Water table dynamics of dune slacks in an arid zone

Abstract

In this study, a characterisation is undertaken of the humid dune slacks water table situated in the arid transgressive coastal dune field of the Maspalomas Special Area of Conservation, ES701007 (Gran Canaria, Canary Islands, Spain). Humid dune slacks are listed as a European Union Habitat (EU Habitat 2190 humid dune slacks) in Annex I of the EU Habitats Directive. This water table is relatively stable throughout the year, with a 41 cm maximum oscillation. The annual dynamics of the flow pattern and water table level depend on the climate conditions. At the end of the hydrological dry season the mean water table drops (ca. 11 cm) and water flows to the lagoon. After rains, the mean water table level rises (ca. 4 cm) and flows towards the Maspalomas beach. The distribution of plant communities (associated to EU Habitat 2190) in the Maspalomas humid dune slacks depends on water table depth, pH and salinity. The knowledge acquired in this study of the water table dynamics has enabled a better understanding of the spatial distribution patterns of the vegetation of these slacks, in particular with respect to the relationship between the water table flux toward the coast during the dry season and the distribution of plant communities in the slacks closest to the coast. The study of the dynamics of the water table of the slacks and the associated vegetation has allowed us to better understand the characteristics of the Maspalomas humid dune slacks and potentially improve their management as EU Habitat. This is especially significant considering that the only European arid climate dune field where this habitat can be found is in Maspalomas.