Data from: Disc Mower vs. Bar Mower: Evaluation of the direct effects of two common mowing techniques on the grassland arthropod fauna

In Central Europe, species-rich grasslands are threatened by intensive
agriculture with frequent mowing, contributing to the reduction of
arthropods such as insects and spiders. However, comprehensive and
standardized studies on the direct effects of the two most agriculturally
relevant mowing techniques, i.e., double-blade bar mower versus disc
mower, are lacking. In a two-year experiment, we have investigated the
direct effect of mowing on eight abundant arthropod groups in grassland,
covering two seasonal mowing events in both years, using a randomized
block design. We compared (a) an unmown control, (b) a double-blade bar
mower, and (c) a disc mower. For most of the taxonomic groups studied, a
significantly lower number of individuals was found in the experimental
plots immediately after mowing, regardless of the mowing technique,
compared to an unmown control. This was not the case for Orthoptera and
Coleoptera, which did not show a significant reduction in the number of
individuals for both mowing techniques (Orthoptera) or only for the
double-blade bar mower (Coleoptera). Between both mowing techniques, no
significant differences were found for all taxonomic groups investigated.
Synthesis and applications. Our findings suggest that mowing in general
has a negative impact on abundant arthropod groups in grassland,
regardless of the method used. Tractor-driven double-blade bar mowers do
not seem to be a truly insect-friendly alternative to a conventional disc
mower. Other factors such as cutting height and mowing regimes should be
seriously considered to protect spiders and insects from the negative
effects of mowing. In addition, we highly recommend the maintenance of
unmown refugial areas. Insects and spiders that are spared by mowing can
take refuge in these unmown areas to avoid subsequent harvesting and
thermally unfavourable conditions that arise on mown areas. Further,
unmown refugia are basic habitat structures for a subsequent
recolonisation of mown areas once the flora has recovered.