Arbuscular Mycorrhizal Fungal Community Assembly and Network Stability Across Urban Green Space Types in Heavy Metal-Contaminated Soils

Arbuscular mycorrhizal fungi (AMF) form symbiotic associations with most vascular plants and play an important role in immobilizing heavy metals in soil. Urban green space ecosystems are increasingly affected by heavy metal pollution; however, how different types of green spaces influence AMF diversity, stability, and coexistence mechanisms under heavy metal stress remains unclear. Here, heavy metal-contaminated soil samples were collected from Zhengzhou, China—a large city in the warm temperate monsoon zone of the North China Plain—to conduct high-throughput sequencing and analyze AMF community assembly. (1) AMF community composition varied significantly among green space types, with higher diversity in park green spaces (Shannon = 21.24 ± 2.24) than in street green spaces (Shannon = 11.36 ± 1.17). (2) Heavy metals were the primary factors driving AMF community assembly. Stochastic processes, mainly dispersal limitation, dominated AMF assembly across sites, with a stronger influence in street green spaces. (3) Specialist taxa (mainly Glomus and Claroideoglomus) exhibited higher network connectivity and stability in park green spaces, whereas generalist taxa maintained network resilience in street green spaces. This study elucidates the ecological processes shaping AMF communities in urban ecosystems and provides a scientific basis for AMF-based approaches to heavy metal remediation and sustainable management of urban green spaces.