The ecological value of a gypsum wetland: soil geochemical and biological indicators

Abstract This article investigates Salada Farrachuela, a saline wetland situated on outcrops of the Barbastro Gypsum Formation, NE Spain, in an inland area with protected species and habitats of the Natura 2000 European network. Farrachuela is an uncultivated and intermittently flooded wetland harboring organisms adapted to high salinity. However, it is not mentioned in the official description of the Natura 2000 ES2410074 site and is not considered for conservation. The soil of salada Farrachuela differs from both the surrounding soils and the comparable saladas of Monegros, located 60 km south, in terms of gypsum content, electrical conductivity, and the proportion of major ions. The sedimentary functioning of Farrachuela and its gypseous character are illustrated here by a thin section of the soil that also shows valves of Ostracods and other organic residues; moreover, plants and specimens of Heterocypris barbara (Gauthier and Brehm 1928) grew in a lab culture of mud. The salinity and halophilous vegetation differ strongly from the surrounding non-saline gypseous land. The salient features of Farrachuela described here highlight its ecological value. Hopefully, the approach and data presented in this article will serve as a reference for future studies and comparisons with other gypseous wetlands in the world, which are often neglected and lacking appropriate methods.