Boxes with artificial habitats support saproxylic beetles in green areas near and within cities

Sammanfattning: The highest terrestrial biodiversity in Sweden is connected to old grown deciduous trees with tree trunk hollows and dead wood, such as oak and maple. A reduction of deciduous forest and old grown trees from anthropological activities has left many habitats wanting in size and fragmented. Many saproxylic species that are dependent on old grown trees with tree trunk hollows are now threatened. The aim of this study was to further develop artificial habitats (boxes) used for conservation of saproxylic beetles. The boxes were made larger, placed in cities’ green areas and filled with produce from the surrounding areas. The study assessed the effectiveness of these boxes, regarding species richness and composition, compared with earlier studies and tree trunk hollows. The study also aimed to assess what variables might affect the species richness and family and species composition. During April to August 2019, 3454 individuals of 105 saproxylic species were collected in 55 boxes. Of the species dependent on tree trunk hollows, 45% were found in the boxes, compared with tree trunk hollows. Of the variables included shading of the box, the amount of buildings surrounding the box and the amount of forest surrounding the box were found to affect species richness. More shading and a larger forest area increased the species richness in the boxes, and a higher concentration of buildings decreased species richness in the boxes. Conclusively, this study showed that boxes placed in cities’ green areas could act as an alternative habitat for saproxylic beetles.