Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 83. (Budapest 1991)

Kisbenedek, T.: Habitat preference and seasonality of spider (Araneae) communities in dolomitic grasslands

ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 83. Budapest, 1991 p. 253-267. Habitat preference and seasonality of spider (Araneae) communities in dolomitic grasslands by T. KISBENEDEK, Budapest KlSBENEDEK, T: Habitat preference and seasonality of spider (Araneae) communities in dolomitic grasslands. -Annlshist-nat. Mus. natn. hung. 1991, 83: 000-000. Abstract - Community structure parameters (number of individuals, number of species, Margalef's richness index, Shannon-Weaver's diversity index, evenness and Berger-Parker's dominance index) in spiders collected by pitfall traps were investigated in dolomitic grasses in the Buda Hills from April to October in 1988. Habitat and seasonal distribution of guilds defined on the basis of the way of prey catching were artso studied. The largest guild (wandering hunters) could be subdivided into two further guilds according to the part of the day (diurnal and nocturnal hpunters). The activities of the guilds were different in each type of grasslands; diurnal hunters mainly occurred in open, or artially open grasslands, while nocturnal hunters preferred the closed one. With 5 tables and 10 figures. INTRODUCTION Community ecology investigates the organization of communities, the conditions of co-existence, and the causes of patterns evolved in space and time. It studies the relevant biological and physical factors affecting the distribution and abundance of species (DIAMOND & CASE 1986, KIKKAWA & ANDERSON Í986). Interspecific competition within a community was considered as the most important organizing process (MACARTHUR & LEVINS 1967, CODY 1974) and the evolved patterns were considered s a result of competition. According to other researchers (PETERS 1976, WIENS 1977), other processes and factors also exist within the community which prevent the populations to reach the size where competition develops among the species (WIENS 1977). Such factors can be prédation, heterogeneity of the environment, and seasonal distribution. Within the community the most significant platforms of interspecific competition are the guilds, i.e. groups of species feeding on and exploiting the same resources in similar ways (ROOT 1973). Among spiders guilds are separated on the basis of the mode of prey catching and groups defined in this way considered to be exploiting similar resources (BALOGH & LOKSA 1948, ENDERS 1976). Spiders have an essential role in the food-chain being predominantly predators (NENTWIG 1988, RIECHERT & BISHOP 1990). According to investigations in laboratories they are generalists, but field studies found mainly phytophagous and detritophagous Arthropoda in their prey (Nentwig 1988). ENDERS (1975) called attention to the different feeding strategies within a spider community, which help to avoid or reduce competition. UETZ (1975, 1977), TURNER & POLIS (1979) reached similar conclusions studying the microhabitats, seasonal and size distribution in litter-dwelling species. According to their opinion deviations in the distributions along each factors serve to avoid competition.