Browsing by Subject "Ecosystem"
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Item Adaptive management : harvesting the benefits while reducing the risks for ecological restoration projects(2010-12) Jarrett, Lara Ann; Butler, Kent S.Adaptive Management (AM) is an “approach to managing natural resources that emphasizes learning from the implementation of policies and strategies” (Allan & Curtis, 2005). The approach involves the monitoring and evaluation of hypotheses regarding system responses and/or the success of individual projects followed by integration of the findings into future efforts. It can be characterized as active (focused upon testing hypotheses) or passive (focused upon implementation). AM has been used by several federal and state agencies for the implementation of large-scale restoration efforts. This paper explores the use of AM in two large, regional water resources projects with state and federal agency involvement and significant ecological and economic resources at risk without intervention: the Sacramento-San Joaquin Bay Delta in California and the Everglades Restoration in Florida. The paper explores potential avenues for further improvement of the AM efforts with an emphasis on: governance; establishment of networks to aid adaptive management, provisions for funding especially for active AM; cost-benefit analyses; and delegation of authority to allow for implementation of adaptive management.Item Ecological mechanisms underlying soil microbial responses to climate change(2013-12) Waring, Bonnie Grace; Hawkes, Christine V.Soil microbes influence the global carbon cycle via their role in the decomposition and formation of soil organic matter. Thus, rates of ecosystem processes such as primary production, soil respiration, and pedogenesis are sensitive to changes in the aggregate functional traits of the entire microbial community. To predict the magnitude and direction of microbial feedbacks on climate change, it is necessary to identify the physiological, ecological, and evolutionary mechanisms that underlie microbes’ responses to altered temperature and rainfall. Therefore, I examined microbial community composition and function in relation to manipulations of resource availability and precipitation in two contrasting ecosystems: a tropical rainforest at La Selva Biological Station, Costa Rica, and a semi-arid grassland in central Texas. I conducted a leaf litter decomposition experiment at La Selva to identify the physiological constraints on microbial allocation to extracellular enzymes, which degrade organic matter. I found strong evidence that microbial enzyme production is decoupled from foliar stoichiometry, consistent with weak links between leaf litter nutrients and decomposition rates at the pan-tropical scale. Next, to examine whether ecological trade-offs within microbial communities may drive shifts in carbon cycling at local spatial scales, I quantified changes in soil fungal and bacterial community composition in response to an in situ precipitation exclusion experiment I established at La Selva. Although drought-induced shifts in community structure were small, large increases in biomass-specific respiration rates were observed under dry conditions. These findings suggest that physiological adjustments to drought may constitute an important feedback on climate change in wet tropical forests. Finally, I focused on microbial community responses to climate change within a meta-community framework, using a reciprocal transplant experiment to investigate how dispersal shapes bacterial community structure along a natural rainfall gradient in central Texas. I found that soils from the wet end of the precipitation gradient exhibited more plastic functional responses to altered water availability. However, soil bacterial community composition was resistant to changes in rainfall and dispersal, preventing functional acclimatization to precipitation regime. Together, the results of these experiments emphasize the potential for physiological plasticity or microevolutionary shifts within microbial populations to drive ecosystem carbon cycling under climate change.Item The Exergy Flows of Siena: Lorenzettl' s Allegories as Ecosystems(2021-12-10) Wilkinson, Rhys WynnItem Invasive plant survey of parks and preserves in East Travis County(2013-12) Menchaca, Jessica Jane; Fowler, Norma L.; Mehdy, Mona Cynthia, 1955-Invasive species are the second-leading cause of the decline of native species, making it a critical global environmental issue (Pimentel 2005). The goal of this study was to identify which non-native invasive plant species are common in eastern Travis County and which environmental factors associate with their establishment and spread in this area. Five parks and preserves were sampled, as they are intended for the conservation of native species and are more accessible for educational use. Six of the 15 species searched for, Bothriochloa ischaemum, Lactuca serriola, Ligustrum lucidum, Lonicera japonica, Melia azedarach, and Sorghum halepense, were each found in at least one of the five sites. The presences and absences of these species were compared to a suite of ecosystem properties, including habitat, disturbance, the average soil depth, and the horizontal and vertical distances to the nearest pond, lake, stream, or river. None of these six species appears to need observable recent disturbance. All of these six species, both woody and herbaceous, can tolerate shallow soils. The woody invasive species Ligustrum lucidum and Melia azedarach seem to prefer more mesic habitats. The invasive grass species Bothriochloa ischaemum and Sorghum halepense seem to prefer habitats that are more open. Several invasions of potential conservation concern were identified.Item Standardization and firms’ innovative activities within ecosystems : two essays on the Formula One industry(2022-08-18) Pyun, Eugene; Toh, Puay Khoon; Polidoro, Francisco; Ranganathan, Ramkumar; Wen, WenThis dissertation studies how standardization can affect ecosystem member organizations’ innovations and performances both in organizational and individual levels. Standardization is an effective coordination tool to help ecosystems overcome coordination challenges by providing compatibility and interoperability within ecosystems. However, to achieve compatibility, standardization needs to fix and limit core technologies and components only to standardized cores and must enforce guidelines to its member organizations. In other words, the coordinating effect of standardization may require hefty prices from its ecosystem. To address the tension between standardization’s positive role as a coordination tool and necessary organizational costs to adopt standards, the current dissertation examines how standardization can influence various aspects of organizational functions. The dissertation is organized as the following. The first section a general introduction and overview of the dissertation. Then the dissertation proceeds to a literature review of relevant prior research on ecosystems and standardization that analyze the theoretical tension between standardization as a coordination tool and required costs to accommodate standards. The chapter will then proceed to identification of research opportunities based on the existing literature. Chapter I then demonstrates the constraining effect of standardization on firms’ innovation through the theoretical lens of knowledge recombination. In addition, using the perspectives of knowledge-based view and organizational change, Chapter II will analyze the disrupting effect of standardization on human capital performances within ecosystem member organizations. Lastly, the dissertation will then provide a conclusion and message of the dissertation. Using data on Formula One motorsports industry regarding standardization which consist of F1 teams’ innovations and drivers’ performances in 1970 - 2020, the dissertation empirically tests the proposed theories. The dissertation utilized machine learning based LDA topic modelling techniques to capture impacts of standardization on components of F1 race cars and track standardization activities among the components. The findings from the empirical analyses of this dissertation demonstrate that standardization can negatively affect various activities of ecosystems’ member organizations.