Freshwater diversions are a relatively recently utilized tool in wetland loss mitigation that stimulate an organic accretion response in marsh vegetation, which is based in root production and thus belowground biomass. The effectiveness of freshwater diversions in slowing marsh loss probably varies across a gradient of the factors they supply: decreased salinity, increased nutrient concentrations, and increased inundation. Flooding stress is commonly thought to be the overriding factor limiting wetland vegetation growth, however its influence may vary across salinity and nutrients. Therefore, plugs of Spartina patens were planted in four marsh organs consisting each of 36 sediment-filled PVC pipes of incremental heights that created a range of growth elevation and thus flooding stress. The organs were located in mean salinities from 2.6-14.7 ppt and two of them fertilized at 22 g N m-2, 11 g P m-2, and 5.5 g K m-2. Twice during the growing season below- and aboveground biomass was harvested, sorted, dried, weighed, and analyzed for relationships between variables. Flooding stress was found to be primary, with a secondary interactive effect between salinity and fertilization that suggests fertilization may help plants resist relatively higher salinity levels. Variations in salinity and nutrient concentrations associated with freshwater diversions, which can differ in intensity and extent, might also be linked to increased nutria herbivory. Therefore, nutria preference for fertilized versus unfertilized vegetation was also tested in a controlled setting on Panicum hemitomon, Sagittaria lancifolia, and S. patens, representative dominant plant species of fresh, fresh-brackish, and brackish marsh. Nutria showed a significant preference for fertilized vegetation within species. It is therefore possible that benefits derived from nutrient-rich fresh floodwater could potentially be negatively impacted by increased preferential herbivory.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-06102014-192930 |
| Date | 08 July 2014 |
| Creators | Ialeggio, James Stephen |
| Contributors | DeLaune, Ronald, Gambrell, Robert, Nyman, John Andrew |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-06102014-192930/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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