sentences:  The mountain layer is characterised by the presence of beeches and at times, in the Pyrenees, by silver firs ("Abies alba"); these beeches and silver firs occupy the cool slopes with shallow soil.The Mediterranean influence is felt in the presence of Holm oaks ("Quercus ilex") with bay laurel, which are situated on the warmest crests and slopes, especially above chalky soil, where the dryness becomes more pronounced.Improvement by humans has transformed much of this woodland into meadows, which conserve at their edges remnant hedgerows, "setos", of the species of the primitive forest.