Aquatic plant distribution is driven by physical and chemical variables and hydroperiod in a mediterranean temporary pond network.

The aim of this study was to assess aquatic plant distribution patterns in a Mediterranean temporary pond network (Doñana National Park, SW Spain). We analyzed differences in species composition employing multivariate ordination techniques; we specifically examined the importance of hydroperiod and physical and chemical variables in the five geomorphological areas across which the pond network is spread. The ponds significantly segregated along a north-south gradient, matching the segregation pattern of the aquatic plant assemblages. Ponds in the three northernmost areas showed higher levels of species richness than ponds in the two southernmost areas. In the north, ponds were present at higher densities, spanned a broader hydroperiod range, and had lower conductivity levels; these features were associated with the presence of wet-meadow species and larger numbers of submerged and emergent species. In the south, alkaline waters were mainly associated with different charophyte species, and the predominance of long-hydroperiod ponds helped in increasing the number of floating species. Managed ponds, which had been artificially deepened, contributed to increase pond heterogeneity and hydroperiod breadth across the entire network. At present, such ponds are key to the preservation of Doñana's rich and unique aquatic plant community. [ABSTRACT FROM AUTHOR]