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Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
The Functional And Distributional Ecology Of Mycetozoans Under Changing Edaphic And Climatic Dynamics, Geoffrey Lloyd Zahn
The Functional And Distributional Ecology Of Mycetozoans Under Changing Edaphic And Climatic Dynamics, Geoffrey Lloyd Zahn
Graduate Theses and Dissertations
Investigations into the distribution and ecosystem functions of fruiting amoebae revealed that local-scale environmental conditions can largely explain broad biogeographical patterns in species assemblage, the way in which amoeboid predators shape bacterial communities and how this top-down influence may affect global biogeochemical processes in a changing climate. The distribution and assemblage of protosteloid amoebae on the islands of New Zealand and Hawaii did not yield any expected patterns of island biogeography, and conformed to other global regions studied. The strongest predictor of species richness in a given region was sampling effort and these species do not appear to have any …
Methane Emissions From Direct-Seeded, Delayed-Flood Rice Grown On A Clay Soil, Alden Daniel Smartt
Methane Emissions From Direct-Seeded, Delayed-Flood Rice Grown On A Clay Soil, Alden Daniel Smartt
Graduate Theses and Dissertations
Due to the production of methane (CH4) under flooded-soil conditions, rice (Oryza sativa L.) cultivation is a major contributor to agricultural CH4 emissions. Studies examining CH4 emissions from rice have only recently been initiated in Arkansas and no data have been collected from rice produced on clay soils in Arkansas. Therefore, research was conducted in 2012 and 2013 at the Northeast Research and Extension Center in Keiser, Arkansas to examine the factors affecting CH4 emissions from rice produced on a Sharkey clay (very-fine, smectitic, thermic Chromic Epiaquerts). The objectives of this study were to determine: 1) the effect of vegetation …
Bacterially-Mediated Formation Of Rock Coatings In Kärkevagge, Swedish Lapland: A Mineralogical And Micro-Environmental Analog For Mars, Cassandra L. Marnocha
Bacterially-Mediated Formation Of Rock Coatings In Kärkevagge, Swedish Lapland: A Mineralogical And Micro-Environmental Analog For Mars, Cassandra L. Marnocha
Graduate Theses and Dissertations
The search for past or present life on Mars is, for now, limited to surface environments. An often neglected surface environment that could have served as an abode for life and could presently preserve evidence of that life is that of rock coatings. Rock coatings are mineral accretions on rock surfaces. On Earth, they are widespread and occur with considerable chemical diversity. There is growing evidence for a biotic role in their formation on Earth, particularly with respect to rock varnish. As a result, rock varnish has become a target of astrobiological interest on Mars, where varnish-like coatings have been …
Litter Conditioning Is Differentially Affected By Leaf Species, Phosphorus Enrichment, And Light Availability, Erin E. Scott
Litter Conditioning Is Differentially Affected By Leaf Species, Phosphorus Enrichment, And Light Availability, Erin E. Scott
Graduate Theses and Dissertations
Anthropogenic enrichment of nitrogen and phosphorus is one of the most pervasive and detrimental threats to aquatic ecosystems worldwide. In streams that rely on allochthonous basal food resources, such as leaves, nutrient pollution can result in altered food quality and decreased carbon (C) standing stocks. However, the magnitude and mechanisms of this change in quality are poorly understood. Laboratory microcosm studies were conducted to 1) quantify the response of litter C:P to a gradient of phosphorus (P) enrichment (0, 0.05, and 0.5 mg SRP/L) across leaf species with variable levels of degradability (sugar maple and oak), and 2) quantify the …
The Use Of Diatoms To Infer Environmental Change Of The Lower White River, Southeastern Arkansas, Ruchi Bhattacharya
The Use Of Diatoms To Infer Environmental Change Of The Lower White River, Southeastern Arkansas, Ruchi Bhattacharya
Graduate Theses and Dissertations
This dissertation describes the limnology of the lower White River oxbow lakes in southeast Arkansas, inundated by the major 2008 spring flood. The flood water and sediment deposited in oxbow lakes were analyzed for water chemistry, sediment geochemistry and diatom assemblages and used as an analogue for past floods. The 2008 spring flood inundated and homogenized the entire floodplain; also represented by the predominantly planktonic diatom assemblage suggesting riverine input. Indicator species for eutrophication were also recorded consistent with the high nutrient content in the lakes. However, the variance in the surface diatom assemblage was best explained by the lake …