Table 4. Direct and indirect causal effects of environmental variables upon the relative abundance of Thaumarchaeota in hypothesized path models.
| Path Model | Causal direction a | Total covariation | Causal covariation (effect) | Noncausal covariation | ||
|---|---|---|---|---|---|---|
| Direct | Indirect | Total | ||||
| A | TC → RTHAUM | -0.563 | -0.176 | -0.387 | -0.563 | 0.000 |
| TN → RTHAUM | -0.708 | -0.593 b | 0.000 | -0.593 | -0.115 | |
| TC → TN | 0.653 | 0.653 | 0.000 | 0.653 | 0.000 | |
| B | WC → RTHAUM | -0.599 | -0.024 | -0.575 | -0.599 | 0.000 |
| NH4 + → RTHAUM | -0.675 | -0.654 | 0.000 | -0.654 | 0.021 | |
| WC → NH4 + | 0.879 | 0.879 | 0.000 | 0.879 | 0.000 | |
a Causal ordering is represented by arrows.
b Significant (p < 0.05, t-statistic calculated from MLR using the OLS method) direct effects are displayed in bold.