29 
PLANT COLONISATION OF THE SOUTHPORT 
SAND SPIT 
A. B. (JRIBB 
Introduction 
Over the past forty to fifty years tliere has been a 
northward migration of the Nerang River bar, the south- 
ern tip of Stradbroke Island being eroded away while 
deposition took place on the nortliern end of the t:^outhport 
sand spit. The history of this migration has been traced 
by Connah (1946) and by Brooks (195-1) wiio liave shown 
that the northern ti]) of the sandspit has advanced at 
varying rates from a point only a few chains north of 
the site of the Jubilee bridge some time between 1901 and 
1911 until, at tlie present time, with erosion of Rtradbroke 
Island still continuing, it is located ai)proximately two and- 
a half miles north of the bridge. As this sand spit has 
been built up the bare dunes have been colonised by various 
plant species and it seems likely that eventually there will 
be developed here a vegetation similar to that which is 
at present being destroyed by the sea on the stabilised 
dxTues of Stradbroke Island. For this reason it seems de- 
sirable that there should exist some short account of the 
vegetation currently occupying both areas. 
Ycgctaiion of the Southern Tip of Sfradbroke Island. 
The bay side of the island is bordered by a band of 
mangrove forest sometimes extending inland (for 100 
yards. Aviccnnia niarina (Forsk.) Vierh. var. resinifera 
(Forst.) Bakh. is the dominant s])ecies but scattered plants 
of Bruguiera ggrnnorrh iza Lam.^ Hh izophora niucronata 
Lam. and Aegiceras corniciihituni Blanco also occur. 
To the landward side of the mangrove forest is often 
developed a sword of the salt-water couch, Sporoholus 
virgiiv'cus Kunth., among Avhicli sometimes occur a fexv 
plants of Salicornia australis Soland. and Suaeda niaritima 
Dumort. The higher parts of this sward ai'e sonudimes 
invaded by dense stands of Juncus nKn’itimus Lam. and 
of Fimhristglis ferruginea Vahl. and beyond this, if the 
land rises only slightly, may be developed a forest of the 
paper-bark tea-tree, Melaleuca u.ndflora. 
Over many of the diuiesBanksia integrifolia L. is the 
most common tree but cleared areas carry a dense cover 
of blady grass, Imperafa cglindrica var. major (Nees) 
C. E. ilub. and the common bracken fern, Pteridiuni 
aquilinum (L.) Kuhn, often with other species such as 
Acacia sp. Stephania hernandiaefolia Walp., Comnielina 
eganae R.Br., Cymhopogon refractus (R.Br.) A. Camus 
