Three isolated massifs in the Sudetes, Central Europe, are elevated sufficiently high to allow for the development of the treeline ecotone. These are the Karkonosze/Krkonoše in the West Sudetes and Hruby Jeseník and Masyw Śnieżnika/Králický Sněžnik in the East Sudetes. The upper limit of closed tree stands (i.e. timberline) is locatedat c. 1250 m a.s.l. on average in the Krkonoše, but with significant variability spanning more than 500 m. In the East Sudetes the respective elevation is higher, above 1300 m a.s.l., and the variability is smaller. While temperature is the primary factor governing the uppermost tree stands, second-order climatic factors play an important role in shaping treeline ecotone position, particularly wind and snow accumulation patterns. Active surface processes such as debris flows and snow avalanches force the timberline to descend and account for its locally very irregular course. There is a history of long-term human impact on the position of the timberline, with its peak in the 17-19th centuries when high-mountain meadows were extensively used for grazing and haymaking. In the last century the overall trend of timberline ascent associated with abandonment of agricultural land and temperature rise has been interrupted by the episode of catastrophic forest decline due to air pollution.
Vaclav Treml, Department of Physical Geography and Geoecology Charles University in Prague Albertov 6, CZ-128 43 Prague: Czech Republic
Piotr Migoń [email@example.com], Institute of Geography and Regional Development University of Wrocław pl. Uniwersytecki 1, 50-137 Wrocław: Poland