Table 2.
Influence of kelp forest status (fixed categorical covariate with two levels: healthy and degraded) and season (fixed categorical covariate with four levels) on the β-biodiversity of seaweed assemblages found at golden kelp stands. β-Biodiversity was estimated at intra-reef (pairwise Jaccard distances among sampling quadrats separated tens of metres) and inter-reef (sampling quadrats separated by hundreds to a few thousand metres) scales. Values are from Wald χ2 tests for the fixed terms fitted with a generalized linear mixed model (GLMM); σ2 for sampling reef as a random covariate nested in season was 0.005 for the intra-reef model while σ2 for sampling a reef pair was 0.007 for the inter-reef model; d.f. = degrees of freedom. Significant P-values are shown in bold.
| β-Diversity intra-reef (Jaccard) | β-Diversity inter-reef (Jaccard) | ||||
|---|---|---|---|---|---|
| Fixed effects | d.f. | Wald χ2 | P-value | Wald χ2 | P-value |
| Kelp forest status = St | 1 | 6.746 | 0.0094 | 19.79 | <0.0001 |
| Season = Se | 3 | 11.19 | 0.0108 | 18.50 | 0.0003 |
| Se × St | 3 | 0.799 | 0.8497 | 33.26 | <0.0001 |
| Model | Gaussian (identity link) | Beta (logit link), dispersion modelled as a function of Se | |||