Sharp but consistent fungi species composition transition during a 40-yr urbanization in a subtropical city of China.

Background: Rapid urbanization has profoundly impacted soil fungal dynamics and thus soil health, however, it remains poorly addressed due to lack of ideal experimental region. Taking Shenzhen of China, a megacity built within 30 years, as the study region, we analyzed the effects of rapid urbanization on soil fungal diversity, species composition, and community stability from the perspective of urbanization stages (within 10, 10-20, 20-30, 30-40, and over 40 years of urbanization), and original (forests, paddy fields, and drylands) and present (parks, streets, and residential areas) urban land-use types.

Results: Results showed that soil fungi of urban areas had significantly lower Chao1 and phylogenetic diversity (PD) than that of natural ecosystem (P < 0.05), i.e., forests in this study, with the lowest PD in street. The urbanization-induced higher phosphorus (P) content and thus lower soil N/P may explain the lower PD in city areas (P < 0.05). As the urbanization proceeded, soil fungal species composition shifted and resilience stability reduced significantly within 10 years (P < 0.05) compared with forests, but then the composition gradually transitioned to a consistent state while stability recovered to a certain extent for the rest of the urbanization stages. Key phyla driving these results included Ascomycota and Mortierellomycota. Original land-use types did not significantly affect urban soil fungal diversity or composition (P > 0.05). However, SparCC-based network analysis revealed no significant differences (P > 0.05) in fungal co-occurrence patterns or stability across different land-use types and urbanization stages, suggesting that urbanization may not strongly restructure fungal interaction networks.

Conclusions: Our findings shed new lights on the scientific understanding and the urban spatial planning when considering soil health under the context of rapid urbanization. Additionally, they emphasize the need to incorporate multiple analytical approaches when studying microbial community interactions.