Table 3. ANOVA results for the effects of mechanical site preparation method (MSP method; least-square means (lsmeans) ± stderr) of planted Norway spruce, Scots pine and lodgepole pine seedlings following each MSP method in field experiments. Survival (%) refers to analyses of the survival of all MSP treatments, as well as of the MSP-effects, i.e. the difference in percentage units between results of the MSP methods and no site preparation (No MSP). For height, both the absolute tree heights (cm) in all treatments and the relative MSP-effects are given. The relative MSP-effect on height and annual height growth refers to the difference in percentage (%) between results of the MSP methods and No MSP. Data obtained 3–27 growing seasons after planting. Values with different letters in the same row indicate statistically significant differences (p < 0.05) for tree species and MSP-method, respectively. NO MSP DATA = studies including a control treatment without MSP.

Data

p-value

Lsmeans, tree species

Lsmeans, MSP-method

Site

Tree species

MSP method

Residual

Norway spruce

Scots pine

Lodgepole pine

No MSP

Patch scarification

Disc trenching

Mounding

Soil inversion

Ploughing

Survival

ALL DATA1 (n = 88)

0.001

0.12

<0.001

<0.001

84 ± 2.3 a

76 ± 3.7 a

86 ± 4.2 a

68 ± 2.3 a

79 ± 2.7 b

81 ± 2.6 bc

84 ± 2.7 bcd

87 ± 2.7 cd

92 ± 3.2 d

NO MSP DATA2 (n = 72)

0.002

0.070

<0.001

<0.001

85 ± 2.7 a

71 ± 5.2 a

84 ± 4.6 a

68 ± 2.7 a

77 ± 3.3 b

83 ± 3.0 bc

82 ± 3.1 bc

86 ± 3.0 c

85 ± 4.8 bc

MSP-effect (n = 46)

0.002

0.015

0.002

0.001

16 ± 1.7 ab

25 ± 3.4 b

11 ± 3.0 a

–

14 ± 2.3 a

16 ± 2.0 a

16 ± 2.0 a

21 ± 2.0 b

19 ± 3.0 ab

Height

NO MSP DATA3 (n = 56)

0.005

0.001

<0.001

<0.001

193 ± 25 a

195 ± 57 ab

298 ± 32 b

187 ± 26a

208 ± 28 ab

215 ± 29 ab

235 ± 27 bc

233 ± 27 bc

295 ± 33 c

MSP-effect4 (n = 36)

0.14

0.12

0.27

0.015

38 ± 6.7 a

26 ± 16 a

10 ± 11 a

–

11 ± 10 a

23 ± 10 a

20 ± 8.6 a

24 ± 9.5 a

46 ± 14 a

Annual height growth

NO MSP DATA5 (n = 56)

0.007

<0.001

<0.001

<0.001

17 ± 1.4 a

21 ± 3.1 a

28 ± 1.9 b

19 ± 1.4 a

21 ± 1.6 ab

22 ± 1.6 b

23 ± 1.5 bc

23 ± 1.5 bc

26 ± 1.9 c

1 Number of years after planting (p = <0.001) was included in the statistical model as a covariate. 2 Number of years after planting (p = 0.003) was included in the statistical model as a covariate. 3 Temperature sum (p = 0.001) and number of years after planting (p = <0.001) were included in the statistical model as covariates. 4 Temperature sum (p = 0.020) was included in the statistical model as a covariate. 5 Temperature sum (p = <0.001) and number of years after planting (p = 0.001) were included in the statistical model as covariates.