Although selection forests have clear advantages over age-group forests in view of their total growth performance, their net product and their stability, not to mention the sustainability of their beneficial effect, the proportion of this type of forest is insignificantly small in Germany and also in mixed forest in the mountains. It is therefore all the more surprising that scarcely any discernable efforts have been made to increase the proportion of selection forests. For a conversion, an alternative model for the treatment of the stands is adopted, whereby it is no longer the encouragement of the growth to maturity of individual trees in the stand which is aimed for, but rather the transformation of the whole stand to a selection forest using available stand elements and elements created by an early initiation of regeneration.
Based on his experience in the forestry district of Kirchzarten in the Black Forest, Germany, the author describes the procedure for a successful conversion. This is to be started as soon as possible, that is to say when the crown height of the trees is about 18 metres and with corresponding usable dimensions, using small group shelter-wood cuts, a so-called initial femel cut. To get the conversion started it is advisable to remove whole groups of predominantly badly situated and overgrown trees. The stand will be additionally structured later through further interventions at short intervals. In the process, here and there really well situated trees will actually be left to stand solitar y, in other places w hol e self-cont aine d groups will b e created and else where valuabl e mixed s tand elements will be selected for permanent preservation, this in order to create a situation in which there are about 35 overstorey trees per hectare. On the basis of his own cost calculations, the author comes to the conclusion that the conversion is, from a financial point of view, superior compared with the age-group forest in that it brings higher proceeds more quickly and more often.
Parametric estimation of supplier's plant construction costs
