For practical purposes, the 700 m contour line is frequently used to differentiate
lowlands from mountains in Continental Portugal (Figure CS6). Above 700 m, the
climatophilous natural potential forests of Quercus robur, Q. pyrenaica and/or Betula
celtiberica are essentially devoid of termophilous plants, and the traditional vineyards/
olive tree/wheat Mediterranean agriculture systems are replaced by chestnut/
meadows/potato/rye mountain agriculture systems. Defined in this way, mountains
occupy 11% of the Portugal continental land surface concentrated in the northern half
of the country. With a few exceptions, Portuguese mountains are granitic or schist
peneplain stretches dissected by river erosion, pushed up in the Pleistocene, with a
temperate climate in the north-west, and a Mediterranean climate towards the south
and east.
