3.4 Diversity and composition of soil fungal
community
A total of 2,625,602 fungal sequences were obtained from the complete
data set, of which 2,446 fungal OTUs belonged to 12 phyla, 36 classes,
89 orders, 226 families, and 417 genera. The rarefaction curves of
fungal showed clear asymptotes, which indicated a near complete and true
sampling of the community. The dominant phyla were in the ranking order:
Ascomycota (85.66%-51.53%), Basidiomycota (31.75%-1.64%),
unclassified Fungi (18.34%-3.45%), unidentified (18.07-2.53%), and
Chytridiomycota (2.93%-0.01%), together accounting for >
98% of fungal sequences across all samples (Fig. S1b). Notably, the
relative abundance of Chytridiomycota (p<0.05) decreased
significantly with addition of
amendments, in which C-M-N decreased the most. No significant
differences were observed in Ascomycota and Basidiomycota (except for
unclassified Fungi and
unidentified) at all amended treatments, and Ascomycota decreased with
the N addition. Basidiomycota increased after M addition and decreased
in C and C+N treatments(Table 3).
Alpha-diversity estimated by Chao1 estimator, and Shannon indices showed
significant differences in species richness and diversity of soil fungal
community between different treatment(P <0.05). Chao1
estimator was significantly higher in C (C-N0), C+M2+N (C-M2-N0,
C-M2-N1, C-M2-N2, C-M2-N3) treatments in CK (P <0.05),
in which M2 level supported higher value (highest in C-M2-N0 treatment).
Simpson indices had no significant difference between amended and CK
treatment. Shannon indices were significantly higher in C+M1+N2 and
C-M2-N2 treatment(Table 4).
PCoA analysis based on Bray-Curtis distances accounted for 42.8% of
total variance among the fungal communities, with axes 1 and 2
explaining 23.7 and 19.1% of the variance, respectively (Fig. 4b). PCoA
analysis showed that fungal communities also were divided into three
major groups. All M2-level treatments (C-M2-N0, C-M2-N1, C-M2-N2,
C-M2-N3) tended to group together, M1 level (C-M1-N0, C-M1-N1, C-M1-N2,
C-M1-N3) clustered into another group, and treatments without M addition
(C-N0, C-N1, C-N2, C-N3) were grouped together with
CK(R2 = 0.504 > 0.5,P <
0.001;PERMANOVA,Test statistic= 2.203,P = 0.001). Overall, three
groups exhibited significant differences in fungal community composition
and were separated mainly by M level.