Effects of grazing on orthopteran assemblages of Central-European sand grasslands

Abstract

The effect of grazing on Orthoptera assemblages has long been the focus of research worldwide due to the high sensitivity of orthopterans to changes in vegetation structure. According to previous studies, grazing has individual, spatially-different effects on orthopteran assemblages. The current case study was carried out between 2012 and 2016 in a subarea dominated by open sandy grasslands in the Carpathian Basin. The ~70 ha study area was grazed by 250–300 sheep in 2012. In the beginning of 2014, the overgrazing pressure was overall reduced, for the most part, in the examined grassland patches. The study aimed to answer how the complete abandonment of grazing and moderate grazing influences the species richness, diversity and density of the orthopteran assemblages. Investigations in Central European sand steppes confirmed that both intense grazing and the abandonment of grazing have a detrimental effect on the structure of orthopteran assemblages: (a) the Shannon diversity index was higher on moderately grazed sites than on grazed and ungrazed ones; (b) the number of habitat specialists of sandy grasslands was higher on moderately grazed patches than in grazed habitats; and (c) the frequency of geophilic species was higher on grazed patches than on moderately grazed and grazing-abandoned ones.