Fraser Island’s Flora
The plant formations of the Great Sandy Region are usually clearly separated from one another by narrow boundaries. The habitats of the different vegetation formations are closely related to:
- depth to the water-table;
- presence or absence of soil horizon differentiation;
- thickness of A horizon;
- soil nutrient status;
- fire history;
- grazing pressure and timber operations
- salt tolerance; and
- exposure to the prevailing wind.
The region contains examples of both progressive and retrogressive forest succession on the podzol chronosequence, showing that the so-called climax forest is not self-sustaining and declines as soil fertility declines.
Some Melaleuca quinquenervia trees growing over 1500 metres east of Lake Wabby show signs of enormous age. Adventitious roots which come from high branches and the trunks are evidence that the trees were engulfed by the same sandblow which is now invading Lake Wabby. The trees avoided suffocation by the engulfing sand with the aid of the adventitious roots. When the sandblow advanced it began to exhume the trees and exposed these adventitious roots. The scarring of the paperbark indicates the level reached by the sand. Since the sandblow is now advancing at only about 50 centimetres per annum, it is possible that it is more than 2,000 years since the trees were buried. There is no evidence of what age the trees were before they were engulfed by the sand in that dramatic event. These melaleuca are probably thousands of years old.
Adjacent to Lake Wabby, are Melaleuca quinquenervia which have their roots at the water table which is well over 40 metres below their crown but they are buried for almost their total height and would not be able to survive without adventitious roots. These Melaleucas are probably the tallest Melaleuca trees in the world.
Two of Australia’s most commercial significant native Eucalypt species, tallowwood (E. microcorys) and blackbutt (E. pilularis) reach their northern most range on Fraser Island. In the case of tallowwood, this species terminates very abruptly at about the lattitude of Happy Valley, just about where it produces some of the largest specimens measured. Another significant Eucalypt with a very disjunct distribution, Gympie messmate, (E. cloeziana) ohas its largest specimens in the world on the border of the region.
Of greatest significance is the Satinay or as better known to the Aborigines, Peebang, (Syncarpia hillii). This tree grows to gigantic proportions several reaching over 3 metres in diameter, although most of the largest specimens have been logged. Such large specimens are all estimated to be at least over a thousand years in age. This species is regarded as endangered and it is virtually endemic to this region.
Some reports of the size and magnificence of the forests of the region can be gauged from some early reports:
- The following sizes (of trees) may be of interest. Kauri pine 80 feet to the first limb; diameter of stump 10 feet 4 inches diameter of top log 6 feet; White beech 60 feet to the first limb diameter of tree 6 feet. Tallowwood 80 feet to first limb diameter of tree 7 feet 3 inches; Blackbutt 65 feet to first limb diameter of tree 6 feet and Red Stringy much the same; Turpentine 80 feet to the first limb and diameter 8 feet 3 inches; These are the largest trees, runners up being hoop pine, scrub box, quandong and bolly gums (hard and soft). (Petrie 1922).
- In 1878, Armitage cut six logs from a Yidney scrub giant. … Bristow and Dempster hauled all but the butt log (10 feet 4 inches diameter)… (Petrie 1922).
- The traveller strikes a “living wall” of giant timber trees up to 150- (one hundred and fifty) feet high, buried in jungle – scrubs so thickly growing that roads or tracks must be cut to enable one to get through. Great piles, 100 to 120 feet clear to the first limb, are there in thousands, straight as an arrow but by far the greater number are much too big for piles, and can only be used as saw-mill logs up to about four or five feet in diameter, containing from five to six thousand feet in each tree. Then beyond that limit again come the super-giants, so big that no saw-mills at present in use in Queensland have any machinery capable of handling them. … (Armitage 1929).
- Dear old Mother Nature’s work on the grand scale can be seen here. Other places in the world, it may be worthwhile to mention or to describe the general character of the great jungles – here called scrubs – in which the timber-trees grow…all of it very tall and dense, the varieties and species are almost beyond counting. The very names almost unknown except to botanists. The general effect is very beautiful – in places great belts and groups of tall graceful feathery-topped palms one hundred feet high, many trees are decked out with big bunches of tree-ferns, staghorns, elkhorns, crown, birds nest, ribbon and others. Here and there small openings called “pockets” are met with and surrounded by such beauties of fern, palm, and other foliage as to suggest a veritable fairy-dell. (Armitage 1929).
- The general observer is mystified by an island with not an acre of soil bearing a dense and luxuriant vegetation not rivalled in size and beauty by the richest flora of the tropics. In the centre of the island, extending for a distance of 40 miles, with a width of 2 to 3 miles, is a dense scrub containing the largest and tallest trees of all Australian scrubs, with hardwood trees up to 9 or 10 feet in diameter, and 200 feet in height, mingled with tall beautiful palms, majestic tree ferns, graceful orchids, splendid mosses and lichens, and a general wealth of luxuriant undergrowth, all growing apparently out of pure sand, the secret lying in the underneath impervious strata of sandstone which intercepts all moisture and decomposing vegetation, and forms a perpetual bed of manure to which the roots of the trees descend for rich supplies of nourishment. (Meston, 1905).
- Outside of this belt of extraordinary scrub the country is covered by heavy forest, the size of the trees decreasing as they near the east and west coasts. There the land is covered by short shrubs, soft grasses, and a great profusion of brightly-tinted and sweetly-scented flowers. (Meston, 1905).
Even after so many giants have been removed this forest still retains its grandeur. Just as enthralling as the scale of the trees are the dramatic transformations from one plant community to a very different ecotype. The vegetation seems to change as abruptly as sets in a stage play. The impression is of a great patchwork of different vegetation types spread across this landscape.
Many people have been passionate about all Australian forests and been determined to protect them. An entourage descended on Fraser Island in 1990 to mount a blockade in an attempt to bring all Fraser Island logging to a halt. Their direct, non-violent action included attaching themselves to the blades of bulldozers with super-glue, sleeping in a cradle atop a very high tripod straddling roads to stop machinery moving or logging trucks entering the forests. That brought a sharp public focus on the impact that 123 years of logging had had on the island’s forest ecology. Certainly it made more people appreciative of just how special the forests of Fraser Island are.
The micro flora is also very significant and play a vital role in enabling the development of such a great biomass on seemingly poor soils.
The region’s sand dunes possess one of the most complex and varied assemblages of soil fungi. These have symbiotic associations with plant roots wherby the fungi make the limited minerals in the sand available to larger plants in return for carbohydrates. These fungi are also important in decomposition of litter and reducing water repellence of the sand. CSIRO collected more than 270 species of larger fungi in Cooloola. This is expected to be much larger because some species had not been identified and collections were not made from the rainforest. Although the distribution of soil fungi is not well studied in Australia or the rest of the world, the study suggested that Cooloola contained an exceptional range and diversity of species.
The proportion of plants with nitrogen fixing properties which occurs on the sand masses is exceptional. There are very high populations of each of the four different varieties of Casuarinas which occur on the sand dunes which have nitrogen fixing capacity. In addition there is also a high population of Macrozamias which can also fix atmospheric nitrogen along with a diverse array of legumes as listed by the CSIRO.
Australia’s largest orchid, Phaius australis, grows in the dune systems of the Great Sandy Region. This spectactuclar orchid, which grows to a height of two metres was once more widely distributed in parts of the coastal mainland and some islands of the Pacific, now has a constricting habitat. Its habitat in the Great Sandy Region is not threatened.
Of the rare and threatened plants of Queensland (Thomas & Mc Donald, 1987) the following are found in the Great Sandy Region: Acacia attenuata, A. bakeri, Archidendron lovelliiae, Artaxon hispidus, Boronia keysii, B. rivularis, Cinnamomum baileyanum, Cryptocarya foetida, Durringtonia paludosa, Eucalyptus hallii, Glycine argyrea, Macarthia complanata, Melalueca cheelii, Phaius australis, P. tancarvilliae, Schoenus scabripes, Symplocos sp. aff. S. bauerlenii, Syncarpia hillii, Tecomanthe hillii, Tephrosia baueri, Xanthostemon oppositifolius.
Some of Australia’s largest trees grow in this region. Blackbutt and Tallowwood some of the most significant commercial Australian hardwoods reach the northern limit of their range in the region. In the case of Tallow wood the line of demarcation is a very definite line at the latitude of Happy Valley.
New plant species have been discovered during the botannical study of Cooloola during the last decade. The status of these plant species is yet to be fully assessed.
Just as studies of Cooloola’s plant communities (Harrold 1976) demonstrated that many plant species not represented on the sand dunes of Cooloola occurred in the degraded sandstone or wallum areas of the upper Noosa River catchment, so can it be said that many further plant species occur in other wallum areas. This is particularly true of the Kinkuna area which contains two rare and restricted tree species, Eucalyptus hallii and Melalueca cheelii.
The Great Sandy Region supports five main vegetation types: rainforest, tall openforest, low open forests and woodlands, heathlands, and melaleuca forests, as well as several lesser ones including cypress forests, tall dry heaths, coastal pioneer associations, riverine and estuarine fringe associations.
Classed as simple evergreen notophyll vine forest and mixed notophyll evergreen forest, this vegetation type occurs on the high dunes at Cooloola and Fraser Island in well-protected sites, mainly interdune corridors. Within the Great Sandy Region approximately 10,000 ha are covered by rainforest. The main emergents are satinay (Syncarpia hillii), brush box (Lophostemon confertus), kauri pine (Agathis robusta), piccabeen palm (Archontophoenix cunninghamiana), hoop pine (Araucaria cunninghamii), with an under-storey including carrol (Backhousia myrtifolia).
The rainforest of the Great Sandy Region is the only rainforest in the world which grows on high sand dunes. Some of the rainforest occurs on sand dunes with an elevation of 240 metres.
Rainforest also occurs on soils derived from shales and siltstone north of Kin Kin Creek. Not only are these small patches the remnants of the extensive Kin Kin Scrubs of the past, but they are also among the last survivors of lowland vine-forest on fertile soils in south-east Queensland. This rainforest is botanically distinct from the Great Sandy Region’s sandmass rainforests – distinguished in part by the presence of proteaceous tree species, a family which is poorly represented in the rainforests of the sandmass.
Tall Open Forests
Tall forests occur mainly on the high dune areas adjoining the rainforest areas at Cooloola and Fraser Island, and in an area lying to the north of Kin Kin Creek. This forest varies from a pure blackbutt (Eucalyptus pilularis) forest to mixtures of blackbutt with tallowwood (E. microcorys) red bloodwood (E. intermedia), brush box (Lophostemon confertus), scribbly gum (E. signata) and forest oak (Casuarina torulosa). Understorey species vary considerably, depending on topography and proximity of rainforest, but commonly include at the drier range Persoonia sp., Monotoca scoparia, various Acacia, Banksia and Leptospermum spp. etc.
Low Open Forests and Woodlands
These are the grassy woodlands to open forests of the western catchment of the Noosa River, the Wide Bay Training Area, some of the islands of the Great Sandy Strait, and areas adjacent to Wathumba Creek on Fraser Island; the shrubby woodlands of the western margins of the sandmasses; and the shrublands to dwarf forests of the sandmasses’ eastern margins; the stunted mallee forests in the north of Great Sandy National Park. Eucalyptus signata, E. intermedia, E. umbra, Angophora costata, Banksia aemula, B. serrata, B. integrifolia and Casuarina littoralis are common component species of the low sclerophyll forests, though these vary between localities.
Boronia keysii, an endangered species, has a very restricted distribution within this community.
This habitat includes Banksia spinulosa which, in the Great Sandy Region only occurs on the degraded sandstones of Wide Bay Training Area and the western catchment of the upper Noosa River. Although this type of plant community was once widely represented in south-east Queensland, due to development it is now poorly represented in protected areas outside the Great Sandy Region.
Heathlands in Australia are important plant communities. Extensive treeless heaths are formed on the sand and peat plains adjacent to the Noosa River, in some of the wetter dune swales, fringing many of the creeks on Fraser Island, and adjoining parts of the estuarine fringes. They are complex mixtures of shrubs (Banksia robur and Leptospermum spp.) and sedges. At their wet extreme they grade into closed sedgelands of Gahnia sieberiana, while the driest areas support mallee-form eucalypts and low tree banksias.
Heaths are considered to be one of the more spectacular and colourful plant communities found in Australia. The Noosa Plain is famous for its spring and summer wildflower displays.
Dominated by the species Melaleuca quinquenervia, these forests occur in the drainage basin in those areas that have a seasonally high water table.
There is a great diversity of melaleuca species in the more poorly drained wallum soils. This particularly true in the Kinkuna area which has the greatest variety of melaleucas to occur in Queensland which must make it one of the most significant melaleuca habitats in the world.
Occupying the niche of low lying dunes in the sub-littoral zone, this forest dominated is by cypress pine (Callitris columellaris). The main occurrences are on the south east corner of Fraser Island and the western sides of the Cooloola and Fraser Island sand masses.
Tall Dry Heath
There is an extensive area in the northern section of Fraser Island where there are few trees or shrubs taller than 1.5 metres. Here Banksia oblongifolia is the most prevalent banksia.
Coastal Pioneer Associations
Along the coast, pioneer vegetation such as sand spinifex (Spinifex sericeus), pigface (Carpobrotus glaucescens), and goats-foot convolvulus (Ipomea pes-caprae) colonizes the raw sand on the exposed fore dune. These are hardy, tenacious plants with a high tolerance to salt spray. However, in this situation they are very susceptible to damage caused by use of the fore dune for off-road vehicle access, camping or grazing. This vegetation is generally backed by low trees dominated by Casuarina equisetifolia, Pandanus spp., and Banksia integrifolia.
Within this community are pioneer rainforest species, including celery wood (Polyscias elegans) and Acronychia laevis indicating seed dispersal by birds.
Estuarine Fringe Associations
Mangroves line the shores of Tin Can Bay Inlet, Great Sandy Strait, the Wathumba Creek estuary, and the Noosa River, south of Fig Tree Lake. Of the 29 species of mangroves in the Australian region, 13 occur in this region. In this region, an additional species Swamp Oak, (Casuarina glauca), grows in the inter-tidal zone and has been classified as a mangrove. In the Great Sandy Strait there are also extensive sea-grasses. The outstanding feature of the sea-grass communities is the dense and extensive meadows of dugong-grass (Cymodocea serrulata) in the Great Sandy Strait. There are also dense stands of eel grasses (Zostera capricorni, Halodule univervis and Halophila ovalis).
Riverine Fringe Associations
Low forest vegetates the banks of the Noosa River and Teewah Creek upstream from Fig Tree Lake. Common trees include cypress pine (Callitris columellaris), swamp box (Lophostemon suaveolens) and Melaleuca quinquenervia, while swamp banksia (Banksia robur) is a common low shrub of the riverbank vegetation. Occasional rainforest trees occur, with larger isolated stands of rainforest of the upper Noosa River, immediately adjacent to the treeless plain.
The Great Sandy Region was visited by both pre and post excursions of the XIII International Botanical Congress in 1981