Supportive effect of uncut refuge strips on grassland arthropods may depends on the amount and width of strips

Abstract

Vast grassland areas disappear due to abandonment, conversion to arable fields or urban areas. Consequently, grassland species have declined dramatically during and since the last century. The majority of remaining European grasslands are managed, many of them by mowing, which, in general, decreases arthropods' abundance and species richness. Here, we aimed to study the effects of width and proportion of refuge areas on local abundance and richness of arthropods in hay meadows. Within a ca. 4000 ha semi‐natural grassland area of the Great Hungarian Plain, we established refuge strips of different widths (3 and 9 m) and proportion of total field area (10 and 25%) following a randomised block design with six replicates per treatment. We studied five arthropod groups (grasshoppers, true bugs, carabids and ground‐dwelling and vegetation‐dwelling spiders), which we sampled 2 weeks after mowing by sweep netting and pitfall traps. Uncut strips were warmer and moister than the mown areas. The effects of refuge strips and their arrangement were stronger on the vegetation‐dwelling than on ground‐dwelling arthropods, although all taxa were affected in some way. We found more true bugs in mown areas between narrow strips than between wide strips. The interaction effect of width and proportion of refuge strips on the abundance of grasshoppers, ground‐dwelling spiders and species richness of carabids showed that wider strips are more beneficial if their proportion is low and narrow strips are more beneficial with high proportion. Synthesis and applications: Our findings provide evidence that uncut refuge strips can harbour diverse and abundant arthropod assemblages in hay meadows and mitigate the adverse effects of uniformly executed mowing on arthropods. Modifying attributes and considering farming practices, wide strips with a low (10%) proportion of total field area seem optimal for both conservation and practitioners.