Evaluating the SPRING pollinator monitoring methods in Flanders (Belgium)

Abstract Pollinator decline, driven by various factors such as land use changes, pesticide use, and climate change, poses serious environmental and economic risks, though the specific impacts remain unclear. In response, the European Parliament's Nature Restoration Law (NRL) mandates restoration initiatives and development of standardised pollinator monitoring schemes to determine changes in their abundance. This study evaluates six monitoring techniques for sampling two important pollinator groups, wild bees and hoverflies, as a preparation for the development of a standardised pollinator monitoring scheme in Flanders, northern Belgium (FL‐PoMS). The SPRING Minimum Viable Scheme (MVS), part of the EU Pollinator Monitoring Scheme (EU‐PoMS), served as a baseline, focusing on transect walks and pan traps, while additional protocols were explored to improve sampling performance. We tested these methods at three sites in Flanders (Belgium), assessing their effectiveness in measuring species richness and abundance, cost efficiency and ease of use by volunteers. Pan traps proved most effective for determining bee diversity, and a combined approach of pan traps and transect walks for hoverflies. Factors such as the use of UV‐reflectance, trap installation height and operational time significantly influenced species capture rates. Although transect surveys were generally cheaper, they require expert taxonomic skills in the field. In contrast, pan traps can be deployed by volunteers making them a more cost‐effective option. Furthermore, seasonal variation in pollinator diversity underscores the importance of monitoring throughout the field season. Practical implication. Our findings support the use of a combined approach of pan traps and transect walks to effectively monitor pollinator diversity, especially for bees and hoverflies. However, due to the expertise required, transects are less suitable for large‐scale, volunteer‐based monitoring programmes for these groups. Aligning FL‐PoMS with EU‐PoMS should enable Flanders to evaluate its regional conservation goals and contribute to broader European pollinator monitoring and conservation efforts.