Surface deposition and elevations in five salt marshes, Humboldt Bay, CA, 2013-2019

Elevation change and surface deposition are important drivers of salt marsh ecological processes and represent two of the fundamental variables for determining marsh resilience to sea-level rise. Surface Elevation Tables with Marker Horizons (SET-MHs) were used to measure plot-scale elevation change (SETs) and surface deposition (MHs) in five USGS study marshes located in Humboldt Bay, CA. SET-MHs were installed in 2014 (Mad River marsh and Manila marsh) and in 2015 (Jacoby marsh, White marsh, and Hookton marsh) and were measured during quarterly site visits. The SET-MH network includes two SETs and six MHs in each of the five study marshes. Measuring elevation change at the two SETs in each study marsh involves attaching a SET reader (an arm with 9 pins) to a receiving collar that is located on top of a permanent benchmark installed by inserting a deep rod into the marsh surface. Nine pins are lowered to the surface in four ninety-degree cardinal directions (0, 90, 180, 270) yielding 36 measurements of elevation for each SET. The SET method produced 72 quarterly measurements in each of the five marshes. Measurement of the six MHs in each study marsh entails removing a small plug of soil using a soil knife, measuring the depth of surface deposition above the feldspar layer on four sides, and replacing the plug. The MH method produced 12 quarterly measurements in each of the five marshes. The SET-MHs were measured with a ruler to the nearest millimeter by a trained technician.

                                            [
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                                            {
  "fn": "Karen M Thorne",
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                                            [
  "California",
  "Hookton marsh",
  "Humboldt Bay",
  "Humboldt County",
  "Jacoby marsh",
  "Mad River marsh",
  "Manila marsh",
  "SET MH",
  "USGS:622be855d34ec9f19eea4446",
  "White marsh",
  "accretion",
  "biota",
  "estuarine processes",
  "marsh ecosystems",
  "salt marsh",
  "surface deposition"
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