A Biological Survey of the Southern Mount Lofty Ranges
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Southern Mount Lofty Ranges Biological Survey RESULTS VEGETATION S. Croft1 and R. Brandle1 INTRODUCTION This chapter has compiled the data from 1,177 survey forest formations (Specht et al. 1961). What appears to quadrats sampled within the Southern Mount Lofty be largely cleared land in the central part of the SMLR Ranges and Fleurieu IBRA regions into a single region would have been extensive broad valley areas of floristic analysis. The survey quadrats are derived SA Blue Gum and River Red Gum forest and from five surveys, conducted from 1977 to 2001. All woodland. The original limits of the dry sclerophyll survey quadrats recorded floristic composition within forests were from the Barossa Valley (Tanunda) in the defined quadrats. The five surveys, however, did not north, to Lobethal in the south, from the edge of the cover grassy ecosytems - the subject of a separate Ranges in the west to Mount Pleasant in the east biological survey (Robertson 1998). Similarly, (longitude 1390 03 ’’) (Specht, Brownell and Hewitt although this report includes a few coastal quadrats, 1961). coastal vegetation has been the focus of a separate Biological Survey (Oppermann 1999). Today, the dominance of savannah woodland over dry sclerophyll forests has been reversed. Savannah The SMLR experience among the highest rainfall remnants are few in number, small and usually averages in the State. As might be expected, therefore, degraded. Approximately 13% of native vegetation forests, woodlands and specialised wetland habitats remains in the SMLR. Most of this remnant vegetation dominate the floristic analysis. This domination also occurs on infertile soils and/or high rainfall upland reflects the specific aims of each of the five vegetation regions. Species tolerant of infertile soils dominated surveys. The earliest Mt Lofty survey targeted high survey records (Eucalyptus fasciculosa, E. obliqua , E. rainfall, high fire-risk communities. The second major cosmophylla, E. baxteri and E. goniocalyx). Most of Mt Lofty survey targeted swamps and other remnant the remnant vegetation stands in the SMLR are vegetation of southern Fleurieu Peninsula and also characterised by a dense sclerophyllous understorey of Long-leaved Box communities (Eucalyptus relatively constant composition. Several of the floristic goniocalyx). The Mt Lofty Emu-wren survey analysis (PATN) groups were distinguished not so concentrated only on swamps of the southern Fleurieu much by differences in species present, but by the Peninsula; the Southern Fleurieu (SEG) Survey only frequency of species. Several species were widespread included roadsides of the southern Fleurieu Peninsula. and common or even dominant across a number of The main aim of the present survey (Southern Mt PATN groups – particularly Xanthorrhoea semiplana, Lofty) was to concentrate on under-surveyed Acacia pycnantha, Lepidosperma semiteres, vegetation communities (further details of the 5 Platylobium obtusangulum, Leptospermum surveys are in the Methods section). This survey bias, myrsinoides, Hakea rostrata, Acacia myrtifolia, although largely a reflection of past clearance patterns, Pultenaea daphnoides and Acrotriche serrulata. has tended to disproportionately represent some communities and plant species in the results, A detailed description of the vegetation ecology of the particularly Long-leaved Box, swamp communities and SMLR is beyond the scope of this chapter. Rather, the possibly Manna Gum (E. viminalis ssp. viminalis). emphasis is upon presenting the results of the Biological Surveys in order to provide a “snap-shot’ As can be seen from Fig. 4, the survey quadrats are desciption of the abundance and distribution of plant concentrated in the western and southern halves of the communities and species. Prevous vegetation studies SMLR study region. The lack of survey quadrats in the are outlined in the Introduction chapter. In particular, eastern third of the region reflects past extensive however ,excellent accounts of the vegetation ecology clearance of this area. The pre-European vegetation (describing species distributions in relation to and remnant vegetation of this eastern zone are environmental factors) include Adamson and Osborne discussed later in this Chapter. (1924), Specht and Perry (1948), Specht, Brownell and Hewitt (1961). Specht (1972), Boomsma and Lewis Prior to European settlement, savannah formations (1980), and Nicolle (1997). They provide general were “much more widespread” than dry sclerophyll information on the distribution and ecology of 1 Biodiversity Survey and Monitoring Section, Science & Conservation Directorate, Department for Environment and Heritage, GPO Box 1047, Adelaide 5001 23 eucalypts and other structural dominants within South The actual number of taxa recorded is thought likely to Australia. be about 1,100 taxa (about 840 native and 260 introduced). Appendix III provides a list of all taxa TOTAL PLANT RECORDS AND TAXA recorded at survey quadrats within the study region. A total of 40,091 vascular plant records were made This list includes taxa name as recorded plus updated during the five surveys included in this data analysis of and grouped names used for this report, and the which: number of quadrats at which recorded. • 35, 920 records were native taxa (90%) and • 4,171 records (10%) were introduced. The Southern Lofty herbarium region contains approximately 1 313 extant native taxa and 960 Because of the numerous records identified only to introduced taxa. These figures were derived from the generic level or species level (rather than sub-species Florlist software program (last updated in 2000), or variety), it is not possible to determine the exact namely the total listed taxa minus all: number of taxa recorded. • taxa listed as “sp.”, • taxa listed to species level only (and A minimum of 992 taxa were recorded of which 753 duplicated by taxa identified to ssp., nothosp., were native (76%) and 239 were introduced (24%). var., These figures ignore all taxa identified only to generic • hybrid species, level (and where no other taxa of the same genus were • species crosses, and recorded), and ignore all taxa identified only to “ssp.” • extinct species. or “var” (and where no other taxa of the same species The number of native taxa recorded during the surveys were identified). Seven hundred and eighty taxa were was between 57% (753) and 68% (1,227) of all considered to be perennials. recorded taxa for the Southern Lofty herbarium region. When comparing these figures it should be noted that a A theoretical maximum of 1 227 taxa were recorded. large area of the St Vincent IBRA region, and smaller This figure includes all taxa identified only to “sp.”, areas of the Murrary Mallee and Northern Lofty IBRA “ssp.” or “var” level and were not taxa already fully regions are also part of the Southern Lofty herbarium identified elsewhere in the results. For example, region and were not included in the study region survey Callitris sp. identified in the survey records could be quadrats. The Introduction to this report provides a Callitris canescens (as this species occurs in the definition of IBRA regions. These excluded regions Southern Lofty botanical region and was not otherwise contain landforms and hence flora not included in the recorded during the survey). This possible maximum survey region e.g. coastal mangroves, samphires and of 1,227 taxa is comprised of a possible 892 native the northern Adelaide Plains. taxa and 335 introduced taxa. Table 9. Summary of native taxa, introduced species, quadrats and total number of plant records in other herbarium (botanical) regions surveyed. Region No. of native No. of introduced No. of quadrats No. of plant taxa recorded species recorded in analysis records Flinders Ranges 1165 263 (22%) 3273 90,698 Southern MLR (minimum 753 239 (24%) 1,177 40,039 estimated) Murray Mallee (Victorian 904 156 (15%) 1,813 (SA = 649; ? and South Australian VIC = 1164) quadrats) Kangaroo Island 563 89 (16%) 369 10,370 Table 10. Summary of readily determined plant species/taxa into taxonomic categories within the SMLR study area. DIVISION CLASS FAMILIES GENERA NATIVE INTRODUCED TAXA TAXA Clubmosses Lycopsida 1 1 2 0 Ferns Filicopsida 9 14 18 0 Non-flowering Gymnospermae 2 2 2 3 Flowering Monocotolydonae 17 126 257 80 Dicotyledonae 73 292 474 156 TOTALS 102 435 753 239 24 COMMON SPECIES Table 11 shows the 20 most commonly recorded Seventy-five (9.6%) perennial species occurred in 10% perennial species and Appendix IV shows perennial or more quadrats and 20 (2.5%) species occurred in and annual species occurring in 10% or more of 30% or more quadrats. Xanthorrhoea semiplana, quadrats. Gonocarpus tetragynus and Lepidosperma semiteres all occurred in over half of all quadrats. Six Because most of the remnant vegetation in the SMLR Eucalyptus species occurred in this list with E. occurs on infertile soils, a large proportion of the most fasciculosa (Pink Gum) most commonly recorded at common plant species in the SMLR are sclerophyllous 493 quadrats (42%), followed by E. obliqua (477 (including Eucalyptus species). Sclerophyllous quadrats = 40%). Table 12 shows the frequency of all vegetation (namely, “hard-leaved”, and often smaller Eucalyptus species recorded at survey quadrats within leaved plants) is associated with infertile soils - the study area. especially soils low in phosphorus and nitrogen. Approximately 75% of the species in Table 11 are No perennial weeds occurred in the 20 most frequently sclerophyllous with the remainder being characteristic