Table 3. Output of a Delaporte count model investigating the effects of fire severity, pre-fire size and site on thicket shrub resprouting shoot count.
Effects include fire severity scored at the base of each shrub (Firebase; orthogonal polynomial contrast trend test; L, linear; Q, quadratic; C, cubic), pre-fire size (Prefiresize), site, fire severity × pre-fire size interaction, fire severity × site interaction, pre-fire size × site interaction and fire severity × pre-fire size × site interactions. Coefficients for sigma and nu are for dispersion (variance), and skewness. Models were fitted using treatment contrasts with Cape St. Francis as the reference level for Site comparison with Knysna (KNS).
| Resprouting shoot count | Regression coefficients are natural logarithms, standard errors are in brackets |
|---|---|
| (Intercept) | 2.38 (0.09)*** |
| Firebase.L | 0.17 (0.21) |
| Firebase.Q | −0.41 (0.18)* |
| Firebase.C | 0.03 (0.14) |
| Prefiresize | 0.40 (0.11)*** |
| SiteKNS | −0.26 (0.12)* |
| Firebase.L:Prefiresize: | 0.31 (0.25) |
| Firebase.Q:Prefiresize: | 0.50 (0.22)* |
| Firebase.C:Prefiresize: | −0.02 (0.19) |
| Prefiresize:SiteKNS | 0.72 (0.19)*** |
| Firebase.L:SiteKNS | −0.26 (0.26) |
| Firebase.Q:SiteKNS | 0.81 (0.23)*** |
| Firebase.C:SiteKNS | −0.35 (0.19) |
| Firebase.L:Prefiresize:SiteKNS | 0.10 (0.44) |
| Firebase.Q:Prefiresize:SiteKNS | −1.25 (0.39)** |
| Firebase.C:Prefiresize:SiteKNS | 0.42 (0.34) |
| sigma (Intercept) | 0.20 (0.10)* |
| nu (Intercept) | −1.36 (0.13)*** |
| Number of observations | 1112 |
| Nagelkerke R2 | 0.09 |
Notes:
*
p < 0.05.
**
p < 0.01.
***
p < 0.001.