Table 1. N fertilizer application intervals for the N treatments at Hagfors. The dosage is shown as kg N ha–1.
Year Treatment
  0N 450N 900N 1800N b)
1981 - 150 150 150
1983 - - - 150
1985 - - 150 150
1987 - - - 150
1989 - 150 150 150
1991 a) - - - 150
1993 a) - - 150 150
1995 a) - - - 150
1997 a) - 150 150 150
1999 a) - - - 150
2001 a) - - 150 150
2003 a) - - - 150
a) Dolomite was added to the fertilizer, which then contained 27% N, 5% Ca, 2% Mg and 0.2% B.
b) At the first five applications, the three 1800N plots received different amounts of other nutrients (0 up to 10 kg per nutrient), see Ring et al. (2011) for more details.
Table 2. N fertilizer application intervals for the different treatments at Nissafors. The dosage is shown as kg N ha–1.
Year Treatment
  0N 450N
1977 - 75 (block 1 and 2), 6x25 (block 3)
1978 - 75 (block 1 and 2)
1984 - 150
1989 a) - 150
a) In addition, 20 kg P ha–1 was applied.
1

Fig. 1. Mortality (% dead seedlings) for seedlings planted in sub-plots with and without scarification at Hagfors five years after planting. Three types of damage were distinguished: damage caused by pine weevils, damage caused by herbivory, and damage caused by unknown factors. 0N, 450N, 900N and 1800N denote the applied total N dosage (in kg ha–1).

2

Fig. 2. Height development (mm) for seedlings grown in the different treatment combinations at Hagfors. 0N, 450N, 900N and 1800N denote the applied N dosage (in kg ha–1). No Sc = no scarification; Sc = scarification (disc trenching).

3

Fig. 3. Aboveground biomass (g dry weight per seedling) for seedlings grown in the different treatment combinations at Hagfors. 0N, 450N, 900N and 1800N denote the applied N dosage (in kg ha–1). No Sc = no scarification; Sc = scarification (disc trenching).

Table 3. Results obtained in the analyses of the different response variables, shown in terms of the p-values for each treatment effect and site.
Site Treatment Variable
Mortality Damage Height Diameter Biomass
Hagfors Fertilization 0.813 0.682 0.337 0.654 0.591
Scarification <0.001 <0.001 <0.001 <0.001 <0.001
Fert. * Scar. <0.001 <0.001 0.291 0.275 0.682
Nissafors Fertilization 0.620   0.577 0.659  
Scarification <0.001   0.002 0.002  
Fert. * Scar. 0.140   0.883 0.486  
Table 4. Concentrations of Al, Ca, K, Mg, Mn, P and S (mg g–1) and B, Cu, Fe, Na and Zn (μg g–1) in the needles of seedlings grown in different treatments at Hagfors and p-values for fertilization, scarification and their interaction according to Eq. 3. Needles were sampled five years after planting. No Sc = no scarification and Sc = scarification.
Element p-values Treatments
Fert. Scar. Fert.*Scar. 0N 450N 900N 1800N
No Sc Sc No Sc Sc No Sc Sc No Sc Sc
Al 0.180 0.015 0.677 0.24 0.27 0.26 0.32 0.22 0.33 0.23 0.30
B 0.001 0.001 0.075 3.67 5.00 7.67 9.33 8.33 13.7 14.0 19.0
Ca 0.411 0.115 0.671 1.85 2.28 1.90 2.23 1.72 2.19 2.37 2.24
Cu 0.213 0.456 0.885 1.67 2.00 1.67 2.00 2.33 2.33 2.00 2.00
Fe 0.147 0.947 0.308 29.7 30.0 60.0 36.0 29.3 36.0 42.0 49.7
K 0.243 0.367 0.376 2.84 3.07 3.31 3.18 2.89 3.49 2.69 2.63
Mg 0.025 0.153 0.743 0.50 0.50 0.58 0.48 0.66 0.61 0.66 0.56
Mn 0.134 0.010 0.820 0.38 0.44 0.41 0.50 0.31 0.43 0.41 0.52
Na 0.685 0.237 0.009 29.3 24.7 30.3 24.0 24.3 33.0 31.5 29.0
P 0.758 0.479 0.148 0.81 0.83 0.87 0.83 0.79 0.94 0.93 0.87
S 0.453 0.800 0.252 0.54 0.54 0.61 0.57 0.53 0.62 0.68 0.58
Zn 0.472 0.306 0.492 35.0 33.7 40.7 34.7 93.3 34.7 40.5 38.0
4

Fig. 4. Nitrogen content (g per seedling) in seedlings grown in the different treatment combinations at Hagfors. 0N, 450N, 900N and 1800N denote the applied N dosage (in kg ha–1). No Sc = no scarification; Sc = scarification (disc trenching).

Table 5. The ratios of the P, K, Ca, Mg and S concentrations to the N concentration in the needles of the seedlings grown at Hagfors in different treatments. Values followed by different letters within the same rows are significantly different. No Sc = no scarification and Sc = scarification.
Ratio Treatments
0N 450N 900N 1800N
No Sc Sc No Sc Sc No Sc Sc No Sc Sc
P:N 0.10a 0.10a 0.10a 0.10a 0.10a 0.12b 0.10a 0.10a
K:N 0.35ac 0.38ab 0.38ab 0.37ac 0.38abc 0.44b 0.29c 0.31ac
Ca:N 0.22 0.28 0.22 0.26 0.22 0.28 0.25 0.27
Mg:N 0.06ab 0.06ab 0.07ab 0.06a 0.09b 0.08ab 0.07ab 0.07ab
S:N 0.07a 0.07a 0.07a 0.07a 0.07a 0.08b 0.07ab 0.07a
5

Fig. 5. Biomass of ground vegetation (g m–2) in the different scarification treatments at Hagfors. For the plots without scarification the overall mean value is shown. In the disc trenched treatment (scarification), mean values are shown for the furrow, the tilt and the area between furrows.

Table 6. Summary of the results of the statistical analysis, shown as p-values, and the weight and chemical contents of the ground vegetation for each treatment at Hagfors (area-weighted values). The contents are given in g m–2 (for weight, C, N, Ca, K, Mg, Mn, P and S) or mg m–2 (for Al, B, Cu, Fe, Na and Zn). Values followed by different letters within the same rows are significantly different.
  p-values Treatments
Fert. Scar. Fert.*Scar. 0N 450N 900N 1800N No Sc Sc
Weight 0.425 0.006 0.901 112.2 97.6 132.6 147.8 158.6a 86.49b
C 0.535 0.007 0.960 57.37 50.25 68.38 71.28 79.71a 43.93b
N 0.278 0.003 0.707 1.227 1.250 1.589 1.871 1.943a 1.025b
Al 0.217 0.058 0.921 19.47 19.82 20.82 11.13 21.38 14.23
B 0.489 0.144 0.942 1.596 1.679 2.251 2.302 2.268 1.646
Ca 0.331 0.006 0.894 0.800 0.713 0.938 0.551 0.989a 0.512b
Cu 0.404 0.015 0.990 0.548 0.452 0.665 0.515 0.667a 0.424b
Fe 0.962 0.766 0.698 8.129 8.895 7.604 8.037 8.431 7.902
K 0.005 0.011 0.068 0.550b 0.503b 0.684b 1.183a 0.977a 0.483b
Mg 0.356 0.006 0.985 0.137 0.125 0.181 0.175 0.197a 0.113b
Mn 0.923 0.037 0.906 0.119 0.101 0.119 0.111 0.140a 0.086b
Na 0.279 0.545 0.840 2.767 3.872 2.964 5.041 3.931 3.391
P 0.266 0.016 0.648 0.139 0.133 0.171 0.205 0.216a 0.108b
S 0.510 0.007 0.967 0.115 0.106 0.145 0.146 0.163a 0.092b
Zn 0.705 0.003 0.937 3.818 3.239 4.399 4.018 5.143a 2.596b