203 



dunes about itself, which, as the original bush dies away, 

 become colonized by Oltaria axillaris and Frankeniu 

 pa uci flora. 



Several patches, some up to half an acre in extent, were 

 strewn with the dead stems of Lavatera pleheja. Professor 

 Wood Jones says he saw thickets of this plant when he landed 

 on the island in December, 1920. One place indicated by 

 him as a locality in which Lavatera was specially dense is now 

 an area of shifting sand (pi. xi., fig. 2). It is believed that 

 the growth of the mallow was largely responsible for this. On 

 sand the plant is mainly biennial, and by its dense growth 

 would tend to kill out the ground vegetation below it . When 

 the Lavatera dies there is nothing left to hold the soil, and, 

 as a result, the sand drifts. 



Summary. 



Plant Succession. — The general trend of succession can 

 only be briefly suggested. The Rhagodia crassi folia shrub- 

 land is the most stable community, and probably represents 

 the climax on the island. It is not unlikely that this associa- 

 tion is really a subclimax, climatic factors limiting the suc- 

 cession, which, to judge from the mainland nearby, one would 

 expect to reach a scrub woodland composed of mallees 

 (Eucalyptus spp.) and Melaleuca parviflora. Though the 

 Rhagodia crassifolia shrubland is regarded as a climax, no sign 

 w^as seen of its spread or regeneration, rather the reverse. 

 Biotic factors, notably the burrowing of birds, operating with 

 the wind factor, disturb the area and tend to the development 

 of drifting sand. Ultimately, if the present set of factors 

 remain unchanged, the whole of the consolidated sands will be 

 removed and the bare granite platform be left. The last 

 stage of the Franklin Islands will be a wave-swept reef similar 

 to that lying immediately south. This is clearly shown by the 

 intermediate phase illustrated on the eastern islet before- 

 mentioned (pi. viii., fig. 1). 



If there be little sign of regeneration of the climax there 

 are earlier stages in succession to be seen. The clearest is the 

 passage from the Frankenia frutici/losa association through 

 a mixed low shrub and grassland with Frankenia pauci flora 

 and Danthonia penicUlata to a mixed open shrubland of 

 Nitraria, Olearia axillaris, Enchylaena, Threlkeldia, etc., with 

 Stipa teretifolia and various annuals. This association is un- 

 stable. The action of birds and wind depresses the succession 

 to the Stipa, Salsola, Lepidium community described. This 

 unstable association is apparently gradually coming to occupy 

 most of the island. The most important sand stabilizer at pre- 

 sent is Nitraria Schoeheri, which, owing to its dune-forming 



