Soil-Plant Relationships in Mediterranean Salt Marshes across Dune-Cultivated Land Gradient.

The relationships between soil factors and plant species were investigated in salt marshes on the west coast of central Italy along a dune-cultivated land gradient with similar topographic elevations. Plant community composition was quantified in three zones (marsh-dune border, central marsh, and marsh-cultivated land border) identified across the gradient. The results suggest that the distribution and variation in abundance "performance" of plant species is mainly ruled by salinity and soil texture gradients (from sandy to silt-clay). Texture seemed to affect vegetation zonation in the marshes near sand dunes, since at the marsh-dune border the percentage of wind-blown sand increases. Variations in field capacity, total organic carbon, pH, and calcium carbonate did not appear to control the performance of plant species. Indications on the performance of six species are provided. Limbarda crithmoides increased with the amount of sand and was often located at the marsh-dune border. Elymus repens and Phragmites australis increased with decreasing salinity and were frequently found at marsh borders, however E. repens also increased with the amount of silt-clay. Sarcocornia fruticosa increased with salinity and silt-clay, while Halimione portulacoides increased with salinity and seemed less subject to changes in soil texture. Elymus pycnanthus increased with salinity and decreased with the amount of silt-clay, however, the ordination suggested that other factors may be determinant for this species. These species could be useful to map saline environments and to reconstruct an appropriate scenario in restoration projects of Mediterranean salt marshes.