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Long Term Residual Effects Of A Nutrient Addition On A Barrier Island Dune Ecosystem, Susan M. Heyel

Biological Sciences Theses & Dissertations

In 1991, 150 m² were fertilized with nitrogen on three dunes on Hog Island, part of the Virginia Coast Reserve Long Term Ecological Research site, to examine plant community response to nitrogen addition. In 2000, the fertilized plots continued to exhibit a positive growth response. This study sampled the aboveground biomass, belowground biomass, and nutrient content of the experimental plots to examine the long- term patterns of nitrogen retention in a nitrogen limited system. Aboveground and belowground biomass was significantly greater in the fertilized plots than in the control plots. Aboveground biomass exhibited was significantly greater in control and …

The Role Of Nitrogen Availability, Hydroperiod And Litter Quality In Root Decomposition Along A Barrier Island Chronosequence, Christine Elizabeth Conn

Biological Sciences Theses & Dissertations

The decomposition of organic matter regulates carbon and nutrient flux between biotic and abiotic pools. Traditional research emphasizes above ground decomposition processes and, by inference, extends these findings to below ground systems. The study, conducted along a southeastern Atlantic Coast barrier island dune and swale chronosequence (Virginia Coast Reserve Long Term Ecological Research site), addressed how hydroperiod, litter quality and nitrogen availability influenced below ground root decay in response to gradients associated with site age and topographic position and in the context of a nitrogen limited ecosystem. Effects on rates of mass loss and nitrogen and phosphorus dynamics during decomposition …

Nitrogen Dynamics Of The Acacia Senegal Agroforestry System In The Sudan, Zakaria Abdalla Mohammed Saad

Biological Sciences Theses & Dissertations

The savanna is characterized by low rainfall, poor soil and vegetation types dominated by the Genus Acacia. Agroforestry systems evolved, the most notable of which is Acacia senegal agroforestry system (ASAS). It yields gum acacia, fuel and fodder and improved soil N, P, and pH and stability against erosion.

This study investigated the climatic, edaphic and biotic interactions of the ASAS that govern the nutrient dynamics, mainly N, and biomass. The effects of limited resources of soil, space and photoperiod on biomass, nodulation and rate of N fixation were investigated. Genetic differences among populations were studied. Progenies of selected …