Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
MANOVA analysis of the differences in acid contents among the tree species
| Effect of Subject | Value | Num DF | Den DF | F Value | Pr>F |
|---|---|---|---|---|---|
| Wilks’ lambda | 0.00 | 25.00 | 31.22 | 45.71 | 0.000 |
| Pillai’s trace | 4.05 | 25.00 | 60.00 | 10.22 | 0.000 |
| Hotelling-Lawley trace | 248.27 | 25.00 | 12.13 | 71.35 | 0.000 |
| Roy’s greatest root | 188.40 | 5.00 | 12.00 | 452.17 | 0.000 |
Active and exchangeable pH and electrical conductance (κ) of the substrate (1:10 (w/v); mean ± st_ dev_, n = 3)
| pH(H2O) | pH(KCl) | κ (mS/cm) |
|---|---|---|
| 5.17±0.00 | 4.65±0.00 | 0.955±0.005 |
Total, bioavailable (CAT) and water-soluble fractions of selected elements in the substrate (mg/kg dry wt_; mean ± st_ dev_, n = 3)
| Fraction | K | Ca | Mg | P | Zn | Fe | Mn | Cu |
|---|---|---|---|---|---|---|---|---|
| Total | 2321±48 | 9655±103 | 1748±42 | 872±11 | 74.1±2.8 | 2089±25 | 462.5±8.6 | 6.03±0.21 |
| CAT | 1272±4 | – | 717±6 | 585±19 | 82.5±3.7 | 508±14 | 407.4±6.7 | 2.02±0.42 |
| H2O | 808±8 | 225±6 | 93±3 | 572±5 | 0.952±0.007 | 6.14±0.00 | 7.15±0.04 | 0.188±0.026 |
Tukey’s HSD test for 4-hydroxybenzoic acid among tree species indicating whether the values are statistically different at the significance level of α ≤ 0_05
| Group 1 | Group 2 | p-value | Reject | Group 1 | Group 2 | p-value | Reject |
|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| s4-hydroxybenzoic acid | p-coumaric acid | ||||||
| AP | FS | 0.0000 | true | AP | FS | 0.3396 | false |
| aP | QR | 0.0000 | true | AP | QR | 0.6966 | false |
| aP | RP | 0.7967 | false | AP | RP | 0.0002 | true |
| aP | ST | 0.0001 | true | AP | ST | 0.0331 | true |
| aP | control | 0.0000 | true | AP | control | 0.9609 | false |
| fS | QR | 1.0000 | false | FS | QR | 0.9827 | false |
| fS | RP | 0.0000 | true | FS | RP | 0.0000 | true |
| fS | ST | 0.1973 | false | FS | ST | 0.6792 | false |
| fS | control | 0.0000 | true | FS | control | 0.7731 | false |
| qR | RP | 0.0000 | true | QR | RP | 0.0000 | true |
| qR | ST | 0.2274 | false | QR | ST | 0.3260 | false |
| qR | control | 0.0000 | true | QR | control | 0.9845 | false |
| rP | ST | 0.0000 | true | RP | ST | 0.0000 | true |
| rP | control | 0.0003 | true | RP | control | 0.0001 | true |
| sT | control | 0.0000 | true | ST | control | 0.1253 | false |
| vanillic acid | Salicylic acid | ||||||
| AP | FS | 0.0749 | false | AP | FS | 0.1614 | false |
| aP | QR | 1.0000 | false | AP | QR | 0.2248 | false |
| aP | RP | 0.0005 | true | AP | RP | 0.6738 | false |
| aP | ST | 0.0000 | true | AP | ST | 0.9833 | false |
| aP | control | 0.0000 | true | AP | control | 0.0001 | true |
| fS | QR | 0.0951 | false | FS | QR | 0.0030 | true |
| fS | RP | 0.0000 | true | FS | RP | 0.0136 | true |
| fS | ST | 0.0024 | true | FS | ST | 0.4073 | false |
| fS | control | 0.0000 | true | FS | control | 0.0000 | true |
| qR | RP | 0.0004 | true | QR | RP | 0.9335 | false |
| qR | ST | 0.0000 | true | QR | ST | 0.0800 | false |
| qR | control | 0.0000 | true | QR | control | 0.0021 | true |
| rP | ST | 0.0000 | true | RP | ST | 0.3240 | false |
| rP | control | 0.0000 | true | RP | control | 0.0005 | true |
| sT | control | 0.0000 | true | ST | control | 0.0000 | true |
| Syringic acid | |||||||
| AP | FS | 0.0069 | true | ||||
| AP | QR | 0.0001 | true | ||||
| AP | RP | 0.9997 | false | ||||
| AP | ST | 0.0000 | true | ||||
| AP | control | 0.9031 | false | ||||
| FS | QR | 0.0509 | false | ||||
| FS | RP | 0.0110 | true | ||||
| FS | ST | 0.0251 | true | ||||
| FS | control | 0.0384 | true | ||||
| QR | RP | 0.0001 | true | ||||
| QR | ST | 0.9979 | false | ||||
| QR | control | 0.0002 | true | ||||
| RP | ST | 0.0000 | true | ||||
| RP | control | 0.9727 | false | ||||
| ST | control | 0.0001 | true | ||||
Pearson product-moment correlation coefficients among the organic acids
| HBA | VA | SyA | pCA | SaA | |
|---|---|---|---|---|---|
| HBA | 0.842* | 0.783* | 0.421 | 0.702* | |
| VA | 0.539 | 0.238 | 0.881** | ||
| SyA | 0.595 | 0.284 | |||
| pCA | 0.199 |
Content of mineral nitrogen forms, total organic carbon (TOC) and humic substances (HS), the degree of polymerisation (DP) and the humification index (HI) of the dry substrate (mean ± st_ dev_; n = 3)
| N-NH4 (mg/kg) | N-NO3 (mg/kg) | TOC (% C) | HS (% C) | DP (HA : FA) | HI (HA : TOC) |
|---|---|---|---|---|---|
| 1421.5±2.6 | 36.6±5.2 | 13.4±0.3 | 6.14±0.03 | 1.80±0.06 | 0.231 |