Microhabitat, phenology and diversity of Orthoptera in a seminatural pasture :

Sammanfattning: I have, as a part of HagmarksMistra, studied how conditions for orthopterans differ between two grazing regimes in a seminatural pasture in Harpsund, Södermanland, Sweden. The two grazing regimes were continuous grazing during the whole season and late grazing starting in late July. The late grazing is considered as a possible substitute to traditional mowing as the time-consuming mowing is largely abandoned due to rationalizations in the Swedish agriculture. Meadows are known to contain a high diversity, especially of vascular plants. Other organism groups are also thought to be favoured by this management. The reduction in meadows that are mowed and extensively grazed pastures is hence a threat to biodiversity. In total 12 orthopteran species were recorded in this study, 5 grasshoppers, 2 groundhoppers and 5 bush-crickets. Grasshoppers were more abundant where there were many ungrazed left-outs. Bush-crickets were more abundant where there were many ungrazed left-outs, a higher vegetation, many flowering plants and no shading. Between the two grazing regimes there were differences in vegetation height, number of flowering plants and litter layer, in every case with higher values in the late grazing. There were more bush-cricket species and individuals in the late grazing regime. This can be explained by the fact that the factors that were positively correlated with bush-crickets had higher values in the late grazing regime. For grasshoppers there were no significant differences between the grazing regimes. The results suggest a possibility to manage seminatural pastures to favour orthopterans.