The influence of cutting height on arthropods in farm grassland

Abstract The implementation of unmown refuges and higher cutting heights is recommended to protect arthropods from the negative effects of mowing. Although there is some evidence supporting the potential of greater cutting heights in providing suitable habitats after mowing, comprehensive studies on their impact across arthropod taxa are lacking. We have investigated the direct and medium‐term effects of mowing at different cutting heights on the arthropod fauna using a randomized block design and comprehensive taxon sampling. Additionally, we have measured the microclimate on the differently treated plots to ascertain whether microclimatic changes could potentially explain the medium‐term effects of mowing. Mowing at 7 cm cutting height significantly reduced the number of individuals directly after mowing in six of the eight studied arthropod taxa, compared to the unmown control. In addition, mowing at 13 cm cutting height resulted in arthropod numbers intermediate between mowing at 7 cm cutting height and the unmown control. Regarding medium‐term effects (four weeks after mowing), the numbers of vegetation‐dwelling arthropods that depend on plants for food or structure were substantially reduced after mowing, irrespective of the cutting height. The numbers of arthropods inhabiting the near‐ground herb layer and ground‐dwelling taxa seemed to be less affected. Microclimate data suggest that mowing at 13 cm cutting height did not result in more favourable conditions compared to mowing at 7 cm cutting height. However, the unusually wet conditions during sampling may have masked microclimatic differences that might appear in hotter and drier weather.