A recent grassland study has suggested that a varied curved mowing pattern may support bees and butterflies better than conventional block mowing.

Farmers in the Flanders region of Belgium have been involved in research where grass is mowed in curved instead of straight lines.

This approach involves marking a path – a ‘sinus’ – through the field and mowing the area either side in curved lines.

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Researchers compared the impact of block mowing and sinus mowing on wild pollinator species (bees and butterflies) abundance and diversity, looking at six pairs of nearby sites in Flanders.

After collecting baseline data on flora and pollinators, the researchers applied block mowing to one site and sinus mowing to the other within each pair, mowing twice a year from 2019 to 2021.

Surveys

They conducted regular transect surveys on each site to record bee, butterfly and flowering plant species between April and September – the season when bees and butterflies are most active.

In total, they recorded observations of 6,827 bees and 4,918 butterflies.

After one year, they found minimal difference between pollinator counts in each mowing regime.

However, in year two, they observed significantly higher values for abundance, species richness and species diversity of bees in sinus-mown sites.

The results for year three agreed with this positive trend for bees, while butterfly abundance was significantly higher for sinus-mown sites in the second and third years and butterfly species richness and diversity apparent in year three.

Decline

A dramatic decline in pollinating insects has been reported in Europe in recent decades.

In the 2020 European Environment Agency state of nature in the EU report, the conservation status of nearly half (49%) of grasslands was assessed as ‘bad’.