To graze or to mow? The influence of grassland management on grasshoppers (Orthoptera) on a flood protection embankment in the Donau-Auen National Park (Austria)

Abstract

Introduction Most Central European grasslands crucially depend on land use, and thus there is a need to comparatively analyse the impacts of different types of land use management on grassland biota. Aims and methods We use grasshoppers (Orthoptera), which are the most important insect herbivores in grasslands, and assess the differences of grazing (sheep) and mowing on species abundance, richness, and composition. We use a river embankment in the National Park Donau Auen as study site, where we have established 28 transects. Orthoptera abundance was surveyed 13 times between May and September 2019 in each transect. Results We recorded 24 Orthoptera species, of which 12 species are listed in the national Red List. The most abundant non-threatened species is Pseudochorthippus parallelus in mown transects, while in grazed transects Euchorthippus declivus is most abundant. Eight of the ten most abundant Orthoptera species differed significantly in abundance between mown and grazed transects. Total abundance of Orthoptera was higher in mown transects, while grazed transects had higher species richness. Most xero-thermophilic species were more abundant in grazed transects, while some species of mesic grassland were more abundant in mown transects. These species-level differences resulted in clearly separated Orthoptera species assemblages between grazed and mown transects. Our findings suggest that the less dense vegetation in grazed transects better fulfilled the habitat requirements of xero-thermophilic species compared to mown transects Discussion Given that mown and grazed transects are located adjacent to each other, that the complete study site was mown for many decades and grazing was only started one year before field data collection, the scale of differences in species richness, composition and abundances between grazed and mown transects is surprising. Thus, our findings indicate that grasshoppers respond rapidly to changing land use. Implications for insect conservation We conclude that river embankments can be important secondary habitats for species-rich grasshopper communities. We recommend that grazing should be continued at the river embankment, ideally as rotational pasture as currently done. Mowing should be changed towards mowing parts of the river embankment at different times and leaving small strips of vegetation unmown.

Re‐surveys reveal biotic homogenization of Orthoptera assemblages as a consequence of environmental change

“…bicolor ), which is in the line with previous studies (e.g. Almásy, Essl, Berger & Schulze, 2021; Fumy, Löffler, Samways & Fartmann, 2020; Gardiner, 2018; Weiss, Zucchi & Hochkirch, 2013).…”

Impact of Land Use on Peat Soil Elemental Content and Carabidae and Plant Species Composition and Abundance

“…A study conducted in Austria on grasshoppers (Orthoptera) showed that the average number of species between mown and grazed areas was very similar, while they differed in terms of the number of individuals. The average abundance in grazed transects was about one-third lower than in mowed transects [68]. In a study carried out by Szyszko-Podgórska [59] on land with different economic uses, it was shown that the number of species did not differ much between mowed and unmowed fallow land.…”

Vegetation changes at oligotrophic grasslands managed for a declining butterfly

“…The years 2015-2018 were the driest in recorded history in Central Europe (Buras et al 2020;John et al 2020) and, while the average temperatures rose by 1.1 °C compared to pre-industrial situation globally (World Meteorological Organization 2019), they regionally increased by 2.1 °C compared to mid-20 th century (Czech Hydrometeorological Institute 2022). The small-scale threats stem from the fact that currently practised interventions differ from those that maintained the biotopes in the past (Valkó et al 2018;Almásy et al 2021;Kuhn et al 2021). Light machine-mowing effects differ from those of manual mowing or low intensity grazing.…”