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Table III
Results of mixed models testing the effect of neighboring species and competition indices (CI, see Tab. II) on different growth variables in silver birch. Diameter growth was analyzed as repeated measures using diameter growth of the latest 10 y. Sb, Sp, and Sl give the mean value ( ± 95% confidence interval) of each response variable with silver birch, Scots pine, and Siberian larch as neighbors, respectively.
| Variable | Effect | Num df | Den df | F | P | Sb | Sp | Sl | |
|---|---|---|---|---|---|---|---|---|---|
| Height increment (cm/year) | 49.1 (7.9) | 54.3 (8.0) | 54.4 (10.0) | ||||||
| Neighbor | 2 | 37.3 | 2.7 | 0.0812 | |||||
| CI6 | 1 | 45.4 | 1.1 | 0.2963 | |||||
| CI6 × neighbor | 2 | 39.2 | 9.1 | 0.0006 | |||||
| Diameter growth (mm/year) | 2.3 (1.3) | 2.7 (1.3) | 2.8 (1.4) | ||||||
| Neighbor | 2 | 24.2 | 1.5 | 0.2541 | |||||
| Year | 9 | 230 | 1.3 | 0.2464 | |||||
| Age | 1 | 31.2 | 9.1 | 0.0052 | |||||
| CI6 | 1 | 28.6 | 9.9 | 0.0039 | |||||
| Shoot length (annual shoot length/total branch length, cm) | 0.11 (0.04) | 0.11 (0.04) | 0.13 (0.05) | ||||||
| Neighbor | 2 | 60.3 | 0.2 | 0.8329 | |||||
| CI1 | 1 | 15.3 | 14.6 | 0.0016 | |||||
| Branch number (branches/cm crown length) | 0.10 (0.01) | 0.11 (0.01) | 0.11 (0.02) | ||||||
| Neighbour | 2 | 46.5 | 2.1 | 0.1368 | |||||
| CI6 | 1 | 41 | 2.6 | 0.1147 | |||||