The development of epigeic fauna in new hedges — a comparison of spatial and temporal trends

The colonisation of a linear sequence of nine young hedge plantations (each 400 m2) within an intensely cultivated landscape about 30 km to the west of Bonn has been studied to compare spatial and temporal distribution patterns of epigeic arthropods in order to consider differences obtained concerning an assessment of colonisation characteristics and dispersal trends. The investigation was started in 1982, the year in which the new hedges were planted and continued until 1991. Pitfall traps—usually six as a standard set—were installed in young hedges and in old wooded habitats of an adjacent semi-natural habitat complex, as well as in surrounding arable fields and in meadow strips connecting the hedge plantations. But only in 1990 nearly all the habitats were sampled at the same time. Between 1982 and 1989 catches were continuously performed only in two habitats, since 1986 in four young habitats. Results on species of the taxonomical groups of Carabidae, Opilionida and Araneida show that the analysis of spatial only or temporal only patterns can lead to different interpretations and sometimes wrong conclusions about the colonisation of new hedge habitats. Both types of data, comprehensive spatial and long-term temporal, are complementary and a combination of both is recommended for properly assessing dispersal of species and other dynamic processes in the landscape. As far as the colonisation of new hedges is concerned it is shown that despite high temporal dynamics in species abundances and remarkable differences between the three taxa considered, the development towards a typical hedge fauna progresses very slowly. Small, 9-year-old hedges do not function well as stepping stones for the dispersal of epigeic forest and forest-edge arthropods, and only a small corridor effect could be established for the linear plantation strip. Remarkable differences in colonisation trends between beetle and spider species of similar ecological preferences are discussed.