Roots with larger specific root length and C: N ratio sustain more complex rhizosphere nematode community

Purpose Roots bridge aboveground and belowground systems, and play a pivotal role in structuring root-associated organisms via influencing food resources and habitat conditions. Most studies focused on the relationships between plant identity and root-associated organisms, however, little is known about how root traits affect nematode communities within the rhizosphere. Methods We investigated the relationships between root traits of four plant species and nematode abundance, community structure and trophic complexity in an ex-arable field. Results While the relative abundance of herbivores was negatively associated with specific root length (SRL), specific root area (SRA), root length density (RLD) and root C: N ratio, free-living nematodes were positively affected by these traits, implying a multifaceted effect of root traits on root-associated organisms. Importantly, we found that finer root systems promoted the complexity of rhizosphere nematode community, by increasing the relative abundance of high trophic-level nematodes (i.e., omnivores and predators) and enhancing nematode diversity. Conclusions Our findings suggest that root traits could comprehensively shape soil community structure and interactions, and provide new insights into soil biodiversity conservation and functional maintenance.