Composition and vegetation structure in a system of coastal dunes of the “de la Plata” river, Uruguay: a comparison with Legrand’s descriptions (1959)

Abstract

Forestation in dune systems blocks the transport of sand, making possible the extension of agriculture or urban development into coastal areas. This process, which has been taking place for a century on the Uruguayan shore, has affected the landscape and the composition and structure of plant communities. In this study, we describe the composition and structure of vegetation stands of a dune system at the seaside resort “El Pinar,” Canelones, Uruguay. In addition, we compare it with a previous survey published by Legrand in Anales del Museo de Historia Natural 6:73, 1959. We recorded 76 species; with Asteraceae, Poaceae, Cyperaceae, and Apiaceae the most represented families. A cluster analysis was used to identify main groups of plant associations. This analysis defined seven groups. The group associated with the foredunes environment exhibits the lowest richness, with indicative species typical of extreme psammophilic environments. Five groups occur in interdune depressions associated with humid sites. The last group was defined in the fixed dunes environment. The species composition similarity was low in comparison with Legrand′s (1959) survey; furthermore we found a greater presence of non-native species. We associate this change with the presence of Acacia longifolia, a species with an extremely high invasive potential, considered an ecosystem transformer. Our proposal is the development of an investigation program to assess the effectiveness and challenges of potential management practices. We also suggest applying the tactic of eradication of A. longifolia on the fixed dunes, through different practices of management (e.g., manual control operations, biologic control agents, and the use of fire).