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The aim of this study was to analyse the effects of cambial age, clone and climatic factors (i.e. monthly mean temperature and monthly total precipitation) on ring width (RW) and ring density (RD) development from pith to bark in 30-years-old Norway spruce (Picea abies) grown on a fertile agricultural soil in southeastern Finland. The material consisted of 20 Finnish clones, which represented south, southwest, southeast and central Finnish origins. We analysed the variability of RW and RD among years, individual trees and clones, by fitting mixed models into tree ring series, with a spline function (used to remove the effect of ring age). The results showed that cambial age, clone and mean temperature of July affected both RW and RD. Furthermore, total precipitation of August affected RW and total precipitation of May affected RD. However, these climate variables explained only 1.9% and 3.4% of the total RW and RD variability, respectively. This may be due to the good site fertility with no lack of soil water availability, but also due to relatively short tree ring series available for data analyses. The effect of mean temperature of July on RW varied among clones, but in general, RW increased with increase in temperature. The increase of total precipitation of August increased, in general, RD regardless of the clone, whereas the effect of mean July temperature on RD was much more variable. However, longer time series are needed in the future to provide a better understanding of the interactive effects of the climate variables and genetic origins, in addition to cambial age, on RW and RD development on different sites.

• Introduction The objective of this work was to study how spacing and genetic entry and/or origin group affect radial growth (ring width and cumulative diameter development) and ring density from pith to bark in Scots pine (Pinus sylvestris L.) and in what sense their annual variability could be explained by the climatic variables. The spacing trial was located in central Finland, with current stand density range of 2,000–4,000 trees per hectare. All the six genetic entries had Kanerva pine (plus tree S1101) as a father tree, whereas the mother tree represented Finnish plus trees from southern, central and northern Finland.

In forest breeding, stem volume and sawn timber quality have typically been used as the most important selection traits. Less attention has been paid to wood density and fibre properties. This study investigates the effects of genetic entry and spacing on the growth and yield traits, branch characteristics, wood density traits and fibre properties in 20-year-old Scots pines (Pinus sylvestris L.). Additionally, the phenotypic variation within, and correlations between, different traits and the effects of cambial age, spacing, genetic entry and climatic variables on the ring width and ring density development from pith to bark are studied. Kanerva pine (Finnish plus tree S1101) was the father tree for most of the genetic entries included in this study, whereas the mother trees represented Finnish plus trees with a relatively wide geographical range from northern to southern Finland. The effects of genetic entry (mainly full-sib families) and spacing on the growth and yield traits, wood density traits and fibre properties were analysed (Papers I-II) based on materials, harvested in 2006, from 10 genetic entries grown in a spacing trial in central Finland, with a current stand density range of 2000-4000 trees/ha. Furthermore, additional material was harvested from the same trial in 2008 to study the effects of genetic entry and spacing on the branch characteristics (Paper III) and the effects of cambial age, spacing, genetic entry and climatic variables on the ring width and ring density development from pith to bark (Paper IV). In this study wood density traits show lower phenotypic variation compared to growth and yield traits, regardless of spacing. Wood density traits present from moderate to strong phenotypic correlations among them (Paper I). Spacing affects significantly (p