Sphagnum cultivation sites as habitat for beetles (Coleoptera) and the effect of vegetation structure on species occurrence and abundance

Abstract

The cultivation of peat mosses (‘Sphagnum farming’) is a new wet and climate-friendly agricultural use of degraded bog sites. However, it is largely unknown to what extent these surrogate habitats are used by bog fauna. This study investigated the potential of Sphagnum cultivation sites as surrogate habitats for beetles and evaluated the relationship between the vegetation structure and the occurrence of beetle species. In 2017 and 2018, comparative surveys were carried out at different sub-areas of two Sphagnum cultivation sites and one near-natural bog. Beetles living in and on the upper Sphagnum layer were studied by manually extracting quadrat samples. Vegetation surveys were conducted in the same quadrats to analyze the occurrence of beetle species based on vegetation parameters. We collected 926 individuals of beetles belonging to 89 species out of 17 families. At the different sections of the cultivation sites, 8–16 bog-typical beetle species were found, while at the sub-areas of the near-natural bog, there were 15 and 19 bog-typical species, respectively. The statistical analyses showed that vegetation structure influenced the numbers of beetle species and individuals at both the cultivation and near-natural sites. Implications for insect conservation A dense and high Sphagnum carpet is a fundamental habitat structure for the beetle fauna of cultivation sites, while vascular plants initially help to create habitat structures on bare peat. Conversely, if the vascular plants overgrow and shade the Sphagnum, this can have a negative effect on bog-typical beetle species, as shown at the near-natural site.