Succession of Diptera on dead beech wood: A 10-year study

Abstract

Summary This study describes the decomposition of dead beech wood and the succession of xylobiont Diptera. Branch wood (∅=4.3–11.5cm) was sampled from two beech trees felled by wind in autumn 1984. In each spring (1987–1995) 6 to 8logs were selected and placed individually in closed emergence traps to collect adult Diptera. Decay state of the logs was described by measuring relative density, water content, bark cover, moss cover, litter cover, carbon and nitrogen contents, C:N ratio, and residual weight. Overall, the environmental factors decreased or increased with log age as expected but variation within cohorts was considerable. For some common dipteran species clear temporal patterns of occurrence were identified, and it was also possible to relate abundances of some species to individual environmental factors. On the community level, mean number of individuals per log tended to increase with log age, suggesting that dead wood becomes a more rewarding food resource in the course of decomposition. Diversity of Diptera measured as the mean number of species per log increased with log age, indicating that resource heterogeneity increased with log age. Diversity of Diptera also increased with water content and moss cover but was negatively correlated with bark cover, C:N ratio, and relative density.