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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.
1

Resilience and management of stochastic renewable resource system

Tinch, Robert R. T. January 2001 (has links)
No description available.
2

Marine Protected Areas: A Tool for Fisheries Management

Greenville, Jared William January 2007 (has links)
Doctor of Philosophy (PhD) / The management of fisheries has progressed over the past century in an attempt to solve the problem of open access. A range of controls, both economic and non-economic in nature, have been used to ration the use of marine resources. Unfortunately, many controls have failed to correct open access problems. Whilst a recent development in fishery control, protected areas defined as an area with a fishery free of extractive pressure, have been put forward as an arrangement which may, in conjunction with other controls, be used to overcome the over-exploitation of marine resources. Marine protected areas have been advocated in areas where other forms of fishery management are impractical or unsuccessful (Sumaila 1998). Arguments for protected area use are based around the heterogeneous nature of fisheries, uncertainties in marine populations and as a hedge strategy to reduce risks of over-exploitation (Conrad 1999a). Through the protection of biodiversity, improving the resilience of the ecosystem, protected areas may mitigate the effects of negative shocks (Ludwig et al. 1993 and Bostford et al. 1997). Further, protected areas have been suggested as a means to manage uncertainty and environmental stochasticity (Grafton and Kompas 2005 and Grafton et al. 2005). The protection of biomass and habitat has the potential to improve fishery returns even when stocks are not overly exploited, with the benefits accruing even from small-sized protected areas (Grafton et al. 2005). The use of marine protected areas as a management tool has resulted from a recognition that it is important to preserve biological habitats as well as stocks. From a societal point of view, the use of protected areas should be evaluated in the context of changes in resource rent and improvements in welfare. As fishery resources are often owned by a common group, usually society, management objectives should be to maximise the return from use of the resources, whether for extractive or non-extractive purposes. Given this decision criterion, protected areas can be evaluated in the sense of opportunity costs and benefits. Protected areas will influence the return from fishery resources through changes in access to fishing grounds, and thus harvest, effort and resource rent. Once a protected area is established, the flow of biomass from the protected area to the remaining fishing ground, may increase biomass, influence the effects of uncertainty and stochasticity, thus effecting mean harvests, effort and resource rent may increase. Changes in resource rent are dependent on other controls. Protected areas are a ‘blunt’ policy instrument, in the sense that they are not an instrument to capture resource rent or change the incentives of fishers. Models of marine protected areas in fisheries vary in complexity, however, a few key elements are necessary in analysing the effects of protected area creation. First, multi-species interactions have the potential to be significant in determining the outcome from a protected area; second, effort expended in the fishery must be dynamic, that is, it must be endogenously determined by the model as fishers will respond to changes in rent brought about through the establishment of a protected area; third, institutional structures that govern the expenditure of effort within a fishery will play an important role in the effectiveness of protected areas in increasing the resource rent of a fishery; and fourth, environmental stochasticity and uncertainty need to be included in the analysis. A stochastic and deterministic model of a predator-prey meta-population fishery was developed to analyse the effects of protected area creation within a fishery. Such a model has not previously been used to analyse protected area creation. The model was analytically solved to find the optimal biomass of each species in an individual patch. This allowed for a comparison of protected areas under a range of management controls ranging from those which led to open access fishing to those which led to an optimal steady-state biomass. The model allowed for linkages between sub-populations based on differing density related flows. Further, due to the linkages between species on both environmental and economic grounds, the effect of protected areas on different groups which target different species could be analysed. The benefits from protected area creation were classified into unique and non-unique benefits. Unique benefits were defined as those which solely flow from the use of a protected area as a tool in fisheries management. Two unique benefits were defined: • Improvements in the resilience of the fishery; and • Reductions in environmental stochasticity. The ability of a protected area to both improve the resilience of the fishery, and smooth fluctuations in environmental stochasticity have been shown to lead to increases in mean resource rent. Thus, protected areas were shown to form part of an optimal fisheries management structure. Generally, the resilience benefits were maximised for small-sized protected areas, whereas the reduced environmental stochasticity benefits were maximised for larger protected areas. The dispersal system between the protected area and the fishing ground affected the unique benefits from protected area creation. Sink-source dispersal increased the unique benefits from protected area creation, as stock movements occurred independently of relative population densities. The independent flow improved the ability of the protected area to hasten the return of the fishery to a steady-state and lessened the variation of harvests in the open fishing grounds. However, in the case where the protected area led to large differences in population densities, and if the area formed a sub-population that was linked to the surrounding fishing ground by density-dependent dispersal, the unique benefits are likely to be greater than under sink-source dispersal. The non-unique benefits were defined as those which could be obtained from other control mechanisms. These benefits were non-unique as they could be achieved from more stringent controls on fisher behaviour. The determinants of the non-unique benefit in terms of dispersal were the same as for the unique benefits. However, the economic conditions of the fishery determined the magnitude of the non-unique benefits. For fisheries with sub-optimal biomass, the unique benefits were greater than those with optimal steady-state biomass. The non-unique benefits identified from protected area creation were: • Changes in biomass towards optimal levels; • Changes in species biomass ratios towards optimal levels; and • Changes in effort towards optimal levels. Protected areas in fisheries may be an optimal policy choice to achieve the non-unique benefits of protected area creation. Protected areas, it has been argued, are a relatively low cost management tool, due to the lower monitoring and enforcement costs. Thus, the use of protected areas offer a solution to the problems of over extraction of fishery resources for lower transaction costs, which may erode the non-unique benefits under different policy instruments. If this is the case, then a protected area larger than is required to maximise the unique benefits of protected area creation could form part of an optimal fisheries management strategy. Whether the protected area is larger or smaller than the size that maximises both the unique and non-unique benefits of protected area creation would depend on the level of transaction costs involved in using alternative policy instruments. Protected areas were found to have distributional effects on the fishery due to changes in the species biomass ratio towards the predator species post protected area creation. The creation of a protected area will have distributional effects on the fishing industry if different fisheries target the different species separately. Fishers targeting predator species are likely to gain from the establishment of a protected area, as now the aggregate level of stocks of this species is greater, leading to both greater unique and non-unique benefits. For fisheries that target prey species, the benefits of protected area creation are lessened. The increased predation within protected area boundaries limited the unique benefits of the protected area. The low cost nature of a protected area will influence the portion of the fishery used for this type of control given an optimal policy programme. If protected areas are relatively low cost in comparison with other controls they should be used relatively more intensely. Further, the use of protected areas may hasten the evolution of fisheries away from open access exploitation towards controls which maximise the value of the fishery. With lower transaction costs, the ability to adopt protected areas over other forms of management is greater, and by doing so, the movement towards optimal exploitation will improve the discounted value of the fishery. The analysis presented in this thesis examined the benefits of protected areas to fisheries. The focus of the study was placed on the benefits to flow to a fishery if a protected area was used as a tool for wild-harvest fisheries management. Marine protected areas also have the potential to generate a range of other benefits, such as recreational values, non-use values, and potential improvements in consumer surplus from fish caught within fisheries that use protected areas. These other benefits would need to be considered when determining whether or not a protected area should be created in a fishery.
3

Marine Protected Areas: A Tool for Fisheries Management

Greenville, Jared William January 2007 (has links)
Doctor of Philosophy (PhD) / The management of fisheries has progressed over the past century in an attempt to solve the problem of open access. A range of controls, both economic and non-economic in nature, have been used to ration the use of marine resources. Unfortunately, many controls have failed to correct open access problems. Whilst a recent development in fishery control, protected areas defined as an area with a fishery free of extractive pressure, have been put forward as an arrangement which may, in conjunction with other controls, be used to overcome the over-exploitation of marine resources. Marine protected areas have been advocated in areas where other forms of fishery management are impractical or unsuccessful (Sumaila 1998). Arguments for protected area use are based around the heterogeneous nature of fisheries, uncertainties in marine populations and as a hedge strategy to reduce risks of over-exploitation (Conrad 1999a). Through the protection of biodiversity, improving the resilience of the ecosystem, protected areas may mitigate the effects of negative shocks (Ludwig et al. 1993 and Bostford et al. 1997). Further, protected areas have been suggested as a means to manage uncertainty and environmental stochasticity (Grafton and Kompas 2005 and Grafton et al. 2005). The protection of biomass and habitat has the potential to improve fishery returns even when stocks are not overly exploited, with the benefits accruing even from small-sized protected areas (Grafton et al. 2005). The use of marine protected areas as a management tool has resulted from a recognition that it is important to preserve biological habitats as well as stocks. From a societal point of view, the use of protected areas should be evaluated in the context of changes in resource rent and improvements in welfare. As fishery resources are often owned by a common group, usually society, management objectives should be to maximise the return from use of the resources, whether for extractive or non-extractive purposes. Given this decision criterion, protected areas can be evaluated in the sense of opportunity costs and benefits. Protected areas will influence the return from fishery resources through changes in access to fishing grounds, and thus harvest, effort and resource rent. Once a protected area is established, the flow of biomass from the protected area to the remaining fishing ground, may increase biomass, influence the effects of uncertainty and stochasticity, thus effecting mean harvests, effort and resource rent may increase. Changes in resource rent are dependent on other controls. Protected areas are a ‘blunt’ policy instrument, in the sense that they are not an instrument to capture resource rent or change the incentives of fishers. Models of marine protected areas in fisheries vary in complexity, however, a few key elements are necessary in analysing the effects of protected area creation. First, multi-species interactions have the potential to be significant in determining the outcome from a protected area; second, effort expended in the fishery must be dynamic, that is, it must be endogenously determined by the model as fishers will respond to changes in rent brought about through the establishment of a protected area; third, institutional structures that govern the expenditure of effort within a fishery will play an important role in the effectiveness of protected areas in increasing the resource rent of a fishery; and fourth, environmental stochasticity and uncertainty need to be included in the analysis. A stochastic and deterministic model of a predator-prey meta-population fishery was developed to analyse the effects of protected area creation within a fishery. Such a model has not previously been used to analyse protected area creation. The model was analytically solved to find the optimal biomass of each species in an individual patch. This allowed for a comparison of protected areas under a range of management controls ranging from those which led to open access fishing to those which led to an optimal steady-state biomass. The model allowed for linkages between sub-populations based on differing density related flows. Further, due to the linkages between species on both environmental and economic grounds, the effect of protected areas on different groups which target different species could be analysed. The benefits from protected area creation were classified into unique and non-unique benefits. Unique benefits were defined as those which solely flow from the use of a protected area as a tool in fisheries management. Two unique benefits were defined: • Improvements in the resilience of the fishery; and • Reductions in environmental stochasticity. The ability of a protected area to both improve the resilience of the fishery, and smooth fluctuations in environmental stochasticity have been shown to lead to increases in mean resource rent. Thus, protected areas were shown to form part of an optimal fisheries management structure. Generally, the resilience benefits were maximised for small-sized protected areas, whereas the reduced environmental stochasticity benefits were maximised for larger protected areas. The dispersal system between the protected area and the fishing ground affected the unique benefits from protected area creation. Sink-source dispersal increased the unique benefits from protected area creation, as stock movements occurred independently of relative population densities. The independent flow improved the ability of the protected area to hasten the return of the fishery to a steady-state and lessened the variation of harvests in the open fishing grounds. However, in the case where the protected area led to large differences in population densities, and if the area formed a sub-population that was linked to the surrounding fishing ground by density-dependent dispersal, the unique benefits are likely to be greater than under sink-source dispersal. The non-unique benefits were defined as those which could be obtained from other control mechanisms. These benefits were non-unique as they could be achieved from more stringent controls on fisher behaviour. The determinants of the non-unique benefit in terms of dispersal were the same as for the unique benefits. However, the economic conditions of the fishery determined the magnitude of the non-unique benefits. For fisheries with sub-optimal biomass, the unique benefits were greater than those with optimal steady-state biomass. The non-unique benefits identified from protected area creation were: • Changes in biomass towards optimal levels; • Changes in species biomass ratios towards optimal levels; and • Changes in effort towards optimal levels. Protected areas in fisheries may be an optimal policy choice to achieve the non-unique benefits of protected area creation. Protected areas, it has been argued, are a relatively low cost management tool, due to the lower monitoring and enforcement costs. Thus, the use of protected areas offer a solution to the problems of over extraction of fishery resources for lower transaction costs, which may erode the non-unique benefits under different policy instruments. If this is the case, then a protected area larger than is required to maximise the unique benefits of protected area creation could form part of an optimal fisheries management strategy. Whether the protected area is larger or smaller than the size that maximises both the unique and non-unique benefits of protected area creation would depend on the level of transaction costs involved in using alternative policy instruments. Protected areas were found to have distributional effects on the fishery due to changes in the species biomass ratio towards the predator species post protected area creation. The creation of a protected area will have distributional effects on the fishing industry if different fisheries target the different species separately. Fishers targeting predator species are likely to gain from the establishment of a protected area, as now the aggregate level of stocks of this species is greater, leading to both greater unique and non-unique benefits. For fisheries that target prey species, the benefits of protected area creation are lessened. The increased predation within protected area boundaries limited the unique benefits of the protected area. The low cost nature of a protected area will influence the portion of the fishery used for this type of control given an optimal policy programme. If protected areas are relatively low cost in comparison with other controls they should be used relatively more intensely. Further, the use of protected areas may hasten the evolution of fisheries away from open access exploitation towards controls which maximise the value of the fishery. With lower transaction costs, the ability to adopt protected areas over other forms of management is greater, and by doing so, the movement towards optimal exploitation will improve the discounted value of the fishery. The analysis presented in this thesis examined the benefits of protected areas to fisheries. The focus of the study was placed on the benefits to flow to a fishery if a protected area was used as a tool for wild-harvest fisheries management. Marine protected areas also have the potential to generate a range of other benefits, such as recreational values, non-use values, and potential improvements in consumer surplus from fish caught within fisheries that use protected areas. These other benefits would need to be considered when determining whether or not a protected area should be created in a fishery.
4

An economic evaluation of coastal wetlands in Korea

Pyo, Hee-Dong January 2001 (has links)
AN ECONOMIC EVALUATION OF COASTAL \VETLANDS IN KOREA BY IIEE-DONG PYO The thesis undertakes a detailed economic analysis of the coastal wetlands of Korea and applies the double-bounded dichotomous choice model and spike model of the contingent valuation method to systematically evaluate their conservation value. Further analysis including an extension of the original spike model using only singlcbounded data (Kristrom, I ()(n) to modelling double-bounded data for more statistical efficiency to deal with /.ero observations was made. As a result, the estimated willingness-to-pay for conserving the coastal wetlands under the study is S3.9 per month per household, and the annual aggregated conservation value for the entire nation is about 175 million dollars in a conservative scenario. The study then applies a benefit-cost analysis (8C';\) to coastal wetlands around the Youngsan River, an area of dispute between development and preservation in Korea, with a synthesised estimation of the ecosystcm functional values for coastal wetlands and rice paddies developed by reclamation. The results show wetland development would be preferred to its preservation in an optimistic seenano and conventional BC A, yielding NPV of $49million at the discount rate of 8(Yo, IRR of 8.28%, and B/C ratio of 1.03. By contrast, a normal scenario rejects economic feasibility for the development project at the discount rate of 8°/c), yielding a NPV of -$271 million, IRR of 6.5% and B/C ratio of 0.84. With an extended Be A including conservation values for I-year, 5-year and 1 O-year payment, the estimates of IRR are 7.42%, 5.42%, and 4.06%, respectively under the optimistic scenario. Meanwhile, under the nOnllal Scenario the estimates of IRR arc 5.85%, 4.25%, and 3.09%, respectively. In addition, this study includes a discussion of a comprehensiYe review of conjoint analysis and the integrated environmental management of coastal wetlands developing sustainability indicators for coastal lisheries using bio-economic models in Appendix.
5

Incorporating Agroforestry Into Water Quality Trading: Evaluating Economic-Environmental Tradeoffs

Scott, Samuel George 05 September 2019 (has links)
Nonpoint source nitrogen runoff from agriculture is a significant contributor to eutrophication in the Chesapeake Bay. The state of Virginia has developed several market and incentive-based water quality credit trading programs to meet federal water quality objectives. In theory, these programs offer a mechanism to achieve environmental goals at least cost. However, in practice these programs face ongoing challenges arising from limited participation by farmers who supply water quality credits and, as a result, often fail to achieve cost efficiency. We build a flexible, accessible, and modular bioeconomic modeling system as a proof-of-concept to evaluate economic-environmental tradeoffs farmers face in an effort to support program participation and achieve environmental goals. We couple a biophysical nitrogen mass-balance model with an agricultural production model and apply the tool to study diverse agroforestry practices. We evaluate the relative efficiency of these practices by empirically estimating a production possibility frontier. We then use our bioeconomic modeling results to define the minimum willingness to accept of farmers, in terms of water quality credit prices, to adopt agroforestry practices that deliver water quality improvements. We extend our model results to estimate water quality credit premiums to compensate risk-averse farmers for undertaking production practices subject to relatively volatile prices in niche fruit markets. We demonstrate that the model generally simulates real-world credit prices, and highlight potential improvements in design for Virginia's trading program. In particular, quality credit trading programs could be more effective and efficient if credits awards reflect heterogeneity in the environmental benefits associated with nuanced land-use alternatives. Our modeling tool offers a framework to support incentive programs that are both economically sound and biophysically grounded. / Master of Science / High levels of nitrogen in the Chesapeake Bay have become an environmental concern for regulatory agencies. A significant portion of nitrogen pollution in the Chesapeake Bay comes from agricultural activities in the Chesapeake Bay watershed. Agricultural nitrogen pollution is not directly regulated at the federal level, so some states have adopted market-based mechanisms to curb emissions. However, some of these programs are seeing less farmer participation than expected. We suggest that part of the low participation rates may be due to program design, and the impact risk plays in farmer decision-making. In an effort to better understand participation in the programs, we develop a method to model these programs’ environmental and economic outcomes. Our method couples a mechanistic model of nitrogen pollution with an agricultural production model and evaluates tradeoffs between economic and environmental values. We find that the modeling method shows promise as a tool for policymakers, researchers, and farmers interested in pollution abatement programs. As a proof-of-concept, we apply the model to a Virginia market-based program and test our low-participation hypotheses. We find that the programs may be more effective if they recognize a greater diversity of farming practices. Our modeling tool offers a framework to support pollution abatement programs that are both economically feasible and environmentally effective.
6

A voz neodarwinista sobre os humanos: os novos significados histórico-sociais da ontologia biocientífica / The neo-Darwinist voice about humans: the new social-historical meanings of the bioscientific ontology

Paschoalotte, Leandro Módolo 03 April 2018 (has links)
Submitted by Leandro Modolo Paschoalotte (modolole@hotmail.com) on 2018-05-25T21:33:39Z No. of bitstreams: 1 TESE de Doutorado - LMP.pdf: 3219496 bytes, checksum: d0e4a3c01d34a773fbb67a46efb7f8b2 (MD5) / Rejected by Aline Aparecida Matias null (alinematias@fclar.unesp.br), reason: Solicitamos que realize correções na submissão seguindo as orientações abaixo: 1) Falta o número do processo da FAPESP nas folhas em que a bolsa é citada. Confirmar com a FAPESP se é necessário colocar o número do processo também nos agradecimentos. 2) Excluir as folhas em branco que estão entre o sumário e a introdução. Agradecemos a compreensão. on 2018-05-28T12:37:04Z (GMT) / Submitted by Leandro Modolo Paschoalotte (modolole@hotmail.com) on 2018-05-28T12:55:00Z No. of bitstreams: 1 TESE de Doutorado - LMP.pdf: 3219474 bytes, checksum: 3d1561985da9b8d968b144a96442458a (MD5) / Approved for entry into archive by Aline Aparecida Matias null (alinematias@fclar.unesp.br) on 2018-05-28T13:08:38Z (GMT) No. of bitstreams: 1 paschoalotte_lm_dr_arafcl.pdf: 3219474 bytes, checksum: 3d1561985da9b8d968b144a96442458a (MD5) / Made available in DSpace on 2018-05-28T13:08:38Z (GMT). No. of bitstreams: 1 paschoalotte_lm_dr_arafcl.pdf: 3219474 bytes, checksum: 3d1561985da9b8d968b144a96442458a (MD5) Previous issue date: 2018-04-03 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Há pelo menos três décadas a esfera pública vem sendo banhada pela figuração do humano como um ser de natureza igual – nem mais nem menos – a todos os outros seres viventes sob a rubrica da biologia molecular, mais precisamente da genômica. Do DNA como representação da “essência do nosso ser” aos “homens geneticamente criminosos”, vemos inúmeros enunciados serem vocalizados em livros, em reportagens e mídias em geral – especializados ou não – que, como diria Gyorgy Lukács, derivam ontologicamente as características do ser social daquelas constitutivas do ser natural. Desde a inauguração, na década de 1970 com a sociobiologia de Edward Wilson e Richard Dawkins, até os dias de hoje, a figuração do humano baseado na Teoria Sintética da Evolução vem se aperfeiçoando e se propagando nas distintas áreas do saber e da cultura. De forma geral, parte dominante desse pensamento interpreta as qualidades ontológicas dos humanos e, por consequência, suas características como resultados adaptacionista da evolução da nossa espécie com base na fitness genética. Sendo assim, no sentido de contribuir na compreensão do cenário no qual subiu ao palco tal figuração, este trabalho assume a tarefa de capturar alguns de seus significados históricosociais contemporâneos. Por consistir numa figuração com suportes teórico-científicos, a intenção, num primeiro momento, é identificar alguns dos seus fundamentos epistemológicos e ontológicos através da construção do que denominamos de grade de inteligibilidade genômico derivacionista, cuja característica central consiste na “dedução ontológica” das esferas menos complexas do ser em geral as mais complexas. Posteriormente, para levarmos a cabo o nosso objetivo, explicaremos o que consideramos efetivamente novo em seu significado histórico-social mediante as suas manifestações ideológicas – pelas quais práticas políticas e econômicas se operacionalizam. A nossa tese é de que, sob a crise estrutura do capital e seus aportes financeiros, emergiram tanto uma bioeconomia quanto uma biopolítica que imprimiram significados radicalmente novos ao modo com que tal figuração do humano se transmuta de discurso científico ao ideológico. / For at least three decades the public sphere has been bathed by the figuration of the human as a being of an equal nature – no more and no less – to all other living beings under the rubric of molecular biology, more precisely genomics. From DNA as a representation of the “essence of our being” to "genetically criminal men," we see innumerable utterances being spoken of in books, in reports, in advertisements and media in general – specialized or not – which, as Gyorgy Lukacs would say, derive ontologically the characteristics of the social being of those constitutive of the natural being. Since the inauguration in the 1970s with the sociobiology of Edward Wilson and Richard Dawkins, to this day, the human figure based on the Synthetic Theory of Evolution has been improving and spreading in the different areas of knowledge and culture. In general, a dominant part of this thought interprets the ontological qualities of humans and, consequently, their characteristics as an adaptational result of the evolution of our species based on genetic fitness. Thus, in order to contribute to the understanding of the scenario in which such figuration came to the stage, this work assumes the task of capturing some of its contemporary social-historical meanings. In the first place, the intention is to identify some of its epistemological and ontological foundations through the construction of what we call a “reductionist genomic intelligibility grid”, whose central characteristic consists of the "ontological deduction" of the less complex spheres of “being in general” the more complex. Subsequently, to accomplish our goal, we will explain what we consider to be effectively new in its historical-social meaning through its ideological manifestations – by which political and economic practices become operational. Our thesis is that, under the crisis of capital structure and its financial devices, both a bioeconomy and a biopolitics have emerged that have given radically new meanings to the way in which such figuration of the human transmutes from scientific to ideological discourse / 2014/27003-2
7

Biodiversity, Dispersal, and Risk: Species Spread in Ecological and Social-Ecological Systems

January 2016 (has links)
abstract: The closer integration of the world economy has yielded many positive benefits including the worldwide diffusion of innovative technologies and efficiency gains following the widening of international markets. However, closer integration also has negative consequences. Specifically, I focus on the ecology and economics of the spread of species and pathogens. I approach the problem using theoretical and applied models in ecology and economics. First, I use a multi-species theoretical network model to evaluate the ability of dispersal to maintain system-level biodiversity and productivity. I then extend this analysis to consider the effects of dispersal in a coupled social-ecological system where people derive benefits from species. Finally, I estimate an empirical model of the foot and mouth disease risks of trade. By combining outbreak and trade data I estimate the disease risks associated with the international trade in live animals while controlling for the biosecurity measures in place in importing countries and the presence of wild reservoirs. I find that the risks associated with the spread and dispersal of species may be positive or negative, but that this relationship depends on the ecological and economic components of the system and the interactions between them. / Dissertation/Thesis / Doctoral Dissertation Biology 2016
8

O antagonismo entre o lucro e a termodinâmica na decisão sobre o uso dos fertilizantes minerais e a sua eficiência na produção de soja do Brasil

Santos, Omar Inacio Benedetti January 2017 (has links)
A produção de alimentos no mundo está condicionada à oferta e ao consumo de fertilizantes inorgânicos, obtidos de fontes naturais não renováveis. Existe um limite entrópico para o atendimento das necessidades crescentes de alimentos. A sustentabilidade da dinâmica dos sistemas agrícolas dependerá da adequação da produção de alimentos à quantidade de recursos naturais disponíveis. No presente trabalho nós testamos essa sustentabilidade, procurando analisar a eficiência do uso de fertilizantes inorgânicos na produção de soja, um dos alimentos básicos nas cadeias alimentares globais, segundo uma abordagem da bioeconomia fundamentada na termodinâmica. Com base nos dados de produção e área cultivada de soja no Brasil, como disponibilizados pelo Instituto Brasileiro de Geografia e Estatística (IBGE), desenvolveu-se um modelo analítico baseado em programação matemática e no princípio de máxima entropia para estimar o uso de fertilizantes por extrato de área cultivada, bem como os respectivos custos totais de produção. Neste trabalho estimou-se a eficiência termodinâmica do uso de fertilizantes e a eficiência econômica da produção de soja nos diferentes extratos de área de produção. Para avaliar essas eficiências utilizou-se um conceito de retorno constante de produtividade da terra (RCP). Esse indicador define o rendimento relativo por hectare da produção de soja nos diferentes extratos de área. Assim, analisando o caso da produção de soja brasileira, verificou-se que no ano de 2008 o aumento de preços das matérias-primas para produzir fertilizantes levou a uma queda no seu respectivo consumo global. A partir dessa observação, procurou-se identificar os fundamentos da tomada de decisão do produtor de soja relativa ao emprego dos fertilizantes no Brasil. Verificou-se que o produtor de soja brasileiro decide as quantidades de fertilizantes que vai empregar, baseando-se na expectativa do lucro da respectiva safra. Os resultados apontam que essa decisão leva a um emprego ineficiente de fertilizantes inorgânicos entre os diferentes extratos de área, principalmente nos extratos inferiores a 20 hectares, em relação a produtores com área superior a 2500 hectares. Essa ineficiência relativa se dá devido ao fato de que, embora a taxa de aplicação de fertilizantes por hectare apresente diferenças pouco significativas entre os extratos de área, as respectivas produtividades são evidentemente distintas. A produtividade da terra em soja é menor nos extratos até 20 hectares, quando comparada à produtividade nos extratos superiores, ocorrendo casos em que essa diferença venha a ser até de duas toneladas de soja por hectare. No período de 1975 a 2011, anos selecionados para este estudo, outros extratos menores, mas superiores a 20 hectares, também apresentaram menor eficiência em relação ao uso de fertilizantes em comparação aos extratos superiores a 2500 hectares. Em relação à respectiva eficiência econômica, verificou-se que os custos de fertilizantes por tonelada de soja são similares entre os extratos, sugerindo-se uma homogeneidade em termos de estrutura de comercialização dos fertilizantes, o que acaba por impactar na lucratividade relativa da produção de soja. Os custos totais de produção refletem também a estrutura tecnológica adotada em cada extrato de área. Ao utilizar-se o conceito de RCP, verifica-se que extratos abaixo de 500 hectares possuem uma menor eficiência econômica quando comparadas com os extratos acima de 2500 hectares. Esses resultados indicam a necessidade de uma escala mínima de produção para o produtor manter-se competitivo do ponto de vista econômico. Desses resultados, e aproveitando-se a modelagem desenvolvida por este estudo, foram derivados alguns cenários pertinentes ao cultivo de soja no Brasil, relativos à produção, área, produtividade e uso de fertilizantes, bem como os custos de produção associados. O modelo desenvolvido para estimar as quantidades de fertilizantes inorgânicos utilizados pelos diferentes extratos de área, relativos à produção de soja, tem como principal característica oferecer a possibilidade de testar-se hipóteses sobre produção, área, produtividade e uso de fertilizantes. Esse modelo pode ser uma ferramenta de apoio à decisão, tanto para gestores de investimentos públicos na agricultura, quanto para a gestão nas unidades de produção agrícola. Os resultados deste presente trabalho sugerem que na produção de soja brasileira o uso de fertilizantes inorgânicos está desconectado de determinantes tecnológicos agronômicos, assim como está dissociado de questões relativas à segurança alimentar ou da sustentabilidade ambiental. Isso porque a tomada de decisão sobre o uso de fertilizantes inorgânicos na agricultura ignora a termodinâmica do processo produtivo como um todo. Para que a produção de soja no Brasil seja efetivamente eficiente e sustentável, do ponto de vista bioeconômico, ou seja, integrador das dimensões econômica, agronômica e termodinâmica, é necessário levar-se em consideração de que são imprescindíveis extratos de produção agrícola de áreas superiores, que contenham uma certa área mínima para a produção de soja, e que se redesenhe com propriedade as tecnologias empregadas nos seus respectivos sistemas de produção, levando-se em conta o limite entrópico da disponibilidade de fertilizantes inorgânicos no mundo. / Food production worldwide is conditioned to supply and consumption of inorganic fertilizers that are obtained from nonrenewable natural sources. The satisfaction of the increasing food needs is limited by an entropic threshold. Therefore, sustainability of the agricultural systems’ dynamics will depend on the adequacy of food production to the amount of available natural resources. In this paper, we examine such sustainability, seeking to analyze the efficiency of the inorganic fertilizers’ use in the production of soybean, one of the basic foods from the global food chain, according to a bioeconomic approach grounded on thermodynamics. Based on data on the soybean production and cultivated areas in Brazil, made available by the Brazilian Institute of Geography and Statistics (IGBE, from the Brazilian Portuguese: “Instituto Brasileiro de Geografia e Estatística”), we have developed an analytical model, which is based on mathematical programing and on the generalized maximum entropy principle, to estimate the use of fertilizers per level of cultivated land, as well as its full production costs. In this paper, we have estimated the efficiency of thermodynamics regarding the use of fertilizers and the economical efficiency of soybean production in different levels of cultivated land. To evaluate such efficiencies, a concept of constant return on land productivity (RCP, from the Brazilian Portuguese: “Retorno Constante de Produtividade”) has been used. This indicator defines the yield per hectare of soybean production in different levels of cultivated land. Thus, analyzing the case of Brazilian soybean production, it’s been asserted that during 2008 the increased price of raw materials used to produce fertilizers lead to a decline in its global consumption. From that observation, we have sought to identify the reasons behind soybean producers’ decision-making regarding the use of fertilizers in Brazil. We’ve discovered that Brazilian soybean producers decide on the amount of fertilizers they will use based on the expectations of profit regarding that particular crop. Results indicate that such decision leads to an inefficient use of inorganic fertilizers per different levels of cultivated land, mainly on portions lower than 20 hectares, from producers holding a field over 2500 hectares. Such relative inefficiency occurs due to the fact that, although the fertilizer’s usage rate per hectare shows little significant differences between producers, their yields are clearly distinct. The soil productivity of soybean is lower in portions up to 20 hectares in comparison to productivity on higher levels of cultivated land and there are instances where such difference is up to two tons of soybean per hectare. From 1975 to 2011, the period selected for this particular study, other smaller levels of cultivated land which were higher than 20 hectares, also evidenced a lower efficiency with regard to the use of fertilizers in comparison to levels higher than 2500 hectares. Regarding their economic efficiency, evidence showed that the costs of fertilizers per ton are similar between levels of cultivated land, suggesting homogeneity in terms of the fertilizers trading structure, resulting in an impact on the relative yielding of soybean production. Total production costs also reflect the technological structure adopted in each level of cultivated land. By applying the concept of RCP, it’s been ascertained that levels lower than 500 hectares have a lower economic efficiency when compared to levels higher than 2500 hectares. Such results indicate the need for a minimal production scale in order for the producer to keep their competitiveness, from an economic perspective. From these results, and taking advantage of the modeling developed for this study, some sceneries pertaining the soybean culture in Brazil have been derived that relate to production, area, yield, and use of fertilizers, as well as related production costs. The model developed to estimate the amounts of inorganic fertilizers used in soybean production, in different levels of cultivated land, holds as its main feature the fact that it allows for the testing of hypothesis on production, area, yield, and use of fertilizers. Such a model can be used as a decision-making supporting tool, both for public agricultural investment managers and for managing the agricultural production units (farms). This paper’s results suggest that, in Brazilian soybean production, the use of inorganic fertilizers is disconnected from agronomic technological determiners and dissociated from food safety and environmental sustainability issues. That happens because decision-making on agricultural use of fertilizers overlooks the thermodynamics of the productive process as a whole. In order for the soybean production in Brazil to be effectively efficient and sustainable, from the bioeconomic point of view, i.e., integrating the economic, agricultural, and thermodynamic dimensions, it is necessary to consider that they are fundamental portions of agricultural production in bigger areas, which contain a minimal area for the production of soybean, and to properly redesign the technologies applied in their production systems, taking into account the entropic threshold of availability of inorganic fertilizers in the world.
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Corantes naturais das cascas das árvores Stryphnodendron adstringens (Mart.) Coville e Croton urucurana Baill., nativas do Brasil: extração, tingimento, solidez de cor e caracterização do efluente / Natural dyes from trees barks Stryphnodendron adstringens (Mart.) Coville and Croton urucurana Baill., native to Brazil: extraction, dyeing, color fastness and wastewater characterization

Silva, Patrícia Muniz dos Santos 27 September 2018 (has links)
Esse trabalho objetivou investigar o potencial dos extratos aquosos das cascas de barbatimão (Stryphnodendron adstringens (Mart.) Coville) e sangra dágua (Croton urucurana Baill.) como corante natural têxtil. Os extratos foram caracterizados quanto ao pH, o teor de sólidos totais e a estabilidade no armazenamento. Os extratos foram liofilizados e avaliados por espectroscopia no infravermelho com transformada de Fourier (FTIR), termogravimetria (TG) e calorimetria exploratória diferencial (DSC). Foram realizados experimentos preliminares de tingimento em tecidos multifibra e em diferentes concentrações dos extratos. A partir desses experimentos, foram definidas as variáveis temperatura, tempo e concentração do extrato para o estudo do tingimento por planejamento experimental 2³, em tecidos 100 % algodão e 100 % lã. Os tecidos tingidos em condição otimizada, sem e com mordentes metálicos, foram avaliados quanto à cor, a solidez de cor à luz, à lavagem, à fricção e ao suor. Os efluentes foram coletados e caracterizados quanto ao pH, turbidez, sólidos totais dissolvidos (STD), oxigênio dissolvido, demanda bioquímica de oxigênio (DBO), demanda química de oxigênio (DQO) e teores de ferro e alumínio dissolvidos. Foram conduzidos ensaios bacteriológicos nos extratos aquosos, etanólicos e liofilizados e nos tecidos tingidos. Os resultados das análises por FTIR indicaram a presença de taninos, lignina e celulose nos extratos. Pelo estudo de estabilidade os extratos possuem duração de 42 dias. Nas análises por TG, os extratos obtiveram perda de massa total similares e não geraram alteração na degradação dos tecidos tingidos. Na análise por DSC os extratos obtiveram picos endotérmico e exotérmixo em temperaturas próximas. As melhores condições para o tingimento dos tecidos avaliados é em 98 °C, por 60 min e na concentração de 100 % do extrato. A solidez de cor dos tecidos tingidos variou de baixa a excelente. Os extratos liofilizados apresentaram propriedades antibacterianas. Os efluentes apresentaram valores de STD, DBO, DQO e alumínio e ferro dissolvidos acima dos limites determinados pela legislação nacional. De modo geral, os resultados obtidos indicam que os extratos das cascas de barbatimão e sangra dágua são promissores para serem utilizados como corantes naturais têxteis / This research aimed to investigate the potential of aqueous extracts of barbatimão (Stryphnodendron adstringens (Mart.) Coville) and sangra dágua (Croton urucurana Baill.) bark as natural textile dyes. The extracts were characterized for pH, total solids content and storage stability. The extracts were lyophilized and evaluated by Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and differential scanning calorimetry (DSC). Preliminary dyeing experiments were carried out on multifiber fabrics and at different extracts concentrations. From these experiments, the variables temperature, time and concentration of the extract for the study of dyeing by experimental design 2³ in 100 % cotton and 100 % wool fabrics were defined. Fabrics dyed in optimized condition, using metal mordants and with no mordents, were evaluated by colorimetry, color fastness to light, wash, rubbing and perspiration. The effluents were collected and characterized by pH, turbidity, total dissolved solids (TDS), dissolved oxygen, biochemical oxygen demand (BOD), chemical oxygen demand (COD) and dissolved iron and aluminum contents. Bacteriological tests were conducted on aqueous, ethanolic and lyophilized extracts and on dyed fabrics. The results of the FTIR analysis indicated the presence of tannins, lignin and cellulose in the extracts. By the stability study were found that the extracts have a duration of 42 days. In the TG analyzes, the extracts obtained similar total mass loss and did not generate alteration in the degradation of the dyed fabrics. In the DSC analysis the extracts obtained endothermic and exotherm peaks at near temperatures. The optimized dyeing for the evaluated fabrics is at 98 °C for 60 min and at the concentration of 100 % of the extract. The color fastness of the dyed fabrics ranged from low to excellent. Lyophilized extracts showed antibacterial properties. The wastewater showed values of TDS, BOD, COD and aluminum and iron dissolved above the limits determined by national legislation. In general, the results indicate that barbatimão and sangra dágua extracts are promising for use as natural textile dyes
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Modeling economies and ecosystems in general equilibrium

Woollacott, Jared 08 April 2016 (has links)
This work exploits the general equilibrium modeling framework to simulate complex systems, an economy and an ecosystem. In an economic application, this work leverages a novel data revision scheme to integrate technological detail on electricity generation and pollution abatement into national accounts data in a traditional economic computed general equilibrium (CGE) model. This integration provides a rich characterization of generation and abatement for multiple fuel sources and pollutants across 72 different generation-abatement technology configurations. Results reveal that the benefits of reductions in oxides of nitrogen and sulfur from a carbon policy in the US electric sector are on the order of $10 bn., which rival the policy's welfare costs and make 12-13% carbon abatement economically justifiable without considering any climate benefits. For ecosystem applications, this work demonstrates how the structure of economic CGE modeling can be adapted to construct a Biological General Equilibrium (BGE) model grounded in the theoretical biology literature. The BGE model contributes a novel synthesis of micro-behavioral, bioenergetic features with macroscopic ecosystem outcomes and empirical food web data. Species respond to prevailing ecosystem scarcity conditions that impinge on their energy budgets driving population outcomes within and across model periods. This adaptive capacity is a critical advance over the commonly-taken phenomenological or first-order parametric approaches. The distinctive design of the BGE model enables numerical examination of how changes in scarcity drives biomass production and consumption in a complex food web. Moreover, the BGE model design can exploit empirical datasets used by extant ecosystem models to offer this level of insight for a wide cast of ecosystems. Monte carlo simulations demonstrate that the BGE framework can produce stable results for the ecosystem robust to a variety of shocks and parameterizations. The BGE model's validity is supported in tests against real-world phenomena within the Aleutian ecosystem - both an invasive species and a harvesting-induced trophic cascade - by mimicking key features of these phenomena. The BGE model's micro-founded dynamics, the stability and robustness of its results, and its validity against real-world phenomena offer a unique and valuable contribution to ecosystem modeling and a way forward for the integrated assessment of human-ecosystem interactions.

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