Drought can favour the growth of small in relation to tall trees in mature stands of Norway spruce and European beech

Forest Ecosystems

Table 5 Upper part: Results of the pairwise comparisons by fitting Eq. 1 (corresponding to Q1)

Pairwise comparisons with regression models after Eq. 1
Comparison	a ₀	SE	a ₁	SE	b ₀	SE	b ₁	SE	R ²	p (model)
N.sp. mono vs. E.be. mono	4.966	3.8434	8.847	5.422	0.992***	0.189	−0.730**	0.267	0.69	0.000
N.sp. mixed vs. E.be. mixed	4.696	4.666	8.865	6.599	0.970***	0.229	−0.843*	0.325	0.69	0.000
Total mixed vs. E.be. mixed	9.757*	3.649	3.804	5.161	0.490*	0.179	−0.362	0.163	0.43	0.000
Total mixed vs. N.sp. mixed	9.757*	4.771	−5.061	6.747	0.490*	0.235	0.481	0.332	0.54	0.000
N.sp. mono vs. N.sp. mixed	4.966	4.930	−0.270	6.972	0.992***	0.242	−0.022	0.343	0.49	0.000
E.be. mono vs. E.be. mixed	13.813***	3.488	−0.252	4.933	0.2625	0.172	−0.135	0.243	0.34	0.003
Resulting linear models iv = a + bM_gs
Category	a	b		diff
N.sp. mono	4.966	0.992		A	diff A is due to a difference in slope only (p = 0.010)
E.be. mono	13.813	0.263		A	diff B is due to a difference in slope only (p = 0.014)
N.sp. mixed	4.696	0.970		B
E.be. mixed	13.561	0.128		B
Total mixed	9.757	0.490

Lower part: Linear models for the different species/stand categories resulting from combining the corresponding parameter estimates from the upper part. If two categories have the same letter under ‘diff’, their linear models differ significantly due to the significances shown in the upper part of the table. Not all possible combinations of categories were tested against each other; see column ‘comparison’ for the performed tests. N.sp, Norway spruce, E.be European beech. Significant differences of the parameters between the groups are indicated by the levels of significance (*p < 0.05, **p < 0.01, ***p < 0.001)