Fogging and Flight Interception Traps-The Evaluation of Two Methods to Collect Canopy Arthropods

The forest canopy is a crucial habitat for a wide variety of species. However, it remains difficult to assess due to significant methodological challenges and uncertainties. Flight intercept traps (FITs) and insecticidal knockdown (FOGGING) are among the most widely used techniques for sampling canopy arthropods, yet systematic comparisons of their taxonomic and ecological coverage remain scarce. We sampled arthropods over 3 months in nine forest plots in the Schorfheide-Chorin Biosphere Reserve, Germany, using both methods on two dominant tree species. A single FIT covered only a small portion of the crown and yielded on average ~100 individuals per month, dominated by Diptera, with a June peak of Coleoptera. In contrast, FOGGING targets entire tree crowns, capturing 1000 individuals on average, providing a broader and more balanced representation of arthropod communities across orders throughout the season. When Coleoptera was used as the target taxon, FOGGING achieved substantially higher sample coverage across families, genera and species than FITs, which primarily collected highly mobile taxa (e.g., Elateridae) and xylobionts (e.g., Scolytinae). FITs exhibited higher beta diversity, reflecting the stochastic sampling of rare species. In contrast, FOGGING sampled more consistent communities with lower turnover. Community-level metrics, including diversity, rank-abundance structure and trait composition (e.g., body size and functional guilds), also differed significantly between the two methods. Our results suggest that FOGGING provides a more comprehensive representation of the taxonomy and ecology of canopy arthropod communities, offering a stronger basis for ecological conclusions. Our findings are consistent with previous research indicating that the two sampling methods complement each other rather than being interchangeable. This emphasises the importance of carefully tailoring sampling methods and trap types to specific research questions.