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Facilitative And Competitive Tradeoffs Between Morella Cerifera Seedlings And Coastal Grasses, Michael N. Sinclair
Facilitative And Competitive Tradeoffs Between Morella Cerifera Seedlings And Coastal Grasses, Michael N. Sinclair
Theses and Dissertations
Morella cerifera is a rapidly expanding native shrub on the Virginia barrier islands which displaces other native coastal species and may interrupt normal sediment dynamics. Barrier islands are considered stressful environments with low nutrients, high solar load, and frequent drought and salt exposure; facilitation often dominates in stressful environments according to the Stress Gradient Hypothesis. The objective of this project was to understand the importance of species interactions with grasses on the growth and physiology of M. cerifera at the seedling life stage through both field and lab experiments. Grasses provided ~1.3°C insulation to shrubs during winter freeze events and …
Impacts Of Rdx Soil Contamination Across An Age Gradient For The Native Shrub Morella Cerifera., Stephen Via
Impacts Of Rdx Soil Contamination Across An Age Gradient For The Native Shrub Morella Cerifera., Stephen Via
Theses and Dissertations
Understanding the impacts of explosive contamination on vegetation is key to understanding explosives behavior in the environment. I quantified shrub growth responses to 1,3,5-trinitroperhydro-1,35-triazine (RDX) soil contamination across three life stages and I hypothesized that RDX would have the greatest impact on seed germination. Morella cerifera seeds were germinated on soils amended with RDX up to 1500 mg RDX kg-1 dry soil. Juvenile and adult individuals were exposed for 6 weeks to soil amended with RDX up to 750 and 1500 mg RDX kg-1 dry soil, respectively. Morphological responses were quantified for juveniles while physiological measurements were quantified for adults. …
Changes In Leaf Morphology, Photosynthesis And Nitrogen Content In Two Coastal Shrubs, Elizabeth Kost
Changes In Leaf Morphology, Photosynthesis And Nitrogen Content In Two Coastal Shrubs, Elizabeth Kost
Theses and Dissertations
It is important to understand mechanisms that facilitate expansion of two common shrubs, Morella cerifera and Baccharis halimifolia in coastal environments. The purpose of my study was to investigate the physiological and structural changes that occur as leaves age. Photosynthesis, incident light, chlorophyll, and leaf C:N ratios were quantified for young, intermediate, and old leaves (distal, central and proximal leaves, respectively). Leaf structural differences were also compared. Leaves did not change morphologically with age. Light decreased with leaf age and during winter months. Photosynthesis showed no seasonal or age related patterns. Chlorophyll increased initially and then declined with age due …
Avian Dispersal Of The Actinomycete Frankia Across A Barrier Island Landscape, Spencer Bissett
Avian Dispersal Of The Actinomycete Frankia Across A Barrier Island Landscape, Spencer Bissett
Theses and Dissertations
In the nutrient-poor soils characteristic of coastal environments, symbiotic association with the nitrogen-fixing root endosymbiont Frankia is essential to establishment and survival of the woody shrub Morella cerifera. Nutrient deficiency quickly becomes severe unless seedlings are infected by Frankia soon after germination. However, the means of arrival of Frankia prior to shrub establishment has not been determined. Using sterilized lab-grown M. cerifera seedlings and fecal samples collected from passerine birds on the Eastern Shore of Virginia, viability of avian dispersal of the bacteria was tested. Although passerine fecal samples did produce nodules on some sterilized M. cerifera seedlings, these experimental …