This dataset is a polygon representation of vegetation communities within the upper Derwent Estuary wetlands of Tasmania. Each polygon represents a single vegetation community; mapping units conform to TASVEG 1.0 mapping unit specifications. Vegetation communities were identified to a 1ha resolution or to 0.25ha where a threatened vegetation community was suspected. This dataset is one of three produced for the upper Derwent Estuary wetlands for the Derwent Estuary Program.

Using the approximate study area supplied by the Derwent Estuary Program, the boundary of the wetlands viewed on ortho-rectified aerial photographs was used to determine the study area. Vegetation communities were mapped within the study area by creating polygons and allocating vegetation community codes (TASVEG mapping units). This was carried out by overlaying the TASVEG (ANZTA0015000012), roads (ANZTA0005000120), geology (Simplified Geology, based on the existing 1:250,000 digital geology of Tasmania) and coastline (from LIST Hydline Digital Topographic Series - ANZTA0005000138) layers over ortho-rectified aerial photographs, viewed at a scale of 1:5000. Vegetation communities were identified to a 1ha resolution or to 0.25ha where a threatened vegetation community was suspected. Existing mapping of Murphy’s Flats has been incorporated (North Barker (2006). Ortho-rectified aerial photographs at a scale of 1:24 000 dated from 4/01/1999 to 17/02/2001 were used. Ground truthing has been carried out and mapping adjusted for 98 percent of the study area. Further information is presented in the report listed under additional metadata.

Position Accuracy: Field data was collected with the assistance of a GPS receiver and hard copy maps of digitised vegetation communities. Orthoimages used in the mapping process were 1:24000 with accuracy generally in the order of ±2m (absolute accuracy ±5m in some place ). Individual polygons are attributed with the scale, and date of photography used. Attribute Accuracy: Approximately 98 percent (by area) of the vegetation communities have been identified in the field by a qualified botanist. Canopy and Structure attributes are reliable were they are recorded. Logical Consistency: The dataset has been checked for general topological errors with MapInfo 8.5 (all overlaps, gaps & self-intersections corrected). All objects are attributed with valid values. Completeness: COMPLETENESS OF COVERAGE The study area encompasses the wetlands in the upper Derwent River Estuary between Boyer and Bridgewater on the north side of the Derwent River and Sorell Creek and Granton on the south side of the River. The full extent of the wetlands has been mapped. All islands in the vicinity have also been mapped. COMPLETENESS OF CLASSIFICATION All polygons have been attributed with VEGCODE. Canopy and Structure attributes are recorded only where relevant and observed. COMPLETENESS OF VERIFICATION All polygons have been verified, individual polygons are attributed with the method of verification. 98 percent of the polygons (99 percent by area) were field verified and the remainder were verified from ecological principles. Additional: Vegetation Community and Weed Mapping - Upper Derwent Estuary Wetlands September 2008, For Derwent Estuary Program, North Barker Ecosystem Services available from the Derwent Estuary Program.