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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.
351

Carbon sequestration in native rainforest tree plantations

Richards, A. Unknown Date (has links)
The recent rapid decline in tropical and subtropical forests and subsequent loss of biodiversity, coupled to the threat posed by climate change, has led to a requirement for sustainable forest systems. Large-scale monocultures supply timber that can no longer be harvested in sufficient quantity from natural forests in subtropical and tropical regions. However, there is a general perception that forest systems need to be managed to provide multiple production and environmental services, including carbon (C) sequestration, restoration of soil fertility, and biodiversity. Overall, traditional plantation monocultures cannot meet all of these new objectives, and native and mixed-species plantations may provide an alternative, when provision of ecosystem services, besides timber, becomes a priority. The objective of this thesis was twofold. Firstly to assess C storage in native rainforest tree (hoop pine, Araucaria cunninghamii) plantations, planted as monocultures in subtropical Australia. Plantations were examined to evaluate their potential as a sustainable forest system for provision of high-value timber products and C sinks. The second objective was to contrast the traditional monoculture system with a multi-species system, and a mixed-species rainforest tree plantation was studied. These systems are receiving substantial attention from private forest growers as they could provide economic benefits, including greater productivity, coupled to biologically desirable outcomes, such as higher biodiversity. The focus of the second objective was to improve the design of mixtures for maximum wood production and C sequestration, so that other ecological benefits could be realised. Subtropical native hoop pine monocultures did not store soil C into long-term storage pools as rapidly as adjacent native rainforest or pastures. In addition, substantial amounts of soil nitrogen were lost from tree plantations, indicating that with current management, these systems may not be sustainable in the long-term. Overall, total C storage, including soil and aboveground biomass C, was higher in tree plantations than pastures highlighting the potential of native tree plantations for C sequestration. The mechanisms behind lower soil C storage of native hoop pine plantations, compared with rainforest and pasture, may be related to differences in soil C stabilization. While native forest and pasture systems stored C within soil aggregates and through organo-mineral interactions, tree plantations did not show a strong aggregate hierarchy and most soil C was associated with mineral-sized particles. Because soil minerals have a limited capacity to adsorb soil organic C, they may limit the C storage capacity of the studied tree plantations. We conclude that changes to management of hoop pine monocultures, such as increasing plant diversity in tree plantations, may create conditions similar to the native forest and promote greater C sequestration in plantation soils by stabilization through both soil aggregation and organomineral interactions. Since traditional monoculture forest production systems may not provide the multiple benefits needed for sustainable forestry, an alternative mixed-species tree plantation was investigated. We examined the dominant paradigm that mixtures of two fast growing species (Grevillea robusta and Elaeocarpus angustifolius) compete for site resources, while mixtures of shade tolerant (Castanospermum australe) and shade intolerant (G. robusta or E. angustifolius) species are complementary. Contrary to predictions, there was evidence for complementary interactions between the fast-growing species in terms of nutrient uptake, nutrient use efficiency and nutrient cycling. Preliminary model simulations of interactions between species for light indicated that G. robusta maintained the highest rates of photosynthesis under different light conditions and may be combined with C. australe and the more light demanding E. angustifolius in mixtures. Overall there was evidence for tree species combinations which could potentially sequester more C, in addition to other benefits including higher biodiversity and improved use of soil resources, in mixed-species plantations. Such knowledge is useful to encourage implementation of these new timber production systems.
352

Models and frameworks that enhance systematic planning for coral reef biodiversity conservation

Beger, Maria Unknown Date (has links)
The global decline of coral reef biodiversity requires rapid, efficient and practical solutions. No-take marine reserves and reserve systems and other managed marine conservation areas are currently considered one of the most effective management methods to deal with this ongoing decline. Although the effects, design, and establishment of coral reef reserves have been widely debated in the literature, few examples of systematic approaches to the design of reserve systems exist. Systematic conservation planning is a procedure to prioritise sites for their inclusion in reserve systems based on data and a set of conservation principles. For coral reefs the systematic design of reserve systems has been hampered by the lack of spatially explicit data, and the lack of practical recommendations to resource managers of how to apply new scientific findings. This thesis fills critical gaps at the interface between theory, planning, and implementation of coral reef reserve systems, and provides practical guidance to reef managers. In the first chapter, literature on marine reserves is discussed and the implications for coral reef reserves are considered. Chapter 2 discusses the lessons learned in the design and implementation of a community-based marine reserve in the Philippines. Reviewing relevant literature, a framework of ‘lessons learnt’ during the establishment of local protected areas is presented, highlighting the importance of a number of factors that are vital to the success of these reserves: (a) an island location; (b) small community population size; (c) minimal effect of land-based development; (d) application of a bottom-up approach; (e) an external facilitating institution; (f) acquisition of title; (g) use of a scientific information database; (h) stakeholder involvement; (i) the establishment of legislation; (j) community empowerment; (k) alternative livelihood schemes; (l) surveillance; (m) tangible management results; (n) continued involvement of external groups after reserve establishment, and (o) small-scale project expansion. To manage coral reef species it is important to understand the processes that influence their distribution. Chapter 3 identifies the environmental factors most influential in determining coral reef fish species distributions on a regional scale. Logistic regression models for 227 fish species related presence-absence data to four remotely determined environmental predictor variables: depth 500 m away from a reef, presence of a land-sea interface, exposure, and the distance to the nearest estuary. A novel method of evaluating model significance identified suitable models for 134 species. All four predictor variables were important for the distributions of the chosen suite of fishes. Depth was the most frequently significant variable in single variable models, and the proximity of a reef to an island was the least frequently important variable. For combinations of two predictor variables, depth and exposure as well as depth and distance from the nearest estuary were the prevalent predictors of fish distributions. Several fish species responded to the combination of the distance from an estuary and the presence of the terrestrial-marine interface, indicating that these species depend on intact coastal reef habitat, which is in decline near the main sediment-laden rivers. Significant models were predominantly developed for habitat specific species. These habitat specific species are of greater conservation concern than widespread species because of their restricted range, or because threats affect them more severely if they are selectively affecting their habitat. For this reason, species distribution modelling may be an efficient method to inform reserve design. The relevance of cross-taxon congruence to the suitability of taxa as conservation representation surrogates of coral reef biodiversity across the Indo-Pacific is tested in Chapter 4, using species lists of fishes, corals, and molluscs. Congruence is identified with a linear regression analysis of dissimilarity values. The utility of a surrogate was determined by the degree to which each taxon can represent the others in a marine reserve network using a greedy reserve selection algorithm. None of the taxonomic groups examined was capable of acting as a general conservation representation surrogate. Even a data-rich taxon like fishes could be severely under-represented in reserve systems designed based on a surrogate taxon such as corals, implying that data-deficient taxa are unlikely to be represented adequately where surrogate taxa are used for planning. Despite the high cross-taxon congruence between fishes and corals, and between corals and molluscs for some regions, cross-taxon congruence was not always a reliable indicator of conservation representation surrogacy. Consequently, in Indo-Pacific coral reef ecosystems one can only be sure that a target taxon is represented fully in a marine reserve network when data on this taxon are used to select reserve sites. The fifth chapter provides a theoretical and practical framework for incorporating ecological processes that span terrestrial, marine, and freshwater environmental realms into systematic conservation planning. Firstly the types of processes are classified as interactions that exist: a) on narrow interfaces such as inter-tidal zones; b) on broad interfaces such as mangrove swamps; c) along constrained connections such as corridors used by amphibian movements between natal ponds and adult habitat; and d) through diffuse connections like bird migrations. A framework of conservation planning approaches to promote the persistence of these types of processes and examples of how they might be implemented is developed. The framework focuses both on problem formulations consistent with existing decision support tools, such as the conservation planning software MARXAN, and on new methods. The review is aimed at a broad audience of scientists, planners, and managers and takes a practical and illustrative approach, providing examples of existing work and pointing readers to tools that are available to enhance conservation planning across realms. In the concluding chapter ideas from all chapters are synthesised. This chapter discusses how the approaches and frameworks presented here could be extended, and profitable areas for future research are suggested. Overall this thesis provides new insights, concepts, and tools that can assist reef managers and scientists struggling to minimise the loss of coral reefs.
353

Carbon sequestration in native rainforest tree plantations

Richards, Anna Elizabeth Unknown Date (has links)
The recent rapid decline in tropical and subtropical forests and subsequent loss of biodiversity, coupled to the threat posed by climate change, has led to a requirement for sustainable forest systems. Large-scale monocultures supply timber that can no longer be harvested in sufficient quantity from natural forests in subtropical and tropical regions. However, there is a general perception that forest systems need to be managed to provide multiple production and environmental services, including carbon (C) sequestration, restoration of soil fertility, and biodiversity. Overall, traditional plantation monocultures cannot meet all of these new objectives, and native and mixed-species plantations may provide an alternative, when provision of ecosystem services, besides timber, becomes a priority. The objective of this thesis was twofold. Firstly to assess C storage in native rainforest tree (hoop pine, Araucaria cunninghamii) plantations, planted as monocultures in subtropical Australia. Plantations were examined to evaluate their potential as a sustainable forest system for provision of high-value timber products and C sinks. The second objective was to contrast the traditional monoculture system with a multi-species system, and a mixed-species rainforest tree plantation was studied. These systems are receiving substantial attention from private forest growers as they could provide economic benefits, including greater productivity, coupled to biologically desirable outcomes, such as higher biodiversity. The focus of the second objective was to improve the design of mixtures for maximum wood production and C sequestration, so that other ecological benefits could be realised. Subtropical native hoop pine monocultures did not store soil C into long-term storage pools as rapidly as adjacent native rainforest or pastures. In addition, substantial amounts of soil nitrogen were lost from tree plantations, indicating that with current management, these systems may not be sustainable in the long-term. Overall, total C storage, including soil and aboveground biomass C, was higher in tree plantations than pastures highlighting the potential of native tree plantations for C sequestration. The mechanisms behind lower soil C storage of native hoop pine plantations, compared with rainforest and pasture, may be related to differences in soil C stabilization. While native forest and pasture systems stored C within soil aggregates and through organo-mineral interactions, tree plantations did not show a strong aggregate hierarchy and most soil C was associated with mineral-sized particles. Because soil minerals have a limited capacity to adsorb soil organic C, they may limit the C storage capacity of the studied tree plantations. We conclude that changes to management of hoop pine monocultures, such as increasing plant diversity in tree plantations, may create conditions similar to the native forest and promote greater C sequestration in plantation soils by stabilization through both soil aggregation and organomineral interactions. Since traditional monoculture forest production systems may not provide the multiple benefits needed for sustainable forestry, an alternative mixed-species tree plantation was investigated. We examined the dominant paradigm that mixtures of two fast growing species (Grevillea robusta and Elaeocarpus angustifolius) compete for site resources, while mixtures of shade tolerant (Castanospermum australe) and shade intolerant (G. robusta or E. angustifolius) species are complementary. Contrary to predictions, there was evidence for complementary interactions between the fast-growing species in terms of nutrient uptake, nutrient use efficiency and nutrient cycling. Preliminary model simulations of interactions between species for light indicated that G. robusta maintained the highest rates of photosynthesis under different light conditions and may be combined with C. australe and the more light demanding E. angustifolius in mixtures. Overall there was evidence for tree species combinations which could potentially sequester more C, in addition to other benefits including higher biodiversity and improved use of soil resources, in mixed-species plantations. Such knowledge is useful to encourage implementation of these new timber production systems.
354

Patterns of resource allocation in Caribbean coral reef sponges

Leong, Wai January 2009 (has links) (PDF)
Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (January 12, 2010) Includes bibliographical references (p. 52-55)
355

A Meta-Analysis of Successful Community-Based Payment for Ecosystem Services Programs

Pritzlaff, Richard G. 13 June 2018 (has links)
<p> Ecosystem services (ES), payments for ecosystem services (PES), and the development of markets for PES are transformational concepts and practices that emerged from environmental and ecological economics. Although the establishment of regulatory markets tends to be &ldquo;top down,&rdquo; there is evidence that more locally acceptable and successful markets tend to come from the community, from the &ldquo;bottom up.&rdquo; This meta-analysis analyzes 20 recent articles that examined approximately 454 PES cases from around the world, most organized from the bottom up. Cross-case analysis reveals possible best practices. Involving communities in design, decision-making, governance, and operation of local PES programs is found in many cases to contribute to improvements in both ecosystems and community livelihoods. Devolving project administration and ES provision monitoring to the local level is found to lower costs, increase project legitimacy, community equity, and leaves efficiency and fairness tradeoff decision-making in the hands of local communities. This in turn adds to feelings of competence, autonomy, and control. The experience of cooperative learning, skill acquisition, and enhanced individual and community capacities that results from participation in PES program design is found to positively influence social, cultural, economic, and multilevel political dynamics, allowing local sustainable resource use and management to emerge. In several cases, there are indications that this leads to a changed local and regional political economy due to successful value capture of enhanced ES resulting from restored ecosystems, as well as indications of other transformative changes in communities. These findings are used to provide recommendations to a watershed restoration initiative in the borderlands of Southern Arizona. </p><p>
356

The role of the state and good governance in energy resource management : the dialectics of change

Botchway, Francis N. N. January 2000 (has links)
The reforms initiated in the global energy industry since the late 1980s have been seen as phenomenal and radical. In the main, the changes are perceived as the manifestation of the inexorable retreat of the state, apparently due to its failings, from the energy business. This thesis argues that the real position in the industry is not conterminous with that postulate. The unique character of the energy industry guarantees that the state's influence may change, but not swept away. Even when methods change, the objectives of state participation - efficiency, equity and stability - remain unalterable. This is demonstrated in three forms: First, domestic regulation of the industry, second, the exploitation of energy resource from a source shared by two or more countries, and third, international trade in energy. Indeed, the ubiquitous presence of the state in the energy industry has yielded varying results in different countries, and as in the case of Ghana, for different utilities. This thesis proposes that good governance is the critical variable that accounts for the difference. The need for stable governance, not characterised by the endurance of dictatorship, but exhibited in the form of competitive democracy, effective bureaucracy, rule of law, discretion and decentralisation, form the macro foundation for the efficient, equitable and stable operation of the energy business.
357

Determinants of Foreign Direct Investment| Natural Resources a Driven Factor| The Case of Ghana, Nigeria, and Togo

Owusu-Nyamekye, Dwobeng 10 August 2018 (has links)
<p> The disappointing economic performance of Nigerian, Ghanaian, and the Togolese economies, coupled with the globalization of activities in the world economy, have forced them to look outward for development strategies. Many studies have been attempted to estimate the impact of natural resources on foreign direct investment (FDI) inflows around the world, but very few have been focused on Ghana, Nigeria and Togo. This study departed from previous studies and employed a gravity-type framework to explicitly explore the question of whether natural resource endowments was a more relevant factor that explained the FDI&rsquo;s attraction to the countries under study. The study also included other FDI determinants. Accordingly, this study served to investigate whether natural resources attracted FDI inflows in Ghana, Nigeria, and Togo. Using time series data from 1980&ndash;2015, the study was conducted to answer two research questions. Two models were established utilizing the pooled ordinary least square method to estimate the coefficients of the models. Preliminary results were obtained using both the random effect and fixed effect models. The results of the study yielded by both techniques registered natural resources to be significant as a driven factor for FDI inflows to the countries under review. Other factors such as GDP per capita, trade openness, political stability, and economic liberalization were also found to be significant in FDI determination. </p><p>
358

The Political Economy of Non-Renewable Resource Ownership and Control

Lokanc, Martin 26 October 2018 (has links)
<p> A large body of literature finds a negative relationship between natural resource abundance and economic efficiency. With few notable exceptions, this literature does not account for variations in the ownership and control of the resources. Through an analytical interpretation of results from a game-theoretic political economy model, this study examines how economic rents, the opportunity cost of firms, potential cost or market access advantages of the private sector and time preferences of politicians combine to affect a politician&rsquo;s preferences for ownership and control of a non-renewable resource. I find that the resulting choice of ownership type, public or private, is context-specific and that no generalisations can be made: among other factors politicians will consider the size of the resource, expected price paths, whether the private sector has a cost or market access advantage over the state when making its decision, prices and the degree to which the government holds a non-controlling equity stake in the firm. With respect to the efficiency of public versus private ownership, I find that either model can be efficient and that the result is driven mainly by: (i) the differences in time preferences between politicians, the private sector and the social optimum; and (ii) the degree to which the private sector holds a non-appropriable competitive advantage over the government. The model provides a rich and nuanced interpretation of the incentives governments face in making ownership decisions over non-renewable resources. The results act as a reminder to advisers to take into consideration country specifics when making recommendations to governments about which forms of ownership and control lead to a more efficient outcome. Results are corroborated by observations in empirical literature and the model&rsquo;s explanatory power is highlighted through a range of country case studies.</p><p>
359

Establishing and Evaluating Agricultural Plantings and Supplemental Cover on Reservoir Mudflats as a Means to Increase Juvenile Game Fish Abundance and Growth

Hatcher, Hunter R. 01 January 2019 (has links)
<p> Reservoirs throughout the country exhibit degraded shorelines and simplified littoral habitats because of aging. This study evaluated the establishment of agricultural plantings on reservoir mudflats and the effectiveness of supplemental brush pile structures in providing recruitment habitat for juvenile fish. The mudflats of Enid Reservoir, Mississippi were seeded during the winter drawdown in October of 2016 and 2017 with agricultural plantings. Monitoring of plantings found grasses performed best in terms of establishment and providing potential fish habitat. During Summer 2017 brush piles and control sites, without brush, were sampled in Enid Reservoir using rotenone to evaluate juvenile fish use. Juvenile fish exhibited greater abundances and larger sizes, on average, in brush pile sites. Larger brush piles placed in shallower water provided the greatest benefit to juvenile fish.</p><p>
360

Herpetofauna Community Responses to Saltcedar (Tamarix spp.) Biological Control and Riparian Restoration Along a Mojave Desert Stream, U.S.A.

January 2014 (has links)
abstract: In riparian ecosystems, reptiles and amphibians are good indicators of environmental conditions. Herpetofauna have been linked to specific microhabitat characteristics, microclimates, and water resources in riparian forests. My objective was to relate herpetofauna abundance to changes in riparian habitat along the Virgin River caused by the Tamarix biological control agent, Diorhabda carinulata, and riparian restoration. During 2013 and 2014, vegetation and herpetofauna were monitored at 21 riparian locations along the Virgin River via trapping and visual encounter surveys. Study sites were divided into four stand types based on density and percent cover of dominant trees (Tamarix, Prosopis, Populus, and Salix) and presence of restoration activities: Tam, Tam-Pros, Tam-Pop/Sal, and Restored Tam-Pop/Sal. Restoration activities consisted of mechanical removal of non-native trees, transplanting native trees, and introduction of water flow. All sites were affected by biological control. I predicted that herpetofauna abundance would vary between stand types and that herpetofauna abundance would be greatest in Restored Tam-Pop/Sal sites due to increased habitat openness and variation following restoration efforts. Results from trapping indicated that Restored Tam-Pop/Sal sites had three times more total lizard and eight times more Sceloporus uniformis captures than other stand types. Anaxyrus woodhousii abundance was greatest in Tam-Pop/Sal and Restored Tam-Pop/Sal sites. Visual encounter surveys indicated that herpetofauna abundance was greatest in the Restored Tam-Pop/Sal site compared to the adjacent Unrestored Tam-Pop/Sal site. Habitat variables were reduced to six components using a principle component analysis and significant differences were detected among stand types. Restored Tam-Pop/Sal sites were most similar to Tam-Pop/Sal sites. S. uniformis were positively associated with large woody debris and high densities of Populus, Salix, and large diameter Prosopis. Restored Tam-Pop/Sal sites likely supported higher abundances of herpetofauna, as these areas exhibited greater habitat heterogeneity. Restoration activities created a mosaic habitat by reducing canopy cover and increasing native tree density and surface water. Natural resource managers should consider implementing additional restoration efforts following biological control when attempting to restore riparian areas dominated by Tamarix and other non-native trees. / Dissertation/Thesis / Masters Thesis Applied Biological Sciences 2014

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