Dune pioneers

The foredune is the harshest ground on the whole coast — shifting sand, salt spray, furnace heat and, to begin with, no soil at all — and almost nothing can live there. What can is a small crew of pioneers whose entire job is to hold the sand still long enough for anything else to follow. The chief of them is spinifex (not the spiky desert spinifex of the inland, confusingly, but a sprawling coastal grass), which throws long runners out across the open sand, pinning it and catching wind-blown grains until a dune begins to build around it. With it grow pigface, its fat leaves storing water against the drought and salt and throwing improbable magenta flowers across the bare sand, and goat's-foot, a beach morning-glory that flings purple-flowered vines metres across the surface like rope thrown across a deck.

Every one of them survives the front on the same economy the hard country runs on everywhere (see sclerophylly): tough, thrifty, well-defended foliage — leathery leaves, water-storing tissue, a low surface to the sun and salt — built to endure rather than to grow fast and soft. And in surviving there they do something the whole coast depends on. The vegetated foredune they build and anchor is the coast's first and cheapest sea defence, a wall of held sand standing between the ocean and everything behind it. Strip the pioneers off, with too many feet or too many vehicles, and the sand is loosed: the dune blows out and begins to walk inland with the next big wind, a moving sandblow that buries the scrub in its path (Cooloola carries some spectacular examples of sand on the move).

Behind the shifting front, where the pioneers have done their work and the sand has settled, the vegetation thickens into dune scrub and then, on the older, stable sand further back, into the low, hard-leaved heath of the wallum — some of the poorest, most species-rich country in Australia. So the sequence reads outward from the sea as a hand-off: the pioneers make the ground stand still; the scrub and the heath move in behind the shelter they build. Note what the pioneers do not do — they do not enrich the sand, which stays as poor as ever; their gift is stability, not fertility. It is the cheapest and least celebrated engineering on the coast, done for free by a handful of plants nobody looks at twice.