Diversity-oriented silviculture in the Boreal Zone of Europe

This article presents the concepts and models of diversity-oriented silviculture in the Boreal Zone of Europe based on literature, Finnish national forest inventories and field experiment data. The basic idea following the natural processes of forest ecosystems in silvicultural practices has been known since the last century but appropriate comparison materials for modelling have been scanty previously. Stand structure classification used in this study is based on the range and shape of stem distribution. The two main groups are even-sized and uneven-sized. A subclass of the latter, regularly all-sized, with dbh distribution resembling a reversed J, forms the primary basis for treatment models. This kind of structure, following the development and dynamics of natural mixed stands, fulfils the requirements for biodiversity according to international resolutions. Single tree selection and group selection are primarily the main treatments and seed tree and shelterwood cuttings are secondary treatments in diversity-oriented silviculture. In addition, regimes aiming to diversify even-sized stands in different development stages are discussed.