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.