Table 3.
Numerator and denominator degrees of freedom, F values and P values for Wald tests for the fixed-effects terms in mixed-effects models with grass, herb, legume and total cover as response variables
| Grass cover | P | Herb cover | P | Legume cover | P | Total cover | P | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| nDFa | dDFb | F | nDF | dDF | F | nDF | dDF | F | nDF | dDF | F | |||||
| Intercept | 1 | 86 | 13.21 | <0.001 | 1 | 124 | 6.54 | 0.012 | 1 | 80 | 0.32 | 0.571 | 1 | 156 | 0.85 | 0.359 |
| Stage | 2 | 86 | 27.1 | <0.001 | 2 | 124 | 10.44 | <0.001 | 2 | 80 | 2.05 | 0.136 | 2 | 156 | 3.71 | 0.027 |
| Log Plant species richness (PSR) | –d | – | – | – | 1 | 61 | 0.50 | 0.484 | 1 | 40 | 0.86 | 0.360 | 1 | 72 | 0.36 | 0.548 |
| Functional group richness (FG) | 1 | 38 | 1.16 | 0.288 | – | – | – | – | 1 | 40 | 1.92 | 0.174 | 1 | 72 | 2.70 | 0.105 |
| Presence of grasses | – | – | – | – | 1 | 61 | 5.28 | 0.025 | – | – | – | – | 1 | 72 | 0.84 | 0.364 |
| Presence of legumes | 1 | 38 | 1.05 | 0.313 | – | – | – | – | – | – | – | – | 1 | 72 | 0.01 | 0.905 |
| Presence of small herbs | 1 | 38 | 2.96 | 0.094 | – | – | – | – | – | – | – | – | 1 | 72 | 0.05 | 0.827 |
| PSR: legume presencec | – | – | – | – | – | – | – | – | – | – | – | – | 1 | 72 | 3.56 | 0.063 |
| FG: grass presence | – | – | – | – | – | – | – | – | – | – | – | – | 1 | 72 | 2.58 | 0.113 |
| FG: legume presence | 1 | 38 | 0.40 | 0.532 | – | – | – | – | – | – | – | – | – | – | – | – |
| Grass: small herb presence | – | – | – | – | – | – | – | – | – | – | – | – | 1 | 72 | 4.11 | 0.046 |
| Legume: small herb presence | 1 | 38 | 3.95 | 0.054 | – | – | – | – | – | – | – | – | – | – | – | – |
| Stage: PSR | – | – | – | – | 2 | 124 | 3.30 | 0.040 | 2 | 80 | 2.50 | 0.089 | – | – | – | – |
| Stage: FG | – | – | – | – | – | – | – | – | 2 | 80 | 2.65 | 0.077 | – | – | – | – |
| Stage: grass presence | – | – | – | – | – | – | – | – | – | – | – | – | 2 | 156 | 5.41 | 0.005 |
| Stage: small herb presence | – | – | – | – | – | – | – | – | – | – | – | – | 2 | 156 | 3.69 | 0.027 |
Each term is added sequentially to a null model containing only the intercept. Grass cover: n = 44 plots × 3 stages = 132; herb cover: n = 64 × 3 = 192; legume cover: n = 43 × 3 = 129; total cover: n = 81 × 3 = 243
a,bNumerator and denominator degrees of freedom
cInteraction terms are indicated by “:”
dTerms excluded during model simplification indicated by “–”