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Native vegetation of the NSW south coast, escarpment and southeast tablelands was classified into 191 floristic assemblages at a level of detail appropriate for the discrimination of Threatened Ecological Communities and other vegetation units referred to in government legislation. Assemblages were derived by a numerical analysis of 10832 field sample quadrats including 8523 compiled from 63 previous vegetation surveys. Past bias in the distribution of field data towards land under public tenure was corrected by extensive surveys carried out on private land. The classification revises and integrates the units described in recent vegetation studies of Eden, Cumberland Plain and Sydney-south coast into a single, consistent classification. Relationships between floristic assemblages and climate, terrain, substrate and vegetation structure were used to map the distribution of communities prior to clearing at 1:100 000 scale. The extent of clearing was mapped using interpretations of remote imagery (1991–2001) from previous work, standardised and merged into a single coverage and supplemented with additional work. Profiles for each assemblage, which we term ‘communities’ or ‘map units’, describe their species composition, vegetation structure, environmental habitat, the extent of clearing and conservation status. Lists of diagnostic species were defined using a statistical fidelity measure and a procedure for using these for community identification is described. Approximately 66% of the study area retains a cover of native vegetation, primarily in areas with low fertility soils and dissected topography. Communities subject to over-clearing (>70%) are concentrated in a few large areas characterised by clay/loam soils and flat to undulating terrain. These include the Sydney metropolis, Wingecarribee Plateau, Illawarra Plain, Shoalhaven floodplain, Araluen Valley and Bega Valley, and various smaller river valleys. Forty-one percent of remaining native vegetation is protected within conservation reserves while 31% occurs on private land, 20% in State Forests and 8% on other Crown lands. Forty-five Threatened Ecological Communities (TECs) were recorded in the study area. The majority of TECs are represented by a single map unit, although in some cases a TEC is included within a broader map unit. Twelve TECs are represented by combinations of two or more map units.
Twenty-two vascular plant communities occurring on, and adjacent to the Cumberland Plain and Hornsby Plateau, are defined using a multi-variate analysis of quantitative field survey data. Communities are described using structural features, habitat characteristics and diagnostic species. Diagnostic species are identified using a statistical fidelity measure. The pre–European spatial distribution of communities is estimated using a decision tree approach to derive relationships between community distribution and geological, climatic and topographical variables. Contemporary vegetation cover is estimated from 1:16 000 scale aerial photography (1997/98) and sorted into six categories based on cover of Eucalyptus species. These categories are only approximately related to vegetation condition: high Eucalyptus cover classes are most likely to contain high levels of floristic diversity, but areas with scattered cover or no cover at all may have either high or low diversity.
Map accuracy is assessed using independent field samples and is primarily limited by the accuracy of 1:100 000 geological maps. Patterns in overstorey composition were mapped at 1:16 000 scale but were less useful in delineating community boundaries than was hoped because few species are confined to a single community. The extent to which observer bias may influence estimates of the present extent of remnant vegetation is investigated by comparing the interpretations of two observers for a subset of the study area.
The community classification is interpreted in light of previous publications and the Endangered Ecological Communities listed under the NSW Threatened Species Conservation (TSC) Act (1995). Four communities listed under the TSC Act (1995) are represented by more than one unit in the new classification: Cumberland Plains Woodland (represented by Shale Plains Woodland, Shale Hills Woodland); Sydney Coastal River Flat Forest (Riparian Woodland, Riparian Forest, Alluvial Woodland); Shale/Sandstone Transition Forest (Shale/Sandstone Transition Forest low sandstone influence, high sandstone influence); and Sydney Turpentine-Ironbark Forest (Turpentine-Ironbark Forest, Turpentine-Ironbark Margin Forest). A further seven listed communities are described in this paper (Cooks River/Castlereagh Ironbark Forest, Shale/ Gravel Transition Forest, Castlereagh Swamp Woodland, Agnes Banks Woodland, Western Sydney Dry Rainforest, Moist Shale Woodland, and Blue Gum High Forest).
As a result of clearing, native vegetation cover on the Cumberland Plain has been reduced to only 13.1% (+ 1.7) of the pre- European extent. Despite high levels of fragmentation, the presence of exotic species and a history of extensive grazing, high numbers of native species were recorded in remnants of all sizes. A large proportion of species was recorded once only (22%), while nearly half of all species were recorded 5 times or less. This suggests that there is a high likelihood that further clearing will lead to a loss of floristic diversity. Two exotic species (Olea europea subsp. africana and Myrsiphyllum asparagoides) are identified as a major threat to the conservation of native flora due to their widespread distribution and ability to out-compete native species. Control of these species should be a high priority in conservation management.
In New South Wales, the Threatened Species Conservation Act 1995 makes provision for the listing of Threatened Ecological Communities (assemblages of species occupying a particular area) as a means to conserving the variety of ecosystems present in the State. Hunter Valley Weeping Myall Woodland is listed as an Endangered Ecological Community under the New South Wales Threatened Species Conservation (TSC) Act 1995 and as a Critically Endangered Ecological Community under the Commonwealth Environment Protection and Biodiversity Conservation (EPBC) Act 1999.
The provenance of populations of Weeping Myall (Acacia pendula, family Fabaceae) in the Hunter Valley has recently been questioned. In this paper we consider the implications of its hypothesized European introduction for listing Hunter Valley Weeping Myall Woodland under the TSC and EPBS Acts. The recognition of any community is contingent on the identification of both a particular assemblage of species and the critical environmental factors that determine their co-occurrence (the area the community occupies in environmental space). Acacia pendula is one of a range of semiarid species which are primarily distributed west of the Great Dividing Range but also occur on Permian sediments in areas receiving the lowest rainfall of the Hunter Valley floor. On this basis we argue there is sufficient evidence to support the listing of Hunter Valley Weeping Myall Woodland under both Acts.
