Vegetation of groundwater discharge sites in the Douro basin, central Spain

Abstract
The chemical composition of the groundwater and the distribution of phreatophytic vegetation in a relatively homogeneous aquifer in the Douro basin appear to depend primarily on groundwater flow patterns within the aquifer. The concentration of major ions in the water is correlated with flow path length, which indicates that the chemical composition of the groundwater changes with the ageing of the water. The distribution of phreatophytic plant species is closely related to both the chemical composition of groundwater discharging in seepage areas, and length of the groundwater flow path. Factors such as heterogeneity in lithology, human influences and local climate are of secondary importance.