ABSTRACT
Thepaper dealswith theproblemofavalanche forma-^{anexpanded weaklayerisanecessarycondition for}
tionandavalanche tracksinmountainforests.Espe-^{the formation of slab avalanches)].}
cially the defoliation of trees in protection forest caused^{Ourstudyfield(35kmawayfromInnsbruckinthe}
byaging,browsingorinappropiatemanagement may^{Stubai Valley) was situated in a larch stand near to the}
accelearte snow gliding and lead to potential avalanche^{timberline (about 1900m,aspect S -SW);4 different}
starting zones,too.Purpose ofthis study is to identify^{measuring positions(dense forest,opening, lowden-}
thesegliding areas and starting zonesand toshowthe^{sity forest,open field) were selected.}
effects of newavalanchetracks(extension of hazardzones^{First results showed that both the conditions for the}
...).^{formation of weak layers and increasing glide rates are}
To find out if avalanches are possible in openings and^{possible in gaps andopeningswith acriticalsize. Struc-}
low density forests it will be necessary first of all to con-^{ture of snow cover also depends on canopy density, re-}
centrate onsnowcovermeasurements[because snow^{spectively stand density.}
slab release depends on structure of snowpack (investi-^{On basis ofthe mentioned investigationspotential}
gations by Salm and Gubler showed that the existence of^{avalanche starting zones in forest stands could be lo-}
catedintherelevantaerialphotos.Newriskmaps
showingthese fracturezones and snowglidingareas
within the forests of the Stubai Valley are elaborated.