Forests of the Iberian Peninsula blackberry bushes, blackthorn, hawthorn and other more or less thorny shrubs; this role can also be filled by smaller thorny plants, "los piornales", and clumps of broom. The major forests in this area are beech, oak, birch, and fir. Beech forests ("Fagus sylvatica") are found in the mountain layer of the Iberian Eurosiberian region from 800 to 1500 metres up. The soil is cool, as often chalky as siliceous (rich in silica), and nearly always acidified by rain. The layer is characterised by the beech tree. The beech tree projects a deep shadow, and so its dense foliage usually excludes
Fagus sylvatica in the buds. In autumn, the tree builds the reserves that will sustain it into spring. Given good conditions, a bud can produce a shoot with up to ten or more leaves. The terminal bud emits a hormonal substance in the spring that halts the development of additional buds. This tendency, though very strong at the beginning of their existence, becomes weaker in older trees. It is only after the budding that root growth of the year begins. The first roots to appear are very thin (with a diameter of less than 0.5 mm). Later, after a wave of above