S. Mahunka szerk.: Folia Entomologica Hungarica 56. (Budapest, 1995)

Table 1. Descriptions of the main vegetation parameters of the grassland sites (H'= ShannonWiener diversity). Paramaters Alfalfa Pasture-land Meadow Vegetation cover (%) 100 100 100 Vertically levels 1 2 2 Vegetation height (cm) 35^10 10-40 30-100 Plant species 6 13 19 H' diversity 0.6625 1.02 1.1275 day, in the morning and the evening, at each occasion the grazing lasted about 1-2 hours on both of sites. There were 100-150 individuals in the flock. The sites were close to each other, only a road and a narrow small woodbelt separated them. In the AL site (Planatagini-Medicaginetum) the vegetation was almost closed. In the SM (Festuco rubraeCynosoretum) and the PL (Agrostidetum tenuis) sites the vegetation was completely closed. The SM and the PL sites were in a northeast exposition, while the AL in a southwest one. The dominant plant species were Trifolium arvense, Lolium perenne in the AL site Agrostis capHlaris, Achillea millefolium in the SM and Agrostis capillaris, Cynodon dactylon, Trifolium sp., Festuca sp. in the PL. Habitat structure parameters were measured by two or three lxl meter quadrat in each of the sampling units at each sampling times (Table 1). MATERIALS AND METHODS The checklist of the Orthoptera fauna of this region was given by Rácz & Varga (1985). Only the imagoes were identified and considered in the analysis of the family Acrididae, Tettigoniidae, Gryllidae and Mantodea. The species belonging to these groups prefer different grassland habitats in Hungary. The sampling methods of the grasshopper populations and the vegetation were a combination of quadrat and strip transect methods. The collecting of insects was carried out by sweep-netting, in four neighbouring 50x50 metres quadrats on each sampling site. Sampling lasted for at least 30 minutes in every occasion and sweep-netting was performed by two persons. We tried to cover during the sampling time (30 minutes) the entire study plot. The samplings were carried out three times, from July to September in 1991. The sweep-netting method is unfortunately selective to particular grasshopper species, and therefore with this method we cannot catch all of the species present. This selectivity is due on one the hand to the daily activity of the species and their microhabitat preference, and on the other, to the body size of the species, owing to their small size (the males of some species were caught with some difficulty). Eventhough, the method follows the changes of abundance of the grasshopper communities very well. For the analysis of data the cluster analysis of the SYN-TAX III program (Podani 1988) was applied, for the comparison between the places and occasions. The program was applied with the following options: the group average technique for sorting strategy and chord distance coefficient for measuring similarity. No data standardisation was carFolia ent. hung. 56, 1995