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Articles 1 - 5 of 5
Full-Text Articles in Life Sciences
Heat And Smoke Effects On Red Brome Soil Seed Banks, Scott R. Abella, E. Cayenne Engel
Heat And Smoke Effects On Red Brome Soil Seed Banks, Scott R. Abella, E. Cayenne Engel
Public Policy and Leadership Faculty Publications
Management of exotic plants that are annuals entails understanding and managing their soil seed banks. We completed a study of the influences of heat and liquid smoke on red brome (Bromus rubens) soil seed banks collected from Red Rock Canyon in southern Nevada as part of a collaborative fire effects monitoring effort with Bureau of Land Management - Las Vegas. We collected the samples from the 2005 Loop Fire, where we observed in a monitoring field study that exotic grasses such as red brome were relatively sparse in the first 2-3 years (which were during a dry period) following the …
Martian Life Detection With Amino Acid Enantiomers, Ali Jamil, Gaosen Zhang, Henry J. Sun
Martian Life Detection With Amino Acid Enantiomers, Ali Jamil, Gaosen Zhang, Henry J. Sun
Undergraduate Research Opportunities Program (UROP)
The Viking mission showed that Martian soil can degrade a heterotrophic medium to carbon dioxide as if live microorganisms were present. The result is considered inconclusive, however, because abiotic oxidants, such as superoxides, may also exist on Mars and would explain the Viking result. One way to resolve this ambiguity is to repeat the Viking experiment with a isomerically pure medium. The consumption of one isomer, either D or L, would indicate biological activity. Indiscriminate destruction of both isomers would indicate abiotic redox processes. This idea was validated for glucose by REU research last summer (Sun et al. 2009). The …
Martian Life Detection With Xylose Enantiomers, Arturo White, Gaosun Zhang, Henry J. Sun
Martian Life Detection With Xylose Enantiomers, Arturo White, Gaosun Zhang, Henry J. Sun
Undergraduate Research Opportunities Program (UROP)
Ability of Martian soil to degrade carbohydrates, shown by the Viking mission, has two interpretations. One possibility is that the soil harbors living microorganisms. Alternatively, the soil is sterile but chemically oxidizing, i.e. it is laden with photochemical oxidants. It was shown by REU research last summer that these two possibilities can be distinguished by the use of glucose enantiomers. Life is selective: Earth organisms use D-glucose, but ignore Lglucose. This stereo selectivity is absent in chemical reactions. The goal of this project is to test if xylose, a five carbon sugar, is also suitable for chiral life detection. Mixed …
Tree Canopy Types Constrain Plant Distributions In Ponderosa Pine- Gambel Oak Forests, Northern Arizona, Scott R. Abella
Tree Canopy Types Constrain Plant Distributions In Ponderosa Pine- Gambel Oak Forests, Northern Arizona, Scott R. Abella
Public Policy and Leadership Faculty Publications
Trees in many forests affect the soils and plants below their canopies. In current high-density southwestern ponderosa pine (Pinus ponderosa) forests, managers have opportunities to enhance multiple ecosystem values by manipulating tree density, distribution, and canopy cover through tree thinning. I performed a study in northern Arizona ponderosa pine-Gambel oak (Quercus gambelii) forests to measure the influences of tree canopy types on understory plant communities and soil properties. On ten 2.5-acre (1-ha) sites, I sampled five 43-ft2 (4-m2) plots below each of the following five canopy types: openings; single ponderosa pine; and Gambel oak single stems, dispersed clumps, and thickets. …
Effects Of Plant Uptake And Micro-Topography On Chloride Transport In Arid Soils, Wenming Nie
Effects Of Plant Uptake And Micro-Topography On Chloride Transport In Arid Soils, Wenming Nie
UNLV Theses, Dissertations, Professional Papers, and Capstones
Chloride concentration profiles to depths of 1 m were evaluated on a young alluvial fan in Eldorado Valley, NV. It was found that chloride beneath plant canopies were 11 to 222 times higher than adjacent (1 - 2 m away) bare soil locations. Two-dimensional numerical simulations using HYDRUS 2D/3D model were used to further explore the impact of plants on chloride transport. The simulation results indicated that lateral flow driven by root uptake concentrated chloride toward root zones, leading to the accumulation of chloride under plant canopies. Results also suggest that locally micro-topography can have a substantial impact on chloride …