Variability in arthropod community surveys: observations of ground-dwelling arthropods are dependent on methodological choices

Sampling approaches are commonly adapted to reflect the study objectives in biodiversity monitoring projects. This approach optimizes findings to be locally relevant but comes at the cost of generalizability of findings. Here, we detail a comparison study directly examining how researchers’ choice of arthropod trap and level of specimen identification affects observations made in small-scale arthropod biodiversity studies. Four arthropod traps (pitfall traps, yellow ramp traps, yellow sticky cards, and novel jar ramp traps) were compared with respect to an array of biodiversity metrics calculated at two levels of identification. The arthropod community captured varied by trap type. Pitfalls and jar ramp traps performed similarly for most biodiversity metrics measured, suggesting that jar ramp traps provide a more comparable measurement of ground-dwelling arthropod communities to pitfall sampling than the yellow ramp traps. Identification to the lowest practical taxonomic unit enabled greater insights, including the mobility of arthropods captured in each trap type. This study illustrates the implications for biodiversity sampling of arthropods in environments with physical constraints on trapping, the tradeoffs that come with choices made in experimental design, and the importance of directly comparing adapted methods to established sampling protocol. Future biodiversity monitoring schemes should conduct comparison experiments to provide important information on performance and potential limitations of sampling methodology.