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Drainage and afforestation of peatlands cause extensive habitat degradation and species losses. Restoration supports peatland biodiversity by creating suitable habitat conditions, including stable high water tables. However, colonization by characteristic species can take decades or even fail. Peatland recovery is often monitored shortly after restoration, but initial trends may not continue, and results might differ among taxonomic groups. This study analyzes trends in plant, dragonfly, and butterfly diversity within 18 years after rewetting of montane peatlands in central Germany. We compared diversity and species composition of 19 restored sites with three drained peatlands and one near‐natural reference site. Restoration resulted in improved habitat conditions and benefited species diversity, but there were marked differences among taxonomic groups. Dragonflies rapidly colonized small water bodies but their diversity did not further increase in older restoration sites. Characteristic peatland vegetation recovered slowly, since it depended on a high water holding capacity that was only reached after peat started accumulating. Generally, plant diversity developed toward reference conditions albeit incompletely, even 18 years after restoration. Butterflies responded less to peatland restoration; generalists increased only temporarily and specialists could not establish. In conclusion, peatland restoration improves habitat conditions and biodiversity, while trajectories of recovery are nonlinear and incomplete after two decades. This highlights the need for long‐term monitoring and a strategic selection of indicator species for evaluation of restoration success. [ABSTRACT FROM AUTHOR]

Abstract: Grassland restoration on arable land is the second most implemented compensation measure in Germany to counteract impacts of infrastructural projects on nature. Most grassland restoration has been carried out using standardized commercial seed mixtures with large amounts of perennial generalists, cultivars and seeds of non-local origin. To evaluate whether this current practice is appropriate for developing regional types of species-rich mesophile grasslands, we analyzed four widely used treatments in a real-world setting (48 plots): (1) sowing a non-site-specific herb-poor mixture; (2) sowing a non-site-specific herb-enriched mixture; (3) sowing a site-specific herb-enriched mixture; and (4) spontaneous regeneration. After up to nine years, restored sites differed from target grasslands in: (1) number of species; (2) abundance and dominance of target species; and (3) dominance structure. Sown fields were dominated by sown species from the beginning. Because most differences were due to increasing cover of a small number of sown species, we found little development toward regional types of species-rich mesophile grasslands. In contrast, species composition on spontaneously regenerated sites changed to a greater degree and showed gradual development toward target grasslands. The limiting factor for successful restoration on all sites was availability of propagules. On sown sites, dominance patterns – particularly of Festuca rubra cultivars – had a negative effect on immigration and development of target species. For future restoration practice, we strongly recommend avoiding standardized commercial non-local seed mixtures. In particular, highly competitive cultivars should never be used. Even spontaneous regeneration should be preferred over standardized mixtures. However, in species-poor environments enrichment with selected species is necessary to reach target state. [Copyright &y& Elsevier]

1. Classical ecological theory predicts a succession towards plant communities that are determined by environmental conditions. However, in ecological restoration, species composition often remains different from the predicted target community, compromising the success of restoration measures. 2. We analysed the relative importance of environmental conditions, management and distance to source populations for floodplain grassland succession following re-conversion from intensive to traditional use. The study was established at 33 grassland sites in central German river valleys. Species composition, environmental variables, past and current management, and the distance to source populations of characteristic species of traditional management (indicator species) were recorded and compared using multivariate statistics. We further tested the speed of colonization by two indicator species, Silaum silaus and Serratula tinctoria, along transects from source populations into unoccupied fields. 4. The species composition of the successional grassland was mainly determined by elevation, total soil nitrogen, distance to remnant species-rich grasslands and frequency of mowing or grazing. Elevation and distance were negatively, and frequency was positively related to the occurrence of late successional species. 5. Colonization by indicator species was only dependent on the distance to source populations; other explanatory variables were not significant. Migration from adjacent source sites of S. silaus and S. tinctoria into re-converted grasslands was slow, reaching only 40 m and 15 m after 15 years. 6. Synthesis and applications. The results demonstrated the limitations of the deterministic view on plant succession and the high relative importance of propagule availability in grassland restoration. Natural colonization will only be successful if source populations of the target species are adjacent to the restoration sites. Artificial introduction techniques are recommended to overcome dispersal barriers. [ABSTRACT FROM AUTHOR]

In 1993, experiments on the restoration of calcareous grasslands on ex-arable fields were started in order to provide new habitats for species of a small nature reserve with ancient grasslands north of Munich (Germany). The effects of diaspore transfer by the application of seed-containing hay on vegetation establishment were studied on restoration fields with and without topsoil removal for 5 years. The aim of the study was to assess plant diversity for the evaluation of restoration success by different methods including determination of species with viable seeds in the hay by germination tests, phenological investigations on hay-transfer source sites at the time of harvest, and vegetation analyses on the restoration sites. Total seed content of the hay and the number and composition of plant species with viable seeds were affected by the time of harvesting and differed between a site which had been used as arable field until 1959 and ancient grassland sites. Nevertheless, the number of established hay-transfer species showed only few differences between restoration fields. The proportion of species transferred to restoration fields in relation to the number of species with viable seeds in the hay was between 69 and 89%. Five years after the hay transfer, the proportion of the established species was still between 58 and 76%. Up to now, topsoil removal had no significant effect on the number of established hay-transfer species. After triple hay application the absolute number of transferred grassland species was higher than on sites with single hay application, but restoration efficiency was lower because many of the species with viable seeds in the hay did not establish. In general, our results showed that the transfer of autochthonous hay is a successful method to overcome dispersal limitation in restoration projects. [ABSTRACT FROM AUTHOR]

Land-use change has been identified as the most important factor responsible for the recent loss of biodiversity. One major problem is the abandonment of management, especially in semi-natural grassland ecosystems. Numerous restoration projects were, therefore, launched to counteract this development. However, the effects of restoration are not yet fully understood. Especially the early successional stage, i.e. the composition of the vegetation in the first years after the restoration measures, has received little attention probably due to its supposedly low conservation value. As study area, we selected the largest area of calcareous grasslands at the northern edge of the German uplands. About 35 ha of formerly abandoned calcareous grasslands have been restored by cutting shrubs here in the last eight years. Within the restored sites, 50 randomly chosen vegetation surveys were made and the results were compared to 50 control plots. Our study revealed that the value of the early successional stage for biodiversity conservation was previously underestimated. Even though the target state – calcareous grassland – is far from being reached, the early successional stage enhances the conservation value of calcareous grasslands by (i) increasing diversity at the landscape scale, (ii) hosting numerous target species as well as (iii) contributing to a higher habitat quality and heterogeneity. Future restoration of calcareous grasslands should focus on sites with low nutrient content of the soil, a shallow topsoil, and a warm microclimate. At such sites, the chances are greatest that species with a high nature conservation value, i.e. characteristic species of calcareous grasslands as well as thermophilous fringe and ruderal species, will re-establish. • Large-scale restoration study within one of the largest calcareous grassland areas of central Germany • The restored sites in their early successional stage increased phytodiversity. • They were characterised by a mixture of plants from many different ecological groups. • Number of thermophilous fringe and ruderal species was highest within the restored sites. • Restored sites harboured a high number of functional plants such as pollen sources for specialised wild bees. [ABSTRACT FROM AUTHOR]