Assessment of Tablelands Snow Gum, Black Sallee, Candlebark and Ribbon Gum Grassy Woodland TEC on NSW Crown Forest Estate

The operational map for Tablelands Snow Gum, Black Sallee, Candlebark and Ribbon Gum Grassy Woodland (Tableland Snow Gum or TSG) was constructed to resolve long-standing issues surrounding its identification, location and extent within the NSW State Forest estate covered by the eastern Regional Forest Agreements. The determination of TSG was reviewed by the project’s Threatened Ecological Community (TEC) Reference Panel (the Panel), and a set of diagnostic parameters for identifying the TSG TEC was agreed upon. These parameters included the bioregions in which TSG is likely to be located in, landscape features such as elevation and geology, and quantitative floristic attributes from vegetation communities explicitly listed in the determination. Using these diagnostic parameters, we defined the study area as being all IBRA subregions that cover the 600-1400m elevation range within the South Eastern Highlands, Sydney Basin, South East Corner and Australian Alps bioregions. We then compiled floristic plot data for all State Forest areas within our study area. Floristic plot data was sourced from both existing flora surveys held in the OEH VIS database and from targeted flora surveys conducted specifically for this project. We compared these plots with those previously assigned to flora communities listed in the determination of TSG. Both dissimilarity-based methods and multivariate regression methods were used for the comparison. The results of the comparison were then used to assess the likelihood that the plots in State forests belonged to one or more of the communities listed in the TSG determination. We also conducted presence-absence predictive distribution modelling to identify potential distributions of each of the primary vegetation communities cited in the determination for TSG. The modelling predicted the likelihood of occurrence for each community across State Forests in the study area based on a modelled relationship with environmental and remotely sensed variables. As such, the modelling assisted in identifying un-surveyed areas of potential TSG habitat and guiding follow-up survey efforts and aerial photography interpretation (API) work. API assessment was carried out for all State Forests where the predictive modelling identified areas with high probability-of-occurrence values. We used recent high resolution stereo digital imagery in a digital 3D GIS environment to delineate areas of potential TSG based on observable patterns in canopy species dominance, understorey characteristics and landform elements. We constructed the operational map by assigning our API polygons as being TSG based on the extent to which the floristic plots within or near to each API polygon belonged to TSG. We used a precautionary approach and assessed a mapped polygon as TSG if the map unit to which it belonged contained any TSG plot.

Operational TEC Mapping have been derived by API at a viewing scale between 1-4000 using ADS40 50 cm pixel imagery and 1 m derived LIDAR DEM grids for floodplain EECs.