Thesis (M.S.) University of Missouri-Columbia, 2006. / 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 August 27, 2007) Includes bibliographical references.

Thesis (M.S.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Mark L. Skidmore. Includes bibliographical references (leaves 69-75).

Techn. Universiẗat, Diss., 2004--Berlin.

Zugl.: Berlin, Univ., Diss., 1991.

Variation in exposure to environmental microbial communities has been implicated in the etiology of allergies, asthma and other chronic and immune disorders. In particular, preliminary research suggests that exposure to a high diversity of microbes during early life, for example through living in highly vegetated environments like farms or forests, may have specific health benefits, including immune system development and stimulation. In the face of rapidly growing cities and potential reductions in urban greenspace, it is vital to clarify our understanding of the relationship between vegetation and microbial communities so that we can better design cities that support human health. To explore whether and how urban airborne bacterial communities vary with the amount and structural diversity of nearby vegetation, I used passive air sampling and culture-independent microbial DNA sequencing combined with more traditional landscape architecture tools, including geographic information systems (GIS) and remote sensing data. The results indicated that locations with little vegetation (i.e., paved parking lots) were marked by significantly different bacterial composition from areas that were heavily vegetated (parks and forests). These differences were largely driven by taxonomic groups and indicator species that were enriched at certain sites. My work also shows that regional agricultural activities during the summer may have a substantial effect on airborne bacterial communities in the Eugene-Springfield metropolitan area (Oregon), specifically through elevated abundance of Sphingomonas faeni, a taxon previously isolated from hay dust. The second part of my work focused on building a conceptual bridge between scientific findings and potential design principles that can be tested in practical application. I performed a narrative review of vegetation-health, vegetation-microbe, and microbe-health relationships, which formed the foundation of a framework to translate scientific findings into design-relevant concepts. Strengthening this linkage between science and design will help ensure that research questions are relevant to design practice and that new scientific knowledge is accessible to designers. This dissertation includes previously published and unpublished co-authored material. / 2020-09-06

A major component of the vegetation cover in the area chosen for this study consists of heather moorland. This provides an essential habitat for diverse populations of ground-nesting moorland birds. Common heather - Calluna vulgaris (L) Hull - is typically the dominant species of this semi-natural habitat, providing both nutrition and cover for these bird populations. Much heather-dominated vegetation is in a successional stage and management is required to prevent its progressive transformation into rough grassland and woodland scrub. Traditionally management by burning and more recently by mowing has been used to achieve this by encouraging the growth of young heather, through the removal of senescent stands of Calluna vulgaris in the degenerate phase of its life cycle. These forms of management however may also have the effect of creating conditions which favour faster growing, acidophilous grasses which may replace Calluna vulgaris over time as the dominant species. This study investigates the hypothesis that particular management treatments may have specific influences on the composition and nature of the post-management vegetation complex. Particular attention is given to the nutrient status of soils, associated with each of the management treatments chosen for investigation. The influence of this on the long-term floristic composition and vertical stratification of the Callunetum is considered. Stands of vegetation belonging to different management regimes were used as the elements of chronosequences, which were utilised to investigate vegetation change over time in relation to particular management treatments. Vegetation was described from quadrats located within this framework and quadrat-specific soil samples were taken for chemical analysis. Dendrochronology was explored as a method for determining the age of Calluna plants in each treatment category from which the efficiency of different methods of removing the Calluna canopy was assessed. Multivariate methods of classification (TWINSPAN) and indirect gradient analysis (DECORANA) were used to reveal pattern in the vegetation data, which might be attributable to the management treatments defining each of the chronosequence stages. TWINSPAN was successful in identifying homogenous groups of samples on the basis of species associations peculiar to particular treatment categories. DECORANA proved successful in suggesting environmental gradients which might be responsible for these groupings. Data obtained from the chemical analysis of soil samples was used to compare soil nutrient status in each of the treatment categories, representative of the chronosequence stages. The vegetation and soils data-sets were then combined for use in direct gradient analysis (CANOCO), to investigate the combination of management treatments and soil nutrient status as factors influencing the formation of the species associations identified at each of the chronosequence stages. Finally, management goals are discussed in the context of the results of these analyses and the role of these procedures as the basis for an extended investigation into post-management, plant/soil inter-relationships as an influence on successional trends is evaluated.

Recently, remotely sensed multispectral data have been proved to be very useful for many applications in the field of Earth surveys. For certain applications, however, limits in the spatial resolution of satellite sensors and variation in ground surface restrict the usefulness of the available data, since the observed spectral signature of the pixels is the result of a number of surface materials found in the area of the pixel. Two mixed pixel classification techniques which have shown high correlation with vegetation coverage of single pixels are described in this thesis: the vegetation indices and the linear mixing model. The two approaches are adjusted in order to deal with sets of pixels and not individual pixels. The sets of pixels are treated as statistical distributions and moments can be estimated. The vegetation indices and the linear mixing model can then be expressed in terms of these statistics. The illumination direction is an important factor that should be taken into account in mixed pixel classification, since it modifies the statistics of the distributions of pixels, and has received no attention until now. The effect of illumination on the relation between the vegetation indices and the proportion of sets of mixed pixels is examined. It is demonstrated that some vegetation indices, which are defined from the ratio of statistics in two spectral bands, can be considered relatively invariant to illumination changes. Finally, a new illumination invariant mixing model is proposed which is expressed in terms of some photometric invariant statistics. It is shown to perform very well and it can be used to un-mix accurately sets of pixels under many illumination angles. The newly introduced mixing model can be considered a suitable choice in the mixed pixel classification field. Key words: Mixed pixels, sets of pixels, vegetation index, illumination invariants.

Soil organic carbon (SOC) is important both for its influence on agricultural productivity and for its role in the carbon cycle. The distribution of SOC is highly variable at the field scale both horizontally and vertically; a portion of SOC's variability can be attributed to differences in vegetative cover and to slope position. This study characterized and compared SOC concentration to a depth of 2 meters across 6 loess-veneered watersheds in the central United States. Data were collected as part of the Shawnee Hills Loess Catenas project, a collaboration between the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service, USDA Forest Service, Purdue University, University of Kentucky, Southern Illinois University at Carbondale, and Illinois State Geological Survey, among others. The study consists of pairs of sites, one under forest cover and one grass cover, located in southern Illinois, southern Indiana, and western Kentucky. Bulk density and SOC data were calculated from genetic horizon samples taken from soil pits laid out as transects along slopes at each site. SOC concentrations were significantly higher under forest cover. Footslopes and toeslopes had significantly higher SOC densities than summits, shoulders, and backslopes. A three-part exponential decay model was the best fit for the relationship between SOC density and depth from the surface. The comparisons and models may be used to more accurately predict SOC concentration and carbon pool size on similar loess-veneered landscapes in the central United States.

The thesis is focused on the endangered wetland moss Hamatocaulis vernicosus. The studies included vegetation and chemical characteristics of the species? habitats and long-term reaction to management and other environmental factors, comparison of ecological requirements of H. vernicosus and two related species, differences of habitat preferences among some European regions (Bohemian Massif, Western Carpathians, Southern Europe) and among parts of the Czech Republic. Recent and historical distribution of the species was compared, including the quantification of all recent populations.

The abundance of invasive alien plants, with their numerous associated negative effects, has resulted in challenging and costly management requirements in South Africa. Management of invasives is further complicated when species have rapid inherent growth rates, atmospheric nitrogen fixing capabilities and large, persistent seed banks. Management strategies other than the usual mechanical, chemical, and biological (and combinations thereof) methods may be more effective. An alternative strategy is ’habitat management’, whereby management may be aimed at favouring native species. If the native species could compete favourably with, and possibly exclude, the invasive species, which is more likely when the species are ecologically similar, management may be more effective. This study investigated the competitive performance of two invasive species, Acacia mearnsii De Wild. and Acacia melanoxylon R.Br., and an indigenous ecological analogue, Virgilia divaricata Adamson, on the southern Cape Coast of South Africa. Both acacias are included among the five worst invasive species in the native forest and fynbos shrubland ecosystems. Performance was compared among the three species in terms of germination success (responses to five stimuli, namely chipping, hot water exposure, dry heat pulse, smoke, and control, incubated at 12 or 20°C), soil-stored seed bank densities and viability at different soil depths, and individual growth performance in seedling and sapling stages (and the effect of inter-specific competition on the latter). Virgilia divaricata performed comparably to the acacias in most aspects. Responses to germination stimuli at both temperature regimes were comparable among species, with chipping and hot water exposure resulting in the highest germination success. Acacia melanoxylon displayed poorer germination response under the cool temperature regime than the warm regime. Of the three species, A. mearnsii (7 596 seeds m-2) had the highest seed bank density, followed by V. divaricata (938 seeds m-2) and A. melanoxylon (274 seeds m-2). Seed viability was high (87-91%) in all three species. Neither seed density nor seed viability differed significantly between soil depths, and there were no clear differences in this aspect between species. In terms of growth during the seedling stage, V. divaricata outperformed A. mearnsii. In the sapling stage, growth was comparable between the three species and was not affected by the extent of competition from neighbouring saplings. Overall, the findings of this study suggest that the success of A. mearnsii as an invader is primarily attributable to its large seed banks. However, the good performance of V. divaricata seedlings and no apparent negative effect of competition on sapling growth from A. mearnsii and A. melanoxylon suggest that it may be used in the management of the acacias along with other management strategies. Due to the similarity observed between the three species, any management operation (such as fire) that would benefit V. divaricata recruitment would benefit the acacias equally (except for potentially reduced germination of A. melanoxylon in cooler seasons). Management should thus attempt to prevent the germination of Acacia seeds. Alternatively, dense localised Acacia seed banks may be reduced by repeat burning. On a small scale, areas where V. divaricata would occur naturally (or which are completely compromised ecologically) can be seeded with pre-treated (chipped or hot water exposure) V. divaricata seeds. If V. divaricata is given enough time to establish dense stands, subsequent germination and growth of the acacias should be suppressed and simultaneously promote forest re-establishment. To further decrease Acacia success, biocontrol (seed-boring weevils, flower-galling midges, and rust fungus) should be widely disseminated.