Altvatergebirge
The higher mountains of the Sudetes lie above the timber line which is made up of Norway spruce. Spruces in wind-exposed areas display features such as flag tree disposition of branches, tilted stems and elongated stem cross sections. Forest-free areas above the timber line have increased historically by deforestation yet lowering of the timber line by human activity is minimal. Areas above the timber line appear discontinuously as "islands" in the Sudetes. At Krkonoše the timber line lies at "c". 1230 m a.s.l. while to the southeast in the Hrubý Jeseník mountains it lie at "c". 1310 m a.s.l. Part of the Hrubý Jeseník mountains have been above the timber line for no less than 5000 years. Mountains rise considerably above the timber line, at most 400 m, a characteristic that sets the Sudetes apart of other "Mittelgebirge" of Central Europe.