Maintaining the ecological integrity of forests is fundamental in the European forest tradition; thus managers invest much time and energy to successfully regenerate their stands. Depending on the assigned objectives different methods are applied. The most important cultural operation is thinning. Silviculture is an activity of low intensity, in particular as it requires only small amounts of chemical input. Nevertheless the forested landscapes we have in mind are highly artificial. This apparent paradox is first and foremost due to the very long-term dynamics of forests. Because of this characteristic time aspect it is important for foresters to predict the evolution of stands, especially by methods simulating the birth, growth and death of trees. The mortality process can either be natural or occur accidentally, as a consequence of diseases, tornadoes, windbreakage, or simply as a result of the competition among trees for light or soil resources in the very hierarchic society represented by the forest