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In recent decades, in forest breeding programmes in Finland, growth has been used as a selection trait of primary importance in Norway spruce (Picea abies (L.) Karst.), whereas wood properties have been taken as secondary traits. However, interest in considering wood density and fibre traits in different genetic entries for future regeneration material has increased recently. In this context, this study aimed to analyse how genetic entry and spacing affected the growth, yield, wood density traits and fibre properties in Norway spruce (Papers I-V). Moreover, phenotypic correlations between different traits were analysed. In addition, effects of competition by neighbours on different traits were studied based on a competition index (Paper V). The harvested materials included both normal and narrow crowned (Picea abies f. pendula) genetic entries. The age of sample trees ranged between 28-30 years for normal crowned clones, representing different origins (Papers I, II, V), and between 14-19 for narrow crowned genetic entries (Papers III-IV). All the materials were harvested from four trials located in Southern Finland on agricultural and medium/fertile forest soils, with spacing ranging from 1 m x 1 m to 2 m x 2.5 m. Wood density traits and fibre properties showed, in general, lower phenotypic variations than the growth and yield traits (Papers I-V). In addition, the phenotypic variations between narrow and normal crowned genetic entries differed when grown in different spacing (Papers III-IV). Between individual clones of normal crowned Norway spruce (Imatra and Kangasniemi trials), differences were found in most of the studied traits, unlike between origins (Papers I-II and V). Moreover, growth and yield traits of narrow crowned genetic entries were less sensitive to spacing than the normal crowned ones and thus, more productive with narrow spacing (Loppi trial), while in wider spacing (Karkkila trial) the result was opposite (Papers III-IV). On average, the phenotypic correlations between growth and wood density traits were in general negative, and from moderate to strong. However, individual genetic entries with weak or no correlation could still be found. Moreover, all the phenotypic correlations among the wood density traits and among the fibre properties were positive (p<0.05), and moderate to strong, indicating that selection for one trait simultaneously affects the others (Papers I-V). On average, the diameter of trees decreased and wood density increased with increasing competition, which explained part of the variation observed among the clones for growth and yield traits (Paper V). As a conclusion, selection for wood density alone reduces in general stem volume and stem mass, whereas selection for fibre properties alone reduces wood density. However, opposite to general trend, for example, clone C43 in normal crowned Norway spruce had in this study simultaneously high stem volume, relatively high wood density and long fibres, for example. The marked differences observed among different genetic entries, as well as lack of clear differences among the origins also revealed that ranking regarding different traits should be based on individual clones (or families) rather than origin/provenances.

Effects of genetic entry and spacing on growth and wood properties in Norway spruce