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

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

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 

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

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

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

Short growing season  Long lasting snow coverage months October 15 May 15

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

Field trials  21 survival trials  5 production trials

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

Field trial design (example)

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).

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

Good growth performance of Larch

Relatively low survival of Larch

Larch does not have straight stems

Larch stems have high stability

Intermediate stem wood quality

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

Large variation in survival

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

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 