Some notes on the vegetation of the west coast south of Macquarie Harbour
by Nick Fitzgerald
Rounded shrubs of Leptecophylla abietina amongst coastal grasses on rocky coast
Lawn damage
Last summer I was fortunate to spend two weeks on the remote south-west coast north of the Spero River. This region is rarely visited on account of the isolation and difficulty of access, although traces of the modern world are apparent in the illegal ATV (All Terrain Vehicle) tracks in the northern part and the countless rubbish washed ashore from boats.
The trip was something of a working holiday, with the purpose of removing weeds from this remote wilderness coastline. An Envirofund grant and support from the local Parks and Wildlife Service provided the boat, float plane and helicopter transport for several groups of volunteer beach-weeders, each tackling a different section of the southwest coast.
Triglochin procerum
Sandy beaches, extensive dunes and brackish lagoons are interspersed with sea cliffs, rugged headlands and cobble beaches. The coastal vegetation, including wetlands, contains a large diversity of edible plants which are often abundant, for example glasswort Sarcocornia quinqueflora, water ribbons Triglochin procerum and native pigface Carpobrotus rossii.
The major sand-binding species on the primary dunes are native pigface and pale biddy-biddy Acaena pallida, with occasional patches of beach spinifex Spinifex sericeus. Fortunately the invasive exotic marram grass Ammophila arenaria is present in very few locations, and these are being targeted by the remote area weeders.
Many beaches have a steep profile composed of cobbles with herbs such as saltbush Atriplex sp. and scrub nettle Urtica incisa living between the rounded stones. The flat cobbled area behind these beaches typically has an extensive cover of climbing lignum Muehlenbeckia adpressa or bracken Pteridium esculentum. Eventually an organic soil will develop on this stony substrate provided rising sea levels do not encroach.
Exposed rocky headlands support hardy lithophytes including saltspray plantain Plantago triantha, and shore spleenwort Asplenium obtusatum subsp. northlandicum. Limestone is common on the coast, resulting in rugged headlands and gulches occupied by hardy coastal grasses and extensive patches of glasswort. Weathering has a peculiar effect on the limestone – rather than smoothing the rock it creates razor-like blades and sharp points which threaten to eat the toughest of footwear.
N. calyceroides
Groundwater seeping from the calcareous rock sometimes forms limestone deposits behind beaches. These tufa herbfields host an array of short herbs, sedges and the like. A characteristic species is spiny everlasting Nablonium (= Ammobium) calyceroides, a small rosette daisy endemic to the west coast and Bass Strait islands.
Herbfields are common elsewhere but are replaced by bracken or grasses on less organic, very sandy soils. Closely-grazed 'marsupial lawns' often occupy old dunes, along with shrubs neatly pruned by wind and wallaby giving an illusory landscaped garden effect. The tiny creeping orange mat-currant Coprosma perpusilla is commonly found in these coastal herbfields although it is usually an alpine plant in Tasmania and New Zealand, and also occurs on Macquarie Island.
Low forest of west coast peppermint Eucalyptus nitida is patchy and best developed in sheltered basins and gullies.
Blechnum nudum
Apart from very isolated stands of swamp gum Eucalyptus ovata, other eucalypt species appear to be absent from the lowlands between Port Davey and Macquarie Harbour. The dampest and most sheltered coastal forest patches support a scrubby rainforest of celery-top pine Phyllocladus aspleniifolius, manuka Leptospermum scoparium, dogwood Pomaderris apetala, fishbone waterfern Blechnum nudum and, sometimes, native laurel Anopterus glandulosus.
Like many coastal areas, scrub is the dominant vegetation type and varies from tall tea-tree scrub with open sedgey understorey to almost-impenetrable low thickets of coastal shrubs such as white correa Correa alba.
Two very common shrubs, the closely related seaspray pinkberry Leptecophylla abietina and common pinkberry L. juniperina, grow in close proximity to each other but rarely occur together. This apparent example of 'niche partitioning' likely reflects differences in competitive ability. Considering that L. abietina appears to be the most salt-tolerant woody plant on the coast it seems able to survive where other shrubs cannot, but at the expense of competitive ability in less harsh environments. Leptecophylla abietina forms low dense bushes in the spray zone, while its larger cousin grows slightly further inland and can reach remarkable heights on the southwest coast compared to elsewhere – around 12 metres in sheltered sites.
[All images have been provided by the author]
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