S. Mahunka szerk.: Folia Entomologica Hungarica 52. (Budapest, 1992)

FOLIA ENTOMOLOGICA HUNGARICA ROVARTANI KÖZLEMÉNYEK LH (1991) 1992 p. 51-58 Structure of grasshopper (Orthoptera) communities in relation to ecological succession of dolomitic grasslands By T. Kisbenedek (Received March 15, 1991) Structure of grasshopper (Ortlxoptera) communities in relation to ecological succession of dolomitic grasslands - Late summer grasshopper comunities were compared to each other according to some structure parameters. Grasshoppers were counted abng 1 m wide transects in southwestern- and north-facing sites, and in different successional stages of dolomitic grasslands in the Buda Hills, Hungary. Community structure parameters revealed high similarity of communities related to the dolomitic succession, but showed a high dissimilarity between these sites and the north-facing site. While diversity showed a positive linear relationship with plant cover, dominance (Berger-Parker index) of species changed in a negative manner. Introduction The vegetation structure and its changes fundamentally influence the organization of animal communities. One of the most direct relationships between plants and animals is that connected with the food chain of organisms, the so-called phytophagy. As the ecological succession proceeds the interactions among the living organisms become in general more heterogenous and multi-layered (Odum 1969). The vegetation cover and diversity of the plants increases (Bach 1990), and the change of vegetation architecture also considerably affects insect communities (Lawton 1983, Stinson and Brown 1983). Taxonomic and trophic diversity of insects also increase during the ecological succession (Brown and Southwood 1983), moreover, phytophagous insects themselves affect the succession of plant associations, too (Bach 1990). In the present study I analyzed the structure of grasshopper communities in different stages of dolomitic succession. The correlation was examined between each of the three grassland associations on dolomite and the relating grasshopper communities, according to how the structure of grasshopper communities changes with increasing vegetation cover, diversity and vertical structure. Study sites The study was carried out in the Buda Hills (4° 35' N, 18° 90' E), on the so-called Odvas Hill, and on the Kutya Hill, the Odvas Hill is found in west and the Kutya Hill is found in northwest direction from Budapest, about 10 km and 20 km far from the town, respectively, and about 12 km far from each other. Both of them have dolomite rock. Responding to rainfall this rock quickly crumbles and breaks. As a consequence of this process the plants can hardly bind the soil, therefore, slopes are strongly eroded and quite