Table 2.

Summary of the phylogenetic distribution of nirS OTUs in 18 clusters represented in six clades on the phylogenetic tree (Figure 8).

Cluster	Number	Clade	C	LF	HF	XF
	of OTUs
1	23	1	1	2	974	2435
2	13	2	1	5	10	3
3	109	3A	4527	2758	2666	1160
4	26	3B	28	722	451	1
5	18	3B	2789	1819	2829	525
6	10	3B	0	1	100	6
7	69	3B	988	1566	237	2274
8	80	3B	5661	5432	659	702
9	108	3B	1975	266	2758	5580
10	42	3C	138	354	1393	74
11	8	3D	2	2	12	1
12	5	3D	1	0	11	4
13	13	3D	365	543	290	24
14	11	3D	5	7	15	0
15	21	3D	128	36	90	289
16	7	3D	1	3	8	15
17	16	3D	247	4035	4121	19
18	6	3D	2	3	8	15
Unaffiliated	53		19	201	55	2780

For each cluster information is provided on the total number of OTUs per cluster, the representative clade, and the number of sequences found in each of the treatments. Unaffiliated OTUs are those distributed throughout the phylogenetic tree but that did not cluster with any of the other groups.