Changes of the avalanche cadastre in the Czech part of the Giant Mts.

Abstract

Giant Mts. are the highest and the only mountain range of the Czech Republic which features considerable avalanche activity. There are at average 22 avalanches events on 47 avalanche paths in a year. Human colonisation and subsequent exploitation during the 16th and 17th centuries led to the growth of treeless area which resulted in an increase of avalanche paths. Reforestation in the course of the 18th to 20th centuries has decreased the risk of spread of avalanches. Since 1980 the Giant Mts. have been strongly afflicted with emissions. Norway spruce monocultures have started to die off, the avalanche cadastre has risen again. Partial analyses reveals that the intensive avalanche activity has been (even in the past) bounded to extraordinary climate conditions and thus the growth of the avalanche cadastre can not be related exclusively to the decline of protective function of the forest. Natural development of mountain slopes should not be omitted as this process includes both snow avalanches and debris.