Author : Abigail Griffin Wood
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (131 download)
Book Synopsis Biological Contributions to Elevation Differ Within Natural and Constructed Tidal Marshes Exposed to Nutrient Enrichment by : Abigail Griffin Wood
Download or read book Biological Contributions to Elevation Differ Within Natural and Constructed Tidal Marshes Exposed to Nutrient Enrichment written by Abigail Griffin Wood and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Restoration and construction of tidal marshes has been encouraged to recover ecosystem structure and function in response to wetland loss. While natural and restored marshes often achieve similar structure, they may not function similarly. Further, the effects of nutrient loading on ecological functions may vary between natural and restored or constructed marshes, with consequences for marsh resilience to sea-level rise. As coastal restoration and creation projects become more common, it is important to understand the similarities and differences in tidal marsh responses to environmental changes, including nutrient enrichment, and their impacts on ecosystem functions and resilience. To test the effects of nutrients on marsh responses, I conducted a controlled, nutrient-enrichment mesocosm experiment (none: no nutrients added; low: 20 g N m-2 yr-1 and 1.25 g P m-2 yr-1 added; high: 40 g N m-2 yr-1 /2.5 g P m-2 yr-1 added) utilizing intact, vegetated sods of Juncus roemerianus collected from natural and constructed tidal marshes along the Fowl River in Alabama. During the 8-month experiment, I measured hydro-edaphic conditions, above- and belowground biomass, primary production, organic matter decomposition, nitrate reduction potentials, and surface elevation change. Above- and belowground biomass was significantly higher in the natural than the constructed marsh, and belowground biomass responded positively to high nutrient additions. As a result, biomass allocation tended to shift belowground with increasing nutrients. Both marsh type and nutrient treatment significantly affected decomposition of J. roemerianus shoot litter, but not of belowground litter. However, given the lower belowground biomass in the constructed marsh, decomposition could have a greater overall impact on elevation in the constructed marsh compared to the natural marsh. Nitrate reduction potentials also differed between marshes and in response to nutrient enrichment. Denitrification (DN) was greater in the natural marsh and increased in response to nutrient additions in both marshes, representing nitrogen removal from the system. Dissimilatory nitrate reduction to ammonium (DNRA) did not differ between marshes or among nutrient treatments in the absence of carbon amendments, but it increased significantly in the natural marsh with carbon amendments, representing nitrogen retention in the system. These biological responses were insufficient to stimulate elevation gains, however, as all mesocosms lost elevation over time. While there were no significant differences in elevation change between marshes or among nutrient treatments, the none treatment retained the most elevation in the natural marsh while the high nutrient treatment retained the most elevation in the constructed marsh. Such differences between marsh types have important implications for coastal restoration success under increasingly eutrophic conditions, and collectively, indicate that nutrient additions may contribute differently to resilience to sea-level rise in natural and constructed tidal marshes.