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- Genre: Academic theses
General ecological thought pertaining to plant biology, conservation, and urban areas has rested on two potentially contradictory underlying assumptions. The first is that non-native plants can spread easily from human developments to “pristine” areas. The second is that native plants cannot disperse through developed areas. Both assume anthropogenic changes to ecosystems create conditions that favor non-native plants and hinder native species. However, it is just as likely that anthropogenic alterations of habitats will favor certain groups of plant species with similar functional traits, whether native or not. Migration of plants can be divided into the following stages: dispersal, germination, establishment, reproduction and spread. Functional traits of species determine which are most successful at each of the stages of invasion or range enlargement. I studied the traits that allow both native and non-native plant species to disperse into freeway corridors, germinate, establish, reproduce, and then disperse along those corridors in Phoenix, Arizona. Field methods included seed bank sample collection and germination, vegetation surveys, and seed trapping. I also evaluated concentrations of plant-available nitrate as a result of localized nitrogen deposition. While many plant species found on the roadsides are either landscape varieties or typical weedy species, some uncommon native species and unexpected non-native species were also encountered. Maintenance regimes greatly influence the amount of vegetative cover and species composition along roadsides. Understanding which traits permit success at various stages of the invasion process indicates whether it is native, non-native, or species with particular traits that are likely to move through the city and establish in the desert. In a related case study conducted in Victoria, Australia, transportation professionals and ecologists were surveyed regarding preferences for roadside landscape design. Roadside design and maintenance projects are typically influenced by different groups of transportation professionals at various stages in a linear project cycle. Landscape architects and design professionals have distinct preferences and priorities compared to other transportation professionals and trained ecologists. The case study reveals the need for collaboration throughout the stages of design, construction and maintenance in order to efficiently manage roadsides for multiple priorities.
can also infect people. In recent decades, and especially since the emergence of highly pathogenic avian influenza (HPAI) H5N1 in 1996, these diseases have become a significant threat to animal and public health across the world. HPAI H5N1 has caused severe damage to poultry populations, killing, or prompting the culling of, millions of birds in Asia, Africa, and Europe. It has also infected hundreds of people, with a mortality rate of approximately 50%. This dissertation focuses on the ecological and socioeconomic drivers of avian influenza risk, particularly in China, the most populous country to be infected. Among the most significant ecological risk factors are landscapes that serve as “mixing zones” for wild waterfowl and poultry, such as rice paddy, and nearby lakes and wetlands that are important breeding and wintering habitats for wild birds. Poultry outbreaks often involve cross infections between wild and domesticated birds. At the international level, trade in live poultry can spread the disease, especially if the imports are from countries not party to trade agreements with well-developed biosecurity standards. However, these risks can be mitigated in a number of ways. Protected habitats, such as Ramsar wetlands, can segregate wild bird and poultry populations, thereby lowering the chance of interspecies transmission. The industrialization of poultry production, while not without ethical and public health problems, can also be risk-reducing by causing wild-domestic segregation and allowing for the more efficient application of surveillance, vaccination, and other biosecurity measures. Disease surveillance is effective at preventing the spread of avian influenza, including across international borders. Economic modernization in general, as reflected in rising per-capita GDP, appears to mitigate avian influenza risks at both the national and sub-national levels. Poultry vaccination has been effective in many cases, but is an incomplete solution because of the practical difficulties of sustained and widespread implementation. The other popular approach to avian influenza control is culling, which can be highly expensive and raise ethical concerns about large-scale animal slaughter. Therefore, it is more economically efficient, and may even be more ethical, to target the socio-ecological drivers of avian influenza risks, including by implementing the policies discussed here.
This dissertation considers three aspects of the problem:
1. the relationship between changes in land cover due to CRP enrollment and changes in water quality, controlling for a range of factors known to have an effect on the filtering role of different land covers;
2. the inter-annual variability in water quality measures and enrollment in different CRP conservation practices to examine the cost-effectiveness of specific conservation practices in mitigating lake sedimentation and eutrophication;
3. discrete choice models to identify what characteristics drive the enrollment by farmers into specific conservation practices.
Results indicate that land cover and CRP have different impacts on different indicators of lake water quality. In addition, conservation practices that were cost-effective for one water quality variable tended to be cost-effective for the other water quality variables. Farmers are making decisions to enroll in CRP based on the opportunity cost of the land. Therefore, it is necessary to alter financial incentives to promote productive land being putting into CRP through continuous sign-up. The United States Department of Agriculture (USDA) needs a more effective way to calculate the payment level for practices in order to be competitive with the predicted value of major crops.
The second substantive chapter explores the conservation potential of a whale permit market under bounded economic uncertainty. Pro- and anti-whaling stakeholders are concerned about a recently proposed, "cap and trade" system for managing the global harvest of whales. Supporters argue that such an approach represents a novel solution to the current gridlock in international whale management. In addition to ethical objections, opponents worry that uncertainty about demand for whale-based products and the environmental benefits of conservation may make it difficult to predict the outcome of a whale share market. In this study, I use population and economic data for minke whales to examine the potential ecological consequences of the establishment of a whale permit market in Norway under bounded but significant economic uncertainty. A bioeconomic model is developed to evaluate the influence of economic uncertainties associated with pro- and anti- whaling demands on long-run steady state whale population size, harvest, and potential allocation. The results indicate that these economic uncertainties, in particular on the conservation demand side, play an important role in determining the steady state ecological outcome of a whale share market. A key finding is that while a whale share market has the potential to yield a wide range of allocations between conservation and whaling interests - outcomes in which conservationists effectively "buy out" the whaling industry seem most likely.
The third substantive chapter examines the sea lice externality between farmed fisheries and wild fisheries. A central issue in the debate over the effect of fish farming on the wild fisheries is the nature of sea lice population dynamics and the wild juvenile mortality rate induced by sea lice infection. This study develops a bioeconomic model that integrates sea lice population dynamics, fish population dynamics, aquaculture and wild capture salmon fisheries in an optimal control framework. It provides a tool to investigate sea lice control policy from the standpoint both of private aquaculture producers and wild fishery managers by considering the sea lice infection externality between farmed and wild fisheries. Numerical results suggest that the state trajectory paths may be quite different under different management regimes, but approach the same steady state. Although the difference in economic benefits is not significant in the particular case considered due to the low value of the wild fishery, I investigate the possibility of levying a tax on aquaculture production for correcting the sea lice externality generated by fish farms.
I analyze the components of Mumford's megamachine and align key concerns in two pivotal works that characterize the impact of collective capacities on society: Bruno Latour's Pasteurization of France (1988) and Elias Canetti's Crowds and Power (1962). As I create a model of collective capacities in the sociotechnical according to the parameters of Mumford's megamachine, I rehabilitate two established ideas about the behavior of crowds and about the undue influence of technological systems on human behavior. I depart from Mumford's tactics and those of Canetti and Latour and propose a novel focus for STS on "sociotechnical crowds" as a meaningful unit of social measure. I make clear that Mumford's critique of the sociotechnical status quo still informs the conditions for innovation today.
Using mixed mode qualitative methods in two types of empirical field studies, I then investigate how a focus on the characteristics and components of collective human capacities in sociotechnical systems can affect the design and performance of TA. I propose a new model of TA, Emergent Technology Assessment (ETA), which includes greater public participation and recognizes the interrelationship among experience, affect and the material in mediating the innovation process. The resulting model -- the "soft" megamachine --introduces new strategies to build capacity for responsible innovation in society.