sentences:  When these forests degrade, they are taken over by thorny plants, "piornales," and in the final extreme heather and gorse.The pedunculate oak would have been indigenous to a large part of the area currently occupied by pine forests and eucalyptus.Along the Atlantic coast, birches ("Betula" species) form small enclaves or copses at the foot of rocky cliff edges or in the clearings of beech forests, on poor or acidic soils, accompanied by aspen ("Populus tremula") and mountain ash ("Sorbus aucuparia").