Anthropogenic disturbances shape soil nematode communities in urban green spaces

Increasing urbanization contributes to the fragmentation and pollution of natural habitats. However, urban green space does not only play ornamental and recreational roles but also provides ecological functions such as the conservation of soil biodiversity. Nematodes occupy a variety of trophic levels and play multiple roles in the soil food web, making them critical to soil ecosystem functioning and then the sustainable development of urban green spaces. In this study, individual density, richness, functional guilds, metabolic footprints, and the distribution of soil nematode communities were investigated to explore the effects of mowing and trampling on such communities. In urban green space habitats, the abundance and richness of soil nematode communities decreased along the disturbance gradient. Specifically, all functional guilds of soil nematodes had the lowest abundances in urban green space habitats with the highest disturbance, whereas the decline of omnivores and predators (OP) with K-strategy was more severe than that of nematodes with r-strategy. The maturity index (MI), the structure index (SI), and the carbon metabolic footprint values of soil nematode communities in the less disturbed habitats were higher, which implies a more stable and complex soil food web. Compared to regular mowing, trampling in recreational lawns had more serious impacts on soil nematodes. Soil water content, soil bulk density, plant coverage, and available nutrients, highly susceptible to human trampling, were the primary drivers for the observed pattern of soil nematode communities. Based on our results, a lower mowing frequency, rotational resting periods, the proper retention of plant litter, and the timely recultivation of exposed soil patches are suggested to improve the soil biodiversity conservation and the health of the soil micro-food web in urban green spaces.