Table 1. Basic information on the afforestation experiments (Exp-N and Exp-S) of Scots pine on cutaway peatlands. Timing of treatments: month/year.
Treatment /Experiment Exp-N Exp-S Comment
Ditching and mounding 10/1986 10/1987
Ditch spacing 15 and 40 m 40 m
Planting 6/1987 5/1988 density 2500 seedlings/ha
Seeding 5/1987 5/1988 density 2500 seeding points/ha
Afforestation fertilization 6/1987 5/1988 P 1.8 and K 3.4 g/seedling
1st re-fertilization No 5/1993 P 4.5 and K 8.0 g/seedling
Seedling stand clearing 5/2003 10/1998 naturally born birch removed
2nd re-fertilization No 5/2002 P 45 and K 80 kg ha–1
Tending of seeded stands No 4/2003
Stand measurement 11/2018 9/2018
No. of replications 3 5–6 n = 5 for seeding in Exp-S
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Fig. 1. The height and DBH distribution of Scots pine trees according to treatments in the afforestation experiment at the Exp-N site after 32 growing seasons since the stand establishment (naturally born trees included). Fertilization treatments: Control and PK fertilization with phosphorus and potassium during the afforestation stage. The ditch spacing is 15 or 40 m. The number of replications was three for all treatments. View larger in new window/tab.

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Fig. 2. The height and DBH distribution of Scots pine trees according to treatments in the afforestation experiment at the Exp-S site after 31 growing seasons since the stand establishment (naturally born trees included). The ditch spacing is 40 m.

Table 2. Applied stumpage prices (€ m–3) and silvicultural costs (€ ha–1) in real terms.
Stumpage prices
Felling method Saw logs ,€ m–3 Pulpwood, € m–3
First commercial thinning 41.75 – 41.84 – 37.26 a) 12.69 – 14.88 – 12.11
Other thinnings 50.08 – 49.73 – 41.40 15.62 – 19.32 – 14.80
Final cut 59.13 – 58.94 – 48.66 18.29 – 23.48 – 17.83
Silvicultural costs, € ha–1
Ditch network maintenance 185.80
Manual planting 697.60
Manual seeding 217.60
Fertilization 314.50
Early pre-commercial thinning 356.50
a) In each line the first value (e.g., 41.75) applies for pine, the second (41.84) for spruce and the third (37.26) for other tree species, in most cases birches.
Table 3. The effect of the afforestation method on the rotation period, mean annual increment of stem wood (MAI) and saw logs (MAI_saw logs), and bare land value (BLV) with two rates of interest at the site in southern Finland (Exp-S; sd = standard deviation). In the financial analysis, 1rf includes one and 2rf two re-fertilizations before the first commercial thinning.
Variable   Rate of interest (%) Treatment (mean ± sd) p-value
Planted Seeded
Rotation (a) 3 71.0 ± 0.9 71.8 ± 1.3 0.259
5 70.3 ± 0.5 68.6 ± 3.2 0.220
MAI (m3 ha–1 a–1) 3 9.5 ± 0.6 9.4 ± 0.6 0.756
5 9.3 ± 0.7 9.2 ± 0.8 0.812
MAI_saw logs (m3 ha–1 a–1) 3 5.5 ± 0.2 5.3 ± 0.3 0.227
5 5.3 ± 0.2 4.9 ± 0.2 0.014
BLV_2rf (€ ha–1) 3 2519.0 ± 405.5 2993.4 ± 389.0 0.081
5 –380.5 ± 211.7 40.6 ± 157.0 0.005
BLV_1rf (€ ha–1)   3 2742.5 ± 405.6 3216.0 ± 388.2 0.081
5 –235.3 ± 207.0 190.0 ± 157.4 0.004
Table 4. The effect of the afforestation method, ditch spacing and fertilization on the rotation period (a), mean annual increment of stem wood (MAI, m3 ha–1 a–1) and saw logs (MAI_saw logs, m3 ha–1 a–1), and bare land value (BLV, € ha–1) with two rates of interest (%) for the Exp-N site (ANOVA p-values).
Source/variable Rotation MAI MAI_sawlogs BLV
Interest rate 3 5 3 5 3 5 3 5
Afforestation (A) 0.247 0.180 <0.001 <0.001 <0.001 <0.001 0.003 0.327
Ditch spacing (D) 0.350 0.693 0.001 <0.001 0.309 0.006 0.002 <0.001
Fertilization (F) 0.504 0.278 0.001 0.009 0.176 0.058 0.050 0.009
Block 0.206 0.170 0.100 0.128 0.109 0.054 0.021 0.024
A*D 0.079 0.262 0.268 0.520 0.808 0.637 0.552 0.529
A*F 0.937 0.555 0.008 0.005 0.545 0.830 0.174 0.147
D*F 1.000 0.693 0.081 0.268 0.433 0.094 0.138 0.036
A*D*F 0.722 0.782 0.872 0.667 0.627 0.830 0.745 0.836
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Fig. 3. Mean annual increment of stem wood (MAI) and saw logs (MAI_sawlogs) of Scots pine dominated stands at the northern Finland site (Exp-N) during a rotation period. The fertilization treatments consisted of a control (O) and fertilization with phosphorus and potassium during the afforestation stage (PK, see Table 1), and with ditch spacing of 15 and 40 m. The rates of interest are 3 and 5% (e.g., MAI3 and MAI5). The standard deviation is shown on top of the bars.

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Fig. 4. Measured and predicted stand volume as a function of stand age, ongoing rotation (an example for a seeded pine stand, with ditch spacing of 15 m and no fertilization during the afforestation stage). Steeper curves are associated with the optimum (compared to Finnish recommendations, i.e. Tapio; Äijälä et al. 2014) and are due to repeated fertilizations.

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Fig. 5. The bare land value (BLV) of different growing alternatives of Scots pine dominated stands on the test sites in northern Finland (Exp-N) at a 3% rate of interest. The fertilization treatments consisted of a control (O) and fertilization with phosphorus and potassium during the afforestation stage (PK, see Table 1), and with ditch spacing of 15 and 40 m. The standard deviation is shown on top of the bars.