Threatened Native Vegetation Communities 2020 (TNVC 2020) is a state-wide mapping layer produced by the Tasmanian Vegetation Monitoring and Mapping Program (TVMMP) showing the indicative extent of threatened native vegetation communities across Tasmania. It estimates the mapped extent of 39 communities listed under Schedule 3A of Threatened native vegetation communities of the Nature Conservation Act (2002). TNVC 2020 is derived from TASVEG 4.0 for all but four of the 39 communities. Four communities (Heathland scrub complex at Wingaroo, Notelaea - Pomaderris - Beyeria forest, Sea bird rookery complex and Riparian scrub) are derived from a combination of TNVC 2014 and TASVEG 4.0. TNVC 2020 is the third major release version of the TNVC layer. It replaces TNVC 2014, which was largely based on TASVEG 3.0.
TNVC 2020 is derived from TASVEG mapping, which is a composite of mapping completed at a range of times and spatial scales. The first version of TASVEG (TASVEG 1.0) was released in 2004. The initial TASVEG release incorporated existing information from the Regional Forest Agreement mapping program and from the World Heritage Area mapping program, with remaining areas of the state mapped by the TVMMP. Since TASVEG 1.0 there have been three minor versions released; 1.1 and 1.2 in 2005 and 1.3 in 2007. Three major updates have also occurred since version 1.0; version 2.0 released in 2009, version 3.0 released in 2013 and version 4.0 (the current version) in 2020. Each new version of TASVEG has been accompanied by a statement indicating which new mapping data has been incorporated since the last release.
Photographic interpretation (PI) of DPIPWE's most current aerial photography is the primary method of data collection for TASVEG updates, with field verification of representative polygons undertaken where practicable. Some aerial photography is analysed stereoscopically where feasible, but the majority of imagery is analysed orthographically within a Geographic Information System. Imagery is interpreted by vegetation scientists within DPIPWE who directly edit a master version of the TASVEG layer. Ancillary information such as geology maps, species records from the Natural Values Atlas, elevation data, hydrographic information and ecology texts are consulted to assist in the accurate typing of vegetation during PI.
TASVEG also incorporates updated mapping supplied by external stakeholders where the veracity of such data can be confirmed.
The TNVC communities whose distribution is directly derived from equivalent TASVEG Mapping Units underwent a checking and review process during the creation of TNVC. Some polygons had undergone clearing and conversion and were removed from both the TASVEG Live and TNVC datasets. Four TNVC communities were identified that had some polygons allocated to other native vegetation communities during the creation of TASVEG 4, which were reinstated during the checking process for TNVC.
Four TNVC communities (Heathland scrub complex at Wingaroo, Notelaea - Pomaderris - Beyeria forest, Sea bird rookery complex and Riparian scrub) were derived from a combination of TNVC 2014 and TASVEG 4.0. Each of these communities was treated differently to produce the current mapped extent.