VIABILITY AND SEASONAL DISTRIBUTION PATTERNS OF SCOTS PINE POLLEN IN FINLAND

Germination ability and airborne counts of Scots pine (Pinus sylvestri s L.) pollen were studied during the spring of 1993 at Turku in southe rn Finland (60 degrees 32' N, 22 degrees 28' E) and at Utsjoki in nort hern Finland (69 degrees 45' N, 27 degrees 01' E). Pollen was trapped from the beginning of May to the end of June in a high-volume air samp ler. Germination tests were performed to determine the in vitro pollen viability of the trapped pollen. Airborne pine pollen counts were obt ained from a continuously operating Burkard trap located near each hig h-volume sampler. When male flowering began, phenological observations were carried out on pollen grains collected in rotored samplers locat ed in pine and spruce stands and open fields near Turku and Utsjoki. I n southern Finland, the peak period of pine pollen production was shor t, lasting for only 3 days, but it accounted for about 80% of the tota l germinating pine pollen yield for the year. The peak count was on Ma y 20, with over 2000 germinating pollen grains per cubic meter of air. Pollen germination rates of up to 70% were obtained during the week p receding the local pollen peak, and rates reached almost 90% on the pe ak day. Pollen viability remained at 45 to 65% for I week after the pe ak. There was no significant difference between the pollen counts for day and night, indicating that during the main pollen season, the poll en source was close to Turku. Before the local pollen peak, the counts of living pine pollen were low, indicating that pine pollen transport ed over long distances was of little ecological importance in 1993 in the Turku area. In northern Finland, the first pollen grains were caug ht on July 4, and the peak day was July 13. However, no viable pollen was observed during this period, indicating that there was little gene drift from southern to northern Finland in 1993.