# Impacts of Millipedes on Acari and Collembola Communities—A Microcosm Experiment

## TL;DR

Millipedes affect soil microarthropods by reducing Collembola in soil while increasing them in litter, and boosting Acari in soil, altering community structures.

## Contribution

This study reveals millipedes' role as ecosystem engineers affecting soil microarthropod communities through non-trophic interactions.

## Key findings

- Millipede activity reduced Collembola abundance and diversity in soil but increased them in the litter layer.
- Acari abundance and diversity increased in soil due to millipede activity.
- Millipedes altered community structures and strengthened correlations between Acari and Collembola.

## Abstract

Interactions among soil organisms are crucial for food webs and ecological functions. However, the effects of millipedes, which play a key role as decomposers in the soil, on soil microarthropods remain unclear. This study demonstrates that millipede activity in the soil decreased the abundance and diversity of Collembola in the soil while increasing their abundance and diversity in the litter layer. Consequently, this led to an increase in the abundance and diversity of Acari in the soil. The dominant species of both Acari and Collembola were most notably affected by the experiment. Millipede activity significantly altered the community structure of Acari and Collembola and strengthened the correlation between these two groups. These findings enhance our understanding of the ecological role of millipedes.

Ecosystem engineers influence the structure and function of soil food webs through non-trophic interactions. The activity of large soil animals, such as earthworms, has a significant impact on the soil microarthropod community. However, the influence of millipedes on soil microarthropod communities remains largely unknown. In this microcosm experiment, we examined the effects of adding, removing, and restricting millipede activity on Acari and Collembola communities in litter and soil by conducting two destructive sampling sessions on days 10 and 30, respectively. At the time of the first sampling event (10 d), Acari and Collembola abundance was shown to increase and the alpha diversity went higher in the treatments with millipedes. At the time of the second sampling event (30 d), millipedes significantly reduced the Collembola abundance and alpha diversity. The results were even more pronounced as the millipedes moved through the soil, which caused the collembolans to be more inclined to inhabit the litter, which in turn resulted in the increase in the abundance and diversity of Acari in the soil. The rapid growth of Collembola in the absence of millipedes significantly inhibited the abundance of Acari. The presence of millipedes altered the community structure of Acari and Collembola, leading to a stronger correlation between the two communities. Changes in these communities were driven by the dominant taxa of Acari and Collembola. These findings suggest that millipedes, as key ecosystem engineers, have varying impacts on different soil microarthropods. This study enhances our understanding of biological interactions and offers a theoretical foundation for soil biodiversity conservation.