Abstract The loss of tropical and subtropical rainforest biodiversity due to increasing anthropogenic pressure lends urgency to understanding the processes which drive species coexistence. Without an understanding of how species are distributed across the landscape and how species assemblages change through time, we cannot derive appropriate management regimes for their persistence. This thesis examines the role of deterministic drivers of spatial and temporal dynamics of Australian rainforests and investigates the potential impacts of a changing climate on Australian rainforests. The findings from three studies are presented in four chapters which examine floristic turnover in situ and at catchment, regional and continental scales. Compositional turnover in tropical rainforest following the passage of a category three cyclone was examined both at five years’ post-cyclone recovery and in the context of local and regional spatial turnover. After five years, the forest remained in an active state of recovery with an approximate 30% increase in stems, 5% decrease in basal area and a 16% increase in species richness. Local spatial turnover suggests differential impacts of cyclones over even short distances and overall, a high degree of temporal stability in these rainforests, despite the impact of frequent catastrophic disturbances. Compositional turnover in subtropical rainforest along steep moisture and temperature gradients was investigated and described along an altitudinal transect in subtropical rainforest. The identification of significant modelled climatic and mapped soil variables suggests that moisture stress is an important driver of floristic turnover in these forests. Existing high levels of turnover across tree assemblages from low to mid elevations in subtropical rainforest were identified. Such turnover is greatly reduced at higher elevations. With increasing atmospheric temperatures, the cloud cap is expected to rise and we predict that subtropical rainforest communities which currently sit at the level of the cloud base (800-900m) will experience increasing in situ floristic turnover. Our findings agree with predictions for cloud forests elsewhere: high elevation endemic species will face an increasing risk of extinction as mesic climatic envelopes move upslope out of reach. Baseline data from this study will be used as a benchmark against which to formulate and test hypotheses for climate induced floristic and structural shift. It is also acknowledged that monitoring floristic turnover as a surrogate of shifting climatic envelopes may be confounded both by a lack of knowledge regarding the underlying turnover rates of rainforest communities and by the disparity in temporal scales of tree community turnover and accelerating anthropogenic climate change. Finally, generalized dissimilarity modelling is utilised to combine disparate biological survey data and remotely sensed environmental data to investigate the determinants of floristic turnover at the regional scale. Generalized dissimilarity modelling identified four environmental predictors of β-diversity in subtropical rainforest, all closely linked with moisture stress: radiation of the driest quarter, precipitation of the driest period, slope and aspect. Ten land classes were identified and mapped for the Mt Warning Caldera and may act as appropriate management units for future climate change planning within the region. This thesis has identified a potential threat to the biodiversity of Australian rainforests under a changing climate. Increasing levels of evapotranspiration, moisture stress and an increased return rate and intensity of disturbance are predicted to lead to the upslope movement of species ranges, increasing levels of in situ floristic turnover, and will likely result in the emergence of novel rainforest communities not present under current conditions. The potential for anthropogenic climate change to impact upon native vegetation communities has emphasised the need for the continuation and expansion of monitoring programs and the development of dynamic management regimes.

The purpose of this study was to examine the backgrounds and experiences of middle school mathematics teachers that often distinguish "quality" teachers, including certification, experience, degree type, and degree level and how those demographics and others vary for different types of schools. The emphasis was on profiling teachers in a large urban district by describing their basic features and distributions, as well as how middle school mathematics teachers, according to those differences, relate to student mathematics achievement, teacher attrition and teacher mobility. Student achievement was measured by test results from the Norm Reference Test-Normal Curve Equivalent (NRT-NCE) mathematics portion of the Florida Comprehensive Assessment Test (FCAT) for two school years (2003-04 and 2004-05). A variety of analytic approaches and methods were used to examine how different teacher characteristics relate to teacher employment patterns and student achievement, including chi-square, Kruskal-Wallace, Mann-Whitney U, ANOVA, and t tests, together with simple descriptives and graphical analysis. Standard multiple regression was used to evaluate whether students' previous test scores and teacher- and school-level predictors could affect the results of students' mathematics achievement. A short survey was administered, which provided some insight to ascertain whether and why teachers choose among schools when seeking employment. A total of 282 teachers and 24,766 students were included for the final analysis. This research revealed high rates of teacher turnover and deficient numbers of well qualified mathematics teachers for this particular demographic. For example, one in three middle school mathematics teachers was in their first year, and over half (55%) had less than three years seniority. It was also apparent that, because of a shortage of well-qualified mathematics teachers, many new teachers were being hired out-of-field--of those first-year teachers, only about half had certification in their content area and most (67%) did not have a degree in mathematics or mathematics education. Middle schools in this district had lost 29% of the mathematics teacher workforce employed the previous year due to mathematics teacher attrition. Of those many resigned, some came back to teach another subject at the same or different middle school, and others transferred to high schools. An additional 5% transferred to other middle schools within the same district bringing the total turnover to 34%. Findings revealed no significant differences in turnover rates in high-poverty versus low-poverty schools, but there were significant differences in the proportions of movers, leavers, and stayers in schools according to whether or not a school was achieving high-standards in mathematics. Although inequities did exist in favor of schools with less at-risk students, in this district--for the most part--teachers were fairly distributed according to the "quality" of their backgrounds and experiences. The only significant gap was in that students in wealthier schools were more likely to have a mathematics teacher with a higher degree. This study also offers results that further understanding on the debate about which attributes of teachers are most likely to translate into effective-classroom performance. When analysis was performed at the student level, the findings revealed that students of middle school mathematics teachers with higher seniority, advanced degrees, or certification in the content area that they taught, performed significantly higher than students in other classrooms. Yet the magnitude of those differences was either modest or very small. When controlling for students' socio-economics status at the classroom level, differences were not significant for seniority or advanced degrees but the results were significant for certification.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of California, San Diego, 2007. / Title from first page of PDF file (viewed October 10, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 104-109).

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of California, San Diego, 1999. / Vita. Includes bibliographical references.

Thesis (Ed.D.)--University of Delaware, 2008. / Principal faculty advisor: Primo V. Toccafondi, School of Education. Includes bibliographical references.

Thesis (M.H.A.)--University of Michigan, 1967.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Daniel S. Hamermesh. Vita. Includes bibliographical references. Also available from UMI.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 25, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Margaret Grogan. Vita. Includes bibliographical references.