Table 1. Description of the conditions at the three study sites located in the south, northeastern and northwestern parts of Sweden respectively, including plot setup, number of seedlings planted and seedling material details for the three sites and for Scots pine, Norway spruce and silver birch respectively. Growing season, mean annual temperature and mean annual precipitation extrapolated for the Swedish Meteorological and Hydrological Institute (SMHI) maps showing normal length of vegetation period 1981–2010 (SMHI 2022a-d). All seedlings were containerized. *Theoretical numbers since the true number for each row sometimes deviated depending on availability of planting positions. **Approximate mean sizes common for the container system, not actual measurements of the seedlings.
Site South (S) site Northeast (NE) site Northwest (NW) site
Coordinates 57.193157,14.821763 64.162174, 19.661918 64.102337, 18.149540
Elevation (m. a.s.l) 225–230 160–165 295–300
Trial establishment date June 17th 2020 June 22nd 2020 June 17th 2019
Landowner Sveaskog Private Sveaskog
Growing season (days) 190–200 150–160 140–150
Coldest month avg. T (°C) –1 to –2 (January) –7 to –8 (January –9 to –10 (January)
Warmest month avg. T (°C) +16 to +17 (July) +15 to +16 (July) +14 to +15 (July)
Mean annual T (°C) 6–7 2–3 1–2
Mean annual precipitation (mm) 600–800 600–800 400–600
Moist class mesic to dry mesic dry–mesic
Harvested stand spruce spruce pine
Landscape Hummocky, but with relatively flat plot areas From flat to moderate W slope Ridges, from flat to gentle slope
Vegetation type Grass + Rubus idaeus L. Vaccinium myrtillus L. Vaccinium myrtillus L. + Vaccinium vitis-idaea L.
Vegetation 2nd season Very rich Moderate Sparse
Tot. size harvested area (ha) 21 5 20
Seedlings per plot* 9 × 9 9 × 9 12 × 12
Seedling spacing (m) 2.6 × 2.6 2.6 × 2.6 2 × 2
Seedling material
Pine Age (yr) 1 1 2
Nursery Lilla Istad, SSP Skogforsk, Sävar Skadom nursery
Seed origin Seed orchard Seed orchard Seed orchard
Provenience 30-G7 Lilla Istad FP-T8 Dal FP 625 T8 Dal
Container system S50 Hiko VAB90 SP90
Height (cm)** 13 13.2 25
Stem base (mm)** 2.45 3.1 5
Pine-weevil protection yes, conniflex no no
Spruce Age (yr) 1.5 1 2
Nursery Trekantens nursery, SSP Skogforsk, Sävar Skadom nursery
Seed origin Seed orchard Seed orchard Forest
Provenience FT-907 Ekebo FP-130 Domsjöänget Fullsborn 61*25
Container system Svepot 115 Hiko VAB90 SP90
Height (cm)** 30.5 24.4 30
Stem base (mm)** 4.6 3.1 6
Pine-weevil protection yes, conniflex no no
Birch Age (yr) 1 1 1
Nursery Mellanå Plant AB Skogforsk, Sävar Skadom nursery
Seed origin Seed orchard Seed orchard Seed orchard
Provenience Ekebo 5 B Lat 62–64° (Finland) SV 413 Oitti (Finland)
Container system PLEK 36 Plantek 49F SP120
Height (cm)** 40–80 N.A. 40
Stem base (mm)** N.A. N.A. 6
1

Fig. 1. Results from ANOVA analysis for A) survival, B) height, and C) stem base diameter means of Scots pine, Norway spruce and silver birch at each site respectively following the second field season. Columns indicate percentage survival and error bars indicate standard error (data backtransformed from log scale in survival models). Different letters indicate significant differences. For height and stem base diameter, only measurements of seedlings classified as vital are included.

Table 2. ANOVA (Type II/III Wald chi-square tests) on generalized mixed linear models for probability of survival and linear mixed models for height and stem base diameter for each site following the second growing season in the field. Significant results are highlighted in bold.
South (S) Northeast (NE) Northwest (NW)
Survival X2 df Pr(>X2) X2 df Pr(>X2) X2 df Pr(>X2)
AP 8.26 1 0.004 0.99 1 0.319 19.19 1 <0.001
Species 34.57 2 <0.001 8.40 2 0.015 8.79 2 0.012
AP × Species 13.44 2 0.001 8.92 2 0.012 - - -
Height
AP 2.55 1 0.1103 17.12 1 <0.001 137.51 1 <0.001
Species 177.43 2 <0.001 2089.17 2 <0.001 80.16 2 <0.001
AP × Species - - - 8.57 2 0.014 30.34 2 <0.001
Diameter
AP 0.20 1 0.65 44.94 1 <0.001 25.55 1 <0.001
Species 24.46 2 <0.001 23.81 2 <0.001 23.14 2 <0.001
AP × Species - - - 13.80 2 0.001 27.17 2 <0.001
2

Fig. 2. Results from ANOVA analysis for damage to living seedlings of Scots pine, Norway spruce and silver birch by A) pine weevil and B) browsing at the south site, and C) browsing at the NW site following the second field season. Columns indicate percentage of living seedlings damaged and error bars indicate standard error (data backtransformed from log scale used in models.) Different letters indicate significant differences.

Table 3. ANOVA (Type II/III Wald chi-square tests) on generalized mixed linear models for probability of registered damage following the second growing season in the field; browsing and pine weevil for the south site and browsing for the northwest site. Significant results are highlighted in bold.
South, pine weevil South, browsing Northwest, browsing
Damage X2 df Pr(>X2) X2 df Pr(>X2) X2 df Pr(>X2)
AP 2.81 1 0.094 0.95 1 0.331 9.70 1 0.002
Species 32.29 2 <0.001 47.52 2 <0.001 17.84 2 <0.001
AP × Species 27.74 2 <0.001 17.22 2 <0.001 - - -