This is part 2 of a look at the amazing and resilient flora of coastal dunes in southern Gippsland. In part 1 I talked about the shrubs and trees found in this habitat and this post I’ll discuss the often less obvious flora; the herbs, grasses and scramblers.
As I mentioned in the last post on dune flora the fore dunes are usually dynamic and frequently mobile, particularly towards the beach where wind and wave action are unpredictable and often dramatic. At the base of the fore dune the vegetation is often sparse and consists of mostly grasses with some herbs, sedges and low shrubs. Common grasses in this ‘pioneer’ area include Spinifex sericeus (Hairy Spinifex) which often dominates this zone as well as Poa poiformis (Coast Tussock-grass), Austrostipa spp (Spear Grass) and Rhytidosperma spp (Wallaby Grass).
In the mid to late 1800’s many dunes were partly cleared and grazed and an initiative to restabilise them was devised which unfortunately involved the introduction of Marram Grass Ammophila arenaria from Europe. This species has since established itself extremely well and has become a serious environmental problem on coastal dunes.
Another serious weed to be found on the lower part of the fore dune is the Mediterranean Euphorbia paralias (Sea Spurge) which was also introduced for dune stabilisation. This widespread weed has a long tap root weed and can alter the shape of the base of the dune to a steeper angle, making it more prone to being undercut by waves.
Extending up the face of the fore dune towards the top you often find amongst the shrubs scattered native ground covers and herbs such as the extremely hardy succulent Carpobrotus rossii (Ross’s Noonflower), Senecio biserratus (Jagged Fireweed) and Actites megalocarpa (Dune Thistle).
Dune Thistles (see above photo of Marram Grass) can look a lot like the introduced thistles and are in the same family Asteraceae. Unfortunately this species may often be mistaken for the weedy variety and I was once told by a person from a large government agency (insert name here) that they got volunteers to remove hundreds of these along a section of coastline before I mentioned to them they are native! Oops.
Once you extend over the crest of the dune the vegetation changes considerably and amongst the shrubs you often notice the abundance of scramblers and climbers extending down the face of the hind dune such as Clematis microphylla (Small-leaved Clematis), Muehlenbeckia australis (Climbing Lignum), Rhagodia candolleana (Seaberry Saltbush) and Tetragonia implexicoma (Bower Spinach). The latter two often grow up to smother other shrubs and can often form dense ‘blankets’ over vegetation and create an important habitat for ground dwelling fauna and refuges for small birds.
The soil here is remarkably different too and less mobile due soil fungi, herbs, grasses and other vegetation taking advantage of the protection from wind to bind the soil together.
As you reach the base of the hind dune the vegetation often consists of various climbers (as mentioned above), grasses, herbs and sedges mixed with shrubs and small trees. Grasses regularly encountered are Distichlis distichophylla (Australian Salt Grass), Poa spp (Tussock Grass) and Lachnogrostis spp (Blown Grass).
Lepidospermum concavum (Sandhill Sword-sedge) is a broad-leaved sedge which can dominate some areas of this zone and is important for some moth species whose larvae feed on the leaves.
Unfortunately the base of the hind dune is often choked with weeds such as African Boxthorn as well as introduced grasses (as in the above photo) and many smaller native species struggle to establish.
This hind dune zone often tends to merge in with other habitats, typically coastal woodland, grassland/sedgeland or swamps and can often include many of the same plants as well as other completely different species.