Unbroken GCPO Estuarine Tidal Marsh Patches, Emergent Veg Cover, and Open Water in Marsh Patches [Draft]

The draft Integrated Science Agenda (ISA) of the Gulf Coastal Plains and Ozarks Landscape Conservation Cooperative (GCPO) identifies Gulf Coast estuarine tidal marsh as a priority system for conservation. We assessed amount, configuration, and condition of this system within the GCPO boundary by evaluating spatial data layers representative of desired ecological states for the system and combining the layers in an additive mapping procedure. The data was developed to address the desired landscape endpoint for estuarine tidal marsh systems related to marsh patch size. We first buffered the GCPO eastern and western boundaries by 10 km, and extended the coastal boundary to the state seaward boundaries to allow appropriate neighborhood analyses if necessary along the GCPO boundary line. We used the 30 m overlay marsh mask, which uses a mosaic  of 10 m Florida Cooperative Land Cover (CLC) data, and 10 m USGS marsh type delineation project (MTDP) data in Louisiana, Alabama, and Mississippi  to build patches. We converted marsh mask pixels to polygons with non-simplified edges. We next ran an Eliminate Polygon Parts tool in ArcGIS to consolidate breaks within marsh interiors (followed by a Union function, and a Dissolve function not allowing for multi-part features), to be used in subsequent analysis of percent vegetative cover, percent open water, marsh interdigitation and submergent vegetation. For summary purposes we selected only marsh patches that intersected the GCPO geography by using a select by location function. We then selected marsh patches >250 ac.  We also used marsh patches overlaid over the mosaiced CLC and MTDP layers and used a Tabulate Area function in ArcGIS Spatial Analyst to determine the area and subsequent percent of emergent vegetative cover and open water cover within each marsh patch. We used selection to extract patches that were >250 ac, and contained >70% emergent vegetative cover and <20% open water for estuarine tidal marsh patches intersecting the GCPO boundary. The three layers available here represent a hierarchical analysis defining 1) vector polygon estuarine tidal marsh patches of all sizes, 2) vector polygon estuarine tidal marsh patches >250 ac in size, and 3) vector polygon representing estuarine tidal marsh patches >250 ac with 70% emergent vegetative cover.