Wildflower strips and soil fauna: multi-taxa responses to management and consequences for decomposition

Despite being a highly popular topic in agroecological research, the impact of wildflower strips (WFSs) on soil biota and related ecosystem services remains poorly understood. To achieve a more comprehensive understanding, we need long-term studies that combine biodiversity and decomposition data while accounting for the additive effects of management. In this study, we analysed earthworm abundance, species richness and biomass, soil arthropod abundance, and litter decomposition rates in WFSs and adjacent crops across three years, controlling for sowing term and seed mixture effects. Furthermore, we evaluated how contrasting WFS tillage managements (tillage vs. no-till) affect epigeic and soil arthropod communities.

Earthworm abundance, species richness, biomass, and soil arthropod abundance were consistently higher in wildflower strips than in cropped margins. Moreover, the effects strengthen over time, suggesting cumulative benefits from reduced disturbance and the establishment of permanent vegetation. Tillage effects showed taxon-specific responses to disturbances, with carabids, isopods, and other soil-dwelling arthropods being negatively affected. In contrast, taxa less bound to soil stability, such as spiders, exhibited transient rebound dynamics. Undisturbed WFSs showed a lower long-term decomposition rate, suggesting a trade-off between biodiversity gains and decomposition under less disturbed soil conditions.

These results underscore the importance of WFSs for soil biota in agricultural contexts, suggesting that disturbance-sensitive management strategies should be implemented to enhance soil biodiversity. However, the potential trade-offs with ecosystem services, such as decomposition, require further investigation to optimise agricultural practices. Building on these findings, we plan to explore further how changes in vegetation structure influence epigeic arthropods, hypothesising that denser, more structurally complex vegetation promotes higher abundance and diversity.