South East Biological Survey RESULTS VEGETATION By L. M. B. Heard 1 INTRODUCTION halmaturorum with samphire) and Thatching Grass The survey area, bounded to the north by 36 degree (Gahnia filum) Sedgelands. There is a general lack of latitude, the coastline to the south and west and the surface streams and rivers except in the east near the border to the east, represents the limit of grassy border where creeks come from Western Victoria and woodlands, open forests and wetland plant in the south along the coast where streams originate communities more typically associated with south­ from springs (e.g. Eight Mile Creek) (Croft et al. eastern Australia (Croft et al. 1999). This area also 1999). represents the southern limit of dryland (inland) mallee plant communities more typically represented in the In the north-east inland portion of the study area, is an Murray Mallee, sandy heath communities and is close area of east-west trending windblown siliceous sand- to the southern limits of some plant communities in dunes (Croft et al. 1999) extending from the Little South Australia such as Eucalyptus diversifolia ssp. Desert in Victoria. Low stunted stringybark diversifolia (2) Mallee. Detailed background on the woodlands and sandy heath dominate this area. North major pre-European settlement vegetation communities of this sandy area is a large tongue of grey cracking of the region is provided in the Historical Vegetation clay soil contributing to the Tatiara District, around Communities chapter. Bordertown (locally referred to as “the good country”), with itsBox and Buloke woodlands (Eucalyptus Edaphic factors (topography, substrate and soils), and microcarpa, E. odorata, E. porosa and Allocasuarina climate drive the diversity of floristic communities luehmannii) on the heavier soils, and South Australian across this region. Typically, the South East is Blue Gum (Eucalyptus leucoxylon) and Pink Gum represented bylow relief and a series of stranded (Eucalyptus fasciculosa) on the loam soils. The Box ancient coastal ridges (calcarenite ranges and stranded and Buloke communities are at the western limit of dunes which rise 20-50m above the plains), formed their range and dominate the adjacent Wimmera region through fluctuations in the sea-level over the last in Victoria. Beyond these areas and to the north-west 700,000 years, which parallel today’s coastline (Croft the area becomes drier and sandier with different et al. 1999). These are vegetated mainly with mallee eucalypt species dominating on both the dunes stringybark woodlands (Eucalyptus obliqua, E. and the heavier soil flats with sandy heath and arenacea and E. baxteri) in the south grading to Broombush (Melaleuca uncinata) also present. Coastal Mallee (E. diversifolia) in the north-west. Woodlands of stringybarks and smooth barked Adding to the diversity of features that characterise the eucalypts (E. fasciculosa, E. leucoxylon) occur on the landscape are the extinct volcanoes (e.g. Mt Gambier ridges to the east. and Mt Schank) where stringybark forests flourish; exposed areas of limestone where sinkholes and caves Between the ridges, are broad open interdunes or have formed (Naracoorte and Mt Gambier areas); and swales (2-10km wide) (Croft et al. 1999) where granite outcrops such as Mt Monster and Jip Jip. surface water naturally ponds. Here it percolates through the substrate toward the coast or accumulates This chapter summarises the results of the field survey in sufficient quantities to flow north to escape around and the subsequent floristic analysis that occurred with the ridges. Vegetation communities of these interdunal the addition of two flora datasets from other biological areas consist mainly of once extensive Cutting Grass surveys in and adjacent to the region (South East Coast (Gahnia trifida) Sedgelands, Honeysuckle (Banksia and Murray Mallee). Both the survey and the floristic marginata) Open Woodlands, River Red Gum analysis formed the basis for the regional mapping. (Eucalyptus camaldulensis var camaldulensis Woodlands, Tea-tree (Leptospermum spp.) While there havebeen numerous studies of the Shrublands, and Baumea spp. of freshwater swamps in vegetation within the region, this study has provided the south. In the north, they consist of Short-leaf the first comprehensive and systematic survey of the Honey-myrtle (Melaleuca brevifolia) Shrublands in the native vegetation across the full extent of the region, brackish swamps, more saline shrublands (Melaleuca and complete regional vegetation community mapping 1 Environmental Information Analysis Branch, Environmental Information, Department for Environment and Heritage, PO Box 550, MARLESTON 5033 2. Based on recent taxonomy and nomenclature in Nicolle (1997). 65 on a 1:50,000 scale. The regional mapping aspect of species per site. For the South East Biological Survey this study drew on as many literature references and the average number of plant species recorded per site other mapping sources as were available, and was 36 species. This 50% increase resulted in more attempted to bring all this information into the final time being required at sites to adequately record the regional coverage (refer to the Vegetation Mapping species present and take appropriate voucher Chapter). specimens. SURVEY COVERAGE In terms of the representation of the landforms there 1991- 1997 was reasonable representation of the dunes (total of At the conclusion of the vegetation survey component dune, crest and slope – 32.7%), sandy plains (8.9%) to of the South East Biological Survey, 358 vegetation plains (16.2%) (total of 25.1%), and hills (total of crest sites had been comprehensively surveyed throughout to footslope – 15.9%). Swamps were also reasonably the 270,000 hectares (ha) of native vegetation represented (11.5%) particularly after the addition of remaining in the 2,100,000 ha study area (Croft et al. 11 sites in swamps in 1997, having had only 30 (8.4%) 1999). As a result, the average site density within the sites placed in swamps in 1991 (Figure 31). The remnant native vegetation was one site per 754 ha. landform elements of swales, interdune corridors, open Figure 30 shows the locations of these sites across the and closed depressions that are also common features study area. A further 12 locations were visited of the South East landscape were poorly represented at opportunistically. A list of sites surveyed in both 1991 sites with 7.8%, 0.3%, 2.5% and 2.8% respectively and 1997, with some associated location and physical (Figure 31). Current coastline foredunes were not well data is provided in Appendix I. represented by this survey because they had been surveyed during the South East Coastal Survey (Figure In terms of the spatial distribution of the survey 34). The gaps in coverage of the broad interdune – coverage compared to the spatial distribution of the swales to depression areas are further supported by native vegetation, there are gaps in the coverage review of the surface soil textures recorded at sites. particularly north east, south east and south west of The majority of sites occurred on sand (48.3%), sandy Bordertown. Areas less well represented were north loam (34.9%) and loam (10.9%) with poor west of Bordertown (north of Cannawigara), south representation of soils in the silty loam to medium west of Keith including most of Gum Lagoon heavy clay range (Figure 33). Conservation Park, east of Mt Tarap across to the Peacock Range and the broad interdune – swale to low Although swamps were considered reasonably rises of Biscuit Flat (west of Kangaroo Inn). represented by 11.5% of sites, this coverage does not adequately reflect their prominence as a landform To some extent gaps were due to an over estimation of within the South East where over 76,000 ha of lakes the number of sites that could reasonably be visited and swamps occur (Croft et al. 1999). and surveyed by a survey team on a daily basis. Estimations were based on the Murray Mallee Biological Survey which had an average of 24 plant 66 Figure 30. Map showing boundary of South East Survey, distribution of quadrats and year vegetation quadrats were sampled. 67 18 16 14 12 10 Percentage 8of Sites 6 4 2 0 pl ain (i ncl und ul ati ng pl ain) Figure 31. Percent frequency of landform element types for South East Survey sites (1991 and 1997) . sand y pl a in In terms of spatial coverage in areas where low lying lim e stone pl ai n landforms are features, the gaps that are obvious are 1991 (n=340) the Lake Frome - Millicent to Mt Schank area, the 1997 (n=18) broad interdune – swales extending from Penola north lunette through Bool Lagoon to west of Padthaway and the swamp system from east of Furner south east to Dismal dune/consolid at e d du ne Swamp and these areas having been extensively cleared, or drained and cleared for farming purposes. du ne c rest Gaps in the site coverage of these areas may have resulted due to a lack of significant blocks of native du ne s lo pe vegetation remaining. The difficulty in recognising remnants of low sedgeland, shrubland and grassland swa le communities on the summer flown aerial photography may have also contributed to a lack of or low numbers inte rdu ne co rrid or of sites selected in these communities. There may be small remnants of the interdunal – swamp vegetation hill cr est communities that could be surveyed. Landform Element hill slop e Species Patterns (Floristic Analysis) Coverage For the analysis of species patterns across the region, hill footslop e the South East Coastal Survey and part of the Murray Mallee Survey datasets’ were combined with this rid ge survey’s dataset (refer to the Methods Chapter swandamp Table 11). Figure 32 indicates the floristic analysis study boundary and the sites used in the analysis. bea ch rid ge Table 11.