Southwest Australian Jarrah Forest
Unlike most of the World’s hardwood forests this type of forest is almost exclusively dominated by a single species the Jarrah (Eucalyptus marginata), which can form almost pure stands in certain areas especially where laterite soils predominate. The only other commonly associated trees are Eucalyptus calophylla (marri), E. patens (blacknut) and E. wandoo (wandoo). Commonly associated under storey species include the strange Casuarine fraserana and various banksias (Proteaceae) such as Banksia grandis, B. menziesii and B. attenuata. However, in addition there are various arborescent monocots such as the endemic Dasypogon hookeri, Kingia australis and Xanthorrhoea gracilis (Xanthorrhoeaceae). The most common liana is the endemic Kennedia coccinea (Fabaceae) and, in fact, both lianas and creepers are common features of these forests. The shrub layer, unlike the canopy, is also rich in species with many endemics. The most common of these is Stirlingia latifolia (Proteaceae), while other species include Acacia alata, Adenanthos barbigerus, Conospermum glumaceum, Dryandra praemorsa, Grevillea willsoni, Hakea lissocarpha, Isopogon sphaerocephalus (Proteaceae), Andersonia axilliflora, Astroloma ciliatum (Epacridaceae), Anigozanthos preissii (Haemodoraceae), Chorizema dicksonii, Daviesia cordata, Gastrolobium villosum (Fabaceae), Darwinia carnea, Hypocalymma robustum (Myrtaceae), Hemiandra linearis (Lamiaceae), Hibbertia hypericoides (Dilleniaceae), Lechenaultia biloba, Scaevola platyphylla (Goodenaceae), and Primelea rosea (Thymeleaceae). The ground layer is also richly endowed with endemics including various orchids such as Caladenia gemmata, Caladenia macrostylis, Caladenia sericea, Prasophyllum fimbria, Pterostylis barbata, Pterostylis recurva and Thelymitra crinita (Orchidaceae), while other ground dwelling, largely perennial herbs include Anigozanthos bicolor, Conostylis androstemma, Conostylis setigera (Haemodoraceae), Dampiera linearis (Goodeniaceae), the insectivorous Drosera microphylla and D. platystigma (Droseraceae), the ground hugging Dryandra nivea (Proteaceae), Goodenia fasciculate, Scaevola striata (Goodeniaceae), Kennedia stirlingii (Fabaceae), Orthrosanthus laxus, Patersonia xanthina (Iridaceae), Ptilotus manglesii (Amaranthaceae), Tetratheca viminea (Tremandraceae) and Trichocline spathulata (Asteraceae).
A slightly sinister aspect of these forests is the many toxic species. These are particularly prevalent in the endemic genus Gastrolobium such as Gastrolobium calycinum (york road poison). Other highly toxic species include the endemic Isotoma hypocrateriformis (woodbridge poison) of the Lobelliaceae, various species of Oxylobium and the endemic cycad Macrozamia riedlei (Zamiaceae). These forests also provide habitat for the strange parasitic plant Pilostyles hamiltonii - Australia’s only representative of the family Rafflesiaceae. A better-known example is Rafflesia arnoldii, which has the World’s largest flower. In contrast Pilostyles has comparatively small flowers, just a few millimeters across, but like its larger relatives, spends most of its life cycle in the tissues of various host plants, which locally include various members of the genus Daviesia.
Southwest Australian Karri Forest
On the loams and sandy loams over granitic and gneissic rocks the forests are mainly dominated by the endemic Eucalyptus diversicolor (karri), which is credited with being one of the three tallest hardwoods in the World measuring up to 90 m. In fact, it dwarfs most of the associated tree, although one of these, Eucalyptus jacksonii, can reach heights of 70 m. Other trees include Agonis juniperina and Eucalypus guilfoylei, while smaller trees growing far below the karri canopy include the endemic Agonis flexuosa (Myrtaceae). Altogether there may be three or four stories to these forests. A dense shrub layer is always present and commonly includes Trymalium spathulatum and the endemic Chorilaena quercifolia (Rutaceae). Other endemic shrubs include Acacia pentodenia (Fabaceae), Chorilaena quercifolia (Rutaceae), Hibbertia cuneiformis (Dilleniaceae), Leucopogon verticillatus (Fabaceae), and a number of very attractive species such as Boronia gracilipes, Crowea angustifolia (Rutaceae), Chorizema ilicifolium and Hovea elliptica (Fabaceae). Few members of the southern heath family Epacridaceae occur in these forests, but the endemic Leucopogon verticillatus may be found. Underneath the shrubs large quantities of litter, bark and leaves accumulate. Despite this a number of herbaceous plants occur including various endemic species such as Dampiera hederacea (Goodeniaceae), and at least five species of fern. Of these Pteridium esculentum (a native bracken) is the most common, and is the largest native species growing to heights of 2 m, while other include Adiantum aethiopicum and Lindsaea linearis.
Southwest Australian Coastal Limestone Communities
In the more exposed situations where salt spray is driven inland by winter storms, just a few small shrubs of Frankenia pauciflora mainly colonize this coastal limestone. Further inland this gives way to a heathland community of Dryandra, Hakea and Melaleuca, while in the more sheltered valleys trees such as Callitris preissii, Eucalyptus gomphocephala, Melaleuca lanceolata may occur. Endemic species found here include shrubs such as Diplolaena angustifolia (Rutaceae), Dryandra sessilis (Proteaceae), Melaleuca heugelii (Myrtaceae), and the creeper Kennedia coccinea (Fabaceae).
Southwest Australian Coastal Sand Dune Communities
In the mobile dunes exposed to salt-laden winds, the main species include various dune grasses such as Spinifex longifolius and S. hirsutus, together with a variety of cosmopolitan species like Cakile maritima. In the more stable zones further inland a form of low heath occurs composed of species such as Acanthocarpus preissii, and the endemic Acacia pullchella (Fabaceae), Calectasia cyanea (Xanthorrhoeaceae) and Hibbertia hypericoides (Dilleniaceae). Other endemics associated with dunes include the shrubs Diplolaena dampieri (Rutaceae) and Rhagodia radiata (Chenopodiaceae). Banksias (Proteaceae) are also a feature of the coastal dunes in the south, particularly between Hopetoun and Israelite Bay. Here showy species such as Banksia speciosa, B. nutans and the endemic B. baxteri and B coccinea occur. Deeper coastal sand provides habitat for members of the endemic genera Anigozanthos and Conostylis including Anigozanthos rufus and the attractive Conostylis bealiana, C. petrophiloides and C. vaginata.
Southwest Australian Bush of Southern Sand Plains
This region includes the undulating plains along the south coast from Pallinup River to Israelite Bay and extends inland to Lake Grace. Two of the more prominent shrubs of these southern bush lands are Hakea crassifolia and the endemic Lambertia inervis (Proteaceae). The latter represents a near endemic genus with all but one species endemic to the southwest. Another widespread endemic shrub found here is the unusual Franklandia fucifolia (Proteaceae), while other important shrubby species are the so-called bottlebrushes Beaufortia micrantha, B. orbifolia and B. schaueri, and the wax flowers Chamelaucium axillare and C. megalopetalum (Mrytaceae). Both genera are endemic to the southwest, with some 15 species of Chamelaucium. Among the endemic herbs are species of the endemic genus Anthotium (Goodeniaceae) including Anthotium humile and A. rubiflorum. Both have perennial rootstocks and rosetted linear leaves.
Southwest Australian Bush of Northern Sand Plains
These sandy plains occur north of Perth between Moore River and Shark Bay. Like their southern counterpart two of the most prominent families are Proteaceae and Myrtaceae. In the former there are at least 20 species of Banksia including the endemic B. burdettii and many species of the endemic Dryandra such as D. nana, D. carlinoides, D. kippistiana, D. shuttleworthiana and D. speciosa. Most dryandras and banksias produce abundant nectar and although birds and insects are attracted to this, it seems that small marsupials are the main pollinators. Other conspicuous members of the Proteaceae include the grevilleas, such as the spectacular white plume grevellea (Grevillea leucopteris) and the endemic smokebush Conospermum stoechadis. Of the Myrtaceae, the intriguing genus Darwinia, with its great diversity of inflorescences, is well represented with some 30 species endemic to the southwest. Two of the more common of these are Darwinia neildiana and D. speciosa. Other indigenous members of this family include various species of the genus Calothamnus. All 25 species of this genus are endemic to the southwest but only about 10 occur on the northern sand plains including Calothamnus blepharospermus, C. homalophyllus and C. quadrifidus. Also present are many poisonous plants of the endemic genus Gastrolobium, such as Gastrolobium oxylobioides, which have caused problems for pastoralists since the early days of settlement. Flowers of many colours are seen in the family Goodeniaceae and even in the genus Lechenaultia with about 25 species, flowers may be blue, white, yellow, red, orange or green. One of the more common of these is the endemic blue lechenaultia (Lechenaultia biloba). In areas of deep sand are various members of the enigmatic, endemic genus Anigozanthos, including Anigozanthos manglesii and A. pulcherrimus (Haemodoraceae), while other endemic members of this family are the so-called cotton-heads such as Conostylis aurea, C. candicans and C. stylidioides. Other endemic genera that are well represented in this area are Beaufortia, Hypocalymma and Scholtzia. Apart from Xanthorrhoea preissii, moncots are not a dominant feature of these sand plains, but the allied Kingia australis is found in a few areas. Orchids are also rarely found but members of the genera Caladenia, Diuris and Thelymitra may be encountered including the endemic Caladenia crebar and C. flava (Orchidaceae). Finally several species of native conifer grow in the area include the endemic sand plain cypress (Actinostrobus arenarius) and its smaller relative the endemic dwarf cypress (A. acuminatus).
Southwest Australian Swamps
The most common shrub found in the heavier swamp soils is the swamp tea-tree (Leptospermum ellipticum), while in areas subject to seasonal flooding there may various species of shrubby Banksia, such as the endemic Banksia occidentalis (Proteaceae), and the endemic shrub Hypocalymma angustifolium (Myrtaceae). The slightly dryer areas provide home for various members of the Haemodoraceae including the endemic shrub Anigozanthos viridus, as well as some of the less spectacular species of the endemic genus Tribonanthes (Haemodoraceae). Also in these areas, especially ones subjected to winter wetness, endemics such as red swamp cranberry Astroloma stomarrhena (Epacridaceae) and Leptocarpus canus (Restionaceae) occur. Some of the more ephemeral swamps, particularly those near the foothills of the Darling Range, are noted for their prevalence of endemic plants, and include a number of insectivorous species, such as Byblis gigantea (Byblidaceae), several sun dews like Drosera menziesii (Droseraceae) and members of the bladderwort family (Lentibulariaceae) such as Utricularia menziesii. Other endemic species found in the swamps of this BioProvince include the shrubs Acacia baxteri (Fabaceae), Beaufortia sparsa, Melaleuca polygaloides (Myrtaceae), Boronia heterophylla, Boronia molloyae (Rutaceae), Cosmelia rubra (Epacridaceae), the perennial herbs Adenanthus obovata (Proteaceae), Anigozanthos flavidus (Haemodoraceae), the pitcher plant Cephalotis folliculare (Cephalotaceae), and the orchids Drakaea elastica, Eriochilus scaber and Prasophyllum regium (Orchidaceae). The latter (P. regium) is one of the giants of the orchid world growing to heights of up to 2 m.
Western Australian Littoral Salt Lake Vegetation (Lake Lefroy)
In this semi-arid zone annual evaporation is about ten times that of rainfall. The salt lake recieves water from various streams but dries up completely for about a quarter of the year. The shorelines soils are highly saline and classed as hypersaline in some cases. Four shorelines have been recognised: siliciclastic dunes, dune swales, gypsum dune beds and scree slopes.
Siliciclastic Dune Vegetation
These large dunes usually above 5 m included both littoral and foredune components. The littoral zone was found to be hypersaline with some of the highest levels of salinity recorded. Consequently it provided difficult condition for plant colonisation and supported just two species: Gunniopsis septifraga and Halosarcia syncarpa. The foredunes were less saline but their combination of salinity and acidity again making them a harsh environment for most plants. The few species recorded included Calandrinia granulifera, Darwinia diosmoides, Jacksonia spinosa and Melaleuca thyoides.
Dune Swale Vegetation
Included here are small interdune swales and hindshore dunes. The charactersitic species included Disphyma crassifolium and Frankenia setosa in the swales and Jacksonia spinosa in the hind dunes areas. Acidity varied but was more pronounced in the hind dunes. Other species found in this zone include Angianthus preissianus, Atriplex nana, Calandrinia polyandra, Calotis hispidula, Centrolepis polygyna, Crassula sieberiana, Disphyma crassifolium, Dodonaea viscosa, Eragrostis dielsii, Eragrostis falcata, Frankenia pauciflora, Gnephosis angianthoides, Gnephosis tenuissima, Grevillea acuaria, Gunniopsis quadrifida, Gunniopsis rodwayi, Gunniopsis septifraga, Halosarcia halocnemoides, Halosarcia indica, Hemichroa diandra, Hyalochlamys globifera, Lepidium phlebopetalum, Maireana amoena, Maireana eriosphaera, Maireana glomerifolia, Scaevola spinescens, Stenopetalum sphaerocarpum, Triglochin calcitrapa, Triglochin cristata and Wurmbea dioica.
Gypsum Dune Bed Vegetation
Lake shores with relict gypsum beds are common in places producing distinctly alkaline conditions. The main species here are Atriplex nana and Disphyma crassifolium. Others include Atriplex codonocarpa, Frankenia desertorum, Rhodanthe floribunda, Senecio glossanthus and the introduced species Hordeum leporinum, Mesembryanthemum nodiflorum and Pentzia suffruticosa.
Scree Slope Vegetation
In places the shoreline is composed of broken fragments of duricrust (Tertiary sediments) ranging in size from gravel to small boulders. The main scree species is Halosarcia lylei with Frankenia pauciflora occurring in the transition zone between scree and the lake surface. The few other species found in this zone include Centrolepis polygyna, Gunniopsis septifraga and Maireana carnosa.
References
Aplin, T. E. H. 1975. The Vegetation of Western Australia. In: Western Australian Year Book No. 14. W. M. Bartlett. Australian Bureau of Statistics.
Barrett, G. 2006. Vegetation communities on the shores of the salt lake in semi-arid Western Australia. Journal of Arid Environments, 67: 77-89.
Beadle, N. C. W. 1981. The Vegetation of Australia. Gustav Fischer Verlag.
Beard, J. S., Chapman, A. R. & Gioia, P. 2000. Species richness and endemism in the Western Australian Flora. Journal of Biogeography, 27: 1257-1268.
Erickson, R. et al. 1973. Flowers and Plants of Western Australia. A. H. & A. W. Reed.
Gardner, C. A. 1959. The vegetation of western Australia. In: Biogeography and Ecology in Australia. Monographiae Biologicae, 8: 275-281.
Sauer, J. 1964. Geographic reconnaissance of western Australian seashore vegetation. Australian Journal of Botany, 13: 39-69.