Seed production in Scots pine seed orchards Finnvid

Seed production in Scots pine seed orchards Finnvid Prescher, Dag Lindgren, Ulfstand Wennström, Curt Almqvist, Seppo Ruotsalainen and Johan Kroon. Syktyvkar 14 september 2005 Prescher et al. 1

Seed set in nature Typical pine stands Location Seeds/m 2 Northern Finland Middle Finland South Finland 50 100 150 Prescher et al. 2

How do we get more seeds? • • Some years after thinning High site class Annual variations Five years after releasing seed trees it may be >200 seeds/m 2 (Karlsson 2000) Prescher et al. 3

Seed orchards versus stand • • • Considerable heavier seeds Heavier cones Not more seeds per cone Less fluctuations among years Probably stands on similar sites and management intensity would produce similar amount of seeds Prescher et al. 4

Seed orchards versus stand, cont’d • Frequent reports about seed orchard harvests • Harvest statistics may not reflect biological production, in particular in old seed orchards • Little actual biological production statistics from Swedish seed orchards Prescher et al. 5

Pine seed orchard Askerud Klocke Lustnäset Latitude 60 60 62 60 Age 34 24 20 23(two years) Grafts/ha 335 350 278 Seeds/m 2 71 70 129 179 Prescher et al. 6

Mature seed orchards • It is more difficult to harvest all cones the older the orchard becomes • Harvest statistics often drops by age, is this reflected in a biological seed drop? • 2004 were all seeds in three grafts per clone of 12 clones harvested in two mature seed orchards, which never have been thinned nor pruned recently. Prescher et al. 7

Skaholma 2005 Prescher et al. 8

Pine seed orchard Skaholma Långtora Latitude 64 60 Age at harvest (oldest grafts) Age (typical graft) 46 42 40 41 Grafts/ha 130 156 Seeds/m 2 231 349 Adjusted by annual cone set statistic in stands in area 153 349 Prescher et al. 9

Conclusion • Seed production can be quite good in old seed orchards, no sign of decrease when orchard get old! Prescher et al. 10

Sävar • The experimental seed orchard at Sävar has 16 large seed orchard plots, all with different treatment (thus no real replications). It is thus unreliable to separate an individual factor like spacing, many factors are confounded. Prescher et al. 11

Experimental seed orchard Sävar Latitude 64 Age 29 Grafts/ha 125 269 525 Seeds/m 2 255 321 323 Adjusted by annual cone set statistic in stands in area 152 191 192 Prescher et al. 12

Conclusion Dense spacing of grafts does not seem to promote cone production beyond 30 years, however this is very scarce and difficult to interpret data. Prescher et al. 13

Cone observed from ground • A rough cone count from ground with unaided eye in mature seed orchards revealed <10% of the cones. Thus estimating cone set in seed orchards require more accurate instructions. Prescher et al. 14

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Variation in female contributions Coefficient of variation among ramets for different seed orchards Seed orchard Långtora Skaholma Filled seeds 0. 682 0. 845 Weight of filled seeds Volume of cones Number of cones Cones observed from ground Seed weight 0. 753 0. 707 0. 686 0. 577 0. 153 0. 800 0. 852 0. 877 0. 721 0. 120 Note that the CV are similar for all fertility characters, thus variation in female reproductive output can be reasonable estimated in any way. The variation in seed weight among ramets in a seed orchard crop is limited. Prescher et al. 16

Thank You! Prescher et al. 17