Mortality of ground beetles (Coleoptera, Carabidae) in discarded containers: Evidence from urban forests

Beverage containers are among the most common types of litter found in the environment. They act as ecological traps for ground-dwelling invertebrates; however, their exact effect on particular animal groups remains unknown.
The aim of this study was to assess taxonomic and functional diversities of ground beetles inhabiting urban forests that are threatened with being trapped in discarded containers. We compared assemblage composition and functional traits of ground beetles found dead inside containers with the assemblage inhabiting the surrounding area. The latter were identified using a combination of three sampling techniques: pitfall traps, hand searching and light searching (hand searching at night with a flashlight).
The study took place in Wrocław, Poland in four urban areas, including three that have not been cleaned for many years and one that was regularly cleaned by the local community.
In total, 53 species were detected, 51% of which were confirmed by container sampling, including species of conservation concern. No species were found exclusively in the containers. In uncleaned forests the frequency of containers with ground beetle remains, as well as their number and diversity, was significantly higher compared to the cleaned site.
Our results confirm that discarded containers act as deadly traps for ground beetles in forest habitats. Despite certain methodological limitations, container sampling can serve as a valuable supplementary method for studying ground-dwelling invertebrates, complementing traditional sampling techniques, particularly in littered habitats. Moreover, regularly repeated clean-up actions can help to reduce the mortality of arthropods caused by anthropogenic debris