Higher up on the dunes it is salt winds that is the invasive force. Aerial parts of vegetation block the wind energy and cause sand to deposit around the vegetation. A characteristic of dune vegetation particularly grasses like spinnifex, pineapple sedge and dune carex is their ability to produce up right stems and sand trapping rhizomes that can grow firm roots in response to sand coverage. This sand deposition around plants results in increase height and width of the dune, a process known as plant induced dune expansion.
The ability of pioneer plants such as Spinifex and Pigface to hold wind blown sand on the frontal dunes helps create conditions which encourage the establishment of other communities such as Woodland Scrub (Acacias, Tuckeroos) Heathland (Banksias, Xerophytes such as Pea plants, Heath and Boronias and Melaleucas and Coastal Forest (Eucalypts and Angophora). All plants (Herbs, shrubs ,reeds, grasses, trees) are of equal importance in developing vegetation. Like the interplay between diverse cell types within the connective tissue meshwork of our skin underlay (dermis) that stops the outer skin from splitting and falling apart these plants enable dune stabilisation to continue indefinitely.
The whole process of dune formation and succession depends primarily on the pioneer plants and of all of these Spinifex is the chief. Spinifex hirsutus (The Captain Cook of the dunes). This is the most successful sand trapping dune coloniser and pioneer along our northern beaches. It provides the basis for a dune and establishes the first of a new set of environmental conditions conducive to the radiation of a more diverse vegetative cover.
These conditions include increased shade, reduced sand temperature, reduced wind movement, and lowered evaporation rates from the sand surface and a catchment for wind blown seeds. This inturn further lowers rates of water loss from leaves. The increase plant diversity it promotes enriches leaf litter and the accumulation of humus. This is the key to a better water holding capacity of dune soils, thus paving the way towards the expansion of bio diversity (Plant and Animal) and stabilisation of successive communities.
This succession conforms to the following set pattern as long as intervening factors don't interrupt the process.
What might some of these intervening factors be?