Shallow landslides triggered off by heavy rainfall are recurrent phenomena on steep slopes. It is widely recognised that vegetation, particularly forest, can stabilize steep slopes. However, there is considerable argument about to what extent trees reduce hydro-geomorphic hazards. This article discusses the effects of forest on shallow landslides on the basis of detailed landslide inventories. A total of six study areas were investigated after different rainfall events in Switzerland. Within the boundary of these areas, all shallow landslides that Occurred during the Specific rainfall events were mapped and related to the site characteristics of the Source area, Such as its geomorphology and vegetation.
Only minor differences in dimensions Were found between landslides in forest areas and those in open land. On the other hand, the field studies showed that landslide densities were lower in forested terrain than in open land. Furthermore, landslides mapped in forests occurred on steeper slopes than slides mapped in open land. The application of these results for predicting landslide occurrence is discussed.