Table 2.

Effects of N addition on soil microbial OTUs and the α-diversity indices.

Microbial species		OTU	Shannon index	Simpson index	Chao1 index	ACE index
Bacteria	CK	3306.33 ± 64.43a	9.66 ± 0.18a	0.9942 ± 0.0024a	3356.27 ± 61.85a	3412.48 ± 47.62a
	N1	3303.00 ± 75.06a	9.50 ± 0.06a	0.9934 ± 0.0010a	3341.75 ± 72.79a	3400.33 ± 67.51a
	N2	3197.33 ± 150.51a	9.67 ± 0.23a	0.9953 ± 0.0016a	3228.85 ± 161.96a	3268.15 ± 159.76a
	N3	3385.67 ± 66.61a	9.80 ± 0.06a	0.9963 ± 0.0003a	3403.61 ± 54.46a	3452.98 ± 43.04a
Fungi	CK	392.33 ± 31.32b	3.79 ± 0.63a	0.7473 ± 0.1033a	396.56 ± 27.64b	400.90 ± 29.12c
	N1	474.00 ± 8.89ab	3.60 ± 0.71a	0.6658 ± 0.1336a	472.81 ± 8.56ab	496.02 ± 5.60ab
	N2	489.33 ± 31.39a	4.86 ± 0.15a	0.8984 ± 0.0205a	492.15 ± 37.92a	505.42 ± 31.92a
	N3	408.33 ± 22.24ab	3.59 ± 0.25a	0.7572 ± 0.0527a	413.09 ± 21.97ab	425.73 ± 20.38bc
Archaea	CK	27.67 ± 1.67a	2.58 ± 0.24a	0.7699 ± 0.0439a	28.33 ± 2.40a	29.41 ± 3.27a
	N1	28.33 ± 1.20a	2.60 ± 0.13a	0.7770 ± 0.0329a	28.88 ± 0.83a	29.08 ± 1.44a
	N2	21.67 ± 3.93a	1.98 ± 0.33a	0.5960 ± 0.0950a	21.79 ± 4.39a	25.03 ± 2.19a
	N3	24.33 ± 3.28a	2.33 ± 0.15a	0.7237 ± 0.0293a	23.82 ± 3.34a	25.80 ± 4.60a

All data are presented as the mean ± standard error. OTU, operational taxonomic unit. CK, 0 kg N ha⁻¹ yr.⁻¹; N1, 5 kg N ha⁻¹ yr.⁻¹; N2, 20 kg N ha⁻¹ yr.⁻¹; N3, 80 kg N ha⁻¹ yr.⁻¹. Different lowercase letters in the same column indicate significance at p < 0.05.