The Pontic mountain range along the north Anatolian coast is a more or less continuous barrier against humid air from the Black Sea, causing high precipitation on the northern slopes of the Pontus all year. Climatic conditions on the northern coast therefore resemble those in central Europe and so does the vegetation. A limited Mediterranean influence is noticeable only on a very narrow coastal strip, but almost completely missing in the north-east. In the lower forest zone often Hornbeam (Carpinus betulus) prevails, frequently intermingled with Sweet Chestnut (Castanea sativa). Further up Oriental Beech (Fagus orientalis) and/or Nordmann Fir (Abies nordmanniana) form extensive forests. Humidity becomes extremely high in Lazistan, where the Pontic barrier culminates in the nearly 4000 m high Kaçkar Mountains. East of Trabzon therefore vegetation becomes somewhat sub-tropic, with a lot of evergreens in the forest and tea plantations everywhere on the slopes.