Type of Document Master's Thesis Author Mullens, Ashley Wilson URN etd-06112007-162947 Title Strategies for Establishing Spartina alterniflora on Newly Constructed Marsh Terraces in Coastal Louisiana Degree Master of Science (M.S.) Department Agronomy & Environmental Management Advisory Committee
Advisor Name Title Maud M. Walsh Committee Chair Charles E. Sasser Committee Member Irving A. Mendelssohn Committee Member Keywords
- Spartina alterniflora
- marsh terracing
- vegetative establishment
Date of Defense 2006-12-04 Availability unrestricted AbstractMarsh terracing is an innovative restoration technique being used in shallow, open water marshes in coastal Louisiana. When properly constructed and planted with an applicable plant species, terraces promote sediment deposition and accumulation by reducing wave energy. Although used extensively for marsh creation, little published information is available on techniques for establishing vegetation on marsh terraces.
The goal of this research was to determine the optimal planting season and most effective plant growth form of Spartina alterniflora for establishing vegetation on newly constructed marsh terraces. Study objectives were to: 1) compare survival and growth rates of different plant growth forms based on planting season, 2) determine the optimal method of handling/storing seed to maximize germination and survival on terraces, 3) characterize soil composition and terrace elevation as compared to ambient marsh, and 4) monitor water depth and salinity of an adjacent water body to determine any relationship to plant response.
This research was conducted on a large-scale terracing project on the Pointe aux Chenes Wildlife Management Area. Vegetative transplants of S. alterniflora were established on the terraces and were quantitatively sampled to examine differences in survival and growth. Treatments included plant growth form: containered plants (trade-gallon) and vegetative plugs; planting season: spring and fall planted; and growth period: 6 and 12 months. There was no significant difference in survival among planting seasons (p=0.0933) or growth forms (p=0.5396). Vegetative plugs and trade-gallons had similar growth rates when comparing aboveground biomass (944.79g/m2 and 1173.39g/m2, respectively) and belowground biomass (1187.82g/m2 and 1262.60g/m2, respectively). In a separate seeding study, there was little germination of S. alterniflora seed on the terraces (less than 1%), though the seed proved to be viable under in controlled germination tests. Although direct seeding is not a viable option on marsh terraces, vegetative transplants of S. alterniflora are effective in establishing vegetation on terraces. This study will add to the knowledge base of coastal restoration technology by evaluating the variability in terrace construction and the hydrologic-soil-plant relationship that is essential to terracing success, thus providing restoration project planners with additional strategies that will better incorporate vegetative establishment into terrace engineering.
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