Fig. 1. Picture A shows a map over Sweden and the locations of the sites divided into the three regions, southern, central and northern Sweden. Picture B shows site 24:1 and the experimental design. The whole site equals one block divided into the two main treatments: clearcut (CC) and shelterwood (SW). The main treatments were then further divided into the two sub-treatments: mechanical site preparation (MSP) and no mechanical site preparation (no abbreviation). The four filled circles in the sub-treatments represent the sample plots established in 2022 or 2023.

Table 1. Description of study sites, using the same regional classification (south, central and north), and site numbers from the original design in Nilsson et al. (2006).
Region Site County Latitude, Longitude Altitude
(m a.s.l.) 		Temperature sum (degree-days) Soil texture SIS 1
(m)
South 6 Jönköping 57°17´N, 15°17´E 185 1385 Sandy-silty 26–27 (SP)
South 7 Kronoberg 57°08´N, 14°49´E 230 1400 Sandy-silty 25–26 (SP)
South 11 Skåne 56°26´N, 14°20´E 150 1450 Sandy-silty 28 (NS)
South 15 Älvsborg 57°28´N, 13°08´E 175 1400 Sandy-silty 22 (NS)
South 16 Skaraborg 58°39´N, 13°47´E 70 1400 Sandy-silty 26 (SP)
Central 4 Södermanland 59°13´N, 16°49´E 60 1375 Sandy-silty 24–27 (SP)
Central 17 Värmland 59°25´N, 13°31´E 90 1380 Sandy-silty 26 (SP)
Central 18 Örebro 59°35´N, 15°27´E 85 1350 Sandy-silty 24–26 (SP)
Central 20 Dalarna 60°27´N, 15°45´E 157 1222 Sandy-silty 23 (NS)
North 23 Jämtland 63°44´N, 15°44´E 290 850 Sandy-silty 29–21 (SP)
North 24:1 Västerbotten 64°04´N, 20°17´E 145 1010 Sandy 23 (SP)
North 24:2 Västerbotten 64°33´N, 18°24´E 340 810 Sandy-silty 20–21 (SP)
1 Site index, estimated from site properties, at experimental establishment, either based on dominant height at age 100 years for Scots pine (SP) or Norway spruce (NS)
Table 2. Site-specific details of forest management operations during the establishment phase (Nilsson et al. 2006).
Site Clearcut
(month, year) 		MSP 1
(month, year) 		MSP 1
(type) 		Planting
(month, year) 		Seedling type Seedling age
(years)
6 Oct-94 Apr-95 Patch May-95 Bare-root 4
7 Mar-95 Nov-95 Disc trench. May-96 Cont 2 1.5
11 Sep-95 Nov-95 Disc trench. Jun-96 Bare-root 4
15 Feb-94 Sep-94 Disc trench. Apr-95 Bare-root 4
16 Apr-94 Nov-94 Disc trench. May-95 Cont 2 2
4 Apr-94 Oct-95 Disc trench. May-96 Cont 2 1
17 Dec-94 Sep-95 Mound May-96 Cont 2 1
18 Oct-95 Oct-96 Disc trench. May-97 Cont 2 1
20 Dec-94 May-95 Disc trench. Jun-95 Cont 2 1.5
23 Mar-95 Jun-96 Mound Jun-96 Cont 2 1
24:1 Aug-94 Jul-96 Disc trench. Sep-96 Cont 2 1
24:2 Jan-95 Sep-96 Disc trench. Jun-97 Cont 2 1
1 Mechanical site preparation
2 Containerized seedlings
2

Fig. 2. Stand density (stems ha–1) for the different regions (south, central and north), treatments (CC, CCMSP, SW and SWMSP), and species (Norway spruce, Scots pine, birch spp. and other). The treatments are abbreviated CC = clearcut without mechanical site preparation, CCMSP = clearcut with mechanical site preparation, SW = shelterwood without mechanical site preparation, and SWMSP = shelterwood with mechanical site preparation.

3

Fig. 3. Total standing volume in m3 ha–1 for the different regions (south, central and north), treatments (CC, CCMSP, SW and SWMSP), and species (Norway spruce, Scots pine, birch spp. and other). The treatments are abbreviated CC = clearcut without mechanical site preparation, CCMSP = clearcut with mechanical site preparation, SW = shelterwood without mechanical site preparation, and SWMSP = shelterwood with mechanical site preparation.

Table 3. Quadratic mean diameter (QMD) ± SE and Lorey’s mean height (HL) ± SE by region and treatment. The treatments are abbreviated CC = clearcut without mechanical site preparation, CCMSP = clearcut with mechanical site preparation, SW = shelterwood without mechanical site preparation, and SWMSP = shelterwood with mechanical site preparation.
Region Treatment QMD (cm) Lorey’s height (m)
Spruce Pine Birch spp. Spruce Pine Birch spp.
South CC 10.3 ± 0.9 6.4 ± 3.7 2.0 ± 0.5 10.0 ± 0.9 7.4 ± 2.3 5.8 ± 1.6
South CCMSP 11.4 ± 1.5 5.7 ± 3.3 4.7 ± 2.2 12.1 ± 0.9 9.5 ± 4.0 6.8 ± 2.4
South SW 9.9 ± 1.0 2.9 ± 1.0 1.8 ± 0.7 9.8 ± 0.9 4.5 ± 1.4 5.2 ± 1.4
South SWMSP 9.6 ± 1.1 0.6 ± 0.4 3.8 ± 1.2 9.7 ± 1.1 2.4 ± 0.2 6.2 ± 1.3
Central CC 10.2 ± 2.3 11.0 ± 1.0 4.3 ± 1.6 10.9 ± 1.0 10.7 ± 0.8 7.3 ± 1.4
Central CCMSP 10.3 ± 0.5 9.7 ± 0.5 2.9 ± 0.5 11.0 ± 1.0 9.7 ± 1.4 6.7 ± 0.7
Central SW 9.0 ± 1.1 8.4 ± 2.2 3.0 ± 1.4 10.1 ± 0.8 8.5 ± 1.9 8.9 ± 1.1
Central SWMSP 9.3 ± 1.0 7.4 ± 2.1 2.0 ± 0.5 10.0 ± 0.6 8.2 ± 2.0 5.1 ± 1.4
North CC 6.4 ± 1.3 5.3 ± 1.7 2.3 ± 0.6 7.1 ± 1.1 4.8 ± 1.3 4.8 ± 1.0
North CCMSP 6.9 ± 0.5 7.1 ± 1.0 1.2 ± 0.3 7.0 ± 0.2 7.5 ± 0.1 3.9 ± 1.2
North SW 4.2 ± 0.7 1.8 ± 0.1 3.4 ± 0.5 4.8 ± 0.5 2.6 ± 0.1 4.8 ± 0.4
North SWMSP 5.1 ± 0.5 2.5 ± 0.6 3.5 ± 0.5 6.2 ± 0.7 3.8 ± 0.5 5.9 ± 0.6
4

Fig. 4. Total basal area of the new regeneration for sites in southern, central and northern Sweden. The shelterwoods were still retained on the northern sites but were not included in the calculated basal area. The treatments are abbreviated CC = clearcut without mechanical site preparation, CCMSP = clearcut with mechanical site preparation, SW = shelterwood without mechanical site preparation, and SWMSP = shelterwood with mechanical site preparation.

5

Fig. 5. Basal area divided by region and species in percent. The black dotted line shows the cut-off for mixed species stands (75%). The treatments are abbreviated CC = clearcut without mechanical site preparation, CCMSP
= clearcut with mechanical site preparation, SW = shelterwood without mechanical site preparation, and SWMSP = shelterwood with mechanical site preparation.

Table 4. The quadratic mean diameter (QMD) for Scots pine and Norway spruce and the QMD ratio for Scots pine vs. Norway spruce for the four central sites. The treatments are abbreviated CC = clearcut without mechanical site preparation, CCMSP = clearcut with mechanical site preparation, SW = shelterwood without mechanical site preparation, and SWMSP = shelterwood with mechanical site preparation.
Site Treatment QMD (cm) QMD ratio
Scots pine Norway spruce
4 CC, CCMSP 11.1 11.5 1.0
4 SW, SWMSP 9.9 9.0 1.1
17 CC, CCMSP 10.6 10.9 1.0
17 SW, SWMSP 11.3 10.5 1.1
18 CC, CCMSP 8.8 6.8 1.3
18 SW, SWMSP 8.4 10.8 0.8
20 CC, CCMSP 10.8 11.9 0.9
20 SW, SWMSP 1.8 6.3 0.3
6

Fig. 6. The diameter distribution of Scots pine and Norway spruce for the clearcut treatments (with and without mechanical site preparation together) and shelterwood treatments (with and without mechanical site preparation together) for the four different sites in central Sweden. The vertical dashed lines represent the mean QMD for Scots pine (dotted, light green) and Norway spruce (dashed, black) for each site. The treatments are abbreviated CC = clearcut without mechanical site preparation, CCMSP = clearcut with mechanical site preparation, SW = shelterwood without mechanical site preparation, and SWMSP = shelterwood with mechanical site preparation. View larger in new window/tab.

Table 5. Starting values for the different stands and treatments, as well as the simulated thinnings and ages at final harvest for the three different interest rates (IR). The values are shown per hectare. The treatments are abbreviated CC = clearcut without mechanical site preparation, CCMSP = clearcut with mechanical site preparation, SW = shelterwood without mechanical site preparation, and SWMSP = shelterwood with mechanical site preparation. View in new window/tab.
Table 6. The financial outcome of the shelterwood by region (south and central) compared to the financial outcome of clearcutting in EUR ha–1 together with the mean and standard errors for the region. A positive number meant shelterwood was more profitable than clearcutting, whereas a negative number indicates that clearcutting was more profitable.
South
IR Site Mean SE
6 7 11 15 16
CF 0% 1042 474.5 731.3 831.4 –162.5 583.4 207.6
LEV 2.5% –873.0 –1424.9 –1776.4 –654.7 –2659.0 –1478.4 355.7
LEV 4% –1797.5 –2341.8 –2987.0 –1372.1 –3864.4 –2472.5 440.8
Central
IR Site Mean SE
4 17 18 20
CF 0% 484.0 1318.8 305.4 752.1 715.0 221.2
LEV 2.5% –1429.3 –1041.1 –2113.0 –1328.2 –1477.9 227.1
LEV 4% –2352.9 –2180.5 –3280.5 –2332.5 –2536.6 251.0
Table 7. Financial results of the simulated full rotation in EUR ha–1 with moderate wind damage. For IR 0%, cash flow (CF) is shown, whereas land expectation value (LEV) is shown for IR 2.5% and 4%.
South Central
IR CC CMSP SW SWMSP CC CMSP SW SWMSP
CF 0% 470 508 415 413 493 487 461 472
LEV 2.5% 4142 5120 1727 1084 5896 4820 2809 2339
LEV 4% 118 430 –2767 –3250 1055 333 –2313 –2801