Figure 4: Change in the biodiversity of four soil taxa groups (Acari, Collembola, earthworms, and nematodes) in response to four global changes (GCs). Hedges’ g was used as the effect size. Negative effect sizes indicate that the GC causes a reduction in biodiversity, and a positive effect size indicates an increase in biodiversity. Error bars indicate 95% confidence intervals. Effect sizes where error bars do not cross the dashed vertical zero line, are significantly different from zero. The values of n indicate the number of cases of each taxa group within GC in the model. Grey shading is for enhancing readability only.
The final taxonomic model (containing Acari, Collembola, earthworms, and nematodes data) retained the interaction between the taxonomic group and the GC. Just over half of the groups showed a significant negative decline in biodiversity with the GCs (9 coefficients out of 16; see Table S3 for coefficients, 95% CIs and p-values). Only earthworms showed a significant increase in biodiversity with the impact of nutrient enrichment, which contrasted with the other three taxonomic groups that showed no significant impact from nutrient enrichment.
Finally, for the habitat model containing habitat types, the six-level GCs variable, and the interaction between the two, habitat type was removed from the model as both from the interaction and the main effect.