Plant cover rather than species richness drives nematode community structure and function on extensive and semi-intensive roof greening

Abstract

Green roofs are important urban habitats, yet the effects of rooftop vegetation management on belowground communities, particularly nematodes, are largely unknown. In this study, we investigated how nematode community structure, abundance, and functional composition are shaped across four types of green rooftops with different management systems; extensive greening with or without irrigation, semi-intensive greening with either native or neophyte plant species. We also tested the effects of weeding as a common disturbance practice. Management type strongly shaped nematode communities. Extensive roofs supported predator-omnivore rich assemblages, while intensive roofs supported bacterivore-rich communities. Total abundance and α-diversity increased with management intensity. Functional indices indicated a higher maturity and structural indices in extensive roofs compared to intensive roofs. Weeding reduced overall nematode abundance but did not significantly alter their community composition. Plant cover and soil carbon-to-nitrogen (C/N) ratios emerged as good predictors of nematode abundance. High plant cover supported high total nematode densities, while high C:N ratios suppressed abundance. Overall, our results indicate that green roof management types are associated with consistent differences in nematode community structure and functional indices, reflecting contrasting belowground ecological conditions across roof types.