The diversity of soil mesofauna declines after bamboo invasion in subtropical China

Plant invasions often act as ecosystem 'simplifiers' to simplify diversity and community structure of soil biota. However, inconsistent relationships between plant invasion and soil fauna have been found and few studies have addressed how soil fauna communities change upon plant invasions across taxa and feeding guilds. Here, we investigated the effects of moso bamboo (Phyllostachys edulis) invasion in subtropical China on soil mesofauna communities using novel high-throughput sequencing (HTS). Specifically, we analyzed the spatio-temporal dynamics of fauna diversity and feeding guilds in the litter and soil layers for three stages of moso bamboo invasion, i.e., uninvaded (secondary broadleaved forest), moderately invaded (mixed bamboo forest) and completely invaded (P. edulis forest). Overall, we found that the completely invaded bamboo forest decreased species richness and diversity of total fauna, herbivores, and microbivores consistently across different soil layers, but less so detritivores and predators. Although we did not find any interaction effects of bamboo invasion and soil layers on soil fauna diversity indices, significant interaction effects were found on the community composition, for total fauna and their feeding guilds. Specifically, the detrimental effects of bamboo invasion on the trophic structure of soil fauna communities were more profound in the litter layer than in the soil layer, suggesting that a litter layer with more diverse taxa does not mean higher resistance to plant invasion in maintaining the soil food web structure. Taken together, our findings suggest that different responses within fauna feeding guilds to plant invasion were pervasive, and a deeper soil layer may better alleviate the negative effects of pant invasion on fauna community structure. These shifts in soil biodiversity may further degrade ecosystem functioning.