Response of tidal marsh vegetation to pulsed increases in flooding and nitrogen

Wetlands Ecology and Management
By: , and 

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Abstract

Worldwide, human activities have modified hydrology and nutrient loading regimes in coastal wetlands. Understanding the interplay between these drivers and subsequent response of wetland plant communities is essential to informing wetland management and restoration efforts. Recent restoration strategies in Louisiana proposes to use sediment diversions from the Mississippi River to build land in adjacent wetlands and reduce the rate of land to open water conversion. In conjunction with sediment delivery, diversions can increase nutrient loads and water levels in the receiving basins. We conducted a greenhouse mesocosm experiment in which we exposed three common tidal freshwater and brackish marsh plants (Panicum hemitomon, Sagittaria lancifolia, and Spartina patens) to two nitrate loading rates [high (35 g N m2 year−1) and low (0.25 g N m2 year−1)], and two flooding treatments (with and without diversion pulsing). Experimental units were set at two different elevations within the treatment tanks to simulate both a healthy and degraded marsh. Plant growth metrics and soil physicochemical properties were measured monthly. Final total biomass was determined at the study’s conclusion. Growth responses differed between species but were not significantly influenced by the treatments. Soil redox potential decreased significantly following the increase in flooding associated with the diversion pulse, but recovered to pre-diversion levels after a 3-month recovery period. Our study suggests short flooding pulses with a recovery period may be key for maintaining healthy marshes, however there remains a need for longer-term empirical studies to understand marsh response to pressures associated with river sediment diversions over time.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Response of tidal marsh vegetation to pulsed increases in flooding and nitrogen
Series title Wetlands Ecology and Management
DOI 10.1007/s11273-019-09699-8
Volume 28
Year Published 2019
Language English
Publisher Springer
Contributing office(s) Wetland and Aquatic Research Center
Description 17 p.
First page 119
Last page 135
Country United States
State Louisiana
Other Geospatial Jean Lafitte National Historical Park and Preserve, Lake Salvador Wildlife Management Area
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