Table 1.

Results of bivariate MA and GLM testing for significant impact of environmental variables on effect sizes of herbivory and fertilization and their interactive effect on richness and evenness of the producer community

Factor	Effects on species richness						Effects on evenness
	Herbivory		Fertilization		Interaction		Herbivory		Fertilization		Interaction
Model	MA	GLM	MA	GLM	MA	GLM	MA	GLM	MA	GLM	MA	GLM
System†	T > F**	T > M > F**	F > T***	/	NS	/	T > F***	/	NS	F = M > T+	NS	/
Productivity (rel. units)	0.062*	0.043+	−0.038*	/	NS	0.081+	NS	/	NS	0.086**	NS	/
Herbivore effect biomass	0.080**	/	—	—	NS	/	NS	/	—	—	NS	−0.081*
Fertilization effect biomass	—	—	NS	/	−0.119**	−0.217*	—	—	NS	/	NS	0.182***
Pielou's evenness (J)	−0.471**	−0.445**	0.267**	0.334**	0.414*	0.435*	—	—	—	—	—	—
Species richness (ln S)	—	—	—	—	—	—	−0.061*	−0.148***	NS	/	−0.144*	/
Experiment duration (ln d)	0.028**	−0.126***	−0.059**	−0.051***	NS	/	NS	/	NS	/	NS	/
Experiment size (ln m2)	NS	/	−0.036**	/	NS	/	NS	/	−0.034*	/	0.036*	0.027*
Latitude,° N or S	NS	/	NS	/		/	−0.004*	/	NS	/	NS	/
F ratio (d.f.)	—	7.46 (5;45)	—	16.68 (2;63)	—	3.53 (3;22)	—	11.92 (1;92)	—	2.30 (3;81)	—	9.23 (3;22)
P	—	<0.0001	—	0.0024	—	0.0316	—	0.0008	—	0.0838	—	0.0004
R2	—	0.453	—	0.346	—	0.325	—	0.115	—	NS	—	0.557

For each response variable, the significant parameter estimates (NS, not significant; /, not included in the final model, –, not applicable) and their significance levels (∗∗∗, P < 0.001; ∗∗, P < 0.01; ∗, P < 0.5; +, P < 0.1; NS, P > 0.1) are given as well as overall model statistics (F ratio with degrees of freedom, significance level, and R²). rel., relative; ln, natural log.

^†Significant differences between terrestrial (T), freshwater (F), and marine (M) ecosystems are shown.