Deciduous and semi-deciduous oak forests (Quercus robur, Q-petraea and Q-pyrenaica) floristic composition in the Northwest Iberian Peninsula

Oak forests in the Northwest Iberian Peninsula represent climax communities with a high floristic diversity of vascular plants. This study presents data from 189 botanical samples randomly collected in stands of deciduous and semi-deciduous oak as Quercus robur (98), Q. petraea (50) and Q. pyrenaica (41). Within these stands, 187 species or subspecies were identified, in addition to 20 genera and 68 families, all of them present in forests of Quercus robur. A total of 126 species occur in more than five releves. The largest number of species corresponds to Poaceae (22), Fabaceae (19) and Rosaceae (14). The biological spectrum is dominated by hemicryptophytes, with mainly Atlantic and Sub-Atlantic floristic elements. The distribution of the stands has been studied by using Two-Way Indicator Species Analysis, obtaining like pseudo-species, with shrubby and arborea form, the following ones: Fagus sylvatica, Castanea sativa, Sorbus aucuparia, Corylus avellana, Crataegus monogyna, Pyrus cordata, Erica arborea, Frangula alnus and Cytisus scoparius.