Salt and brackish marsh vegetation distribution was documented using cover classes (modified Braun-Blanquet) on individual plots along 9 transects in the Plum Island Estuary. The plots were also surveyed for elevation rel mNAVD88 using RTK GPS . The plots and transects had been surveyed for vegetation and elevation in 2001. The re-survey is designed to monitor changes in species composition and marsh elevation across a broad spatial scale over the previous 20 years. The survey will also serve as a baseline for future marsh monitoring work with UAVs.
Nine sites within the PIE LTER were surveyed for vegetation cover, species composition and marsh elevation in summer 2021. The sites were selected from a database of 40 sites that were surveyed in 2001.
The length and number of sampling points of each transect varied based on the size of the marsh being investigated. Each of the sample points on each of the original transects were visited in 2021. A Topcon Hiper-V antenna RTK system was used with MaCORS satellites to relocate the points and measure elevation. Some points could not be re-sampled because they were located in open water due to changes in creek morphology or creek bank erosion. When necessary, new points were established to indicate the beginning or end of a transect.
At each sample point, a 1m x 1m quadrat was placed on the marsh surface with the sample point in the center of the quadrat. All vegetation in the quadrat was identified to the species level when possible, and cover classes were assigned to each species present. Spartina alterniflora was divided into 3 height categories (short (<50 cm); medium (50-80 cm); tall (>80 cm)). A modified Braun-Blanquet classification scheme with six classes was used. Non-plant categories such as wrack, pool, bare sediment, and creek were also assigned cover classes. Standing dead Juncus gerardia vegetation from the 2021 growing season was included in the cover class as that species had already senesced at the time of the surveys. No other dead vegetaion was included in the survey. The cover classes were as follows:
Cover Class Description
0 0% cover
1 0.1-5% cover
2 6-25% cover
3 26-50% cover
4 51-75% cover
5 76-100% cover
Plant data and elevation of each point was recorded on data sheets in the field, and transcribed into an Excel spreadsheet.
Version 1: March 11, 2022, original upload of data and metadata to comply with importation to DEIMS7 and LTER Data Portal. Used MarcrosExportEML_HTML (working)pie_excel2007.xlsm 28/12 8:18 PM for QA/QC to EML 2.1.0