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Doctoral thesis2001Open access

Direct seeding of Pinus sylvestris (L.) in the boreal forest using orchard or stand seed

Wennström, Ulfstand


The overall aim was to analyse the possibilities for operational forestry of using Pinus sylvestris (L.) orchard seeds (0s) for direct seeding in the boreal forest. The use of 0s instead of stand seeds (SS) increased seedling establishment by 41% two years after mechanical direct seeding at four sites in northern Sweden. 0s was advantageous to use in combination with microsite preparation to achieve desired spacing and different regeneration strategies, at low cost, and on an operational scale. On average, 0s had 16% and 12% higher seedling emergence than SS in a northern (Lat 64"N) and southern (Lat 60"N) field experimental series where six orchard seed lots and six stand seed lots of adequate geographical origins were analysed with up to six seeding years. The survival rate from year 1 to year 4 was 77% and 72% in the northern series and 58% and 49% in the southern series for orchard and stand seedlings respectively. On average, 0s were 26% and 13% taller than SS after four years in the northern and southern series, respectively. Effects on early seedling growth of seeding 0s and SS in different mixtures (100,75,50, 25, and 0% of 0s) at 4-cm target spacing were quantified in a nursery (optimal) and a field (harsh) experiment. SS in high competition vs. low competition (mixture 75% vs. 25%) were 11% taller, had 15% greater slender value, and 25% less root biomass after two years in the nursery. 0s had 9% greater slender value in mixture 100% compared to mixture 25%. In the field experiment the influence of mixture was not significant after five years. The tallest 0s in each plot compared with the tallest SS were 22% taller and had 103% larger stem volume. After thinning, leaving the tallest seedling in each plot, 79% of the seedlings in 50% mixtures would be 0s. Seedlings sown in 12-cm spacing were 79% taller and had 527% larger stem volume than seedlings in 4-cm spacing. An increase of seed weight from 3 to 7 mg increased height growth by 1845% and 10-27% in the field and nursery experiment, respectively. Seed weight explained approximately 3 1-56% and 7546% of the increased growth of using 0s compared to SS in the field and nursery experiment. Two-year-old 0s seedlings allocated 10% more to needles and had 113% longer total needle length than SS in the field experiment. In the nursery experiment 0s did not allocate more to needles than SS did. The high cost of 0s makes a mixture of 0s and SS as a suitable alternative in several regeneration strategies. SS can be used complementary to OS, i.e., to increase stand density, reduce the cost of seeds, as insurance if seedling establishment is low, and to increase the total wood production and timber quality. The genetically improved orchard seedlings will be dominant after future thinn


biomass allocation; competition; early growth; Scots pine; seed weight; seedling emergence; seed type; seed quality; survival

Published in

Acta Universitatis Agriculturae Sueciae. Silvestria
2001, number: 204
ISBN: 91-576-6088-3
Publisher: Swedish University of Agricultural Sciences

      SLU Authors

    • Wennström, Ulfstand

      • Department of Silviculture, Swedish University of Agricultural Sciences

    UKÄ Subject classification

    Forest Science

    Permanent link to this page (URI)