Patterns of floristic composition of Mediterranean meadows and mesophytic grasslands in eastern Continental Portugal

Abstract

It is becoming increasingly necessary to gain a deeper understanding of the ecological gradients underlying the floristic pattern of meadows and grasslands, because their distribution area and dynamics may be affected by the increased dryness resulting from climate change. Thus, the objectives are (1) to identify community types in Molinio–Arrhenatheretea meadows and Stipo giganteae–Agrostietea castellanae grasslands in Eastern Continental Portugal; (2) to recognize those communities that configure habitat types of the European Union Habitats Directive; (3) to establish environmental gradients underlying their spatial variation. Combining the Braun–Blanquet approach with numerical analysis, 292 relevés and 448 species were classified and ordered using two-way indicator species analysis (Twinspan classification) and canonical correspondence analysis (CCA). Partial CCA was applied to assess the relative influence of land use factors. About 17 community types were identified and those floristic patterns were mainly related to environmental gradients linked to pedological factors and humidity gradients. Based on biogeography and the determination of diagnostic species, four new phytosociological associations were proposed: Mentho pulegii–Cyperetum badii ass. nova hoc loco; Trifolio resupinati–Menthetum suaveolentis ass. nova hoc loco; Mentho suaveolentis–Holcetum lanati ass. nova hoc loco and Festuco amplae–Brachypodietum phoenicoidis ass. nova hoc loco.