Protective Forests and Silvicultural Stability

Protection is of vital importance to human populations and activities in the European Alps. In the short to medium term, failure to manage alpine protective forests leads to intolerable risks for people who live and make a living in alpine valleys. The most important features of a protective forest are its stability properties, that is, its ability to carry out its protective function reliably and continuously and, if this is achieved, its ability to maintain its structure and vitality in the face of internal and external influences. Since maintaining and improving stability properties is costly and labor intensive, the objective of interventions should be an acceptable—rather than an ideal—degree of stability in order to ensure the functions required of the protective forest over a 20–50 year period. Such interventions are collectively referred to as minimal tending. A case study of the Ban de Ville forest in Courmayeur (Aosta Valley, Italy) illustrates aspects of silvicultural planning. Only one third of the Ban de Ville forest was found to be acceptably stable. The main causes of instability were unsuitable species composition, simplified vertical structure and cover, presence of Ips typographus and Heterobasidion annosum, and presence of high densities of wild ungulates. Measures to improve stability properties aimed to increase the presence of larch among a homogenous stand of Norway spruce and gradually establish a multilayered, small group structure.