The effects of altered inudation and wrack deposition on nitrification, denitrification, and the standing stocks of NO₃- and NO₂- / by James Harvey Taylor III.
| Author/creator | Taylor, James Harvey author. |
| Other author | Christian, Robert R. (Robert Raymond), 1947- degree supervisor. |
| Other author | East Carolina University. Department of Biology. |
| Format | Theses and dissertations |
| Production | 1995. |
| Description | xiii, 169 leaves : illustrations ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | Concentrations of groundwater ammonium, nitrate, and nitrite and gaseous nitrous oxide were measured to estimate nitrification and denitrification rates and determine how altered inundation and wrack deposition affected nitrogen cycling. Three blocks (Blocks 1-3) were established at the junction of a vegetative patch of Juncus roemerianus and a community dominated by both Spartina patens and Distichlis spicata. Each block contained three plots that received a different inundation treatment: (1) Flooded (F), a plot receiving water pumped from the tidal creek and surrounded by a border to help retain the pumped water; (2) Border Control (BC), a plot surrounded by a border; and (3) Control (C), a plot delineated by four pieces of 3-foot PVC; one in each corner. Each inundation plot (F, BC, and C) was divided in half, and each half received a different vegetative treatment: (1) Wrack (W), the half of the plot where wrack covered the vegetation; and (2) Vegetation (V), the half of the plot was left unaltered. Fifteen cores were taken from each vegetative treatment, and the acetylene inhibition technique was used to estimate nitrification and denitrification rates. Nitrification rates were obtained by measuring the changes in the concentrations of (1) NO3 and (2) N02 after a six hour incubation period with and without acetylene. Nitrate and nitrite concentrations and nitrification rates were measured during June, August, and September. Denitrification rates were obtained for August and September. In October, similar techniques were used to determine if short-term changes in the moisture of the soil affected the rates of nitrification or denitrification. The rates of nitrification and denitrification obtained during the experiment were within the range of 0 to 30 [mu]mol m-2 h-1 and agreed with previously published data. Altered inundation patterns did not affect nitrification or denitrification rates. Nitrogen cycling in tidal salt-marsh soils appear relatively insensitive to changes in flooding regimes since the biota of the system have adapted to live in areas that experience rapid changes in flooding conditions--tides, storm surges, flooding events cause by rainfall, among others. Wrack deposition, unlike flooding conditions, affected nitrification and denitrification rates. Although the acetylene based method used in the study detected increased nitrification rates only during September, wrack is hypothesized to increase nitrification rates. Denitrification rates were much higher where wrack deposition occurred. I propose that wrack provides more labile carbon that denitrifying organisms require. In conclusion, flooding conditions may stress soil ecosystems, but they should not affect processes occurring in tidally influenced salt-marshes if those systems are exposed to sudden changes in the flooding conditions--storm surges, rainfall, flooding, and tides--on a routine basis. However, the disturbance event of wrack deposition may affect biogeochemical processes--nitrificaion and denitrification--since the biotic and abiotic factors controlling the cycling are more directly impacted by the die-off of vegetation. |
| General note | Submitted to the faculty of the Department of Biology. |
| General note | Advisor: Robert R. Christian |
| Dissertation note | M.S. East Carolina University 1995 |
| Bibliography note | Includes bibliographical references (leaves 161-169). |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
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