Comparison of Belowground Biomass in C3- and C4-Dominated Mixed Communities in a Chesapeake Bay Brackish Marsh

Belowground biomass is a critical factor regulating ecosystem functions of coastal marshes, including soil organic matter (SOM) accumulation and the ability of these systems to keep pace with sea-level rise. Nevertheless, belowground biomass responses to environmental and vegetation changes have been given little emphasis marsh studies. Here we present a method using stable carbon isotopes and color to identify root and rhizomes of Schoenoplectus americanus (Pers.) Volk. ex Schinz and R. Keller (C3) and Spartina patens (Ait.) Muhl. (C4) occurring in C3��� and C4-dominated communities in a Chesapeake Bay brackish marsh. The functional significance of the biomass classes we identified is underscored by differences in their chemistry, depth profiles, and variation in biomass and profiles relative to abiotic and biotic factors. C3 rhizomes had the lowest concentrations of cellulose (29.19%) and lignin (14.43%) and the lowest C:N (46.97) and lignin:N (0.16) ratios. We distinguished two types of C3 roots, and of these, the dark red C3 roots had anomalously high C:N (195.35) and lignin:N (1.14) ratios, compared with other root and rhizome classes examined here and with previously published values. The C4-dominated community had significantly greater belowground biomass (4119.1 g m���2) than the C3-dominated community (3256.9 g m���2), due to greater total root biomass and a 3.6-fold higher C3-root:rhizome ratio in the C4-dominated community. C3 rhizomes were distributed significantly shallower in the C4-dominated community, while C3 roots were significantly deeper. Variability in C3 rhizome depth distributions was explained primarily by C4 biomass, and C3 roots were explained primarily by water table height. Our results suggest that belowground biomass in this system is sensitive to slight variations in water table height (across an 8 cm range), and that the reduced overlap between C3 and C4 root profiles in the C4-dominated community may account for the greater total root biomass observed in that community. Given that future elevated atmospheric CO2 and accelerated sea-level rise are likely to increase C3 abundance in Atlantic and Gulf coast marshes, investigations that quantify how patterns of C3 and C4 belowground biomass respond to environmental and biological factors stand to improve our understanding of ecosystem-wide impacts of global changes on coastal wetlands.

An empirical analysis of the global audit market: International Financial Reporting Standards-related changes and differences within the Big 4 global networks

Ongoing debates within the professional and academic communities have raised a number of questions specific to the international audit market. This dissertation consists of three related essays that address such issues. First, I examine whether the propensity to switch between auditors of different sizes (i.e., Big 4 versus non-Big 4) changes as adoption of International Financial Reporting Standards (IFRS) becomes a more common phenomenon, arguing that smaller auditors have an opportunity to invest in necessary skills and training needed to enter this market. Findings suggest that clients are relatively less (more) likely to switch to (away from) a Big 4 auditor if the client's adoption of IFRS occurs in more recent years. ^ In the second essay, I draw on these inferences and test whether the change in audit fees in the year of IFRS adoption changes over time. As the market becomes less concentrated, larger auditors becomes less able to demand a premium for their services. Consistent with my arguments, results suggest that the change in audit service fees declines over time, although this effect seems concentrated among the Big 4. I also find that this effect is partially attributable to a differential effect of the auditors' experience in pricing audit services related to IFRS based on the period in which adoption occurs. The results of these two essays offer important implications to policy debates on the costs and benefits of IFRS adoption. ^ In the third essay, I differentiate Big 4 auditors into three classifications���Parent firms, Brand Name affiliates, and Local affiliates���and test for differences in audit fee premiums (relative to non-Big 4 auditors) and audit quality. Results suggest that there is significant heterogeneity between the three classifications based on both of these characteristics, which is an important consideration for future research. Overall, this dissertation provides additional insights into a variety of aspects of the global audit market.^

Estimation of global systematic risk for securities listed in multiple markets

The market model is the most frequently estimated model in financial economics and has proven extremely useful in the estimation of systematic risk. In this era of rapid globalization of financial markets there has been a substantial increase in cross listings of stocks in foreign and regional capital markets. As many as a third to a half of the stocks in some major exchanges are foreign listed. The multiple listings of stocks has major implications for the estimation of systematic risk. The traditiona1 method of estimating the market model by using data from only one market will lead to misleading estimates of beta. This study demonstrates that the estimator for systematic risk and the methodology itself changes when stocks are listed in multiple markets. General expressions are developed to obtain the estimator of global beta under a variety of assumptions about the error terms of the market models for different capital markets. The assumptions pertain both to the volatilities of the abnormal returns in each market, and to the relationship between the markets. ^ Explicit expressions are derived for the estimation of global systematic risk beta when the returns are homoscedastic and also under different heteroscedastic conditions both within and/or between markets. These results for the estimation of global beta are further extended when return generating process follows an autoregressive scheme.^

Tennessee trabajadores: Global wage arbitrage comes home to roost

In the 1980s, the American meat industry began restructuring both its domestic production methods and the distribution of its processing facilities. Many meat and poultry processing facilities have since been relocated into small rural communities. The red meat industry was once highly-paid and unionized, but now work in both meat and poultry processing is a dangerous, low-paid manufacturing job, heavily reliant on immigrant workers who must turn to local social services to supplement their wages and benefits. In an attempt to discover the manner in which the social relations of a specific locale may be enmeshed with global production, this research explored perceptions of social power and alliances after a rural community became host to a foreign workforce employed by the local poultry processing plant. On-site semi-structured interviews were conducted with sixteen local residents, and a content analysis of the community newspaper was undertaken. ^ The research found that as new production relations were inserted into the community, the society continued to reproduce and social relations remained relatively unchanged. The community's cultural standards and social infrastructure dictate that residents are respectful of authority, extend Christian charity to those less fortunate, and are generally accepting of a community known for low wages, low taxation, and low standards of education. Hegemonic ideologies seem to dictate the goals and beneficiaries of social power, and residents are unable to name any power vectors even in the face of sustained community support of, for example, the company that introduced the immigrant labor into the community. While there are indications of displeasure with the influx of immigrants appearing in the newspaper and the interviews, there are tangible examples that the community was proactive in welcoming the immigrants into their community. Thus, given that the last time elements of the community united around an issue was in the mid-1970s and no other issue has evoked any type of tangible struggle since then, there is no indication that any social alliances will be formed in reaction to changes in the community wrought by the globalization of its economy. ^

Arctic ecosystem responses to changes in water availability and warming: Short and long-term responses

Arctic soils store close to 14% of the global soil carbon. Most of arctic carbon is stored below ground in the permafrost. With climate warming the decomposition of the soil carbon could represent a significant positive feedback to global greenhouse warming. Recent evidence has shown that the temperature of the Arctic is already increasing, and this change is associated mostly with anthropogenic activities. Warmer soils will contribute to permafrost degradation and accelerate organic matter decay and thus increase the flux of carbon dioxide and methane into the atmosphere. Temperature and water availability are also important drivers of ecosystem performance, but effects can be complex and in opposition. Temperature and moisture changes can affect ecosystem respiration (ER) and gross primary productivity (GPP) independently; an increase in the net ecosystem exchange can be a result of either a decrease in ER or an increase in GPP. Therefore, understanding the effects of changes in ecosystem water and temperature on the carbon flux components becomes key to predicting the responses of the Arctic to climate change. The overall goal of this work was to determine the response of arctic systems to simulated climate change scenarios with simultaneous changes in temperature and moisture. A temperature and hydrological manipulation in a naturally-drained lakebed was used to assess the short-term effect of changes in water and temperature on the carbon cycle. Also, as part of International Tundra Experiment Network (ITEX), I determined the long-term effect of warming on the carbon cycle in a natural hydrological gradient established in the mid 90's. I found that the carbon balance is highly sensitive to short-term changes in water table and warming. However, over longer time periods, hydrological and temperature changed soil biophysical properties, nutrient cycles, and other ecosystem structural and functional components that down regulated GPP and ER, especially in wet areas.

Global Assemblages, Resilience, and Earth Stewardship in the Anthropocene

In this paper, we argue that the Anthropocene is an epoch characterized not only by the anthropogenic dominance of the Earth's ecosystems but also by new forms of environmental governance and institutions. Echoing the literature in political ecology, we call these new forms of environmental governance ���global assemblages���. Socioecological changes associated with global assemblages disproportionately impact poorer nations and communities along the development continuum, or the ���Global South���, and others who depend on natural resources for subsistence. Although global assemblages are powerful mechanisms of socioecological change, we show how transnational networks of grassroots organizations are able to resist their negative social and environmental impacts, and thus foster socioecological resilience.

Undergraduate Students��� Perceptions of Study Abroad and Their Level of Achievement of Global Learning Outcomes

This study expanded on current research on study abroad and global learning, using the Global Perspective Inventory (GPI), and conducted at Florida International University (FIU) in Miami, FL. The GPI assesses the holistic development of a global perspective in higher education within three domains and their respective FIU-determined equivalents: cognitive (global awareness), intrapersonal (global perspective), and interpersonal (global engagement). The main purpose of this study was to assess FIU���s undergraduate students��� perceptions of study abroad on their level of achievement of global awareness, global perspective, and global engagement. The secondary purpose was to determine how the students described their study abroad experience and achievement of global learning. The research design for this study consisted of parallel mixed methods. The quantitative component was an ex post facto with hypothesis design, using a pretest/posttest nonequivalent group methodology. FIU undergraduates (N=147) who studied abroad for one semester or more completed the GPI pre- and post-tests. Descriptive statistics and paired t-tests were conducted to compare the means. The interviews included 10 students, and were analyzed through Structural coding, Salda��a���s In Vivo coding, and Value coding. Quantitative analyses indicated positive changes in the students��� global awareness and global perspective. These analyses also showed that the FIU students achieved higher post-test means on all the domains of the GPI compared to other studies. Qualitative analyses showed that the students��� experiences incorporated all three global learning outcomes, most notably global awareness and perspective.