Overall best solutions of non-parametric multiple regression of potential rates.

The best solution of potential denitrification (DN) and nitrate reduction to ammonium (DNRA) multiple regressions against environmental and biotic variables was found after fitting all possible models and selecting the model with the smallest value of Akaike's Criterion (AIC). %Var: percentage of variance in nitrate reduction rate data explained by the model. 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. RSS: Residual Sum of Squares.