Table 1. Significant differences of the four alpha indexes among groups.

	Chao1	ACE	PD	Shannon
CCY02	4746.71 ± 155.81a	4825.48 ± 137.84a	179.89 ± 7.65a	9.69 ± 0.16ab
CCY05	4344.43 ± 195.09b	4387.67 ± 188.26b	162.66 ± 4.50b	9.51 ± 0.09b
CCY10	4769.57 ± 164.57a	4886.41 ± 137.82a	178.89 ± 3.22a	9.72 ± 0.06a

Notes.

Values represent the mean ± standard deviation (n = 4). Different lowercase letters within the same column indicate significant differences among different continuous cropping years (Kruskal-Wallis, P < 0.05).