Discussion about clonal number in seed orchards

August 30

Tore (Dag's interpretation): Do we really need to care for selfing losses, very few self- trees will remain to contribute to production?

Dag: In my Swedish scenario I assumed that the production will be reduced by half the percentage of self-plants. There are scientific investigations indicating that the fraction of self- trees among mature trees is reduced to almost zero even if there are some self-plants, so my figure may be doubted, and a lower reduction used in the scenario. But if self-plants die, unproductive gaps appear in the forest, the spacing will be less than optimal, for interior northern Sweden survival is critical to get successful plantations, so even if self-plants die, production losses occur. I disregarded the economical consequences of the reduced seed set and the reduced plant yield following selfing in my model, that may be a reason not disregard the later effects of selfing also. Further on I do not want my suggestion of clone number to be based on too optimistic assumptions.  Just to get the authorities and environmental defenders to tolerate 20 in elite seed orchards instead of 30 may be considered a large step. 

Sept 04 from Seppo Ruotsalainen

"Otherwise I agree with the calculations, but according to my mind the loss

of production caused by reduction of gene diversity is estimated to be too

high. It is has been difficult to show any advantage in forestry of using more

diverse regeneration material, although such results have been obtained in


However, when I experimented a little bit with the Excel workbook, I noticed

that DivCoeff had not so dramatic effect on the clone number as I expected;

the optimum number for the Swedish scenario dropped somewhat below 10

when DivCoeff was put to 0. I suggest that you should experiment with

different values of DivCoeff to see the robustness of the situation for this



See if anyone contributes anything more. Unfortunately the experiences from FORESTGEN and my own efforts are that Forest Geneticists are dull when it comes to written discussions. But there are exceptions, like Seppo. I hope Finland nurture this plant well.