Potenziale und Grenzen der Torfmooskultivierung als Beitrag zum Erhalt der faunistischen Biodiversität von Hochmooren

Species specialised in bogs are often highly endangered and isolated in their populations due to the large-scale, drainage-based use and conversion of their habitats. Nevertheless, only a small proportion of peatlands is available for restoration, as over 75% of peatlands in Germany are currently used for agriculture and forestry. To reduce greenhouse gas emissions from the drainage-based cultivation, paludiculture is being tested as a wet and climate-friendly form of agricultural use. On nutrient-poor bog soils, the cultivation of peat mosses (Sphagnum sp.) has emerged as promising and Sphagnum cultivation sites could provide potential substitute habitats for bog fauna. This dissertation aimed to evaluate the potential of Sphagnum cultivation sites as substitute habitats for bog fauna. For this reason, the occurrence of different animal species groups at Sphagnum cultivation sites and the use as feeding and reproduction habitats were assessed in comparison to restored and near-natural raised bog sites. Additionally, the influence of factors related to site installation- and management (e.g. location, irrigation system, donor material, vascular plant management and Sphagnum harvesting) as well as habitat structural characteristics (vegetation structure) on the occurrence of bog fauna is considered. Recommendations for promoting bog fauna during the installation and management of Sphagnum cultivation sites were derived from the results. The investigation focused on two Sphagnum cultivation sites created on rewetted peat extraction sites in Lower Saxony. Two near-natural donor sites and two rewetted cut-over restoration sites without the introduction of Sphagnum biomass were assessed as reference sites. Area-wide surveys were carried out for birds, amphibians, dragonflies, damselflies and butterflies. The epigeic arthropod fauna living in and on the upper Sphagnum layer were studied by manually extracting quadrat samples. This study shows that Sphagnum cultivation sites offer great potential for creating substitute habitats for some species of bog fauna. Only one to three years after the sites were installed, typical bog species from almost all species groups (except for butterflies) were found at the Sphagnum cultivation sites. These included both bog generalists and specialists, each of which showed a preference for the open, wood-free structures with wet Sphagnum lawns and bog-typical grass stands, as well as the small-structured water bodies of the Sphagnum cultivation sites. From a large-scale perspective, it can be assumed that Sphagnum cultivation sites supplement the landscape with additional habitats and, in particular, promote open land species and selected bog-typical species in their populations. Eleven orders of epigeic arthropods were detected in the Sphagnum donor material during site installation. However, only Araneae, Coleoptera and Hemiptera established with significant numbers of individuals at the Sphagnum cultivation sites during the initial phase. The rapid establishment of suitable habitat conditions, particularly concerning vegetation structure, is essential for successful colonisation. It has been demonstrated that vegetation structure significantly influences both the abundance of epigeic arthropods and the number of beetle species. In the analyses, the height of the Sphagnum lawn proved to be the most important factor influencing abundance and species numbers positively. A negative impact of Sphagnum harvesting on ants (Formicidae) was demonstrated at the near-natural donor sites due to nest destruction. For other epigeic arthropods, harvesting results in a loss of individuals, which are removed with harvested material from the site. If harvesting is staggered in time and space, with some Sphagnum areas always remaining as refuges, the harvested areas will likely be recolonised quickly. However, harvesting does lead to a change in vegetation and habitat structure. Given the potentially increased establishment of Sphagnum cultivation sites and the associated opportunities and risks for the bog fauna, it is crucial to establish nature conservation standards for the installation and management of Sphagnum cultivation sites as a prerequisite for funding in all programs from the outset. The recommendations developed in this work for improving the habitat function and quality of Sphagnum cultivation sites for bog fauna provide indications of the necessary standards and possible further enhancement options.