The 'Coastal Beach Complex' formation occurs at the

interface between terrestrial and marine environments.

The formation is exposed to a number of variable and

often harsh environmental controls. Factors that

influence vegetation development include salinity (both

from tidal exchange and salt spray), exposure to

prevailing tradewinds, mobile and infertile substrates,

and regular severe weather events. Micro-topography,

which frequently and rapidly changes across the young

and mobile dune landform, is a major influence on the

expression of these communities. As such, the grouping

encompasses a broad range of structural and floristic

variations.

Association 64a, a coastal foredune community, beginsimmediately landward of the high tide level with aherbaceous cover of creeping plants including Ipomoeapes-caprea, Canavalia rosea, Spinifex sericeus and Cassythafiliformis. This gives way to a low and often sparseshrubland comprising, amongst other species, Scaevolataccada, Premna serratifolia, Hibiscus tilieacous and Acaciacrassicarpa. Casuarina equisetifolia typifies the complexforming shrubland, woodland and low open forestexpressions on the upper and most landward portions ofthe foredune. Casuarina is a colonizing species and itsoccurence in pure stands is generally related to historicalerosion or fire. Depending on site history, casuarina maybe a precursor to the establishment of more permanentvine forest species including Calophyllum inophyllum andSyzygium forte subsp. forte which ultimately have astabilising influence on the dune landform. In exposedlocalities, the foredune is subject to frequent erosionevents leaving a steep cut-away scarp and undercutcasuarinas stranded at the high tide level.

Association 64b is restricted to the Wonga Beach areawhere it is located within narrow dune swales as a lowsprawling canopy of Hibiscus tileaceus with emergentCalophylum australianum and Dillenia alata. Theassociation is essentially a brackish swamp communityinfluenced by water table fluctuations and occasionalsaltwater incursion during extreme tidal events. Itgenerally forms narrow linear bands separatingAssociation 64a from the more landward occurrence ofnotophyll vine forest (Association 8a).

Association 64c is a vegetation complex confined toHinchinbrook Islands northern seaward margin. Theexposed headland of Cape Sandwich has provided afavorable trap for migrating marine sand, with the

resultant deposition of vast quantities of aeolian sand inthe Ramsay Bay area. The dune field is composed of aseries of longitudinal sand ridges reaching heights of 60m,with deep swales on the systems landward margins. Thevegetation is a complex of several communities andtransitional phases that vary in response to topographicvariations on the dune field. The deeper swales tend to bedominated by low closed forest with a mix of Melaleucaleucadendra and simple vine forest species. Exposed andelevated areas on the sand dunes are occupied by openwoodland and shrubland communities. Unvegetated sandblows are common and are testament to the dynamicnature of the landscape.

Facts and figures

Major alliances Coastal dune complexesPresent extent 1,169haArea protected 401ha

Geography

The formation is restricted to coastal environs with 64a themost cosmopolitan association, occurring as adiscontinuous narrow margin along mch of the Wet Tropicscoastline. Associations 64b and 64c are confined to WongaBeach and Hinchinbrook Island respectively.

VEGETATION COMPLEXES AND MOSAICS

OF THE WET TROPICS BIOREGIONCoastal beach complexes (vegetation codes 64a-64b)

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Impact and changes

This formation has been heavily impacted by coastaldevelopment, both directly and indirectly. Clearing of theforeshore has resulted in severe fragmentation ofAssociation 64a with most accessible areas affected tosome degree by floristic changes to both canopy and sub-canopy species. Extensive stands in the Mission Beacharea are dominated by naturalized species including Cocosnucifera with the understorey structure severely altered.Exotic species, the most pervasive being Singapore Daisy(Sphagneticola trilobata) are becoming increasinglyprominent in otherwise undisturbed locations. Thisinfestation is dramatically influencing the diversity ofground covers in some locations, with the foreshore northof Flying Fish Point, extending northward to the Ella BayNational Park being heavily impacted.

A large number of beach systems within the Wet Tropicsbioregion are for various reasons in a state of sand deficitand cyclic erosion is causing a rapid retreat of the coastallandform. This may be a natural phenomena in somelocalities although anthropogenic influence can often beattributed as an influence in the majority of situations.

Constructed rock walls and groynes shift the focus ofbeach front erosion northwards, the direction of thepredominant longshore drift. The severe erosion ofbeachfront areas to the north of Cairns and Flying FishPoint may be partially attributed to this factor. More subtleresponses may result from disruption to the predominantsupply of coastal sand that is derived from the major riversystems. This disruption may be caused by sandextraction, entrapment behind wiers and impoundments,or entrapment by an over-abundance of choking exoticgrasses on river bars and banks.

Threatening processes

• Clearing and fragmentation

• Erosion facilitated by anthropogenic disturbance

• Erosion facilitated by rising sea levels

• Degradation through invasion of exotic species.

Key values

As well as their scenic amenity and recreation values, thehealth of coastal foredune communities is essential tomaintenance of the coastal landform. Historically wellmanaged coastal dune systems provide a protecting bufferto sensitive landward habitats (including swamps and vineforests) as well as mitigating against damage toinfrastructure caused by coastal erosion. They areimportant habitats to a number of threatened species andimportant nesting areas for marine turtles and sea birds.

Tenure

Well conserved examples are found within the majority ofcoastal national parks including Daintree, HinchinbrookIsland and Ella Bay. Extensive areas are held within councilmanaged lands.

Management considerations

• Control of exotic species (shrub and ground layers)

• Restoration of natural coastal processes (removal ofgroynes and rock walls)

• Fire management is required, particularly incommunities adjacent to the formation, to preventincursion of severe destructive wildfire

• Restoration and rehabilitation in heavily disturbedexamples.