Silva Fennica

Fig. 1. From left to right: (A) a defect-free tree with neither codominant stems nor a double crown; (B) a tree with codominant stems; (C) a tree with a double crown; (D) a codominant stem that has split into a double crown. Diameter at breast height (DBH) was measured by the harvester during the field study. Consequently, breast height is approximately 1.3 m above ground level. The forking always occurred above the breast-height level in our study.

Table 1. Random effect (i.e., block) estimates (s tree^–1) from the linear mixed model (LMM) analysis for the dependent variables. Diameter at breast height (DBH) is provided in cm. The number of trees (n) in the final dataset was 1503. All trees were lodgepole pines (Pinus contorta Douglas ex Loudon).
	Dependent variable						Mean DBH^(a	n
	Total time		Crane-out		Processing
	Estimate	p-value	Estimate	p-value	Estimate	p-value
Block 1: operator A, old machine	0.097	0.947	0.118	0.799	–0.023	0.983	25.8	579
Block 2: operator A, new machine	–3.269	0.026	–1.239	0.008	–1.971	0.071	23.0	391
Block 3: operator B, old machine	3.565	0.018	0.673	0.164	2.824	0.012	25.1	191
Block 4: operator B, new machine	–0.393	0.790	0.448	0.340	–0.830	0.449	23.6	342
^a)The dataset’s overall mean DBH was 24.5 cm.

Table 2. Fixed effect estimates (s tree⁻¹) from the LMM analysis for the dependent variables. The machine was either repositioned during the crane-out work element or not (driving: yes/no). Driving and processing did not occur simultaneously. The covariate DBH should be provided in cm.
Dependent variable	Effect		Estimate	Standard error	t-value	p-value
Total time	Intercept		46.03	2.25	20.43	<0.001
	DBH		0.80	0.05	17.46	<0.001
	Codominant stems:	No	–31.31	0.96	–32.47	<0.001
	Codominant stems:	Yes	0
	Double crown:	No	–1.81	0.58	–3.14	0.002
	Double crown:	Yes	0
	Driving:	No^(a	–6.94	0.44	–15.84	<0.001
	Driving:	Yes	0
Crane-out	Intercept		13.43	0.87	15.52	0.001
	DBH		0.00	0.02	0.07	0.941
	Codominant stems:	No	–1.29	0.41	–3.14	0.002
	Codominant stems:	Yes	0
	Double crown:	No	0.01	0.25	0.05	0.956
	Double crown:	Yes	0
	Driving:	No^(a	–6.80	0.19	–36.40	<0.001
	Driving:	Yes	0
Processing	Intercept		32.50	1.83	17.80	<0.001
	DBH		0.80	0.04	20.21	<0.001
	Codominant stems:	No	–30.03	0.83	–36.08	<0.001
	Codominant stems:	Yes	0
	Double crown:	No	–1.83	0.50	–3.67	<0.001
	Double crown:	Yes	0
^a)In the results section’s example calculations, we used estimates –6.94 × 0.564 and –6.80 × 0.564, where 0.564 was the probability of a tree being unaffected by a driving event during the field study.