Restoration of raised bogs-Land-use history determines the composition of dragonfly assemblages

Abstract

Even though bogs function as the most important terrestrial carbon store on Earth and play a crucial role in the conservation of highly endangered species, the area covered by peatlands is declining globally. Consequently, numerous restoration efforts within degraded bogs have been realized. In many cases, however, it is unknown whether the conservation measures have been successful. We used Odonata (hereafter referred to as dragonflies) as ecological indicators to evaluate the restoration success of rewetting measures in central European degraded raised bogs. Depending on their land-use history (rewetted industrial peat cuts with and without former agricultural use), two types of bog restoration were compared with rural peat cuts (control). Our study demonstrated that restored bogs are important habitats for dragonfly conservation. Both types of restored bogs were as diverse in overall species richness as the control plots. However, land-use history had a strong effect on restoration success. All raised-bog species of the study area were able to recolonize at least some of the nutrient-poor restored bogs. The situation was different for the nutrient-rich restored bogs. Due to the high nutrient content - caused by the former agricultural use - the characteristic dragonfly fauna of raised bogs will be unlikely to be able to recolonize in these locations in the long term. Nevertheless, the nutrient-rich restored bogs represent an important secondary habitat, especially for transition-bog species. In conclusion, the conducted restoration measures created a network of small oligo- to mesotrophic water bodies, which fosters aquatic macroinvertebrate diversity in bogs.