Assessment of Bangalay Sand Forest TEC on NSW Crown Forest Estate

Bangalay Sand Forest is a threatened ecological community (TEC) associated with coastal sand plains found in the Sydney Basin and South East Corner bioregions. The most common tree species are Eucalyptus botryoides (bangalay) and Banksia integrifolia (coast banksia). The understorey is characterised by a mix of sclerophyll and mesophyll species. In this report, we focus on the distribution of this TEC in the NSW South Coast region, an area that extends from Sydney to the Victorian border. This study assesses whether Bangalay Sand Forest is located within the 350,000 hectares of state forest found in our southern study area. Our interpretation of Bangalay Sand Forest (BASF) was informed by the six previously described vegetation communities cited in the final determination that were relevant to the South Coast region. Four are eucalypt-dominated forests and one a coastal scrub dominated by Banksia integrifolia and Leptospermum species. An additional community has a mixed canopy composition for which the final determination includes a qualifying statement to exclude stands dominated by Casuarina glauca. Initially we examined existing maps of coastal sand landforms and geology along with available vegetation maps to determine the likely extent of habitats suitable to support the presence of the TEC within state forest. We reviewed candidate areas that were within or proximate to state forests using interpretation of high-resolution digital aerial imagery as a basis for planning field surveys. We identified a small number of areas in Termeil and East Boyd State Forests that were plausible locations for BASF and an additional two areas in Nullica and Mogo State Forests identified from existing vegetation mapping. Sites that had not already been subject to field survey were visited and were either systematically sampled or were rejected on site where the species composition and landform were clearly mapping inaccuracies (e.g. estuarine mudflat) Our analyses of plot data assigned 66 plots (out of 8452) to Bangalay Sand Forest, based on allocation to a previously defined community cited in the final determination and agreed substrate qualifiers. We used plot data and a selection of environmental and remote-sensing variables to develop a Random Forest (RF) presence-absence model of the probability of occurrence of Bangalay Sand Forest across the study area. We used the RF model and the locations of plot data to further assess whether Bangalay Sand Forest occurred on state forest.

We found no evidence of Bangalay Sand Forest occurring on any state forest within our study area based on the results of our field surveys, analysis of plot data, review of existing map data and predictive models.