Patterns and rates of nutrient input to the forest floor in litterfall, throughfall and stemflow were investigated in plots of low and high abundance of ectomycorrhizal species. The aim of the study was to examine the comparative advantage of the ectomycorrhizal species in nutrient acquisition and cycling on nutrient-poor soils in Korup. Litterfall was similar in both forests with annual estimates of 9.00 and 8.33 t ha-1 yr-1 for LEM and HEM forests respectively. Litterfall distribution followed a mono-modal pattern, with peaks in the dry season in both forests and the HEM forest showing stronger seasonality. The concentrations N, K and Ca in total litterfall were higher in the LEM forest while those of P and Mg were higher in the HEM forest. The bulk of nutrients in total litterfall was in leaf litter with the reproductive fractions having the highest concentrations of nutrients. Ectomycorrhizal species showed lesser internal redistribution of nutrients than non-ectomycorrhizal species which resulted in their higher leaf litter concentrations of nutrients. Breakdown of litter was relatively faster in the LEM forest with an annual decomposition constant (KL) of 3.21 compared to 2.43 for the HEM forest. The reproductive fractions had relatively higher annual decomposition constants of 8.20 and 4.27 in the LEM and HEM forests respectively compared to the other fractions. The overall element mobility in decomposing leaf litter was similar in both forests and in the following order: Mg>K>Ca>P>N. Mineralization of N, P and K in the decomposing leaf litter was similar in both forests and higher in the HEM forest for Mg and Ca. Throughfall was 96.6% and 92.4%, and stemflow 1.5% and 2.2%, of gross rainfall in LEM and HEM forests respectively. Considerable amounts of Ca, Mg and P were brought to the forest canopy in gross rainfall (24-45% of total input through this route) with higher amounts of K and Ca leached from plant parts by the rainwater. The amounts of P, K and Ca in stemflow and throughfall were of the same magnitude in both forests with the enhancement of N slightly higher in the LEM forest and Mg in the HEM forest.

Significant species differences in foliar litter quality have been well-documented but differences within species, as a function of variation in genotype or environment, have not been directly addressed and, thus, remain poorly understood. We studied the significance of genetics, the environment, and their interaction in regulating forest nutrient dynamics and productivity using trees from four full-sib black spruce (Picea mariana (Mill.) B.S.P.) families of a complete 7 x 7 diallel cross experiment at the Petawawa National Forestry Institute (Chalk River, Ontario). Foliar litter composites from each family-plot on two sites of contrasting water availability were collected in October, 1993, and sub-samples were analyzed for initial N, P, K, Ca, Mg, cellulose and lignin concentrations. Inherent decomposition rates and nutrient dynamics of the litter composites were followed for one year. Samples of forest floor and mineral soil collected from within each plot were used to determine organic matter accumulation, pH, total nutrient contents in the forest floor and extractable nutrient concentrations in the mineral soil. Height, dbh, and total tree cubic volume, were used to characterize tree productivity. (Abstract shortened by UMI.)

In 1990 James D. Lewis made a conjecture on the representability of algebraic Chow groups of projective algebraic manifolds. We prove that his conjecture holds for smooth complex complete intersections satisfying a numerical condition and consider some applications to motives. / Mathematics

In economic time series modelling, dynamic relationships frequently have to be modelled where the explanatory variables influence the dependent variable over more than one period. Such dynamic relationships are found in business cycle forecasting with leading indicators, in marketing models describing the relationship between advertising and sales, and in many traditional econometric models. In this dissertation the transfer function model proposed by Box and Jenkins is used to describe the dynamic structure. There are several approaches that could be used to specify the model. A two-step regression approach is proposed by the author and tested by three simulation studies. Finally, the regression approach and two other approaches are used to identify transfer function models for the Swedish Index of Industrial Production using financial variables as leading indicators. / Diss. Stockholm : Handelshögsk. S. 1-22: sammanfattning, s. 23-162: 4 uppsatser

The oil shortages and price rises of the 1970s led to a broad spectrum of policies designed to save fuel in transport. One such group of policies concentrated on utilising the longstanding observation that congestion-free driving improves vehicular fuel economy. In particular, improving the average speed of urban traffic was believed to reduce urban fuel use. Strategies to create free-flowing traffic networks through traffic engineering and management techniques became an integral part of most transport energy conservation strategies. At the same time urban systems studies were appearing which suggested that urban land use factors are fundamental in determining transport energy demand. Some cities with denser, more centralised developnent patterns and congested traffic systems appeared to have lower per capita transport energy use than cities with low density, dispersed land use and free-flowing traffic networks. Conflicts thus began to be recognised between these land use studies and the traffic studies but they were never systematically examined. This thesis focuses on explaining and attempting to resolve these apparent conflicts by drawing out the relative importance of freeflowing, fuel efficient traffic and broader land use/transport factors in determining urban system fuel efficiency. It does this by showing how a holistic understanding of transport energy use can be achieved by recognising the different levels of know1edge involved and by integrating research a t all these levels. Adopting this approach, a detailed examination is made of transport energy use in Perth, Western Australia. Spatial and temporal patterns of urban driving and vehicular fuel consumption are derived using a computer-instrumented vehicle within a framework of urban ecology. These patterns are described in detail and are found to be understandable in terms of a simple model of intersection and vehicle-based traffic events. Using this simple model, urban driving and fuel consumption patterns are then systematically linked back to their urban ecological framework. Centrality, as expressed by urban activity intensity emerges as the major underlying factor in both the urban ecological framework and driving patterns. Driving cycles for central to outer areas as well as the whole city are produced and a detailed examination is made of driving cycle development procedures, including the issue of data resolution. Two new methods of driving cycle synthesis are formulated. Driving cycles together with travel survey and land use/transport model data are then used to estimate spatial differences in transport energy use per capita within the urban ecological framework. This case study is used to test two conceptual models of transport energy conservation implied by the traffic and land use studies: a linear assumptions model which suggests reductions in urban system fuel use through freer-flowing traffic and a feedback assumptions model which introduces some possible broader system effects of free-flowing and congested traffic. The results suggest very strong support for the feedback model and a reversal of the linear model. Urban structural factors such as distance from the CBD and density are found to be the major explanatory factors of Perth's transport energy use. The much higher vehicular fuel consumption in Perth's inner areas due to restricted traffic flows are completely offset by energy conserving land use and transport features which result in lower per capita energy use in these areas; the lower vehicular fuel consumption in uncongested outer areas is swamped by land use factors which result in longer travel distances and less use of energy conserving modes, resulting in markedly higher per capita energy use, i .e. a trade-off is found between a fuel efficient traffic system and a fuel efficient urban system. It is concluded that policies which propose fuel savings from "blanket" improvements in urban trraffic flow, such as major road building programmes will be counter-productive, while urban planning policies which encourage higher density, more compact cities will tend to lower energy use. It is suggested that a key area of research is now how to combine selective traffic system improvements with urban land use policies so that both may work in concert to produce a more fuel efficient urban system.

Thesis (M.S.) in Plant, Soil and Environmental Sciences--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 72-83).

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 100-125). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Economics, 2007. / Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on December 28, 2007) Includes bibliographical references.

Thesis (Ph.D.). / Written for the Dept. of Earth and Planetary Sciences. Title from title page of PDF (viewed 2008/01/12). Includes bibliographical references.