Abstract
Abstract. Extensively managed grasslands, particularly in mountain regions, are considered to be one of the most diverse agroecosystems worldwide. Their decline due to land use abandonment affects the diversity of both plants and associated pollinators. Extensive grasslands constitute an important habitat type and food resource for hoverflies (syrphids); however, not much is known about the effects of abandonment on this important pollinator group. In the present study, we investigated how abandonment affects species richness and the composition of syrphids in mountainous meadows. We recorded the richness of vascular plants, vegetation cover, flower cover and the surrounding landscape to examine whether and how syrphids are affected by plant and landscape parameters. We investigated the species richness, abundance and species composition of syrphids by sweep netting and by using observation plots in 18 semidry meadows across two Austrian regions and one Swiss region. For each region, we selected three meadows abandoned for more than 20 years and three annually mown non-fertilized meadows. Abandonment or mowing had no significant effect on the total number of syrphid species or individuals or on the number of aphidophagous and non-aphidophagous species and individuals. However, the total number of species and the number of non-aphidophagous species significantly increased with the increasing number of plant species. The surrounding landscape and other plant parameters showed no association with the assessed syrphid parameters. Although syrphids were unaffected by abandonment, higher syrphid species numbers in response to a higher plant richness in annual mown meadows suggest that the management of mountain meadows is beneficial in preserving syrphid richness.
Highlights
Seminatural grasslands are considered one of the most valuable agroecosystems throughout Central European landscapes and are characterized by a high biodiversity (Chytrý et al, 2015; Habel et al, 2013; Maurer et al, 2006)
Regarding the total number of species and individuals, we found no differences between both meadow types
There is a very important contribution by Kök et al (2020) which focused on the tritrophic relationships between plants, aphids and hoverflies. They found that plant species host different aphid species which in turn are a suitable prey for the larvae of aphidophagous hoverfly species like Sphaerophoria scripta and Episyrphus balteatus
Summary
Seminatural grasslands are considered one of the most valuable agroecosystems throughout Central European landscapes and are characterized by a high biodiversity (Chytrý et al, 2015; Habel et al, 2013; Maurer et al, 2006). Extensive management by mowing or grazing is an important management scheme to maintain these habitats of high nature conservation value (Hansson and Fogelfors, 2000; Moog et al, 2002) Most of these grassland habitats have a long history and were maintained by local farmers for hay making and animal husbandry over hundreds of years (Chemini and Rizzoli, 2003; Poschlod and WallisDeVries, 2002). Since their conservation relies strongly on human land use activities, they are considered seminatural habitats (Heijcman et al, 2013). To increase the yield, new agricultural and cultivation techniques were developed which have led to an intensification of grasslands in favorable regions on the one hand and afforestation or abandonment in marginal
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