Table 2.
Summary of ANCOVA analyses on vegetation structural characteristics shown in Fig. 2. The models fit were all of the form response variable = β0 + β1 × block + β2 × time + β3 × treatment + β4 × time × treatment; if the response variable was ln-transformed prior to analysis, that is noted in the column heading. Values shown in the first four rows are F-statistics, associated degrees of freedom, and P-values; parameter estimates (SE) for the four treatments – C (hemlock control); G (girdled), L (logged), and H (hardwood control) – are given in the next three rows. Parameter estimates are not back-transformed (for models fit to ln-transformed data). Parameter estimates that are significantly different from 0 are shown in italics.
| Understory richness | Understory cover | ln(Tree seedling density) | ln(Tree seedling cover) | ln(Sapling density +1) | ln(Snag and stump volume) | CWD volume | |
|---|---|---|---|---|---|---|---|
| Sources of variation | |||||||
| Intercept | F1,39 = 671.34 | F1,47 = 132.35 | F1,47 = 2967.94 | F1,47 = 0.03 | F1,15 = 148.05 | F1,15 = 1135.32 | F1,15 = 151.22 |
| P < 0.0001 | P < 0.0001 | P < 0.0001 | P = 0.8615 | P < 0.0001 | P < 0.0001 | P < 0.0001 | |
| Time | F1,39 = 23.65 | F1,47 = 21.82 | F1,47 = 11.80 | F1,47 = 82.57 | F1,15 = 1.27 | F1,15 = 10.85 | F1,15 = 0.00 |
| P < 0.0001 | P < 0.0001 | P = 0.0012 | P < 0.0001 | P = 0.2779 | P = 0.0049 | P = 0.9867 | |
| Treatment | F3,39 = 53.13 | F3,47 = 80.34 | F3,47 = 2.55 | F3,47 = 32.84 | F3,15 = 2.85 | F3,15 = 14.53 | F3,15 = 43.51 |
| P < 0.0001 | P < 0.0001 | P = 0.0668 | P < 0.0001 | P = 0.0728 | P = 0.0001 | P < 0.0001 | |
| Time × Treatment | F3,39 = 4.29 | F3,47 = 12.58 | F3,47 = 4.16 | F3,47 = 15.14 | F3,15 = 0.49 | F3,15 = 7.39 | F3,15 = 0.90 |
| P = 0.0104 | P < 0.0001 | P = 0.0108 | P < 0.0001 | P = 0.6929 | P = 0.0029 | P = 0.4634 | |
| Parameter estimates | |||||||
| Intercept (β0) | 8.38 (1.57) | 0.78 (1.62) | 10.04 (0.34) | −1.98 (0.33) | 3.42 (1.18) | 3.22 (0.39) | 25.42 (8.24) |
| Time (β2) | 0.06 (0.58) | 0.15 (0.62) | 0.18(0.12) | 0.22 (0.12) | 0.02 (0.39) | 0.08 (0.13) | 2.89 (2.56) |
| Treatment (β3) | G: 0.44 (2.22) | G: 0.49 (2.19) | G: 0.17 (0.42) | G: 0.15 (0.42) | G: 0.55 (1.67) | G: −0.29 (0.55) | G: −2.08 (10.81) |
| L: −2.12 (2.22) | L: 0.32 (2.19) | L: 0.21 (0.42) | L: 0.88 (0.42) | L: 0.05 (0.55) | L: 64.45 (10.81) | ||
| H: 17.34 (2.22) | H: 23.71 (2.19) | H: 1.07 (0.42) | H: 3.50 (0.42) | L: 1.71 (1.67) | H: −0.37 (0.55) | H: 18.51 (10.81) | |
| H: 1.94 (1.67) | |||||||
| Time×Treat(β4) | G: 2.49 (0.82) | G: 0.38 (0.88) | G: 0.36 (0.17) | G: 0.73 (0.17) | G: 0.08 (0.56) | G: 0.66 (0.18) | G: −1.82 (3.62) |
| L: 2.25 (0.82) | L: 4.59 (0.88) | L: −0.05 (0.17) | L: 0.7 (0.17) | L: −0.10 (0.18) | L: −4.28 (3.62) | ||
| H: 0.68 (0.82) | H: 0.23 (0.88) | H: −0.22(0.17) | H: −0.14 (0.17) | L: 0.61 (0.56) | H: 0.04 (0.18) | H: −5.40 (3.62) | |
| H: 0.11 (0.56) |