MATING SYSTEM ESTIMATES AND EFFECTIVE POPULATION NUMBERS FOR AN ISOLATED NOBLE FIR (ABIES PROCERA) CLONAL SEED ORCHARD IN DENMARK

The mating system of a seed orchard of noble fir (Abies procera Rehd.) in Denmark was analyzed, with variation being found at two unlinked i sozyme loci. Comparison of allele frequencies in the pollen pool ferti lizing the upper and the lower parts of the trees showed a homogeneous distribution. There was no difference in the outcrossing rates estima ted for cones harvested at the top and the lowermost branches carrying cones. Both were slightly greater than 1, as was the combined estimat e that did not differ significantly from 1. The clones present in the seed orchard are outcrossing, and the allele frequencies found in the pollen pool agree with the frequencies found in the clones of the seed orchard on average. However, the allele frequencies varied significan tly between the 20 families, suggesting that the pollen pool has been variable within the seed orchard. The inbreeding and variance effectiv e population numbers were estimated by assuming that the differences i n flowering reflected variation in gamete contribution from the clones to the offspring. The inbreeding effective population number was foun d to be 65% of the total number of clones. The variance effective popu lation number was 121% of the number of clones when it was assumed tha t a large number of offspring were harvested from every clone.