Table S1.

Variation explained by the environmental variables in the distance-based regression models of Bacteria and Archaea composition by N pathway

Environmental variables	Ammonia assimilation	Assimilatory nitrate to nitrite	Assimilatory nitrite to ammonia	N fixation	Nitrification	Dissimilatory nitrate to nitrite	Denitrification	Dissimilatory nitrite to ammonia
Habitat	0.06	0.14	0.07	0.04		0.07	0.05	0.04
Precipitation	0.02		0.02	0.01	0.03	0.01	0.02	0.01
Temperature	0.01	0.03	0.03	0.01	0.11	0.02	0.03	0.01
Soil pH		0.02			0.02
Organic C				0.01	0.02	0.01	0.01
Total N					0.02	0.01	0.01	0.01
Adjusted R2	0.09	0.18	0.11	0.07	0.19	0.12	0.12	0.06

Estimates of the variation explained are reported for significant variables (P < 0.05, bold type) and marginally significant variables (P < 0.1). Samples were only included when all environmental variables could be obtained for that location (n = 99).