Table 1. ANOVA results of the multiple regression models fitted for the two dependent variables nitrifying and denitrifying enzyme activities for October 2006, using plant diversity components only as explanatory variables.

Nitrifying enzyme activity
Source of variation	d.f.	s.s.	m.s.	F pr.
Spatial variation	4	1.237	0.309	<.001
LogSR	1	0.183	0.183	0.009
Legume abundance (% sown)	1	2.446	2.446	<.001
Residual	69	1.755	0.025
Total	75	5.62	0.0749
Denitrifying enzyme activity
Source of variation	d.f.	s.s.	m.s.	F pr.
Spatial variation	6	14.29	2.38	<.001
logSR	1	0.96	0.96	0.004
SR	3	1.05	0.35	0.025
Presence of legumes	1	2.57	2.57	<.001
Grass abundance (% sown)	1	0.54	0.54	0.027
Residual	63	6.62	0.11
Total	75	26.03	0.35

LogSR and SR respectively refer to the decomposition of the species richness factor into a contrast for log-linear richness and remainder (deviation from log-linearity). For each table, values are presented only for variables that had a significant effect on activity. ANOVA results for 2007 are very similar and are presented in Table S1. d.f.: degree of freedom; s.s.: sum of squares; m.s.: mean sum of squares; F pr.: significance level (F-test).