Elevation and Vegetation Data for the Global Change Research Wetland, Summer 2016

The Global Change Research Wetland (GCReW) is one of the most intensively studied tidal wetlands systems in the world, with the majority of the previous research spent on two native functional groups of plants (C₃ sedges and C₄ grasses) and the invasive reed Phragmites australis. These previous studies have been concentrated in clusters of long-term study plots which make up a relatively small and non-representative portion of a larger 22 hectare marsh. So far no studies have documented site-wide trends in elevation, plant species presence, and plant species dominance, which are needed for scaling up models of wetland response to sea-level rise. This data release documents three datasets collected in summer of 2016 in order to better quantify relationships between plant cover and elevation, to contextualize ongoing monitoring and experiments as well as support future planning at GCReW.

First, we performed 48 hour occupations of four elevation monuments on the Smithsonian Environmental Research Center's campus, using total station GPS. This was done so that we could better reference marsh heights to North American Vertical Datum of 1988. One of these monuments was used as a base station for real-time kinematic GPS surveying. Second, we surveyed the bounds and elevations of long-term vegetation monitoring plots associated with the Tennembaum Marine Observatory Network. Third and finally we performed a 20 by 20 meter real time kinematic GPS elevation survey of the entire marsh, accompanied by a Braun-Blaunquet vegetation survey to map the presence and relative dominance of wetland plant communities. These analysis data products provide valuable context to, and further research direction for, the temporally rich but spatially restricted plant and elevation data collected at GCReW over the last three decades.