Staggered Mowing of Dikes Aims to Boost Insect Habitat While Preserving Flood Defences

Municipalities across the Netherlands are adopting a new approach to dike maintenance, mowing the grassy verges in stages rather than clearing them all at once. The method is designed to extend the growing season for insects that rely on the vegetation, while still meeting the safety requirements of flood protection.

Ecologist Constant Swinkels of Radboud University explained that regular mowing remains a cornerstone of dike stability. "If you don't mow, trees or sturdy shrubs…" can take hold, potentially compromising the structural integrity of the earthwork. By limiting the height of vegetation, authorities reduce the risk of root systems that could undermine the dike, while still leaving pockets of taller growth for pollinators and other insects.

The staged mowing practice creates a mosaic of habitats along the dike corridors. Some sections are cut early in the season, allowing the remaining strips to flower later and provide nectar and pollen when other areas have already been trimmed. This patchwork benefits a range of insects, from bees and butterflies to beetles, which are experiencing declines across Europe due to habitat loss.

Local water boards have begun to incorporate these ecological considerations into their routine inspection schedules. By coordinating mowing crews to work on alternating sections, they can maintain the required slope and drainage characteristics of the dikes while delivering a longer window of food resources for insects. The approach aligns with broader European Union biodiversity strategies that encourage the integration of nature-friendly measures into infrastructure upkeep.

While the technique is gaining traction, experts caution that it must be carefully monitored. Overgrown vegetation can still pose a threat if it becomes too dense or if invasive species take hold. Ongoing assessments will compare the health of the dikes with insect population surveys to ensure that safety and ecological goals remain balanced. If successful, the practice could serve as a model for other countries seeking to reconcile flood defence with biodiversity conservation.