Graduation date: 2005

Thesis (Ph. D.)--University of Wisconsin, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of California, San Diego, 2004. / Vita. Includes bibliographical references (leaves 475-496).

This work aimed to contribute to the understanding of tree - grass inter-cropping interactions so that the productivity and sustainability of extensive livestock husbandry can be increased. The work was carried out in the context of a small farm in Oaxaca, Mexico, where increases in productivity are limited by shortage of capital and where the tree component would be used as green manure. It is difficult to investigate the effectiveness of such a system by only using conventional field trials. I constructed a mathematical model to simulate how the main components of the system function under conditions that would not be evaluated in the field. Issues such as how many trees to plant and what tree species combine with grass cattle and environment, can be answered with the model. The particular features of the model are: 1) It describes an agro-ecosystem where trees perform several biological functions like nitrogen capture for use in the silvopastoral system, 2) It links grass and trees with the animal and 3) Nutrient availability depends mainly on soil organic matter decomposition and mineralisation rather than on external inputs. The present research consisted of 1) constructing the model prototype using data from the literature, 2) conducting field experiments to investigate the actual performance of the silvopastoral system, 3) perform laboratory research and greenhouse experiments complementarily to the field experiments and 4) elaborate on the carbon and nitrogen balance of the silvopastoral experiment, by combining research results and the mathematical model. The field experiment consisted of an array of 13 plots with one of the tree species Gliricidia sepium, Leucaena leucocephala, Delonix regia and Lysiloma auritum in a gradient of plant densities within a Brachiaria decumbens paddock. Results showed that the presence of trees in pastures is potentially useful for retaining nitrogen and carbon that would be lost in the grass mono-crop. Trees did not incorporate nitrogen through biological fixation, perhaps because the lack of adequate nodulation and they did not established their rooting systems to a depth beyond the grass roots (> 1.20m) so as to recover leached nutrients. However, trees produced mulch that was rich in nitrogen (3.8%) and whose decomposition rate ensures a slow release to prevent leaching. At the plant density used, the tree population caused no harm to grass as to production and nutritive value. Further increments in tree density in order to improve the potential for nitrogen capture should be evaluated in terms of the reduction of grass production. Several biological attributes of the species were determined, in some cases for the first time: biomass productivity, specific leaf area, nutritive value, phenolic content, root biomass, grass root longevity, root vertical distribution, etc. Such characterisation is useful for the understanding of the system inter-cropping and specially for the parameterisation of the silvopastoral model. Even though the mixtures proved able to survive for the span of the experiment, the sustainability of tree - grass inter-cropping as to the stabilisation of soil fertility requires longer monitoring. Other limiting factors such as phosphorus availability and the management of grazing systems have to be incorporated for an adequate evaluation of the silvopastoral system.

Thesis (Ph.D.)--Vanderbilt University, 2002. / Includes bibliographical references.

Thesis (M.S.)--George Mason University, 2008. / Vita: p. 116. Thesis director: Wallace Warfield. Submitted in partial fulfillment of the requirements for the degree of Master of Science in Conflict Analysis and Resolution. Title from PDF t.p. (viewed Aug. 28, 2008). Includes bibliographical references (p. 109-115). Also issued in print.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

No description available.

This dissertation is a concise examination of the complete obverse manuscript (document 1) of the pre-Hispanic pictogram screen-fold painted by the Mixtec Indians of Oaxaca. The study begins with the historiography of Native American Mexican screen-fold books as related by the first historian of the New World, Peter Martyr d’Anghera, in his De orbe novo and proceeds through major authors from the early twentieth century to present day. The nature of “native” history is explored as is the nature of pictogram narrative history. The superficial narrative structure of Codex Zouche-Nuttall, document 1 is then defined and interpretative reading techniques employed in this dissertation are applied to it. The codex document 1 contents (pages 1-41) are then listed in detail by section, structure, personnel, events, and native dates corresponded with the European calendar, this latter in so far as is possible. This definition explicates each of three bifurcated sections of the document, each section consisting of a story plus genealogy or genealogies. Additionally, essays on codex contents are provided to further elaborate these divisions of study within Codex Zouche-Nuttall document 1. These essays explore certain mysterious parts of the stories, as in the case of the Ladies Three Flint and the Four Lords from Apoala. Inferences are made from codex text regarding Postclassic Period Mixtec social organization via both political structure and religion. The end result is a concise elaboration and explanation of the entire document. / text

Thesis (doctoral)--Leiden University, 2007. / Includes bibliographical references (p. [335]-361) and index.