Converting Norway spruce stands with beech - a review of arguments and techniques

Abstract

After 25 years of introducing beech into pure Norway spruce forests some foresters, economists, but also forest scientists are concerned about the increasing proportion of beech. We therefore reviewed the existing literature on the ecological and economic consequences of an enrichment of Norway spruce stands by beech. From this review it can be concluded that, though generalisations are difficult, beech improves soil properties, biodiversity, and productivity of pure spruce forests in many cases. Moreover, recent financial considerations revealed new and tangible arguments for the replacement of pure stands of Norway spruce by mixtures of Norway spruce and beech. In addition, introducing beech or other broad leaved species into Norway spruce stands is strongly recommended because of the high vulnerability of the latter species against climate change. In the second section of the paper we refer to silvicultural strategies for the conversion of Norway spruce stands and discuss the relevant techniques, planting and direct seeding. Factors which may affect the success of planting and direct seeding of beech are summarised. We conclude that converting pure spruce stands into mixed ones by the introduction of broadleaved tree species such as beech is still a sound option and that there are cost effective methods to realize this. However, the decision in favour of a substantial percentage of beech should not be hampered by the demand of conservationists to ban forestry from beech forests by arguing that these forests represent the natural vegetation type in Central Europe.