Coastal Dune Vegetation of the Southern Pampas (Buenos Aires, Argentina) and Its Value for Conservation

MONSERRAT, A.L.; CELSI, C.E., and FONTANA, S.L., 2012. Coastal dune vegetation of the Southern Pampas (Buenos Aires, Argentina) and its value for conservation. Journal of Coastal Research, 28(1), 23-35. West Palm Beach (Florida), ISSN 0749-0208. Vegetation structure and species composition of southern Pampas coastal dunes were studied to evaluate their significance for conservation. The vegetation was described in 41 plots of 100 m(2) along four transects perpendicular to the coast. The floristic dataset was classified by two-way indicator species analysis. Vegetation distribution patterns were analysed in relation to the geomorphology and environmental factors. Fifty-one taxa (19 families) of vascular plants were recorded, with Asteraceae, Poaceae, and Fabaceae being the most abundant. The main vegetation groups obtained from the classification are related to distinctive geomorphology. (1) Upper beach and active dunes are habitats with extreme conditions, characterized by species-poor associations with low vegetation cover; group dominated by few shrubs and gramines like Panicum urvilleanum, Calycera crassifolia, and Senecio bergii. (2) Fixed/semifixed dunes are habitats with more stable substrate, characterized by dense vegetation, high species richness, and woody life forms; group dominated by Poa lanuginosa, Hyalis argentea var. latisquama, Oenothera mollissima, and Glycyrrhiza astragalina. (3) Hygrophilous communities are mostly associated with dune slacks with high herbaceous vegetation cover; group largely dominated by Cortaderia selloana, Typha sp., and Intperata brasiliensis. Detrended correspondence analysis shows that the major floristic variation follows a gradient from the beach inland. Also, there is a clear zonation pattern strongly associated with geomorphologic heterogeneity. The occurrence of threatened species (e.g., Adesmia filipes, Neosparton ephedroides) and endemic taxa (S. bergii and Baccharis divaricata) plus the high habitat diversity and plant species richness confers to the area special value for conservation. The ecological role of dune vegetation is discussed in conservation and management context.