Forests can provide protective functions against the impacts of natural hazards such as debris flows, debris floods, floods, rock falls, and snow avalanches (hydrogeomorphic processes). Where this function is recognized, forests can be set aside as reserves. Unmanaged reserves may provide adequate protection for a period of time. However, it is common for natural disturbances and succession to reduce the protective value of the forest over time. To maintain optimum protection, consideration should be given to managing these forests. This is called Protection Forestry. This volume presents a series of papers on how forests provide protection from hydrogeomorphic processes, how they can be managed to maintain protective roles, and the implications of the lack of forest management. The objective in presenting these papers is to kindle worldwide recognition that forests can play a significant role, if managed appropriately, in the reduction of impacts from hydrogeomorphic processes.