Evaluation of drainage enhancement for vegetation recovery in New ENgland satl marshes using public domain, high-resolution aerail imagery (Dataset, R Code, and Tidal Watershed Boundary Shapefiles)

<b>EVALUATION OF DRAINAGE ENHANCEMENT FOR VEGETATION RECOVERY IN SALT MARSHES IN NEW ENGLAND USING PUBLIC AERIAL IMAGERY</b><b>Authors: </b><b>J Grant McKown</b>^{<strong>*</strong>}<b>, David M Burdick</b><b>, Gregg E Moore</b><b>, Jennifer L Gibson</b><b>, and Wenley Ferguson</b><b>Contact Information: Grant McKown ([e-mail], [e-mail])</b>^{<strong>Institution: Jackson Estuarine Laboratory, University of New Hampshire</strong>}<b>Project Description:</b>Paired stressors of sea level rise and abandoned ditches and embankments from historic farming practices has exacerbated waterlogging and accelerated replacement of valuable interior high marsh with large pools throughout the United States Atlantic seaboard. High marsh loss has contributed to substantial population declines and the threat of future extinction of the Saltmarsh Sparrow (<i>Ammodramus caudacutus</i>), an endemic species of coastal wetlands. Creation of runnels and selective ditch maintenance has been promoted as a short- and medium-term solution to conserve and restore high marsh habitat and restore natural single-channel hydrology. A comprehensive monitoring program was launched in 2020 to evaluate the impact of runnels and maintenance of selective ditches on the hydrology, vegetation, and elevation of interior marshes across 19 sites of Maine, Massachusetts, and Rhode Island with the explicit goal of habitat conservation for the Saltmarsh Sparrow. The marsh surface was classified from 2010 – 2021 with public aerial imagery to document the change in aerial extent of the vegetated marsh surface and unvegetated – vegetated ratio (UVVR) of tidal watersheds (mean size = 2.12 + 0.18 ha) associated with specific management actions: runnelling, reference healthy marshes, and no action pannes and pools. Runnels reversed the expansion of pools and pannes with annual declines of -0.037 UVVR and gains of 1.55 % vegetated area. Tidal watersheds gained an overall net 2.08 ha vegetated surface post-restoration, despite continued losses in reference and no action tidal watersheds. Re-establishing hydrologic paths to allow regular tidal flooding and drainage promotes revegetation of shallow waterlogged pools – a first step toward rebuilding marsh elevation and conserving habitat for saltmarsh sparrows.<br><b>Dataset Description:</b>Please note that each folder as a README file that should be reviewed beforehand. All columns in excel and CSV files are explained in the README file.<b>Drainage Enhancement Dataset and Metadata </b>- The master dataset of calculated unvegetated - vegetated ratio (UVVR) and vegetated marsh surface (hectares) of image classification of salt marshes across New England of 2010 - 2021. The dataset additionally includes the background information and metadata about drainage enhancement construction, salt marsh site characteristics, tidal watershed descriptions, and experimental design. Spatial accuracy assessments for each image classification of individual sites and years is provided as well.<b>Drainage Enhancement Tidesheds File Geodatabase </b>- The tidal watershed boundaries in polygon shapefiles for each salt marsh site in the study. Each shapefile has the size (acres and hectares) for each tidal watershed and UVVR scores and vegetated marsh surface (hectares) from 2010 - 2021.<b>Drainage Enhancement Analysis and R Code </b>- Input data analysis CSV file (also found in the Drainage Enhancement Dataset) and the R code for post-image classification analysis. R code is well-annotated with details and explanations for each step. R code formats the dataset, computes statistics, creates figures, and calculates change metrics found in the publication.