extract y-diversity of woody perennials from the survey data, and to remove the influence of sampling effort. Data were aggregated by biogeographic region, rarefaction was used to remove most of the influence of sampling effort, and additional correction removed the residual influence of sampling effort. Finally, additive partitioning of species diversity allowed extraction of indices of a-, β- and y-diversity free from the influence of sampling effort. However, this woody perennial vegetation y-diversity did not address the need for a spatially extensive, fine scale measure of biodiversity at the extent of the study region. The aggregation of point data to large regions, a necessary part of this index, produces spatially coarse results. To formulate and test remotely sensed surrogates of biodiversity, it is necessary to understand the determinants of and pressures on biodiversity in the Australian rangelands. The most compelling explanation for the distribution of biodiversity at the extensive scales of the Australian rangelands is the Productivity Theory, which reasons that the greater the amount and duration of primary productivity the greater the capacity to generate and support high biodiversity. The most significant pressure on biodiversity in the study area is grazing-induced degradation, or overgrazing. Two potential spatially comprehensive surrogates of pressure on biodiversity were identified. The first surrogate was based on the differential effect of overgrazing on waterenergy balance and net primary productivity: water-energy balance is a function of climatic variables, and therefore a measure of potential or expected primary productivity; net primary productivity is reduced by high grazing pressure. The second surrogate was based on the effect of grazing-induced degradation on the temporal variability of net primary productivity: overgrazing reduces mean net primary productivity and rainfall use efficiency, and increases variation in net primary productivity and rainfall use efficiency. The two surrogates of biodiversity stress were derived from the best available remotely sensed and climate data for the study area: actual evapotranspiration recorded by climate stations was considered an index of water-energy balance; net primary productivity was measured from NOAA AVHRR integrated NDVI; rainfall use efficiency (biomass per unit rainfall) was calculated from rainfall data collected at climate stations and the net primary productivity measure. Finally, the surrogates were evaluated against the index of woody perennial a-, β- and y-diversity, on the assumption that prolonged biodiversity stress would reduce vegetation species diversity. No link was found between Surrogate 1 and woody perennial a-, β- or y-diversity. The relationship of Surrogate 2 to woody perennial diversity was more complex. Only some of the results supported the hypothesis that overgrazing decreases y-diversity and average NPP and RUE. Importantly, none of the results supported the most important part of the hypothesis that the proposed indices of biodiversity pressure would co-vary with woody perennial a-diversity. Thus, the analysis did not reveal a convincing link between either surrogate and vegetation species diversity. However, the analysis was hampered to a large degree by the climate data, which is interpolated from a very sparse network of climate stations. This thesis has contributed significantly to the measurement and monitoring of biodiversity in the Australian rangelands. The identification of false-negative errors as a cause for concern will allow future analyses of the vegetation survey data to adopt methods to counteract these errors, and hence extract more robust information. The method for extracting sampling effort corrected indices of a-, β- and y-diversity allow for the examination and comparison of species diversity across regions, regardless of differences in sampling effort. These indices are not limited to rangelands, and can be extracted from any vegetation quadrat survey data obtained within a prescribed methodology. Therefore, these tools contribute to global biodiversity measurement and monitoring. Finally, the remotely sensed surrogates of biodiversity are theoretically sound and applicable in any rangeland where over-grazing is a significant source of degradation. However, because the evaluation of these surrogates in this thesis was hampered by available data, further testing is necessary. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1346544 / Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2008
16

The multi-criteria assessment of ecosystem services at a landscape level to support decision-making in regional and landscape planning / Die multikriterielle Erfassung von Ökosystemdienstleistungen auf Landschaftsebene zur Unterstützung der Entscheidungsfindung in der Regional- und Landschaftsplanung

Koschke, Lars 25 February 2016 (has links) (PDF)
The growing pressure on natural resources and biodiversity has led to a widespread acknowledgement of the services nature provides for humans. The appropriate representation of the benefits of sustainable land use in decision-making is still a challenge and tools that facilitate land use planning processes are needed. The dissertation presents a multicriteria assessment approach for a qualitative estimation of regional potentials to provide ecosystem services. This approach has been applied in several case studies in Saxony, Eastern Germany and Brasil. The ecosystem services concept builts the methodological framework for the assessment as it offers a universal approach to evaluate the impact of Land use/ Land cover change (LULCC) on human well-being. Since standardized methodical approaches for ecosystem services assessment at the landscape level are lacking, a particular requirement was to conceive a method that is easily transferable to other case study areas. Further the method should enable the use of existing and easily available environmental data, and it should be transparent for stakeholders and decision makers. The results of our study show that the combination of selected ecosystem services and land cover data such as CORINE Land Cover (CLC) can contribute to regional planning by communicating the effect of LULCC on ecosystem services, especially when applied as an evaluation basis in the tool GISCAME. The approach supports also the assessment of the performance of a region to provide ecosystem services and the comparison of regions towards this aspect. In the discussion section, the limitations of the developed approach are discussed. Main sources of uncertainty are related to coarse land cover data, lacking knowledge on the provision of ecosystem services at a landscape scale, and the difficulty to make relevant the ecosystem services concept in regional planning processes.
17

Intraspecific Trait Plasticity in Coffee Agroforestry Systems of Costa Rica

Gagliardi, Stephanie 18 March 2014 (has links)
Although a common plant response to environmental gradients, leaf trait plasticity is often uncharted in agroforestry systems. The objective of this study was to examine the effect of a i) local-scale gradient (light, nutrients) induced by shade tree diversity and ii) large-scale gradient (climato-edaphic) induced by altitude on coffee plant response on multiple agroforestry research farms in Costa Rica. Results show large variability of coffee traits: leaf photosynthetic rates, specific leaf area (SLA) and number of fruiting nodes deviate along both gradients. Mean SLA increased with increasing shade tree diversity. However, with increasing altitude, full sun coffee photosynthesized at higher rates than shaded coffee. Concurrently, other coffee leaf physiological and morphological traits differentiated between full sun and shaded coffee with increasing altitude. Results suggest soil moisture and light availability dominate environmental correlates to intraspecific coffee trait plasticity, providing insight to sources of coffee performance variability in monoculture and agroforestry systems.
18

Intraspecific Trait Plasticity in Coffee Agroforestry Systems of Costa Rica

Gagliardi, Stephanie 18 March 2014 (has links)
Although a common plant response to environmental gradients, leaf trait plasticity is often uncharted in agroforestry systems. The objective of this study was to examine the effect of a i) local-scale gradient (light, nutrients) induced by shade tree diversity and ii) large-scale gradient (climato-edaphic) induced by altitude on coffee plant response on multiple agroforestry research farms in Costa Rica. Results show large variability of coffee traits: leaf photosynthetic rates, specific leaf area (SLA) and number of fruiting nodes deviate along both gradients. Mean SLA increased with increasing shade tree diversity. However, with increasing altitude, full sun coffee photosynthesized at higher rates than shaded coffee. Concurrently, other coffee leaf physiological and morphological traits differentiated between full sun and shaded coffee with increasing altitude. Results suggest soil moisture and light availability dominate environmental correlates to intraspecific coffee trait plasticity, providing insight to sources of coffee performance variability in monoculture and agroforestry systems.
19

The multi-criteria assessment of ecosystem services at a landscape level to support decision-making in regional and landscape planning

Koschke, Lars 24 April 2015 (has links)
The growing pressure on natural resources and biodiversity has led to a widespread acknowledgement of the services nature provides for humans. The appropriate representation of the benefits of sustainable land use in decision-making is still a challenge and tools that facilitate land use planning processes are needed. The dissertation presents a multicriteria assessment approach for a qualitative estimation of regional potentials to provide ecosystem services. This approach has been applied in several case studies in Saxony, Eastern Germany and Brasil. The ecosystem services concept builts the methodological framework for the assessment as it offers a universal approach to evaluate the impact of Land use/ Land cover change (LULCC) on human well-being. Since standardized methodical approaches for ecosystem services assessment at the landscape level are lacking, a particular requirement was to conceive a method that is easily transferable to other case study areas. Further the method should enable the use of existing and easily available environmental data, and it should be transparent for stakeholders and decision makers. The results of our study show that the combination of selected ecosystem services and land cover data such as CORINE Land Cover (CLC) can contribute to regional planning by communicating the effect of LULCC on ecosystem services, especially when applied as an evaluation basis in the tool GISCAME. The approach supports also the assessment of the performance of a region to provide ecosystem services and the comparison of regions towards this aspect. In the discussion section, the limitations of the developed approach are discussed. Main sources of uncertainty are related to coarse land cover data, lacking knowledge on the provision of ecosystem services at a landscape scale, and the difficulty to make relevant the ecosystem services concept in regional planning processes.
20

Socio-Ecological Resilience: ‘Weaving’ to scale Nature-based Solutions

Hussain, Sally, Carolina, Obara, Seefeld, Leon, Tjoelker, Tijn January 2022 (has links)
The sustainability challenge is a complex interplay of interconnected challenges that requires an integrated and systemic approach. Nature-based Solutions (NbS) are seen as a key tool for addressing such challenges but are currently not mainstreaming and scaling to the landscape level. The emerging leadership practice of Weaving is believed to help cohere fragmented change-making efforts and increase the adaptive capacity and resilience of socio-ecological systems. However, scientific research on NbS and Weaving is scarce and studies on their intersection are non-existent.  To investigate how Weaving practices could foster the conditions for scaling NbS to the landscape level, rapid literature reviews and semi-structured interviews were conducted with academic experts, Weaving practitioners, and grass-root entrepreneurs. On this basis, two conceptual frameworks were iteratively developed that serve as a basis for two practical toolkits. They comprise (1) seven barriers and nine enablers for scaling NbS to the landscape level and (2) a Weaving working definition and five core Weaving practices.  There are indications that Weaving practices have the potential to address several of the barriers and enablers for scaling NbS if approached with a systematic lens. Ultimately, interconnected challenges, such as barriers and enablers to scaling NbS, require interwoven approaches as provided by Weaving.

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