Appendix 3—table 5. Results of mediation tests from structural equation modeling (SEM) analysis based on data using log-response ratio as an effect size.

C statistic and associated p-value for SEM without the path from biodiversity or abundance to decomposition for the four datasets: Stressors - Diversity, Stressors - Abundance, Nutrients - Diversity and Nutrients - Abundance. ΔAIC is the difference in AIC score between models with and without biodiversity- or abundance-mediated effects.

Dataset	C statistic	Df	p-value	$\mathrm{\Delta }$AIC	No. of studies	N
Stressors, Biodiv	4.11	6	0.662	−0.02	22	70
Stressors, Abdc	5.59	4	0.232	−2.22	37	150
Nutrient, Biodiv	8.03	6	0.236	−2.08	14	78
Nutrient, Abdc	3.41	4	0.492	−0.44	21	307