The major aims of this thesis were to study silica deposits in cereal inflorescences and wheat roots and investigate soluble/deposited silica partitioning and uptake of silica by wheat. The morphology of a particular phytolith (the papilla) from inflorescence bracts of 70 species from Triticum (wheat). Hordeum, Aegilops families and Secale cereale was analyzed. Using papilla pit number and/or diameter it is possible to distinguish between Hordeum sp. and Triticum sp., and between wheats of different ploidy levels. The root growth of T. aestivum was reduced by silica in the nutrient solution (Si+) during the first six days of growth, compared to plants grown in solution not supplemented by silica (Si-), After a further four days Si+ plants had significantly longer roots than Si- plants. At the light microscope level, a time course for silicification of the inner tangential wall of the root endodermis of T. aestivum was elucidated over ten days. Very few walls were silicified after 24 hours exposure to Si+ solution, but by day 10 up to 80% of endodermal cells in the basal area of the root were silicified. The percentage of silicified cells increased from the apex to the base of the root. Silica in T. aestivum was measured quantitatively using a molybdate blue detection method. Typically, 99% of the total silica in the seedlings was in the deposited form. The average concentration of soluble silica within the xylem exudate was 3.6 mM. The uptake of silica was affected by the silica concentration and pH of the nutrient solution. By measuring transpirational water loss and the silica content of the plants, it was concluded that silica uptake was active in T. aestivum. Uptake mechanisms were investigated by growing seedlings in nutrient solutions containing 2 mM Si and an inhibitor for 24 hours. The inhibitors used were ATPase inhibitors ( sodium orthovanadate, diethylstilbestrol, erythrosin B) and ionophores (nigericin, FCCP). The data suggests that functional ATPases and a proton gradient are required for silica uptake. Transport into the xylem and uptake at the root surface may be differentially affected by the inhibitors.

Thesis (Ph. D.)--University of Oregon, 1999. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 202-211). Also available for download from the Internet; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p9948017.

Thesis (M.A.)--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 January 3, 2008) Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 96-108). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 96-108). Also available on the Internet.

Thesis (Ph.D)--Utah State University, 2008. / Includes vita. Title from title screen (viewed Dec. 15, 2008). Department: Wildland Resources. Includes bibliographical references. Archival copy available in print.

This dissertation is a multidisciplinary study combining both archaeological andpaleoecological data to examine the rise of early Formative societies in Uruguay, La Plata Basin.It is contextualized within broader anthropological concerns related to the emergence of culturalcomplexity, the significance of ritual and public architecture in intermediate-level societies, andthe role of human-environment interactions during the mid-Holocene. This investigationgenerated the first Late Quaternary paleoclimatic record, based on pollen and phytolith analyses,documenting that the mid-Holocene (ca. 6,620 to ca. 4,040 bp) was a period of environmentalflux and increased aridity. It describes the occupational history of the Los Ajos site from thecreation of a household-based community integrating a centralized communal space during thePreceramic Mound Component (ca. 4,120 – 3,000- 2,500 bp) to the Ceramic Mound Component(ca. 3,000 2,500 bp to the Contact Period), where Los Ajos acquired a strong public ritualcharacter through the formatilization and spatial segregation of its mounded architecture. Duringthe Ceramic Mound Period, the site exhibited both internal stratification (inner versus outerprecincts) and dual asymmetrical architecture in its central sector, which suggest the emergenceof incipient social differentiation. This study also marks the earliest occurrence of at least twodomesticated crops in the region: corn (Zea mays) and squash (Cucurbita spp.), showing that theearly Formative societies adopted a mixed economy shortly after 4,120 bp. Collectively, theseresults challenge the long-standing view that the La Plata Basin was a marginal area byevidencing an early and idiosyncratic emergence of social complexity never before registered inthis region of South America.

A debate that has received much attention in recent years is the nature and scale of pre-Columbian impact in the Amazon lowlands. While the notion that Amazonia is a “pristine wilderness" has long been debunked, several papers have proposed that human impact in western regions was more sporadic and on a smaller scale than impacts in central and eastern regions, and that western Amazonia supported sparse pre-Columbian populations. The discovery of over 400 geometrically-patterned earthworks (geoglyphs) in the western Brazilian Amazon, which until recently lay under in-tact tropical forest, has raised important questions about the kind of societies that built them and the impact that they had on the terra firme upland landscapes. This study represents the very first investigations into human-environment interactions in the geoglyph region. By analysing phytoliths, charcoal and stable carbon isotopes from a series of soil profiles in the vicinities of two well-dated and excavated geoglyph sites, this study aims to discern the nature of the environment before, during and after the construction and use of the sites, and the spatial and temporal scales of landscape transformations that were effected by the geoglyph cultures. The data call for a re-appraisal of what is meant by “scales" of human impact in Amazonia, and propose that an understanding of the diversity of human-environment interactions must be considered through studies that closely combine regionally-sensitive archaeological and palaeoecological data.

The role of plants in Neanderthal subsistence is less well known than the role of animals due to differences in preservation and a subsequent lack of study. Phytoliths, the silica infillings of plant cells, are more durable than organic components of plants and can be used to reconstruct human activities, local plant ecology, and diagenetic alteration of archaeological sediments. This dissertation, comprising three articles, examines the relationship between Neanderthals and plants during the Middle Paleolithic (ca. 100,000-40,000 BP) of southwest France using phytolith analysis. The first article provides an analysis of the phytoliths recovered from the cave site of Roc de Marsal, relating phytolith concentrations and identifications to environmental change, natural deposition, and Neanderthal pyrotechnology. The analysis of 115 phytolith samples provides evidence for spatial patterning in plant remains related to hearth features and diachronic change in plant use coincident with a shift from warm stadial to cold glacial conditions. The second article applies morphometric statistics to a specific class of phytoliths, grass cells known as bilobates, to understand the range of variation within and among grass genera and to compare these results with an archaeological phytolith assemblage. More than 200 archaeological bilobates from Roc de Marsal are compared with those from seven modern reference specimens to assess these links. The analysis of the modern material indicates that some species are good candidates for morphometrics, but others should be avoided. The range of variation and lack of patterning in the archaeological assemblage suggest that Neanderthals at this site used multiple grass species. The third article presents the analysis of 102 phytolith samples from Pech de l’Azé IV in comparison to those from Roc de Marsal. The two sites are similar in terms of chronology, stratigraphy, artifacts, and preserved combustion features, but there are key differences in the structure/morphology of hearths and phytolith densities. The comparison of these two sites highlights variation in Neanderthal pyrotechnology and fuel use. The analysis also indicates that different phytolith recovery protocols are needed to maximize phytolith extraction due to differences in formation processes between sites and should be evaluated on a site by site basis. / 2019-11-27T00:00:00Z

New pedologic, carbon isotope and phytolith analyses along with stratigraphic correlations to nearby archaeological sites record the spatial and temporal distribution of past vegetation patterns in the Sac Valley Archaeological District of southwest Missouri. Radiocarbon ages obtained from a soil core along Bear Creek, CB5, are related to those from Hajic et al. (1998, 2000) indicating that the CB5 location contains correlative middle Rodgers Shelter submember deposits. This relationship also indicates that sedimentation was approximately two times greater at the CB5 locality than at the Big Eddy (23CE426) archaeological site providing much higher temporal resolution for the alluvial history as well as the vegetation proxies during the early to middle Holocene. Most midcontinent climate proxy records include indications of an early Holocene warm period when prairie replaced forests, then a cooler period in which trees dominated the landscape, followed by a warmer middle Holocene period when prairie vegetation was dominant. However, the CB5 δ13C profile of mixed C3/C4 vegetation indicates either that the vegetation at this location was not as sensitive to climate change or that this location was buffered from other influences, e.g. fires, which were critical to the expansion of prairie vegetation. On the other hand, the phytolith assemblages at CB5 indicate that there were periods with abundant C4 grasses even though the δ13C values indicate a dominance of C3 vegetation. This indicates that in the mixed forest/prairie ecotone interpretations of past vegetation from either carbon isotopes or phytolith assemblages alone may not accurately reflect patterns of vegetation. A new core, DDY-KR2, was obtained from the Big Eddy (23CE426) archaeological site and a finer resolution of δ13C values at Big Eddy increased the detail about alluvial activity and revealed subtle changes in the vegetation. The vegetation types suggested by the δ13C values for DDY-KR2 are reflected in the phytolith assemblages validating their usefulness in reconstructing local vegetation history.