The crowns of spruces, firs, and beeches in selection forests and evenaged regularly managed stands in the Swiss Mittelland, the Pre-Alps, the Jura and the Alps were assessed, and the trees subsequently observed over several years in terms of survival or mortality. The mortality rate was found to be statistically significant in relation to crown transparency. There was no correlation indicating additional effects of other parameters estimated, i.e. site conditions, stand conditions, or features of individual trees. Spruce and firs blown by the winter storms of 1990 displayed a significantly greater needle loss than those which survived. Mortality rates due to storm damage were already considerably greater in trees with 10 percent needle loss than in those with 0 percent needle loss. The close statistical relationships between crown transparency, mortality rates in the absence of extreme storms, and storm hazard show the great significance of leaf or needle loss for the survival or death of trees, especially for fir and spruce.