Marsh Resilience Research

> Marsh Vegetation

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The Deal Island Marsh & Community Project

Measuring Marsh Elevation Change
Jenny Allen, Maryland Department of Natural Resources

Elevation change in a marsh is an important indicator of the health of the marsh ecosystem. The ability of the marsh to increase or maintain its elevation at the same pace as sea level rise is critical for the survival of the marsh. If the surface of the marsh is not building up quickly enough, it may become vulnerable to degradation and conversion to open water.  In order to accurately measure the marsh surface over time, surface elevation tables (SETs) were installed at each of the seven sites. Two types of SETs were installed at each site: 1) shallow SETs, which shows elevation changes within the marsh root zone, and 2) deep SETs which shows elevation changes deeper in the soil profile. Having both types of SETs allows us to monitor elevation changes across different depths of the soil profile. At each site, 3 sets of paired SETs (both shallow and deep) were installed, totaling 24 SETs on the Deal Island sites, 12 SETs on the EA Vaughn Sites, and 6 SETs on the Monie Bay Reference site. The SETs were

installed during in December 2012 and baseline measurements were taken in April 2013. The shallow SETs are measured four times a year and the Deep SET s are measured twice a year during the growing and non-growing seasons.

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The primary research question related to marsh elevation change is to better understand what affect the ditch plugging

restoration may have on marsh surface dynamics. Analysis of

Becky Swerida, MD-DNR, measures SETs installed at one of the research sites.   

the SET data, both shallow and deep, showed no significant difference on elevation change between the ditched and unditched sites (Fig 1). There is a large amount of variability in the measurements; however, this is expected in the first few years after installing a SET. There is often disturbance created on the marsh surface when installing the SET as well as initial settling of the equipment once it is installed. It is too soon to tell what affect the ditch plug restoration may have on the marsh elevation, and future measurements are necessary to have an accurate picture of changes to the marsh surface.

Figure 1: Cumulative elevation change (cm/yr) of the shallow SETs.
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