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endangered mountain areas. In other cases we were interested to 
study the influence of several year's tourism in such a high moun- 
tain area. 
In the case of the test field Stubnerkogel the 'change detection' 
method was of interest. The Stubnerkogel area is typical also for 
other well known high mountain skiing places in Austria. 
In the begin of the 'pre-touristic'-age skiing slopes also were 
used as greenland for cows. Winter tourism has more and more dis- 
placed the former use of those areas. Soon they were left by them- 
selves and only lift companies had to take care of them. In a step- 
wise manner such soils and their vegetation began to change their 
structure. 
o Grasland is not cut anymore and begins to grow downwards 
according to the slopes gradient. It may become a length of 
more than one meter. This is an ideal sub-surface layer for 
avalances. 
In the case of Stubnerkogel we also detected another interesting 
phenomenon which was the sudden growth of Alnus glutinosa bushes. 
Finally this study came to the conlusion as follows: 
o There ist no other tool available to measure the size of an 
effected area than by aireal photography. 
o Remote Sensing, for example using false colored film, gives de- 
tailed and quantitative informations on the variation of vege- 
tation (change detection). 
o No other mean than the ortophoto applied for change detection 
purposes can clearly show slow changes in the nature. 
o Photogrammetry gives us the tool to work calculate trends in 
the nature's development. 
o and finally to prohibit and guideline further activities of 
building and preparing new skiing slopes, fundamental know- 
ledge of ecology is necessary.