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Summary 0[ Dipteran communities were studied in _ve terrestrial habitats ðbeech forest "BE#\ oak and hornbeam forest "OH#\ hedgerow "HE#\ meadow "ME#\ alder and willow forest "AW#Ł using emergence traps and diversity patterns of three trophic groups with soil!dwelling larvae "zoophages\ phytosaprophages and surface scrapers# were analysed in detail[ 1[ Across habitats\ sampling e}ort was a poor predictor of species richness\ and species richness increased more steeply with sample size in the zoophages than in the phytosaprophages and surface scrapers[ 2[ Point diversity "S:trap# of phytosaprophages and surface scrapers increased "as predicted# with resource heterogeneity in the litter layer\ but that of zoophages did not[ It is suggested that this may be due to di}erential resource requirements of the three trophic groups during adult life[

Abstract. The spider community of a beech forest on limestone was studied for one year using four sampling techniques: emergence traps, pitfall traps, soil samples, and arboreal eclectors. 87 spider species were recorded. Emergence traps and arboreal eclectors were particularly efficient in detecting spider species. Dominance identity (percentage similarity) was highest for catches from emer gence traps and pitfall traps. Species recorded were assigned to various ecological groups. In terms of proportional abundance, repre sentation of the ecological groups varied and appeared related to the sampling method used. Stratum type and type of prey capture strategy accounted for >60% of the variance in the catch results (canonical correspondence analysis). Proportional abundance of funnel-web spiders was much higher in pitfall trap catches (31.7%) than in any other method (1.0-11.6%).

Adult Ceratopogonidae were sampled using emergence traps in four terrestrial habitats (1986–1989). The number of species (S) was low in the mesoxerophytic meadow (S = 8) and the hedgerow (S = 2), compared to the alder/willow forest (S = 12) and the oak/hornbeam forest (S = 14) studied. Annual emergence abundance of adults was usually higher in the two forest habitats (33 to 194.0 ind./m2/y) compared to the meadow (0.5 to 40.7 ind./m2/y) and the hedgerow (3.3 to 15.1 ind./m2/y). The two forest habitats were fairly similar with respect to species composition but differed in dominant species. Emergence of most species peaked in spring (April/May) and/or in summer (July/August) but Serromyia species emerged mainly in June.

The food web centering on Allium ursinum (Liliaceae) in a beech forest (Germany) is described, and temporal variation of active trophic links is related to species' life cycles. The most important insect herbivores are Cheilosia fasciata (a larval leaf miner) and Portevinia maculata (a larva bulb miner) (Diptera: Syrphidae). Energy, carbon and nitrogen flow in the food chain (Allium-Cheilosia-Phygadeuon ursini) are investigated and analysed with respect to differences in resource allocation by the leaf miner and its hymenoptereous parasitoid. In C. fasciata nitrogen is likely to be the limiting resource, while growth in Phygadeuon ursini appears energy-limited. Larval feeding habits of C. fasciata and Portevinia maculata determined the timing of the species' life cycles and, as a consequence, appeared to preclude the existence of a pupal parasitoid in Portevinia maculata. Further details of life history traits are demonstrated and discussed.