1. Species trials in the interior of northern Sweden - Evaluation after 20 years Johan Westin

2. 8 species tested… Abies lasiocarpa Abies sibirica Pinus sylvestris Picea glauca Picea marianaPicea abies Pinus contorta Larix sibirica (L.sukaczewi)

3. Conclusions  Good growth performance of larch – the best?  Survival can be improved - better nursery management - other seed sources?  Stem straightness could become a future problem  Suitable soil types appear to be ”spruce” types 

4. Background  70’s - a predicted future shortage of wood  Need to utilize forests in the interior of northern Sweden  How to re-forestate? - cold climate - low production

5. Sponsors  Sveaskog  Holmen  SCA  Norrbottens och Västerbottens allmänningsskogar (=community forests)  Swedish Forest Agency

6. Difficult to regenerate  Spring & autumn frosts  Frost damages during the growing period  Variable climate - Frequent occasions with ”destructive” weather  Flat sites, frost prone sites, frost ”pockets”  Vinter/Early spring damages

7. Short growing season  Long lasting snow coverage - 7-8 months October 15 May 15

8. How to improve regeneration?  Fresch clear-cuts  Site preparation  Well adapted provenances - growth rhythm  Planting material - seedling size, - planting time - seedlings in ”rest”

9. Field trials  21 survival trials  5 production trials

10. Species & provenances; # per site, # total used  Picea abies (L.) Karst. 1-3 prov./site, 12 used  Pinus sylvestris L. 2-3 6  Pinus contorta ssp. Latifolia 2 3  Abies sibirica Led. 1-2 2  Picea glauca (Moench) Voss 1-3 9  Picea mariana (Mill.) 2-4 8  Larix sibirica 2-4 7 (L.sukaczewi) (4 SO, 3 prov.)  Abies lasiocarpa (Hook.) Nutt. 1-3 7

11. Field trial design (example)

12. Traits assessed on each tree  Vitality 0-3 (Survival 1/0)  Tree height, dm  Stem straightness class, 0-2,  Stem stability class, 0-3  Wood quality class, 0-4 Predicted future wood quality based on defects on the main stem. (stem stability considered separately).

13. Transfer effects  Inoptimal seed sources - three species  Limitations on lat.transfer but… ≥ 1 provenance/ species & trial  Pinus sylvestris >1.1° southward transfer  Pinus contorta <5.1° northward transfer  Picea mariana <1.3° southward transfer Northward ► ◄ Southward

14. Good growth performance of Larch

15. Relatively low survival of Larch

16. Larch does not have straight stems

17. Larch stems have high stability

18. Intermediate stem wood quality

19. Site type effects  Various variables tested Spruce type?, Soil productivity, South facing?, Soiltype class,Texture class, Moisture class, Soilwater flow?, Slope-degrees?, Wind exposed?, Frostprone?  Larch survival + spruce types (not pine), soil water flow, no frost sites - high productive soils  Larch height growth + fine soils (silt, loam), wind exposure - high productive soils

20. Large variation in survival

21. Nursery related problems with Larch  Autumn frost damages in the nursery → Short day (SD) treatment  Grey mold (Botrytis cinerea) → plant density & humidity, removal of dead needles  Planting of seedlings in rest → cool room storage → freezer storage

22. Conclusions  Good growth performance of larch – the best?  Survival can be improved - better nursery management - other seed sources?  Stem straightness could become a future problem  Suitable soil types appear to be ”spruce” types 