Table 1.
Enzyme activities.
| Site | Carbon enzymes | Phosphorus enzymes | Nitrogen enzymes | Sum of enzymes | Sum of enzymes/Cmic |
|---|---|---|---|---|---|
| (%) | (nmol h−1 g−1) | ||||
| N1 (0–25 years) | 5.83 (0.68) b | 84.3 (3.53) a | 9.89 (3.42) b | 31 (8.85) c | 2.82 (0.70) a |
| N2 (26–54 years) | 3.72 (0.67) bc | 49.1 (5.12) b | 47.2 (5.68) a | 248 (36.1) b | 2.95 (0.46) a |
| N3 (55–79 years) | 2.69 (0.32) c | 34 (4.04) c | 63.3 (4.24) a | 366 (19.5) b | 2.66 (0.33) ab |
| NR (10 000 years) | 17.7 (4.24) a | 36.1 (5.40) bc | 46.2 (4.95) a | 876 (104) a | 1.19 (0.16) b |
| Forefield | * | * | NS | NS | * |
| S1 (0–25 years) | 3.83 (0.45) b | 59.5 (3.44) a | 36.7 (3.46) c | 359 (45.9) b | 2.86 (0.49) b |
| S2 (26–54 years) | 1.42 (0.19) c | 36.0 (2.76) b | 62.5 (2.83) a | 394 (39.5) b | 6.03 (0.27) a |
| S3 (55–79 years) | 6.04 (1.02) b | 32.5 (3.83) b | 61.5 (4.16) ab | 375 (29.4) b | 3.15 (0.67) b |
| SR (10 000 years) | 10.9 (1.31) a | 44.4 (4.47) ab | 44.7 (5.58) bc | 957 (106) a | 0.75 (0.09) c |
Statistics: effect of a forefield on enzyme activities (*** ∼ P < .001,** ∼ P < .01, * ∼ P = .01–.05, NS ∼ not significant) determined with a glmer model with a Gamma distribution and a logarithmic link function and a likelihood-ratio test. Effect of time on enzyme activities was evaluated separately for each forefield using Tukey’s HSD post hoc tests (different letters indicate significant differences; P < .05 between sites within the forefield). Brackets indicate ± standard error (within each site, n = 9), n.d. ∼ not detected.
Interpretation: carbon enzymes = sum of β-glucosidase (GLU) and cellobiohydrolase (CELL) activity, phosphorus enzymes = phosphatase (PHO) acitivity, and nitrogen enzymes = sum of leucin aminopeptidase (ALA) and chitinase (CHIT) activity.