We’re conducting an experiment to compare plant traits, soil composition, and prevailing hydrological conditions between a pioneer- and high-marsh community right next to the mudflat, to test the hypothesis that plant traits shift from reinforcing erosion (low erosion-resistance but quick seedling recovery) to resisting erosion (high erosion-resistance but slow seedling recovery) in response to small differences in the prevailing hydrological regime. Mwche Marsh on the Taf is ideally suited for this study because we already understand a lot about how the marshes have changed over time.
Along the marsh edge, we have several ‘mini buoys’ which measure inundation frequency, wave height, and current speed. The mini buoy consists of three ‘off-the-shelf’ items: an accelerometer (the same sort of thing you’d find in a smartphone) inside a UV-protected centrifuge tube, which is anchored to the mudflat by fishing line. The accelerometer in the mini buoy continuously records how the mini buoy moves. The first sign of movement indicates that the tide is in and the mini buoy has started floating (giving us the start of the inundation period). A consistent dip in the data indicates that the mini buoy is being pulled by the current in a certain direction. The angle of dip gives us current speed. If the accelerometer records that it’s swaying back and forth, this indicates that a wave is passing over the mini buoy. From this movement we can infer wave height. When the accelerometer no longer records any movement, this indicates the tide is out. The length of time since it started floating gives us the inundation frequency.
We’ve also gathered plant and soil samples from the marsh. These will be used to determine how characteristics of the plants’ physiology differ between pioneer and high-marsh communities. Differences in erosion, or recover quickly from it.