The water courses of southern Portugal are ecosystems subject to constant fluctuations between periods of flooding and desiccation associated with
seasonal dryness. In these unstable ecological conditions, a considerable diversity of riparian plant communities occurs. The objective of this study,
carried out in the Monchique Sierran and Andévalo Districts, is to compare the perennial grasslands community dominated by Festuca ampla Hack, using a phytosociological approach (Braun-Blanquet methodology) and numerical analysis (hierarchical cluster analysis and ordination). From these results, a new hygrophilous community of perennial grasslands type was identified, Narcisso jonquillae-Festucetum amplae, as a result of the floristic, ecological and biogeographical differences from other associations already described within the Agrostion castellanae alliance, in the
southwestern Iberian Peninsula. The association occurs in the thermomediterranean to mesomediterranean belts under dry to sub-humid ombrotypes,
on siliceous soils that have temporary waterlogging. This new association corresponds with priority 6220 Habitat - Pseudo-steppe with grasses and annuals of the Thero-Brachypodietea, under the Natura 2000 code
