Marginal tests of non-parametric multiple regressions of potential rates.

Potential denitrification (DN) and nitrate reduction to ammonium (DNRA) multiple regressions against environmental and biotic variables for each variable taken individually (ignoring other variables). %Var: percentage of variance in nitrate reduction rate data explained by that variable. There were two groups of highly collinear (r>0.9) variables [napA1, napA3, narG1, narG2, nrfA] and [nirSm, nirSn]. Only one variable from each group was included. Functional gene abundances were ln(x+1) transformed. SS: Sums of Squares. Significant relationships are noted with asterisks p<0.05: *, p<0.01 **, p<0.001 ***.