Table 1.

Summary of meta‐analytic mixed‐effects models testing the relationships between introduced earthworm biomass, density, and ecological group richness and plant diversity, native and non‐native status, and functional group cover of forest understory communities in North America

Response variable	Studies	Observations	AICc	Residual heterogeneity	L
Plant diversity
Plant species richness	13	83	56.1	209.2	0.4
Plant species diversity	10	75	43.0	112.8	0.4
Plant species evenness	10	75	28.2	98.0	0.5
Plant functional groups
Herbaceous cover	11	102	35.5	188.8	3.4
Graminoid cover	9	88	37.1	203.9	1.2
Woody cover	11	102	458.6	816.6	3.4
Plant native status
Native plant cover	10	61	67.1	262.0	7.9
Non‐native plant cover	9	59	60.5	221.4	8.7

Meta‐analytic mixed‐effects models evaluated the size effects representing the association between a measure of introduced earthworm community abundance or structure (density, biomass, richness of earthworm ecological groups) and plant diversity, plant native and non‐native status, or cover of plant functional groups. Plant species diversity is Shannon–Wiener diversity, plant species evenness is Smith and Wilson's evenness measure (‘Evar’; Smith & Wilson, 1996). Residual heterogeneity shows if the variability of the effect sizes not captured by the moderator variables is heterogeneous. The moderator variable in all models was a categorical factor representing measures of introduced earthworm communities. L is the likelihood ratio test statistic for model coefficients. Values of residual heterogeneity and L in black italics indicate statistical significance (α = 0.05).