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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.
1351

The efficacy of reintroducing the New Zealand falcon into the vineyards of Marlborough for pest control and falcon conservation

Kross, Sara Mae January 2012 (has links)
In our ever more populated world, the rapid expansion and intensification of agriculture is driving worldwide biodiversity loss, and the interactions between production landscapes and wildlife conservation are becoming increasingly important. Farming systems depend on ecosystem services such as biological control, while conservationists are calling for the establishment of conservation initiatives in non-preserve landscapes. Despite this, the goals of agriculture and the goals of predator-conservation are rarely mutual. Here, I demonstrate one of the first examples of a mutually beneficial scenario between agriculture and predator conservation. I used, as a case study, a reintroduction project that translocated individuals of the threatened New Zealand falcon (Falco novaeseelandiae) from the hills of Marlborough into vineyards, to determine if predators can survive within an agricultural landscape while simultaneously providing that landscape with biological control services. Examples of vertebrates providing biological control to agriculture are rare. I show that the presence of falcons in vineyards caused an economically important reduction in grape damage worth over US $230/ ha. Falcon presence caused a 78- 83% reduction in the number of introduced European pest birds, which resulted in a 95% reduction in the damage caused by these species. Falcon presence did not cause a reduction in the abundance of the native silvereye (Zosterops lateralis), but did halve the damage caused by this species. To assess the conservation value of the falcon translocations, I used remote videography, direct observations and prey analysis to measure the behavioural changes associated with the relocation of falcons from their natural habitat in the hills and into vineyards. Falcons in vineyard nests had higher nest attendance, higher brooding rates, and higher feeding rates than falcons in hill nests. Additionally, parents in vineyard nests fed their chicks a greater amount of total prey and larger prey items compared to parents in hill nests. I also found an absence of any significant diet differences between falcons in hill and vineyard habitats, suggesting that the latter may be a suitable alternative habitat for falcons. Because reintroduced juvenile falcons were released in areas devoid of adult falcons, it was possible that they were missing essential training normally provided by their parents. I used direct observations to demonstrate that the presence of siblings had similar effects to the presence of parents on the development of juvenile behaviour, with individuals flying, hunting, and playing more often when conspecifics were present. Finally, through the use of artificial nests and remote videography, I identified that falcons nesting in vineyards are likely to suffer lower predation rates. I also found that falcons in vineyards are predated by a less dangerous suite of animals (such as hedgehogs, Erinaceus europaeus, and avian predators), than their counterparts in the hills, which are predated by more voracious species (such as stoats, Mustela erminea, and feral cats, Felis catus). The work presented in this thesis has also added to the current knowledge of New Zealand falcon breeding behaviour, prey preferences, and behavioural development. Although agricultural regions globally are rarely associated with raptor conservation, and the ability of raptors to control the pests of agricultural crops has not been previously quantified, these results suggest that translocating New Zealand falcons into vineyards has potential for both the conservation of this species, and for providing biological control services to agriculture
1352

THE ECOLOGY OF DISTURBANCES AND GLOBAL CHANGE IN THE MONTANE GRASSLANDS OF THE NILGIRIS, SOUTH INDIA

Srinivasan, Madhusudan P. 01 January 2011 (has links)
Biodiversity rich regions worldwide face threats from various global change agents. This research quantifies environmental influences on vegetation, and the impacts of exotic woody plant invasion and anthropogenic nitrogen (N) deposition in a global biodiversity hotspot. The study was conducted in the montane grasslands of the Nilgiris, Western Ghats, and outlines potential management options for this region. Specifically, I examined (1) the role of environmental factors in influencing native plant distribution and ecosystem properties, (2) the status and impact of exotic shrub (Scotch broom, henceforth broom) invasion, (3) the role of disturbances in the success of broom, (4) the role of fire in restoring invaded grasslands, and (5) the impacts of terrestrial N loading on the grassland ecosystem. I used experiments and surveys to assess these. Distributions of several key species were explained by a few complex environmental gradients. In invaded-grasslands, broom populations consisted mainly of intermediate size and age classes, with no clear indication of population decline. Invasion negatively impacted plant community structure and drastically changed composition, favoring shade-tolerant and weedy species. However, invasion did not greatly alter ecosystem function. Fire successfully eliminated mature broom stands, but resulted in a short-term increase in broom seedling recruitment. At the end of 18 months, the fire effects on uninvaded-grasslands were not apparent, but there was no conclusive evidence of the formerly invaded patches attaining the composition of uninvaded-grasslands following burning. N fertilization strongly influenced soil N dynamics, and shoot N concentrations, but effects on aboveground production were weak. Surprisingly, N enrichment had positive effects on diversity in the short-term. It is clear that these grasslands need immediate management intervention to forestall degradation from invasion. Fire could be used to eliminate mature broom stands and deplete persistent seedbanks, which will facilitate colonization by shade-intolerant grassland plants. Active restoration should be mindful of environmental preferences of framework species. Long-term studies of the impacts of N deposition in the context of disturbances will help determine realistic critical thresholds and utilize disturbances to buffer the potential adverse effects of increasing N loading.
1353

On the dynamic management of marine resources

Dunn, Daniel Carl January 2014 (has links)
<p>Mismatches in the spatiotemporal variability of resource, resource users and management actions breeds inefficiency in the management of marine resources. To date, the spatiotemporal resolution and extent of fisheries management has been largely dictated by logistical and political constraints, and secondarily by the geographic range of the species or meta-population dynamics. Management units are rarely smaller than 1000 km2 in developed coastal fisheries, and management measures generally occur at resolutions larger than 100 km2. From a temporal perspective, the finest resolution of management measures is at best a month but more generally a year. As such, attempts to manage processes and patterns at sub-10 km, sub-1 month resolution often involve some level of spatiotemporal mismatch. To address the obvious spatiotemporal mismatch between a dynamic ocean and static management, to allow for a comprehensive implementation of ecosystem-based fisheries management, and to minimize inefficiency in our management of marine resources, we must seek to develop more dynamic management measures that allow managers to address scales, processes and patterns occurring under ten kilometers.</p><p>In this dissertation I apply point pattern processes, cumulative distribution functions, receiver operator characteristic curves, simulated annealing tools, regression models and clustering techniques to develop examples of two dynamic management measures and to compare the efficiency of static versus dynamic management measures. I show that autocorrelation analysis can inform the distances and times used in real-time closures based on move-on rules. Further, I identify optimum bottom temperature threshold values to separate individual species within the Northeast Multispecies Fishery from Atlantic cod. Results demonstrate that dynamic spatiotemporal management measures are widely applicable, and more effective and more efficient than static time-area closures. Unexpected trends in some results due to a changing climate indicate possible increasing thermal overlap between Atlantic cod and many other species in the fishery. Implications of scale in fisheries management and the importance of coarse scale (1 - 10km) ecological patterns to fisheries are discussed.</p> / Dissertation
1354

Efficacy of an Electronic Scarecrow on 4 Mammalian Crop-Raiders in Limpopo Province, South Africa

Richardson, Merrie Renee 01 August 2014 (has links)
In South Africa, 2 primate species, Chacma baboons (Papio ursinus) and vervet monkeys (Chlorocebus pygerythrus), and 2 nocturnal mammals, Cape porcupine (Hystrix africaeaustralis) and bushbuck (Tragelaphus scriptus), are among many species of crop raiders. Currently, cost-effective, non-lethal solutions are lacking. From June through December 2012, I installed novel electronic scarecrows on two commercial citrus orchards and a private reserve and used video-recording remote cameras to assess cropraiders’ reactions to them in Limpopo Province, South Africa. I used focal animal sampling data from treatment and control group animals to examine differences in activity budgets and behaviors of interest between groups. Compared to animals at sites with an inactive or no scarecrow, I hypothesized that animals in the treatment group would have altered activity budgets and rates of behaviors; that they would forage or feed less, run more (as a result of being frightened), be more vigilant and thus scan their surroundings more often, and display a visible startle in response to stimuli from scarecrows. Bushbuck at treatment sites spent a larger proportion of their activity budget running, and were more often startled. However, foraging was never observed, and bushbuck in the control group scanned their surroundings more often. Porcupines at treatment sites spent a larger portion of their activity budget running, though foraging was only observed in 1 control group animal and looking was never observed. For primates, treatment (control, scarecrow) was meaningful in explaining differences in focal animal activity budgets of baboons (F = 5.49, P = 0.001) and vervet monkeys (F = 7.09, P = 0.001) as indicated by a permutational MANOVA in R. In baboons, treatment was positively correlated with running; ratios of baboons that ran to baboons that did not run differed between treatment groups (G = 15.78, P < 0.001). Treatment was negatively correlated with feeding; ratios of baboons that fed or foraged to baboons that did not feed or forage differed (G = 5.39, P = 0.02). Significant differences between groups of vervet monkeys were not found with G-tests for the same behaviors of interest. Electronic scarecrows are promising tools for human-wildlife conflict mitigation, particularly for nocturnal antelopes. For primates, further innovation in design of scarecrows to incorporate a visual stimulus is recommended.
1355

Valuing ecosystem services - linking ecology and policy

Noring, Maria January 2014 (has links)
Ecosystem services constitute a precondition for human welfare and survival. This concept has also become increasingly popular among both scientists and policymakers. Several initiatives have been taken to identify and value ecosystem services. Several services are threatened, and it has been concluded that in order to better manage ecosystem services they need to be further investigated and valued. By measuring them using a common metric—monetary value—they can be more easily compared and included in decision-making tools. This thesis contributes to this goal by presenting values for several ecosystem services and also including them in decision-making tools. Starting with a discussion of the concept of ecosystem services, this thesis aims to present values for certain ecosystem services and to illustrate the use of these values in systems-analysis tools such as cost-benefit analyses (CBA) and a weighting set. Links between ecology, economics and policy are discussed within a broader framework of ecosystem services. Five papers are included, in which two contingent valuation studies (CV) have been used to find values for different ecosystem services. One valuation study is focused on the effects from tributyltin (TBT) in Swedish marine waters. In addition, a quantitative assessment framework has been developed in order to simplify analysis of environmental status, progress in environmental surveillance and the relevance of different measures. It is suggested that the framework should also be used when assessing the impacts of other substances affecting the environment. The second valuation study investigates the risk of an oil spill in northern Norway. The results have been included in two CBAs and a weighting set. The first CBA compares costs for remediation of polluted sediments, caused by TBT, with the benefits of reducing TBT levels. The second CBA compares costs and benefits for reducing the probability of an oil spill. The weighting set includes monetary values on a number of impact categories where marine toxicity is based on the valuation study on TBT.  One study also examines the inclusion of environmental costs in life cycle costing (LCC) in different sectors in Sweden. Results show that respondents consider ecosystem values to be important. The values of Swedish marine waters and coastal areas outside Lofoten-Vesterålen in Norway have been identified and quantified in terms of biodiversity, habitat, recreation and scenery. In the Norwegian case, an ongoing debate on the issue of oil and gas exploration has had an impact on the number of protest bids found in the study. Based on the cost and benefits of limiting impacts on ecosystem services derived from the valuation studies, CBAs show that the suggested measures are most likely beneficial for society, and the results contribute to policy recommendations. A weighting set has been updated with new values through value transfer. The weighting set is compatible with LCA. The final study shows that companies and public organisations use environmental costs (internal and external) in a limited manner. In this thesis the ecosystem service concept is used both as an introduction and a guiding thread for the reader, as a way to frame the studies undertaken. The concept of ecosystem services can be useful, as it emphasises the importance of the services to humans. By finding and presenting values of ecosystem services, such services are more easily incorporated into decision-making. / <p>QC 20141121</p>
1356

Implementation of the push-pull strategy for Eldana saccharina control on sugarcane in KwaZulu-Natal, South Africa / J.J. Cockburn

Cockburn, Jessica Jane January 2013 (has links)
The aim of the research presented in this dissertation was to further the implementation of push-pull for control of Eldana saccharina on sugarcane in the Midlands North region, KwaZulu-Natal, South Africa. Eldana saccharina, an indigenous stem borer, is the most damaging pest of sugarcane in South Africa, and sustainable control has still not been achieved. The push-pull strategy, a form of habitat management, has been developed for E. saccharina and is recommended as part of an integrated pest management (IPM) approach. Implementation of this strategy for both large- and small-scale farmers was facilitated through mixed methods social research. It included a novel exploratory network analysis to understand the process of technology adoption by farmers. Surveys showed that large-scale farmers have a good knowledge of E. saccharina, IPM and push-pull but that they needed more practical knowledge for implementation of the strategy. Farmers recommended experiential learning opportunities such as field days and model farms to get to know more about this technology. Despite demonstrating a positive attitude towards push-pull, farmers perceived it to be a ‘hassle’ and this is potentially the biggest barrier to its adoption. However, with suitable learning opportunities for farmers and good support for planting inputs, implementation of push-pull is likely to succeed. Sugarcane was shown to play an important role in the livelihoods and farming systems of small-scale growers. They did not perceive E. saccharina as a serious production constraint and had poor knowledge of the pest and its control. Extension for small-scale growers in this region should focus primarily on weed management and on reducing input costs, but still raising awareness of the increasing threat of E. saccharina. On-farm push-pull field trials showed a significant reduction of E. saccharina damage on two farms. Mean percentage damaged internodes decreased from 4.1% to 2.7% and from 1.7% to 1.1% in the presence of the repellent grass species, Melinis minutiflora. Where farmers did not manage their crops well, push-pull was not effective. It is therefore crucial that push-pull within an IPM framework be implemented together with good crop management practices. Stem borer surveys in wetlands on sugarcane farms revealed a high diversity of indigenous stem borers and parasitoids, including a stem borer species, Pirateolea piscator, which may pose a threat to crops in the future. These findings, together with a literature review on the significance of on-farm biodiversity and ecosystem services, demonstrated the value which wetlands have for pest management on sugarcane farms. Wetland health assessments were used to develop a tool for farmers to assess and utilise the wetlands on their farms for improved management of E. saccharina. This study highlights the importance of a farmer-participatory approach to implementation of knowledge-intensive farming practices such as push-pull. The importance of wetlands for providing pest regulatory services on sugarcane farms has shown that environmental sustainability needs to become a fundamental principle of farming and agricultural research. Participatory implementation of push-pull, as recommended in this dissertation, could act as a driving force for agroecology in the South African sugar industry and move sustainable farming practices off the pages of journals and manuals onto farmers’ fields. / Thesis (MSc (Zoology))--North-West University, Potchefstroom Campus, 2013
1357

Implementation of the push-pull strategy for Eldana saccharina control on sugarcane in KwaZulu-Natal, South Africa / J.J. Cockburn

Cockburn, Jessica Jane January 2013 (has links)
The aim of the research presented in this dissertation was to further the implementation of push-pull for control of Eldana saccharina on sugarcane in the Midlands North region, KwaZulu-Natal, South Africa. Eldana saccharina, an indigenous stem borer, is the most damaging pest of sugarcane in South Africa, and sustainable control has still not been achieved. The push-pull strategy, a form of habitat management, has been developed for E. saccharina and is recommended as part of an integrated pest management (IPM) approach. Implementation of this strategy for both large- and small-scale farmers was facilitated through mixed methods social research. It included a novel exploratory network analysis to understand the process of technology adoption by farmers. Surveys showed that large-scale farmers have a good knowledge of E. saccharina, IPM and push-pull but that they needed more practical knowledge for implementation of the strategy. Farmers recommended experiential learning opportunities such as field days and model farms to get to know more about this technology. Despite demonstrating a positive attitude towards push-pull, farmers perceived it to be a ‘hassle’ and this is potentially the biggest barrier to its adoption. However, with suitable learning opportunities for farmers and good support for planting inputs, implementation of push-pull is likely to succeed. Sugarcane was shown to play an important role in the livelihoods and farming systems of small-scale growers. They did not perceive E. saccharina as a serious production constraint and had poor knowledge of the pest and its control. Extension for small-scale growers in this region should focus primarily on weed management and on reducing input costs, but still raising awareness of the increasing threat of E. saccharina. On-farm push-pull field trials showed a significant reduction of E. saccharina damage on two farms. Mean percentage damaged internodes decreased from 4.1% to 2.7% and from 1.7% to 1.1% in the presence of the repellent grass species, Melinis minutiflora. Where farmers did not manage their crops well, push-pull was not effective. It is therefore crucial that push-pull within an IPM framework be implemented together with good crop management practices. Stem borer surveys in wetlands on sugarcane farms revealed a high diversity of indigenous stem borers and parasitoids, including a stem borer species, Pirateolea piscator, which may pose a threat to crops in the future. These findings, together with a literature review on the significance of on-farm biodiversity and ecosystem services, demonstrated the value which wetlands have for pest management on sugarcane farms. Wetland health assessments were used to develop a tool for farmers to assess and utilise the wetlands on their farms for improved management of E. saccharina. This study highlights the importance of a farmer-participatory approach to implementation of knowledge-intensive farming practices such as push-pull. The importance of wetlands for providing pest regulatory services on sugarcane farms has shown that environmental sustainability needs to become a fundamental principle of farming and agricultural research. Participatory implementation of push-pull, as recommended in this dissertation, could act as a driving force for agroecology in the South African sugar industry and move sustainable farming practices off the pages of journals and manuals onto farmers’ fields. / Thesis (MSc (Zoology))--North-West University, Potchefstroom Campus, 2013
1358

Plant and arthropod diversity of maize agro–ecosystems in the Highveld and Lowveld regions of South Africa / Bheki George Maliba

Maliba, Bheki George January 2011 (has links)
Surveys of plant and selected insect species was conducted in Highveld and Lowveld agro–ecosystems of four provinces of South Africa, namely North–West, Mpumalanga, KwaZulu–Natal and Limpopo. The objectives of the study were to compare insect and plant diversity between localities (grassland and savanna) and treatments (maize field, semi–transformed and untransformed) to test for a general relationship between plant and insect diversity along a maize field–field margin gradient. Plant and insect diversity patterns were studied along the gradient and quantified in terms of richness and diversity indices. Plant and insect species compositional turnover was also measured along the maize field–field margin gradient. Plant diversity increased with increasing distance from maize fields into the margin. The flora in maize fields and of margins differed, but in contrast, insect species assemblages were similar in maize fields and margins. There was no statistical difference in insect diversity between treatments (maize field, semi–transformed and transformed). A relationship was revealed between plant and insect diversity, as plant diversity enhanced insect diversity. / Thesis (M.Sc. (Environmental Sciences))--North-West University, Potchefstroom Campus, 2011.
1359

Evaluating and Predicting Ecosystem Services

Kadykalo, Andrew 10 September 2013 (has links)
The valuation of ecosystem services requires first and foremost, that the current level or stock of a service first be estimated. Here, I investigate the relationship between the fields of environmental science and ecological economics in their research effort of ecosystem services and the implications this may have on the ecosystem valuation research program. I investigate two ecological functions described as ecosystem services within specific ecosystem types: the flood control provisioning services of wetlands and pollination service provisioning by pollinator populations in agroecosystems. I examined the environmental literature to provide quantitative estimates of a) the distribution of the level of service delivered as well as b) the ability of environmental scientists to predict this level of service. The results presented here suggest a moderately strong correlation between research efforts in environmental science and ecological economics at the pooled level of ecosystem types and services. I suggest however, an integrated research enterprise between social and environmental scientists may provide greater efficiency by means of a global ecosystem service research network and repository. I found that, on average, consistent with conventional wisdom, wetlands do indeed have a positive effect by reducing the frequency and magnitude of floods, increasing low flows, and increasing water storage. In the same vein, I found on average and consistent with conventional wisdom, there is a consistent and comparatively strong association between pollinator abundance and agroecosystem productivity as inferred from measures of plant fertilization success. In both investigations however, metaregression analysis indicated that our current ability to predict either pollination or flood control services is poor to modest at best. The low predictive power combined with the observed heterogeneity in effect size in both investigations suggest that flood control service delivered by wetlands or pollination services delivered by natural pollinator populations in agroecosystems and the expected changes in the level of services delivered under a candidate management scenario, will have a large uncertainty. Such uncertainty should be explicitly incorporated into estimates of both the current economic value of ecosystem services, as well as estimates of how these values are likely to change under alternative management scenarios. Given these, I suggest that the implications for the development of Market-based instruments (MBIs) or any payment of ecosystem services to conserve ecosystem services: that the associated ecological function(s) must be few and well characterized, and we must agree on what endpoints ought to properly be used to characterize these functions. If this condition is not met, an ordinal ranking is the best we can do and in the absence of obvious enthusiasm for more detailed scientific research which leads to the conclusion that perhaps alternate strategies like command and control may be the better alternative to protect ecosystem services.
1360

CO2 exchange in a subarctic sedge fen in the Hudson Bay Lowland during two consecutive growing seasons

Swystun, Kyle A. 11 April 2011 (has links)
Net ecosystem carbon dioxide exchange (NEE) was measured using the eddy covariance (EC) technique at a wetland tundra-sedge fen near Churchill, Manitoba, Canada during two consecutive growing seasons (2007 and 2008). Mean daily NEE at the fen (DOY 157-254) was -3.5 (± 0.26 S.E.) g CO2 m-2 d-1 in 2007 and -4.6 (± 0.36) g CO2 m-2 d-1 in 2008. The fen was a net carbon dioxide (CO2) sink during both the 2007 and 2008 growing seasons of -343 (± 79) and -450 (± 87) g CO2 m-2, respectively. Mean air temperature during the summer (June 1-August 31) was about 1°C greater than the historical average (1971-2000) in 2007 and about 2°C greater in 2008. Growing season precipitation was 107.5 mm below normal in 2007 and 359.5 mm above normal in 2008. These data suggest that if future climate change brings warmer temperatures and near-to-above average precipitation maintaining the water table near the surface, similar subarctic ecosystems will experience increased gross ecosystem productivity enhancing CO2 sequestration during the growing season.

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