Seed production in Scots pine seed orchards

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Seed production in Scots pine seed orchards

• Finnvid Prescher, Dag Lindgren, Ulfstand
  Wennström, Curt Almqvist, Seppo Ruotsalainen and
  Johan Kroon.
• Syktyvkar 14 september 2005

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Seed set in nature
Typical pine stands Typical pine stands
Location Seeds/m2
Northern Finland 50
Middle Finland 100
South Finland 150
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How do we get more seeds?

• Some years after thinning
• High site class
• Annual variations
• Five years after releasing seed trees it may be
  gt200 seeds/m2 (Karlsson 2000)

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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

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Seed orchards versus stand, contd

• 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

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Pine seed orchard Pine seed orchard Pine seed orchard Pine seed orchard
Askerud Askerud Klocke Lustnäset
Latitude 60 60 62 60
Age 34 24 20 23(two years)
Grafts/ha 335 350 270 278
Seeds/m2 71 70 129 179
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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.

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Skaholma 2005
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Pine seed orchard Pine seed orchard
Skaholma Långtora
Latitude 64 60
Age at harvest (oldest grafts) 46 42
Age (typical graft) 40 41
Grafts/ha 130 156
Seeds/m2 231 349
Adjusted by annual cone set statistic in stands in area 153 349
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Conclusion

• Seed production can be quite good in old seed
  orchards, no sign of decrease when orchard get
  old!

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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.

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Experimental seed orchard Sävar Experimental seed orchard Sävar Experimental seed orchard Sävar
Latitude 64 64 64
Age 29 29 29
Grafts/ha 125 269 525
Seeds/m2 255 321 323
Adjusted by annual cone set statistic in stands in area 152 191 192
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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.

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Cone observed from ground

• A rough cone count from ground with unaided eye
  in mature seed orchards revealed lt10 of the
  cones. Thus estimating cone set in seed orchards
  require more accurate instructions.

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Variation in female contributions
Coefficient of variation among ramets for different seed orchards Coefficient of variation among ramets for different seed orchards Coefficient of variation among ramets for different seed orchards Coefficient of variation among ramets for different seed orchards Coefficient of variation among ramets for different seed orchards Coefficient of variation among ramets for different seed orchards Coefficient of variation among ramets for different seed orchards
Seed orchard Långtora Långtora Långtora Skaholma Skaholma Skaholma
Filled seeds Filled seeds 0.682 0.682 0.845
Weight of filled seeds Weight of filled seeds 0.753 0.753 0.800
Volume of cones Volume of cones 0.707 0.707 0.852
Number of cones Number of cones 0.686 0.686 0.877
Cones observed from ground Cones observed from ground 0.577 0.577 0.721
Seed weight Seed weight 0.153 0.153 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.
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Thank You!