Vegetation Changes in Mediterranean Abstract: This paper reviews the vege- 1 tation of the mediterranean regions of Australia Since European Settlement Australia : as it was before European settlement less than 200 years ago, its degradation under agricultural practices with introduced plants and animals, and Marilyn D. Fox2 current and future land use. The main agencies of change have been clearing, grazing, fertilizing, altered fire regime and introduced species, both exotic plant species and introduced grazers. There have been extinctions (both total and local) while other native species have had their demographies and distributions altered.

The Australian continent has only by an industrialized people and their recently been exposed to the effects of retinue of plants, animals and micro- the agricultural and industrial revolut- organisms. The Australian biota which ions. Its existence was known to navi- had evolved in isolation suddenly en- gators of the late sixteenth century, and countered the domesticated animals and in particular its northern and western crop plants of Europe. More tragically, coasts were charted through the early the aboriginal people suddenly encount- seventeenth century but with few record- ered the disease organisms of Europe, ed excursions ashore. these together with alcohol and the more direct measures of poisoning and shooting, The first European settlement was at decimated their populations in just a few Sydney in 1788, with the mediterranean decades. regions being settled later: on the Swan River (Perth) in Western Australia in Mediterranean Climate in Australia 1828 and in the Gulf of St. Vincent (Adelaide) in South Australia during 1836. The occurrence of mediterranean At the time of exploration and settlement climate in Australia has been interpreted the continent was home to an aboriginal differently by different authors. Those people who had been there for at least who have used the stricter interpretation 40,000 years. The dingo (Canis of Köppen's Cs type (Köppen 1936), of a familiaris dingo) was the only animal distinct summer half-year drought with associated with these hunter-gatherers appreciable rainfall during the winter and their only tools were spears, months, include Aschmann (1973) and woomeras (throwing sticks), boomerangs Milewski (1979). Specht and Moll (in and stone axes, plus their use of fire. press) extended this by including the Fire, then and now, was used to drive cool semiarid (BSk) type. Figure 1 shows large game into ambush, but more sign- the distributions of these types, as well ificantly it attracted game to the as that of the hot semiarid (BSh) type resulting soft regenerating growth which where this corresponds more closely with was also gathered by the women. The vegetation boundaries. The figure is Australian aborigine did not practise redrawn from Dick (1975, after Köppen agriculture; fire was the only agent used 1936). The mediterranean-type climate to modify the environment. (Csa, Csb and BSk) occurs over 8 percent of the continental area. With the coming of European man, a continent that had known only the The mediterranean regions are roughly sparsely dispersed aborigines was invaded the south-west of Western Australia and the eastern edge of the Great Australian Bight. Perth and Adelaide are the only 1Presented at the Symposium on centres of population in these regions. Dynamics and Management of Mediterranean To the north the mediterranean regions -Type Ecosystems, June 22-26, 1981, San are bounded by the arid (BW) zone while Diego, California. to the east the climate is humid with more evenly distributed rainfall (Cf). 2Ecologist, National Herbarium of New South Wales, Royal Botanic Gardens, Sydney, 2000, Australia.

Gen. Tech. Rep. PSW-58. Berkeley, CA: Pacific Southwest Forest and Range 112 Experiment Station, Forest Service, U.S. Department of Agriculture; 1982.

Figure 1-- The climates of temperate Australia after Koppen (1936) from a map by Dick (1975). The mediterr- anean climates (Cs) and cool semiarid (BSk) types are shown as well as the warm semiarid (BSh) type where this corresponds to vegetation boundaries

THE ORIGINAL VEGETATION open forests on soils derived from granite and gneiss by karri (E. diversicolor), the The vegetation of the mediterranean drier open forests on soils from the regions of Australia is illustrated in ancient laterites by jarrah (E. marginata). Fig.2 (based on a map by Moore 1969). Woodlands are also usually dominated by This ranges from the impressive forests of eucalypts such as the black box south western Australia through the wood- (E. largiflorens) of south-western NSW, lands of characteristically "mallee" but may also be composed of acacias such eucalypts, to the heathlands and chenopod as mulga (A. aneura). shrublands. Given the uniformity of climate, the principal determinant of The eucalypt shrublands or mallee is vegetation structure is the nature and the form of vegetation most closely nutrient status of the substrate and associated with the mediterranean regions. absolute amount of precipitation. The These multistemmed, low (usually less than three major soil suites of southern 10m) eucalypts grow where the soil is Australia are the base-rich, nutrient-poor sandy but often overlies an alkaline clay and calcium-rich soils, and their relation- subsoil (Rossiter and Ozanne 1975). The ship to vegetation is reviewed by Specht understorey can vary from a chenopod and Moll (in press). synusium to one dominated by porcupine grass (Triodia irritans). Temperate sclerophyll forests grow in mediterranean regions of the south-west Much comparative work has been done on of Western Australia. These forests are the sclerophyllous low shrublands or dominated by eucalypts, the wetter tall heaths of Australia and other mediterranean

Figure 2-- The vegetation of the mediterranean regions of Australia from a map by Moore (1969). The limit of the mediterr- anean-type climate (Csa, Csb and BSk) is shown as a heavy dashed line.

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Figure 3-- Sources of alienation of the mediterranean regions of Australia. The distribution of the wheat belts and sheep grazing areas are shown and the limit of the mediterranean -type climate. The location of major conservation areas is also shown.

regions (e.g. Specht and Moll in press). Figure 3 summarizes the major land Extending into the semiarid regions, this uses or sources of alienation within the is replaced by chenopod shrublands or mediterranean regions. Major conservation shrub steppe of Moore (1969). areas are also shown; these are usually national parks, however some are The arid zone extends to the coast at aboriginal reserves. the head of the Great Australian Bight and effectively divides the mediterranean The mediterranean regions correspond regions into western and eastern provinces. with the wheat belts and sheep grazing These are recognised as separate floristic areas so that generally the level of zones (Burbidge 1960), the south-western disturbance is high (Adamson and Fox, in temperate zone being the richest floristic press). In such areas the alienation is zone on the continent. compounded by the use of fertilizers, suppression of fire and an abundance of The vegetation of Western Australia introduced animals and plants. has recently been mapped by Beard (see Beard 1979 for a review). Satellite With the loss of habitat many native imagery was used to map the environments animals have become locally extinct. A (including vegetation) of South Australia small marsupial, the tammar wallaby (Laut et al 1977) and previously the (Macropus eugenii), which was once "the vegetation was described by Specht (1971). most plentiful and widely-distributed The mediterranean region of Victoria has wallaby in the south-west" (Thomas, 1888), received the sporadic attention of but "rapidly disappearing in the cultivated ecologists and botanists. It is mapped on districts" (Shortridge 1909) is "now Carnahan's (1976) map of the natural restricted to a few small scattered main- vegetation of Australia. The vegetation land colonies, and a number of islands" of western New South Wales was mapped by (Poole 1978). Beadle (1948) and Fox (1980) is currently mapping it at a larger scale. The effects of fertilizers on compos- ition and growth of heathlands in LAND USE IN MEDITERRANEAN REGIONS OF mediterranean South Australia have been AUSTRALIA demonstrated by Heddle and Specht (1975). Contamination of conservation areas, often Degree of Alienation islands in a sea of alienated land, is a major management problem. There is the In less than 200 years of European dual response of death or suppression of settlement the entire continent has been native species and invasion by exotic alienated to some extent. The degree of species adapted to the higher nutrient alienation ranges from clearing and levels. subsequent cultivation, altered nutrient levels, altered fire regime, to At present about ten percent of vascu- interaction with introduced animals and lar plants in Australia are exotics (Wace plants. 1973). The highest incidences of these

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Figure 4-- Plant species at risk in the mediterranean regions of Australia (based on figures in Hartley and Leigh 1979). The total number of species considered at risk in each state is shown, as is the total for each subdivision, and the number considered to be endangered and vulnerable.

are in the humid regions of the south- populations in the fifties. Today the east of Australia, with relatively few main control measures include poisoning, in the mediterranean regions. fumigation, warren-ripping, shooting and fencing. However in over a century of The successful weeds of the mediterr- occupation they have markedly altered the anean regions generally have vegetation of vast areas by both grazing Mediterranean origins and are often close- and browsing pressure as well as ly associated with crops. One such plant selective feeding. is skeleton weed (Chondrilla juncea). It was introduced to south-eastern Australia As with exotic plant species, the prior to 1910; it has spread steadily and introduced animals have either completely now covers most of the eastern mediterr- replaced entire endemic communities, such anean region and across to the coast near as with sheep and cattle, or have entered Canberra. In Western Australia it was an otherwise pristine community, such as ;first recorded in 1963 and is spreading the early colonizing rabbits or more rapidly, especially along the railway recently, feral goats (Capra hircus). In net-I work (Cullen and Groves 1977). the second instance the introduced animal is having an insidious effect on the With the conversion of natural vege- vegetation without manipulation by people. tation to improved pasture in the last sixty years or so, a very large area Changes in the Vegetation (almost 5 million hectares) of south western Western Australia now supports With the widespread clearance of land sub-clover (Trifolium subterraneum) an for agriculture there have been losses of introduced legume. This is maintained by associations and of species. It is substantial addition of fertilizers such possible that there were species, of both as superphosphate. Other exotic species, plants and animals, that were never known such as the South African capeweed to science. Some areas such as the (Arctotheca calendula) can become coastal sand plain near Perth are virtually established in these annual pastures. unrepresented in any conservation area.

Possibly the most disastrous animal Recently Hartley and Leigh (1979) introduction to Australia was that of the have classified over two thousand plant rabbit (Oryctolagus cuniculus L.). Rabbits species in various risk categories. arrived with the first settlers but the Figure 4 shows those regional subdivisions main release which established them as they used which encompass the mediterr- feral populations was in 1859. They anean regions. The total number of spread rapidly and now can be found through- species considered at risk in the state is out mainland Australia south of the tropic shown, as is the total for each sub- of Capricorn. The populations in some division, and the number considered to be mediterranean habitats have the highest endangered and vulnerable. The four sub- capacity for increase, with almost divisions corresponding to the Western 30 young per female per year, compared to Australia wheat belt have the highest a mean of about five for other habitats incidence of species at risk (a distinct- (Myers 1970). Biological control through ion shared only by the rainforest of Cape the myxoma virus dramatically reduced York).

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There is a range of responses of rabbit grazing) of the perennial veget- plant species to the altered environments ation (Hall, Specht and Eardley 1964). in which they now grow. The most extreme of these is extinction; this can be total Much of the mallee country of north- and there are some species believed to be western Victoria has been cleared and extinct (Hartley and Leigh 1979), or it Onans and Parsons (1980) have recently can be local. An example of local reported on the regeneration of sites extinction is of the highly palatable old cleared and left undisturbed for periods man saltbush (Atriplex nummularia). This up to 39 years. When an adequate seed once widespread chenopod is now found in source is lacking they found areas would very restricted areas. Other palatable regenerate to a shrubland of seral species plants are now less dense and restricted of Acacia and Dodonaea. compared to their former distributions. By contrast unpalatable species may THE FUTURE OF THE VEGETATION IN become more dominant. These often woody MEDITERRANEAN REGIONS OF AUSTRALIA shrubs such as turpentine bush (Eremophila sturtii) are an increasing Vast areas of the mediterranean problem in grazed semiarid regions such regions of Australia have been modified as western New South Wales. since the arrival of European settlement. Even where the overt forms of alienation There may also be delayed responses such as clearing are absent, there are still working through ageing populations. covert forms in the introduced animals Recent studies have demonstrated that with their destructive grazing. The many individuals of shrubs and small grazing pressure from feral and domestic trees of the mediterranean and semi-arid animals may have reduced some long-lived zones may be older than European settle- shrub and tree species to senescent ment here. Crisp (1978) has found that populations which will not be replaced mulga (Acacia aneura) and other acacias unless the grazing pressure is reduced. can live to about 250 years and that bluebush (Maireana sedifolia) individuals There are some large conservation reach similarly impressive ages. However, areas within the mediterranean regions recruitment of seedlings is very rare or and attempts are being made to minimize episodic, and given the current grazing the impact of exotic grazers. However pressure it is possible that individuals park authorities must accept the respons- of these dominant shrubs will not be ibility when land is acquired to attempt replaced. It is probable that this to have it revert to its pre-European combination of very old and senescing condition. As well as removing exotic individuals with reproduction suppressed weeds and pests, this means removing by grazing pressure is a common feature sources of nutrients and maintaining of especially the semiarid zone. The "natural" fire regimes (or at best a progressive senescence and eventual death mosaic of patches of different ages since of living shrubs may cause slow extinct- last fire). ion. LITERATURE CITED In discussing these changes to the vegetation I have emphasized the role of Adamson, D.A.; Fox, M.D. Change in grazing. Altered fire regimes can have Australasian vegetation since European similar effects with some species being settlement. In: Smith, J.M.B. ed. enhanced, others disadvantaged by A History of Australasian vegetation, changed intensity, frequency or season of Sydney: McGraw Hill; (in press). burn. Aschmann, H. Distribution and peculiarity of mediterranean ecosystems. In: Regeneration Studies DiCastri, F.; Mooney, H.A., eds. Mediterranean-type ecosystems, origin Although the history of settlement is and structure. Berlin: Springer; 1973: short there are some outstanding studies 11-19. of regeneration after degradation of Beadle, N.C.W. The vegetation and pastures habitat. One of the most famous is for of Western New South Wales. Sydney: Koonamore in the semiarid region of South Department of Soil Conservation; 1948. Australia (Osborn, Wood and Paltridge Beard, J.S. Vegetation mapping in 1935). The vegetation reserve was Western Australia. J. Royal Society of established in 1925 and permanent quadrats Western Australia. 62: 75-82; 1979. were studied from 1926. In particular Burbidge, N.T. The phytogeography of the permanent photopoints have supplied data Australian region. Australian J. on the regeneration (after sheep and Botany 8: 75-211; 1960.

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Carnahan, J.A. Natural Vegetation. In: Moore, R.M. Vegetation of Australia. In: Atlas of Australian resources, 2nd Moore, R.M., ed. Australian Grasslands. series. Canberra : Dept. of Natural Canberra: Australian National University Resources; 1976. Press; 1969. Crisp, M.D. Demography and survival under Myers, K. The rabbit in Australia. In: grazing of three Australian semi-desert Dynamics of populations. Proceedings of shrubs. Oikos 30: 520-528; 1978. the Advanced Study Institute, Cullen, J.M.; Groves, R.H. The population Oosterbeck. Wageningen: Centre for biology of Chondrilla juncea L. in Agricultural Publishing and Document- Australia. In: Anderson, D., ed. ation; 1970: 478-506. Exotic species in Australia - their Osborn, T.G.B.; Wood, J.G.; Paltridge, establishment and success. Proceedings T.B. On the climate and vegetation of of the Ecological Society of Australia the Koonamore Vegetation Reserve to 1931 10: 121-134; 1977. Proceedings of the Linnean Society of Dick, R.S. A map of the climates of N.S.W. 60: 392-427; 1935. Australia : according to Köppen's Poole, W.E. The status of the Australian principles of definition. Queensland Macropodidae. In: Tyler, M.J., ed. Geographical Journal, 3rd Series, 3: The status of endangered Australasian 33-69; 1975. wildlife. Adelaide: Royal Zoological Fox, M.D. Mapping the vegetation of the Society of South Australia; 1978: mallee landscapes. In: R.R.Storrier-M.E. 13-27. Stannard Aeolian Landscapes in the semi- Rossiter, R.C.; Ozanne, P.G. In: Moore, arid zone of south eastern Australia. R.M. ed. South-western temperate Riverina branch: Australian Society of forests, woodlands and heaths in Soil Science, Inc.; 1980: 147-148. Australian Grasslands. A.N.U. Press, Hall, E.A.A.; Specht, R.L.; Eardley, C.M. Canberra; 1975. Regeneration of the vegetation on Shortridge, G.C. An account of the Koonamore Vegetation Reserve, 1926-1962. geographical distribution of the Mar- Australian J. Botany 12: 205-64; 1964. supials and Monotremes of south-west Hartley, W.; Leigh, J. Plants at risk in Australia. Proceedings of the Zoological Australia. Occasional paper No.3, Society of London 60: 803-848; 1909. Australian National Parks and Wildlife Specht, R.L. The vegetation of South Service, Canberra: 1979. Australia, 2nd edition. Adelaide: Heddle, E.M. and Specht, R.L. Dark Island Government Printer; 1972. Heath (Ninety-Mile Plain, South Specht, R.L.; Moll, E.J. Heathlands and Australia). VIII The effect of sclerophyllous shrublands - an overview. fertilizers on composition and growth, In: Nutrients as determinants of the 1950-1972. Australian J. Botany 23: structure and functioning of mediterr- 151-164; 1975. anean-type ecosystems. Proceedings of Köppen, W. Das geographische System der Third International Conference on Klimate In: Köppen, W.; Geiger, R., Mediterranean-type Ecosystems (in press). eds. Handbuch der Klimatologie. Thomas, O. Catalogue of the Marsupialia Berlin: Borntraeger, Bd. I. Teil C; and Monotremata in the collection of 1936: 1-44. the British Museum (Natural History). Laut, P.; Heyligers, P.C.; Keig, Gael; British Museum, London; 1888. Löffler, E.; Margules, C.; Scott, R.M. Wace, N. Naturalized plants and native Environments of South Australia. vegetation in Australia. Proceedings Canberra: Division of Land Use Second Victorian Weeds Conference 7: Research, CSIRO; 1977. 13-29. Milewski, A.V. A climatic basis for the study of convergence of vegetation structure in mediterranean Australia and southern Africa. J. of Biogeography 6:293-299; 1979.

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