III Vegetation and Flora G.J. Keighery, K.R. Newbey and N.J. Hall Background In the Norseman-Balladonia Study Area, Woodlands (15-20 m high) occurred on Calcareous Plains, Broad Valleys and Hills (Greenstone). Low Woodlands «IS m) were the dominant vegetation type in the Study Area, particularly on Calcareous Plains, Undulating Plains and Broad Valleys. Mallees (3-6 m) were common on Calcareous Plains and Salt Lake Features, and present on Sandplain, Undulating Plains and Granite Exposures. Tall Shrublands (>1 m) occurred on Granite Exposures, Salt Lake Features, Sandplain, Undulating Plains (Basic Granulite) and Calcareous Plains. Low Shrublands «1 m) dominated Salt Lake Features with scattered occurrences on Calcareous Plains. Complexes were common on Granite Exposures. The structural formations have been described and mapped at a scale of I: 1,000,000 (Beard 1975). During the survey 162 sites were sampled using the plotless reIeve technique. This technique, the selection ofsites and the parameters recorded, are detailed by the Biological Surveys Committee of Western Australia (1984). The sites are broadly classified on vegetation structure and plant species composition of the upper stratum, into vegetation types. Two of the types (Granite and Lake Margin) are referred to as vegetation' complexes, where vegetation structure and species composition changed markedly over a few metres. A typical site for each vegetation type is described in Appendix I, together with relevant data on geology, landforms and soils. Appendix I provides data on the detailed composition of 49 sites in the Norseman­ Balladonia Study Area (see Figure 2 for locations). Table I summarises the relationship between landforms, lithology, soils, vegetation structure and floristic composition. Some examples ofthe range in vegetation types present within the Study Area are shown in Plates I-IS. Vegetation descriptions are listed below by landform unit. Only a few of the species occurring in the Norseman-Balladonia Study Area have accepted common names; they are listed where the species first occurs in the text. Plant taxonomy follows Green (1986) except for eucalypts (Brooker & Kleinig 1990; Johnson & Hill 1990) and orchids (Hoffman & Brown 1992). Vegetation Descriptions Granite Exposure (G): Inner and outer aprons: Aprons in the south-eastern and south-western corners of the Norseman-Balladonia Study Area were similar in composition to those in more northern sections. Shrub density, however, was much greater and individual plants were larger and more luxuriant in the southern areas. This was particularly obvious for the sedgelands of Lepidosperma drummondii and hummock grasslands of Triodia scariosa. In some areas the bunch grasses (e.g. Danthonia setacea, Stipa spp.) became dominant forming large open glades in the mallee formations. These areas of Lepidosperma sedgelands and Triodia hummock grasslands were only found in the south-eastern margins of the Study Area. 20 Some differences were also noted in the shrub flora. For example, Ponier Rock has a shrubland of Acacia saligna and scattered trees of Allocasuarina huegeliana, neither of which has been recorded north of this rock. The herbaceous flora increases in species richness from the northern areas to the south-eastern margins of the Study Area. For example, a comparison of the orchids recorded on a number of granite exposures provides an indication ofthe differences in herb floras throughout the Study Area. In the north-west of the Study Area, two species were recorded at Buldania Rocks (Diuris aff. corymbosa, Pterostylis aff. nana). At Boingaring Rocks and Afghan Rock in the north-east, an additional four orchid species were recorded (Caladenia microchila, Pterostylis aff. rufa, Prasophyllum ringens, Thelymitra aff. nuda). In the central section, 10 species were recorded on a series of granite exposures in the vicinity of Mt. Andrew. These granites supported the above plus an additional four orchids (Caladeniaflava, C. marginata, Microtis unifolia, Pterostylis allantoidea). In the south-eastern corner of the Study Area, 14 additional orchid species - that were not recorded on granites to the north - occurred on Ponier Rock, Mt. Newmont and granite exposures on the margins o(salt lakes. These included Declared Rare Flora Caladenia voigtii, C. latifolia and Pterostylis aff. scabra. Mt. Newmont (lOkm west of site NB43) supported an impressive orchid flora of22 taxa that included an additionalll orchids (Caladenia attingens ssp. gracillima, C. brevisura, C. saccharata, C. sigmoidea, Cyanicula caerula ssp. apertala, Cyrtostylis robusta, Pterostylis mutica, P. recurva, P. aff. rufa, P. sar"gentii, P. vittata, Thelymitra aritennifera). Jyndabinbin Rocks (Ag) in the north-western section ofthe Study Area, supported a Granite Complex that comprised a rich assemblage of herbs with no particular dominance shown (composites, mainly, but with numerous bulbous perennials). The apron surrounding Jyndabinbin "Rocks supported Low Woodlands of Acacia ac.uminaia (Jam) over scattered shrubs and herbs including Gnephosis pusilla, Gonocarpus nodulosus, Rutidosis multiflora and Waitzia acuminata. The outer apron (Ag) of a small granite exposure in the north-western portion supported an Acacia Tall Shrubland that included A. acuminata over Lepidosperma drummondii, Prostanthera incurvata and the bunch grass, Amphipogon debilis. The Granite Complex present on Boingaring Rocks (Py), in the north-eastern section of the Study Area, contained a similar assemblage of herbs as found on Jyndabinbin Rocks, but with a reduced species diversity. The granite endemic Eucalyptus histophylla surrounded Boingaring Rocks, while the peripheral apron supported Tall Shrublands of Thryptomene australis with Dodonaea lobulata, Eremophila alternifolia var. latifolia over Melaleuca elliptica and a selection of herbs from the Granite Complex. In the south-eastern section ofthe Study Area, Ponier Rock (Pm) supported a Granite Complex on deeper soil than both Jyndabinbin and Boingaring Rocks, and hence supported Dodonaea lobulata and Bossiaea walkeri with Beyeria lechenaultii over herbs rather than a herbfield. 21 Rises of Calcareous Loams at Ponier Rock supported Eucalyptus melanoxylon Low Woodlands over Atriplex vesicaria (Bladder Saltbush), Carpobrotus rossii, Disphyma crassifolium, Enchylaena tomentosa, Geijera linearifolia, Olearia revoluta, Sclerolaena diacantha and Threlkeldia difJusa. Small clumps of Acacia saligna, Allocasuarina heugeliana, Melaleuca elliptica, Muehlenbeckia adpressa and Polygonum prostratum occurred on slopes and in rills around the granite exposures. Granite exposures were also common on the margins of salt lakes in the Norseman­ Balladonia Study Area. An exposure (Pc) in the north-eastern section supported a Granite Complex similar to the outer aprons of Ponier or Boingaring Rocks, being a shrubland of Dodonaea lobulata and Eremophila alternifolia var. latifolia over herbs. The peripheral apron of a granite (PI) in the south-eastern corner, supported a Hummock Grassland of Lepidosperma drummondii with bunch grasses of Danthonia setacea and Stipa aff. trichophylla over scattered annuals. Hill, Greenstone (HN): Slopes and summits: In the north-western section of the Norseman-Balladonia Study Area, greenstone slopes and summits with a variety of lithological surfaces (Aeo, Awb, Abd) supported Woodlands of Eucalyptus brockwayi (Dundas Mahogany), and Low Woodlands of E. lesouefii (Goldfield's Blackbutt) and mixed Eucalyptus species. On the margins of Lake Dundas, the summit ofa greenstone hill (Apz) was mantled with Shallow Calcareous Earths. This surface supported Eucalyptus torquata(Coral Gum) with occasional E. dundasii(Dundas Blackbutt) over Atriplex vesicaria, Eremophila scoparia and Pittosporum phylliraeoides (Weeping Pittosporum). In the Dundas Hills north-west of Norseman, Jimberlana Hill (Pd) supported a Low Woodland of Eucalyptus oleosa (Red Mallee), which included Declared Rare Flora Eucalyptus aff. diversifolia (KRN 6754), with Allocasuarina campestris ssp. grossa over shrubs of Cryptandra pungens and Melaleuca elliptica. The recently described Eucalyptusjimberlanica is known only from Jimberlana Hill (Johnson & Hill 1990). Hill, Basic' Granulite (HR): Slopes and summits: The slopes and summit of a Basic Granulite hill (Px), near Mt Pleasant in the Fraser Range, supported a unique Granite Complex. Trees of Allocasuarina huegeliana and Pittosporum phylliraeoides occurred with shrubs of Beyeria lechenaultii and Dodonaea microzyga over bunch grasses of Aristida contorta. This element extends north into the adjacent Study Area (Newbey & Hnatiuk 1984). Salt Lake Features (L): Lakefloors: The species composition ofsalt lake floors (Qra) did not change markedly across the Study Area. A lake floor in the south-eastern section supported Atriplex vesicaria, Disphyma crassifolium, Halosarcia halocnemoides, H. indica var. bidens, H. peltata and H. syncarpa. Lake floors in the north-western portion supported Halosarcia Low Shrublands comprised of Disphyma crassifolium, Halosarcia halocnemoides, H. indica var. bidens, H. lylei, Hemichroa diandra, Frankenia pauciflora and Maireana glomerifolia. Small playas of the Esperance salt 22 lake chains on the south-western periphery of the Study Area were relatively poor in species; only three species were recorded on one lake. Lake slopes: In the north-western portion of the Study Area, margins of the extensive Lake Dundas (Qps) support Low Woodlands of Eucalyptus lesouefii over