On limy soils something similar takes place, above all at altitudes of over 900 metres, oaks are accompanied by Spanish juniper ("Juniperus thurifera") and the scarcity of shrubs is such that the same Holm oak ("Q. ilex" subsp. "rotundifolia" or "ballota") dominates almost entirely on its own the first phases of deterioration of the forest. The degradation caused by burning or felling leads to thickets of Scorpion's thorn ("Genista scorpius"), thyme and common lavender ("Lavandula angustifolia"). Cork oak forests occupy around 10,000 square kilometres on the peninsula, more than half of the world's extension of this kind of forest. The cork oak forest needs siliceous soils of a sandy texture, and a mild, slightly damp climate. Under such conditions it totally or partially displaces the Holm oak; Holm oak may be found in stands of Cork Oak with a certain frequency, as well as Portuguese oaks ("Quercus faginea" subsp "broteroi"). The area occupied by oak forests corresponds above all to the southwest quadrant of the peninsula, but also to Catalonia, Menorca and even the non-coastal valleys of Galicia. They often alternate with the oaks, which occupy the drier slopes and with the "quejigares" of Algerian oak ("Quercus canariensis"), that occupy the ravines and cool, shady northward slopes. The cork oak forests often contain wild olives, and like some of the cool groves, are often accompanied by strawberry trees ("Arbutus unedo") with mock privet ("Phillyrea angustifolia") which grow in the clearings of these forests and dominate their regressive phases. In western Andalusia, other common components of the ecosystem are the areas of common broom, genus "Teline". The term "quejigar" refers to forests of many different characteristics. Forests of Algerian oaks ("Quercus canariensis") are well represented in western Andalusia and very patchily by hybridizations in Catalonia and the Cordillera Mariánica. They are the most demanding as to temperature and humidity, and therefore do not usually stray too far from areas with a maritime climate; they prefer the cooler, shady northward slopes, damp meadows and the banks of streams of the lower ground. In general, they alternate with the Cork Oaks, which they displace in the coolest zones; both prefer siliceous soils.