Using Norway spruce clones in Swedish forestry: Swedish forest conditions, tree breeding program and experiences with clones in field trials

Abstract

Conditions in Sweden for using vegetative propagation and clones for forest regeneration differ from many other parts of the world where clones are used. In this paper, we describe how Swedish forestry takes place under semi-natural conditions, which should be considered when planning for conservation of species genetic diversity. We also describe how the Swedish long-term breeding program is sustainable by combining genetic progress and gene conservation. It involves clonal replication as the standard field-test strategy. In this way, the breeding program continuously supplies a large number of tested genotypes to be used as parents for recurrent breeding, seed orchards and for vegetative propagation of nursery stock. By computer simulation, we illustrate the progress of genetic gain and diversity in reforestation material from the breeding program. Finally, we briefly refer to Swedish experiences of clones in field trials.