ESTIMATION OF FAGUS-SYLVATICA L MATING SYSTEM PARAMETERS IN NATURAL-POPULATIONS

The mating system of beech (Fagus sylvatica L) was investigated using polymorphism at 4 allozyme loci and the multilocus model of Ritland an d Jain (1981). Beech appears to be a highly outcrossing species: the o utcrossing rate ranges from 0.94 to 1. No significant differences were found in outcrossing rates according to environmental factors or amon g or within trees. Comparison of single-locus and multilocus estimates indicated that little or no inbreeding occurred. Outcross pollen pool was not homogeneous and heterogeneity in pollen allelic frequencies w as observed even among nearby trees. A possible explanation may be the temporal variability of the pollen pool due to variation in flowering time and to matings between phenologically synchronous trees.