Open Access

Ilma M. Brewer, Robert J. Whelan

• Sand mining has been responsible for much of the degradation of the indigenous flora of sand dunes in New South Wales, to the extent that authentic foredune plant communities are now uncommon in much of NSW and southern Queensland. Dune heaths are very susceptible to invasion and infestation by the weed, bitou bush (Chrysanthemoides monilifera subsp. rotunda). This paper compares the floristic composition of dunes in 1941 (before sand mining) and 1997 & 1999 (after sand mining and invasion by bitou bush), at Bennetts Beach, Hawks Nest, on the lower north coast of NSW. The 1941 data provide a unique example of authentic foredune vegetation and is the first quantitative analysis of coastal dune vegetation in NSW. In 1941, 25 native species were recorded in the 0.5 ha site. Nine of these were considered to be characteristic of dune communities and eight of these nine were also recorded in a 1939 survey at Myall Lakes. Four other studies in the intervening 60 years contain species lists of dune vegetation in this general area (1986, 1995, 1997 and 1999). Of a total of 17 species considered to be strongly associated with dune habitats, five were reported in all of six surveys and 15 occurred in one or more of the more recent surveys (1986 and later); the two exceptions were Austrofestuca littoralis and Senecio spathulatus. Only one introduced weed was recorded in 1941 (Cakile edentula) and the only weeds recorded in 1939 were Cakile edentula and Oxalis corniculata, both cosmopolitan species. Thirteen additional weed species, the most abundant being Chrysanthemoides monilifera, were recorded in the more recent surveys. A set of 14 native species that are more typical of heath and eucalypt forest and woodland communities than of the dunes were absent in the 1939 and 1941 surveys but occurred in one or more of the post-mining surveys of 1995, 1997 and 1999. Detailed plant distribution and abundance were assessed in the same part of Bennetts Beach in 1941, 1997 and 1999. All show some patterns of zonation across the sand dune. However, clear phytosociological patterns of the dominant species that were obvious in 1941 were lacking in the 1997 and 1999 analyses. These contrasts suggest that post-mining revegetation has resulted in weed invasion, addition of native species from other communities, and a disruption of the distributions of typical dune species of species across the sand dunes that has been only partially recovered since sand mining and invasion of bitou bush.