• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • Tagged with
  • 18
  • 18
  • 18
  • 17
  • 6
  • 5
  • 5
  • 5
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 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

Modelling carbon dynamics within tropical rainforest environments: Using the 3-PG and process models

Nightingale, J. M. Unknown Date (has links)
No description available.
12

The choice between rural living and agriculture: Implications for land use and subdivision policy

Anstey, Geoff Unknown Date (has links)
In much of Australia and the United States, the almost universal right to have a house on rural allotments has resulted in rural living settlement in areas intended, by land use planning policy, to be used for agriculture. Such ‘unplanned’ rural living has a range of potential adverse impacts, including, among other things, loss of agricultural production, land use conflicts with agriculture, land value constraints on farm restructuring, and changes to the rural landscape character. Given the strongly held community perception of a house as a development right, this research was motivated by the need to understand the effects of that right, in order to assess the potential value of any change in policy. An integral consideration was the influence of the size of allotments with any such right. The research was also driven by an interest in explaining the pattern of unplanned rural living settlement, i.e. why are particular allotments converted and others not? Largely in the absence of previous studies of unplanned rural living as a distinct phenomenon, there was scope for this thesis to make a contribution to knowledge in these respects. The research involved three stages of empirical analysis. Firstly, a Queensland-wide survey of land use conversion from sugarcane production supported the choice of the Bundaberg region as the study area. Contingency table analyses were then conducted into the current land use and other attributes of land in the study area that, in 1980, was used for sugarcane. Those analyses identified distinguishing attributes of the different land use sub-sets of allotments, and informed the selection of observation units for the third stage. The third stage provided the principal basis for fulfilling the research objectives. It focused on logit models of the choice, at the time of sale, between using a particular allotment for unplanned rural living or sugarcane production. Those analyses provided an indication of the role of individual land attributes while controlling for the effects of other attributes. It was found there had been limited conversion of suitable, productive sugarcane land to unplanned rural living. Compared to those allotments that remained in sugarcane production, allotments converted to rural living were, on average, much smaller, of less value, had lower agricultural production potential, and were situated in more undulating and forested landscapes further from Bundaberg. These clear distinctions between rural living and sugarcane allotments contributed to logit models with high explanatory power. The expected productive income of allotments had overwhelming weight and was highly statistically significant in explaining the land use choice between unplanned rural living and sugarcane. This is a notable finding, because some other studies have not shown such a strong relationship between land use and measures such as soil productivity. There was a degree of natural coincidence between more undulating and forested landscapes and lower productive potential. Notably, landscape attributes appeared to be of secondary importance in determining land use. The presence of a house at the time of sale was not a statistically significant explanatory factor for land use. This finding, together with that of limited conversion of suitable, productive land to unplanned rural living, meant there was a lack of evidence to support a change to the right to have a house on rural allotments. The findings did indicate that the allotment area required to avoid conversion to unplanned rural living was different to the area required for agricultural viability. In the circumstances of this study area and period, 20 ha would have been an acceptable minimum to retain suitable cropping land in productive use. This is compared to the 60 ha suggested as necessary for farm viability. However, the potential for changed economic conditions to reduce the productive value of agricultural land, and increase demand for rural living, makes it appropriate to be cautious about permitted allotment sizes. A detailed conceptual framework informed the selection of observation units and variables for the third stage of analyses. The framework helped to confirm allotment sales as the observation units, and provided the rationale for excluding the difficult to measure influences of a landowner’s attachment to the land, and inertia, as explanatory variables. The high explanatory power of the logit models provides support for the approach, which may be useful in future studies.
13

The choice between rural living and agriculture: Implications for land use and subdivision policy

Anstey, Geoff Unknown Date (has links)
In much of Australia and the United States, the almost universal right to have a house on rural allotments has resulted in rural living settlement in areas intended, by land use planning policy, to be used for agriculture. Such ‘unplanned’ rural living has a range of potential adverse impacts, including, among other things, loss of agricultural production, land use conflicts with agriculture, land value constraints on farm restructuring, and changes to the rural landscape character. Given the strongly held community perception of a house as a development right, this research was motivated by the need to understand the effects of that right, in order to assess the potential value of any change in policy. An integral consideration was the influence of the size of allotments with any such right. The research was also driven by an interest in explaining the pattern of unplanned rural living settlement, i.e. why are particular allotments converted and others not? Largely in the absence of previous studies of unplanned rural living as a distinct phenomenon, there was scope for this thesis to make a contribution to knowledge in these respects. The research involved three stages of empirical analysis. Firstly, a Queensland-wide survey of land use conversion from sugarcane production supported the choice of the Bundaberg region as the study area. Contingency table analyses were then conducted into the current land use and other attributes of land in the study area that, in 1980, was used for sugarcane. Those analyses identified distinguishing attributes of the different land use sub-sets of allotments, and informed the selection of observation units for the third stage. The third stage provided the principal basis for fulfilling the research objectives. It focused on logit models of the choice, at the time of sale, between using a particular allotment for unplanned rural living or sugarcane production. Those analyses provided an indication of the role of individual land attributes while controlling for the effects of other attributes. It was found there had been limited conversion of suitable, productive sugarcane land to unplanned rural living. Compared to those allotments that remained in sugarcane production, allotments converted to rural living were, on average, much smaller, of less value, had lower agricultural production potential, and were situated in more undulating and forested landscapes further from Bundaberg. These clear distinctions between rural living and sugarcane allotments contributed to logit models with high explanatory power. The expected productive income of allotments had overwhelming weight and was highly statistically significant in explaining the land use choice between unplanned rural living and sugarcane. This is a notable finding, because some other studies have not shown such a strong relationship between land use and measures such as soil productivity. There was a degree of natural coincidence between more undulating and forested landscapes and lower productive potential. Notably, landscape attributes appeared to be of secondary importance in determining land use. The presence of a house at the time of sale was not a statistically significant explanatory factor for land use. This finding, together with that of limited conversion of suitable, productive land to unplanned rural living, meant there was a lack of evidence to support a change to the right to have a house on rural allotments. The findings did indicate that the allotment area required to avoid conversion to unplanned rural living was different to the area required for agricultural viability. In the circumstances of this study area and period, 20 ha would have been an acceptable minimum to retain suitable cropping land in productive use. This is compared to the 60 ha suggested as necessary for farm viability. However, the potential for changed economic conditions to reduce the productive value of agricultural land, and increase demand for rural living, makes it appropriate to be cautious about permitted allotment sizes. A detailed conceptual framework informed the selection of observation units and variables for the third stage of analyses. The framework helped to confirm allotment sales as the observation units, and provided the rationale for excluding the difficult to measure influences of a landowner’s attachment to the land, and inertia, as explanatory variables. The high explanatory power of the logit models provides support for the approach, which may be useful in future studies.
14

The choice between rural living and agriculture: Implications for land use and subdivision policy

Anstey, Geoff Unknown Date (has links)
In much of Australia and the United States, the almost universal right to have a house on rural allotments has resulted in rural living settlement in areas intended, by land use planning policy, to be used for agriculture. Such ‘unplanned’ rural living has a range of potential adverse impacts, including, among other things, loss of agricultural production, land use conflicts with agriculture, land value constraints on farm restructuring, and changes to the rural landscape character. Given the strongly held community perception of a house as a development right, this research was motivated by the need to understand the effects of that right, in order to assess the potential value of any change in policy. An integral consideration was the influence of the size of allotments with any such right. The research was also driven by an interest in explaining the pattern of unplanned rural living settlement, i.e. why are particular allotments converted and others not? Largely in the absence of previous studies of unplanned rural living as a distinct phenomenon, there was scope for this thesis to make a contribution to knowledge in these respects. The research involved three stages of empirical analysis. Firstly, a Queensland-wide survey of land use conversion from sugarcane production supported the choice of the Bundaberg region as the study area. Contingency table analyses were then conducted into the current land use and other attributes of land in the study area that, in 1980, was used for sugarcane. Those analyses identified distinguishing attributes of the different land use sub-sets of allotments, and informed the selection of observation units for the third stage. The third stage provided the principal basis for fulfilling the research objectives. It focused on logit models of the choice, at the time of sale, between using a particular allotment for unplanned rural living or sugarcane production. Those analyses provided an indication of the role of individual land attributes while controlling for the effects of other attributes. It was found there had been limited conversion of suitable, productive sugarcane land to unplanned rural living. Compared to those allotments that remained in sugarcane production, allotments converted to rural living were, on average, much smaller, of less value, had lower agricultural production potential, and were situated in more undulating and forested landscapes further from Bundaberg. These clear distinctions between rural living and sugarcane allotments contributed to logit models with high explanatory power. The expected productive income of allotments had overwhelming weight and was highly statistically significant in explaining the land use choice between unplanned rural living and sugarcane. This is a notable finding, because some other studies have not shown such a strong relationship between land use and measures such as soil productivity. There was a degree of natural coincidence between more undulating and forested landscapes and lower productive potential. Notably, landscape attributes appeared to be of secondary importance in determining land use. The presence of a house at the time of sale was not a statistically significant explanatory factor for land use. This finding, together with that of limited conversion of suitable, productive land to unplanned rural living, meant there was a lack of evidence to support a change to the right to have a house on rural allotments. The findings did indicate that the allotment area required to avoid conversion to unplanned rural living was different to the area required for agricultural viability. In the circumstances of this study area and period, 20 ha would have been an acceptable minimum to retain suitable cropping land in productive use. This is compared to the 60 ha suggested as necessary for farm viability. However, the potential for changed economic conditions to reduce the productive value of agricultural land, and increase demand for rural living, makes it appropriate to be cautious about permitted allotment sizes. A detailed conceptual framework informed the selection of observation units and variables for the third stage of analyses. The framework helped to confirm allotment sales as the observation units, and provided the rationale for excluding the difficult to measure influences of a landowner’s attachment to the land, and inertia, as explanatory variables. The high explanatory power of the logit models provides support for the approach, which may be useful in future studies.
15

The choice between rural living and agriculture: Implications for land use and subdivision policy

Anstey, Geoff Unknown Date (has links)
In much of Australia and the United States, the almost universal right to have a house on rural allotments has resulted in rural living settlement in areas intended, by land use planning policy, to be used for agriculture. Such ‘unplanned’ rural living has a range of potential adverse impacts, including, among other things, loss of agricultural production, land use conflicts with agriculture, land value constraints on farm restructuring, and changes to the rural landscape character. Given the strongly held community perception of a house as a development right, this research was motivated by the need to understand the effects of that right, in order to assess the potential value of any change in policy. An integral consideration was the influence of the size of allotments with any such right. The research was also driven by an interest in explaining the pattern of unplanned rural living settlement, i.e. why are particular allotments converted and others not? Largely in the absence of previous studies of unplanned rural living as a distinct phenomenon, there was scope for this thesis to make a contribution to knowledge in these respects. The research involved three stages of empirical analysis. Firstly, a Queensland-wide survey of land use conversion from sugarcane production supported the choice of the Bundaberg region as the study area. Contingency table analyses were then conducted into the current land use and other attributes of land in the study area that, in 1980, was used for sugarcane. Those analyses identified distinguishing attributes of the different land use sub-sets of allotments, and informed the selection of observation units for the third stage. The third stage provided the principal basis for fulfilling the research objectives. It focused on logit models of the choice, at the time of sale, between using a particular allotment for unplanned rural living or sugarcane production. Those analyses provided an indication of the role of individual land attributes while controlling for the effects of other attributes. It was found there had been limited conversion of suitable, productive sugarcane land to unplanned rural living. Compared to those allotments that remained in sugarcane production, allotments converted to rural living were, on average, much smaller, of less value, had lower agricultural production potential, and were situated in more undulating and forested landscapes further from Bundaberg. These clear distinctions between rural living and sugarcane allotments contributed to logit models with high explanatory power. The expected productive income of allotments had overwhelming weight and was highly statistically significant in explaining the land use choice between unplanned rural living and sugarcane. This is a notable finding, because some other studies have not shown such a strong relationship between land use and measures such as soil productivity. There was a degree of natural coincidence between more undulating and forested landscapes and lower productive potential. Notably, landscape attributes appeared to be of secondary importance in determining land use. The presence of a house at the time of sale was not a statistically significant explanatory factor for land use. This finding, together with that of limited conversion of suitable, productive land to unplanned rural living, meant there was a lack of evidence to support a change to the right to have a house on rural allotments. The findings did indicate that the allotment area required to avoid conversion to unplanned rural living was different to the area required for agricultural viability. In the circumstances of this study area and period, 20 ha would have been an acceptable minimum to retain suitable cropping land in productive use. This is compared to the 60 ha suggested as necessary for farm viability. However, the potential for changed economic conditions to reduce the productive value of agricultural land, and increase demand for rural living, makes it appropriate to be cautious about permitted allotment sizes. A detailed conceptual framework informed the selection of observation units and variables for the third stage of analyses. The framework helped to confirm allotment sales as the observation units, and provided the rationale for excluding the difficult to measure influences of a landowner’s attachment to the land, and inertia, as explanatory variables. The high explanatory power of the logit models provides support for the approach, which may be useful in future studies.
16

Valoração, cobrança pelo uso da água e a gestão das bacias hidrográficas do Alto Iguaçu e afluentes do Alto Ribeira = uma abordagem econômico-ecológica / Valuation, charging for water use and managemente of Alto Iguaçu and tributaries of the Alto Ribeira watersheds : an economic-ecological approach

Garcia, Júnior Ruiz 19 August 2018 (has links)
Orientador: Ademar Ribeiro Romeiro / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Economia / Made available in DSpace on 2018-08-19T17:45:44Z (GMT). No. of bitstreams: 1 Garcia_JuniorRuiz_D.pdf: 6539061 bytes, checksum: 3299be86825d39bff0ed1420da87e665 (MD5) Previous issue date: 2012 / Resumo: A degradação do sistema natural ao longo do século XX pode ser caracterizada pela tendência ascendente e estreita relação com a escala física da atividade econômica, que demanda quantidades crescentes de recursos naturais, seja como fonte de insumos, seja como fonte para a absorção de resíduos. Desta forma, o que antes era considerado um bem ou serviço provido gratuitamente pelo sistema natural, por exemplo, água limpa, controle de enchentes, fertilidade do solo etc., no período recente está associado a custos crescentes. Neste contexto, a disponibilidade de recursos hídricos tornou-se objeto de constante preocupação por parte de diversos agentes públicos e privados. Essa preocupação resultou no desenvolvimento e na implantação de sistemas de gestão de bacias hidrográficas, cujo objetivo é promover o uso racional, a preservação e a melhoria da qualidade dos recursos hídricos. Em 1997, o Brasil instituiu a Política Nacional de Recursos Hídricos que reconheceu o valor econômico da água e autoriza a cobrança pelo direito de uso. Entretanto, a valoração e a precificação da água não se mostrou uma tarefa trivial para os Comitês de Bacias Hidrográficas. Ainda, a definição do "preço da água" no Brasil tem sido realizada de maneira arbitrária, onde o principal objetivo é alcançar o menor impacto possível na planilha de custos dos usuários. Outro aspecto peculiar da gestão hídrica é o tratamento isolado dos componentes do ecossistema, ignorando a interdependência ecossistêmica. Neste sentido, o principal objetivo deste trabalho é aplicar nas Bacias Hidrográficas do Alto Iguaçu e Afluentes do Alto Ribeira, localizadas na Região Metropolitana de Curitiba, novos procedimentos de valoração econômico-ecológica dos serviços ecossistêmicos responsáveis pela disposição de água de qualidade, visando subsidiar a construção de uma política de precificação da água, bem como o estabelecimento de esquemas de Pagamento por Serviços Ambientais (PSA's). A avaliação ecossistêmica realizada nas bacias hidrográficas com auxílio do InVEST Model mostrou que a recuperação do déficit de mata ciliar, adequação do uso das terras segundo sua aptidão agrícola e a adoção de práticas conservacionistas pelos produtores rurais poderia elevar a disponibilidade de água em 878 milhões de m³ ao ano, reduzir o consumo de água em 330 milhões de m³ ao ano, reduzir a perda de solo em quase 80 milhões de toneladas ao ano e elevar o estoque total de carbono em 36 milhões de toneladas, além de melhorar a qualidade da água. Em síntese, a intervenção em prol da melhoria da qualidade dos recursos hídricos também afetará o provimento de outros serviços ecossistêmicos, logo, a gestão de bacias hidrográficas não pode considerar de maneira isolada os componentes do ecossistema, mas o ecossistema como um todo / Abstract: The degradation of the natural system throughout the century XX can be characterized by the upward trend and close relationship with the scale of economic activity, which requires increasing amounts of natural resources as a source of inputs as a source for the absorption of waste. Thus, what was once considered a good or service provided free by the natural system, for example, freshwater, flood control, soil fertility, etc., in recent years is associated with rising costs. In this context, the availability of water has become an object of constant concern on the part of several public and private. This concern resulted in the development and deployment of watershed management, which aims to promote the rational use, preservation, and improvement of water of quality. In 1997, Brazil created the Política Nacional de Recursos Hídricos (National Policy of Water), which recognized the economic value of water and allow charging for the right use. However, the valuation process and pricing of water was not a trivial task for the Watershed Committees. The definition of "water price" in Brazil has been realized in an arbitrary manner in which the main criteria have been the least impact on cost spreadsheet users. Another peculiar aspect of water management is the treatment of isolated components of the ecosystem, ignoring the interdependence ecosystem. In this sense, the main objective of this research is applying in the Alto Iguaçu and Afluentes do Alto Ribeira Watersheds, located in Metropolitan Region of Curitiba, new procedures for ecological-economic valuation process of ecosystem services responsible for the supply of freshwater of quality, to support the establishment of a water pricing policy, as well as the establishment of Payment Environmental Services (PES) schemes. Ecosystem Assessment of the watersheds with support InVEST Model showed that the recovery of the riparian forest, adaptation of the land-use according to their use capacity or usability, and adoption of the conservation practices by farmers could increase the freshwater availability in 878 million cubic meters per year, reduce freshwater consumption in 330 million cubic meters per year, reduce the soil loss in almost 80 million tons per year, and raise the total carbon storage in 36 million tons, in addition to improving freshwater of quality. In summary, the intervention in improving the quality of supply water will also affect the provision of other ecosystem services, so the watershed management can not be considered in isolation of the components of the ecosystem, but the ecosystem as a whole / Doutorado / Desenvolvimento Economico, Espaço e Meio Ambiente / Doutor em Desenvolvimento Economico
17

An Ecosystem-Based Approach to Reef Fish Management in the Gulf of Mexico

Masi, Michelle D. 10 November 2016 (has links)
Fisheries managers have the potential to significantly improve reef fish management in the Gulf of Mexico through the use of ecosystem-based approaches to fisheries management. Ecosystem-based approaches are needed to address the effects of fishing on trophodynamic interactions, to better account for ecosystem-scale processes in model projections, and to recognize the short and long-term biomass tradeoffs associated with making regulatory choices. My research was concentrated around three objectives: (1) characterizing the trophodynamic interactions between Gulf of Mexico fishes, in order to construct an invaluable tool (a Gulf of Mexico Atlantis model) to be used in ecological hypothesis testing and policy performance evaluation for years to come; (2) predicting ecological indicators for the Gulf of Mexico that both respond to fishing pressure and are robust to observational error, and; (3) evaluating the performance of an ecosystem-based policy options for managing reef fish species in the Gulf of Mexico. To accomplish these objectives, a spatial, trophodynamic ecosystem model- Atlantis, was employed to represent the Gulf of Mexico marine ecosystem. To characterize trophic interactions between modeled species, I applied a maximum likelihood estimation procedure to produce Dirichlet probability distributions representing the likely contribution of prey species to predators’ diets. This provided mode values (the peak of the distribution) and associated error ranges, which describe the likely contribution of a prey item in a predator’s diet. The mode values were used to parameterize the availabilities (diet) matrix of the Gulf of Mexico Atlantis model. Investigating trophic interactions was useful for determining which species within the Atlantis model were data rich, and justified the emphasis on reef fish species and their prey items in subsequent analyses. Once parameterized and calibrated, I used the Atlantis model to project ecological indicators over a 50 year time horizon (2010-2060) under varying levels of fishing mortality. Principal component analysis was used to evaluate ecological indicator trajectories in multivariate space, to rank indicators according to how well they describe variability in ecosystem structure (termed ‘importance’), to reveal redundancies in the information conveyed, to quantify interannual noise and to determine how robust indicators are to observational error. Reef fish catch, Red snapper biomass, King mackerel biomass and Species richness indicators ranked the highest in terms of importance and robustness to error and in having low levels of interannual noise (i.e., requiring less frequent monitoring). I then used a management strategy evaluation (MSE) framework in Atlantis to evaluate some of these same indicators under an ecosystem-based approach to fisheries management – using robust harvest control rules to manage reef fishes. I found that this ecosystem-based policy option was able to maintain higher reef fish biomass, catch and ecosystem-wide biodiversity under any given level of fishing mortality when compared to a status quo management approach. These results suggest that harvesting under the HCRs encourages an alternative ecosystem state with a more Pareto-efficient tradeoff frontier than the status-quo policy. A potentially reduced extinction risk for reef fish is plausible under this ecosystem-based policy option. This research provides a quantitative look at the fishery performance and ecological tradeoffs associated with various policy options. MSE methodology using ecosystem-based policy performance metrics is also demonstrated. Tool development and findings from this research should aid in the development of ecosystem-based policies for this region.
18

A Framework for Identifying Appropriate Sub-Regions for Ecosystem-Based Management in Northern Gulf of Mexico Coastal and Marine Environments

Ziegler, Jennifer Sloan 14 December 2013 (has links)
Nearly half of the population of the United States lives in coastal regions, and millions of visitors from across the nation and world enjoy the coasts every year. Coastal and marine areas provide for recreation, economic activities essential for the financial health of the nation, and vital ecological services. As they provide so many benefits to the U.S., it is vital to protect and preserve the coastal and ocean areas from the increasing, competing demands they are facing. In order to protect and preserve these complex systems, a comprehensive approach incorporating science, engineering, humanities, and social sciences should be taken; this approach is commonly referred to as Ecosystem-Based Management. This dissertation focuses on developing a framework that can be used to identify appropriate sub-regions in Northern Gulf of Mexico coastal and marine environments for the purposes of Ecosystem-Based Management. Through this work, the roles of three management protocols used for managing coastal areas – coastal and marine spatial planning, ecosystem-based management, and integrated ecosystem assessment – were examined individually as well as their integrations with each other. Biological, ecological, physical, human, and economic indicators for partitioning an ecosystem were developed and weighted for each management protocol using the analytic hierarchy process and expert elicitation. Using the weighted indicators, a framework for identifying sub-regions and estuarine classification system was developed. The framework and classification system were applied to five estuaries within the Northern Gulf of Mexico: Barataria, Galveston, Mobile, and Perdido Bays and Mississippi Sound. Initial results from this work show that: 1. Sub-regions can be identified as associated to each other based upon indicator data values and not upon physical location. 2. Even though the weights calculated for the management protocols vary significantly, for systems that were not highly homogeneous in indicator data values, the different weights did not produce the vastly different cluster maps expected. 3. The scale work indicates that to identify appropriate sub-regions using the developed framework, a larger grid size produces more consistent results for larger systems whereas a smaller grid size produces more consistent results for smaller systems. Recommendations for further research are also presented.

Page generated in 0.1658 seconds