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Gladiolus gueinzii (Iridaceae) and Trachyandra divaricata (Liliaceae s.l.) are South African dune plants naturalised in Australia. Gladiolus gueinzii has two modes of dispersal: winged seeds, and cormels that may float for up to seven months in seawater. Its Australian occurrences are restricted to New South Wales. It was first collected in 1950 near Newcastle and has spread 250 km to the north and 500 km to the south. From large distances between the early herbarium records it was inferred that buoyancy of the cormels enables Gladiolus gueinzii to establish at sites remote from existing populations. The climatic conditions of the area over which Gladiolus gueinzii presently occurs are broadly similar to those of the more humid part of its native range. Further spread may be restricted due to unfavourable thermal factors.
Trachyandra divaricata is a "tumbleweed". Wind dislodges and carries away the "crowns" of tangled mature infructescences, in the process peppering their trails with innumerable small seeds. In the 1930s Trachyandra divaricata became established near Perth, Western Australia, while in 1940 it was also found near Karridale, 300 km further south. In the intervening area it has become a major weed in the dunes and has spread to paddocks inland, causing poisoning of livestock. Trachyandra divaricata has also turned up at several other outlying coastal locations as well as at an inland site. The distances involved are suggestive of dispersal by human agency, for instance through cars or boats. The Mediterranean and adjacent semi-arid climates of the south-west of Western Australia mirror a similar situation in southern Africa. Hence, the area appears to be well suited to Trachyandra divaricata and further spread can be expected.
In New South Wales Trachyandra divaricata was first found in 1968 at a dune rehabilitation site near Wollongong. It possibly came in as a contaminant of Acacia saligna planting stock from Western Australia. Since then it has become established at several other reclaimed areas, but has not spread much beyond such sites, possibly because of unfavourable climatic conditions. Nevertheless, in case aggressiveness takes a turn for the worse, it would appear desirable to eradicate occurrences in New South Wales while this is still achievable.
The sand spit that separates Shallow Inlet from Waratah Bay (38º52ʹ S, 146º13ʹ E), near Wilsons Promontory in southern Victoria, has developed since the previous spit was washed out in 1901. Initially without vegetation, the spit was colonised in the 1960s by the exotic grasses *Thinopyrum junceiforme and to a lesser extent *Ammophila arenaria. These species are native to the coast of western Europe, where they fulfil a key role in dune establishment. Being able to grow through sand accumulating among the culms, these grasses formed mounds where seeds or rhizome fragments were washed up during king tides. Where somewhat sheltered from the strongest impact of the westerlies, mounds gradually coalesced and formed short ridges at the landward side of the spit, and ‘dune fields’ towards its distal end. Circumstances favourable for dune field formation were enhanced by episodic processes in spit growth due to channel shifting in the tidal delta and the gradual lengthening of the main outlet channel.
Austrofestuca littoralis and Spinifex sericeus joined the two foreign grasses in their pioneering role. The herbaceous Actites megalocarpa and the shrub Ozothamnus turbinatus established in the lee of the grasses, but conditions on mounds, dune crests and windward slopes are too severe for other species. Only at more sheltered sites is further development of vegetation possible. In the lee of the dune fields it has progressed into an open shrubland, initially of Ozothamnus turbinatus, Olearia axillaris and Olearia glutinosa, later enriched by Acacia longifolia var. sophorae, Leptospermum laevigatum and Leucopogon parviflorus. Wind-dispersed taxa form the dominant component of the vegetation, but several animal-dispersed species became established as well. The complement of woody species begins to resemble that of the dune scrub found elsewhere along this part of the Victorian coast, but several wind-dispersed species, notably Banksia integrifolia, are still lacking and it would appear that dispersal is still a limiting factor in vegetation development. It is pointed out that dune development on the sand spit was initiated by exotic grasses and that without their presence, it is doubtful whether any vegetation would have established there.
Many photos support the text- the narrative will say what words can say but words can never say it all (Love 1999).
Euphorbia paralias, Sea Spurge (Euphorbiaceae), indigenous to the sandy shores of southern Europe and northern Africa, was first collected in Australia near harbours: at Albany, Western Australia in 1927 and at Port Victoria, South Australia in 1934. E. paralias seeds are buoyant and dispersed by ocean currents. By 1974 E. paralias had reached Wilsons Promontory, but was not recorded from southern New South Wales until 1987, while in East Gippsland it was first recorded in 1993. Since then it has spread to other beaches in this region and has also turned up on Lord Howe Island.
Surveys have been carried out to ascertain the status of Euphorbia paralias in East Gippsland and southern New South Wales during the last decade. The results together with other observations have been correlated with the published results of drifter experiments. The latter relied on reporting back of stranded bottles, cards or envelopes released at certain distances offshore. The establishment of E. paralias in southern New South Wales, before doing so in East Gippsland, is in agreement with the stranding pattern of bottles released west of Wilsons Promontory. Another bottle and two cards released in eastern Bass Strait washed up on Lord Howe Island, thus underpinning the assumption that the colonising E. paralias seed was carried there on ocean currents. E. paralias is still expanding its range in New South Wales. Modelling based on climatic parameters has shown that extension to the lower North Coast of New South Wales can be expected. However, the spread of the introduced sea-rocket Cakile edentula beyond its known climatic range into the Great Barrier Reef area could provide a precedent for what may also happen in the case of E. paralias.
Between 1993 and 2005 I investigated the introduced plant species on the Newcastle foreshores at Stockton and Macquaries Pier (lat 32º 56’ S, long 151º 47’ E). At North Stockton in a rehabilitated area, cleared of *Chrysanthemoides monilifera subsp. rotundata, and planted with *Ammophila arenaria interspersed with native shrubs, mainly Acacia longifolia subsp. sophorae and Leptospermum laevigatum, is a rich flora of introduced species of which *Panicum racemosum and *Cyperus conglomeratus have gradually become dominant in the groundcover. Notwithstanding continuing maintenance, *Chrysanthemoides monilifera subsp. rotundata has re-established among the native shrubs, and together with Acacia longifolia subsp. sophorae, is important in sand stabilisation along the seaward edge of the dune terrace. The foredune of Little Park Beach, just inside the Northern Breakwater, is dominated by Spinifex sericeus and backed by Acacia longifolia subsp. sophorae-*Chrysanthemoides monilifera subsp. rotundata shrubbery. In places the shrubbery has given way to introduced species such as *Oenothera drummondii, *Tetragonia decumbens and especially *Heterotheca grandiflora. At Macquaries Pier *Chrysanthemoides monilifera subsp. rotundata forms an almost continuous fringe between the rocks that protect the pier against heavy southerlies. However, its presence on adjacent Nobbys Beach is localised and the general aspect of this beach is no different from any other along the coast as it is dominated by Spinifex sericeus. Many foreign plant species occur around the sandy foreshores at Port Hunter. Since the first coal exports in the 1850s the Newcastle wharves and ballast-ground at Stockton became points of entry for foreign species, either directly, or via stopovers at other Australian ports. Some of these, *Panicum racemosum, *Tetragonia decumbens, *Ursinia speciosa, *Hebenstretia dentata and until recently, *Heterotheca grandiflora, remained restricted to the Newcastle region, while others, e.g. *Chrysanthemum monilifera subsp. rotundata, *Hydrocotyle bonariensis, *Gladiolus gueinzii and *Oenothera drummondii, spread further afield, but only colonised their preferred coastal habitat. Many more species spread far and wide, their port of introduction no longer recognisable. Other species were introduced as garden plants, escaped and became naturalised. However, for most foreign, generally widespread, species their mode of entry can no longer be determined. 99 species were recorded in the six areas regularly visited, about 25% native to Australia, and 75% about evenly divided between species from Africa, Asia and Europe. More detailed information on 15 of the more notable introduced species is provided in an appendix. On the dune terrace vegetation of North Stockton, only about 20% of the 50 species are native to Australia, the only one of any prominence being Acacia longifolia subsp. sophorae. Nevertheless, on first impression this ‘multinational’ assemblage looks quite normal, and when one compares the ecological functioning of the 1930s vegetation with that of the present vegetation, it appears that, due to presence of more graminoids, and the fact that *Panicum racemosum produces a denser sward than Spinifex sericeus, the present vegetation is more effective in sand-catching and dune stabilisation than the vegetation in the 1930s would have been. However in view of the increasing influence of climate change, e.g. a rise in sea level and more extreme weather events, there is no indication that the present terrace, notwithstanding the increased density of the rhizomatous species and a sprawling shrubby vegetation along the crest, will endure such attacks any better than in the 1990s.
The aim of this study was to assess the role of currents in the dispersal of seashore species with buoyant propagules. Four introduced species which have now attained a wide distribution in southern and eastern Australia were used as indicators: Cakile edentula, Cakile maritima (Brassicaceae), Euphorbia paralias (Euphorbiaceae) and Arctotheca populifolia (Asteraceae). None arrived in Australia unaided, as all early collection localities are near ports and early long-distance dispersal within Australia was often due to shipping. Buoyancy and viability of propagules were tested to assess dispersal and colonisation potential. Propagule spread was analysed using information from herbarium specimens and fieldwork. A progression of herbarium specimen collection dates could often be explained by regional current regimes, as revealed by stranding locations of drift bottles and drift cards. The eastward spread of Euphorbia paralias from King George Sound, Western Australia, correlated well with stranding patterns of drift bottles released south of the Sound. The colonisation by Arctotheca populifolia of the southern extremity of the Eyre Peninsula and the south-east of South Australia was achieved through fruits carried from Western Australia by the Leeuwin Current. These and other congruencies between patterns of spread and the results of drifter releases are analysed and discussed.
The Entrance Point Scientific Reference Area (lat 38º 48’ S long 146º 38’ E) in the north-eastern corner of Wilsons Promontory, Victoria, is notable for numerous parallel sandy dune ridges covered with dense Leptospermum laevigatum scrub. As a result of some demanding field work in a relatively remote area, together with aerial photos, I have been able to observe the development of this dune topography and follow the vegetation succession from 1981 to 2000. After a period of erosion early in the 20th century, shore progradation and ridge formation resumed in the central section of the beach between Entrance and Hunter Points and later extended southward. The parallel ridges were found to be the result of successive berm and pool formation on the upper beach of the prograding shoreline. Berm overwash during spring and storm tides fills the depression behind the berm and after the tide has gone out leaves behind a long narrow pool. Buoyant Atriplex cinerea fruits present in the flotsam strand on either or both of the pool margins, depending on prevailing wind directions. After fruits have germinated, seedlings provide nuclei for sand accumulation. If they are sufficiently numerous, a dune ridge builds up along the outer pool margin while plants on the inner margin contribute to the consolidation of the previous ridge. As long as progradation continues, this process is repeated at intervals and results in the formation of series of parallel dune ridges. A small number of other species establish in the lee of the new ridge. Acacia sophorae with its fast growth and spreading habit, together with Olearia glutinosa contribute to stabilising the ridge. They provide protection for Leptospermum laevigatum, Myoporum insulare and Banksia integrifolia during their early growth. After about 20 years, Leptospermum laevigatum becomes the dominant element of the scrub as Acacia sophorae diminishes in vigour and eventually dies. Virtually no evidence, even on the oldest ridges, was found of candidate species to continue the succession and hence, Leptospermum laevigatum thicket needs to be regarded as the end of the succession on young dune ridges. Once the pool depressions are cut off from flooding by seawater, the groundwater freshens and a sward of Isolepis cernua and Samolus repens, often with Juncus kraussii and Isolepis nodosa on somewhat higher areas, becomes established. Flooding occurs during heavy rain and water may stay above the surface for several days. At the same time, the older ridges of the central section were attacked by erosion which left large amounts of tree debris on the upper beach. This erosion resulted in the formation of a spit which, in time, carried a series of successively younger ridges built on flotsam lines. Atriplex cinerea was again the dominant pioneer species, but in the 1990s the influence of *Thinopyrum junceiforme had become equally important. Succession on these ridges was similar to that of the ridges on the prograding beach, but scrub height remained somewhat lower. Saltmarsh vegetation, dominated by Sarcocornia quinqueflora, gradually established in the lower sections between the ridges. However, the impact of erosion which had provided the sediment for building the spit, gradually shifted northward and began to destroy what had come into existence only decades earlier. Beach progradation along the western entrance to Corner Inlet is fortuitous and linked to changing channel locations in the tidal delta, while the dominant role of Atriplex cinerea in incipient dune formation is a consequence of the relatively sheltered environment at the entrance. It could well be that this combination of environmental factors is rarely if ever duplicated elsewhere in Australia.
Montagu Island (36°15’S; 150°14’E) is situated about 10 km east of Narooma on the New South Wales South Coast. The paper presents evidence about the changes in the terrestrial vegetation of the island since it was first seen by Europeans, provides a floristic inventory and gives a perspective on the effects of introduced species.
Flinders (1814) mentions that the island "produced small trees." This is the only record of what grew on the island until in 1880 annotations on a map, made at the time of the construction of the lighthouse, mentioned the presence of scrub, trees and rank grass. This is confirmed by photographic evidence, but by 1932, when the botanist F. A. Rodway visited the island, the trees had disappeared. In 1973, during a land use survey of the South Coast, a team of CSIRO described the vegetation as a distinct series of dune communities belonging to the Lomandra longifolia – Pteridium esculentum – Phragmites australis complex. Vegetation mapping in the late 1980s confirmed the prevalence of these species, except that Pennisetum clandestinum then covered a large area along the west side of the island.
Excluding taxa used for ornamental or culinary purposes, nearly 200 species of vascular plants have been recorded since 1932 of which about 140 were still present in the late 1990s. There are ten species of ferns e.g. Pteridium esculentum, widespread and sometimes codominant with Lomandra longifolia, and Asplenium obtusatum, frequently found among the rocks along the east side of the island. The only taxon unique to Montagu Island is a hybrid of this species and Asplenium australasicum. Among the flowering plants there are about 110 native species and about 70 species naturalised in Australia. About 85 and 40, respectively, are still present today. Many of these have a wide distribution in Australia and only about 25 have a more restricted coastal distribution. The species that have disappeared include many that were weeds in the vegetable gardens or around the chicken sheds. Several naturalised species still present are notorious for their capacity to overrun existing vegetation. Foremost among these is Pennisetum clandestinum, which now covers about one-third of the island; Acetosa sagittata is a close second. Other contenders are Dipogon lignosus and Delairea odorata. It is now apparent that these species were kept in check by the feral goats that roamed the island before it was declared a Nature Reserve in December 1987.