Genetic parameter estimates of growth and survival of Pinus sylvestris with mixed model multiple-trait restricted maximum likelihood analysis

To improve adaptation and production of forest trees in areas with a harsh climate, it is important to consider survival ability in addition to growth traits. For breeding decisions, parameters such as heritabilities and genetic correlations between such traits need to be estimated. Multitrait, restricted maximum likelihood (REML) estimation was used in a full-sib Scots pine (Pinus sylvestris L.) progeny trial in northern Sweden to utilize all available information regarding survival and growth on the individual tree level and to avoid bias due to selection caused by mortality. The trial was evaluated at the ages of 6, 11 15 and 27 yrs, including estimation of age-age genetic correlations, which were high. During the period, the mortality reached 36%, the heritability of survival increased from 0.02 to 0.05, and heritability of tree height varied between 0.06 and 0.13. The genetic correlation estimates between survival and height were all positive and varied between 0.03 and 0.65. Univariate estimation, considering only growth and ignoring survival, resulted in much higher heritabilities of tree height. This should be an effect due to the mortality and thus a bias caused by selection.