| Summary: | Many of Europe’s day-living butterflies have shown decreasing populations during the last decades and many species are threatened. Many butterflies are dependent on managed semi-natural grasslands because of their richness in nectar sources and host plants for the butterfly larva. Swedish pastures are mostly managed through grazing. The number of cattle in Sweden have been decreasing while the number of sheep in the country increased by 30%. I examined if there was any differences in the butterfly and herb species diversity between pastures grazed by cattle or sheep. During the fieldwork, ten structurally similar pastures in the vicinity of Linköping, Östergötland were studied. Grazing by cattle was favourable both for butterfly and herb species with respect to species richness. Larger amounts of grass biomass and ground coverage by grass were in this study linked to sheep grazing. There have earlier been proposed that sheep graze more selective on herbs in favour of grass, with decreasing amounts of herbs and increasing amounts of grass in sheep grazed pastures, as a result. This theory is confirmed in this paper. The hypothesis that lower amounts of herbs give lower supply of larval host plants, which result in declining populations of day-living butterflies was strengthened by this study.
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