Long-Term Nickel Contamination Increased Soil Fungal Diversity and Altered Fungal Community Structure and Co-Occurrence Patterns in Agricultural Soils

Nickel (Ni) contamination imposes deleterious effects on the stability of soil ecosystem. Soil fungal community as a crucial moderator of soil remediation and biochemical processes has attracted more and more interests. In the present study, soil fungal community composition and diversity under long-term Ni contamination were investigated and fungal interaction networks were built to reveal fungal co-occurrence patterns. The results showed that moderate Ni contamination significantly increased fungal diversity and altered fungal community structure. Specific biomarkers were selected by Linear discriminant analysis effect size analysis. Functional predictions based on FUNGuild suggested that the richness of symbiotrophic fungi significantly increased at moderate Ni contamination level and then decreased at heavy contamination level. Ni contamination strengthened fungal interactions. Keystone taxa at different Ni contamination levels, such as Penicillium, were identified, which might have ecological significance in maintaining the stability of fungal community to Ni stress. The present study provided a deeper insight into the effect of long-term Ni contamination on fungal community composition and co-occurrence patterns, and was helpful to further explore ecological risk assessment in cultivated field