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Ausgedehnte Weidelgras-Weißkleeweiden mit Massenvorkommen von Cynosurus cristatus prägen den reliefreichen Standortübungsplatz Hildesheim. Die untersuchten Bestände sind dem Lolio-Cynosuretum Br.-Bl. & De Leeuw 1936 nom.inv. zugeordnet und in zwei Subassoziationen gegliedert: das L.-C. ranunculetosum bulbosi mit Trennarten der Halbtrockenrasen auf Rendzinen des Muschelkalks und das L.-C. typicum auf tiefgründigen Parabraunerden. Als Besonderheiten sind hier Bupleurum tenuissimum und Lathyrus nissolia vertreten. Der hohe Naturschutzwert der floristisch reich gegliederten Weiden wird herausgestellt, die durch die Beibehaltung der extensiven Schafbeweidung langfristig erhalten werden können.
Succession and management of calcareous dry grasslands in the Northern Franconian Jura, Germany
(2009)
The massive decline of calcareous grasslands in the Franconian Jura is caused mainly by land use abandonment and afforestation. In the district Lichtenfels, the northernmost part of the Franconian Alb, management measures were put in action since the middle of the 1980s to conserve or restore those threatened ecosystems. Important actions were removal of trees (mainly Pinus sylvestris) and shrubs as well as reintroduction of sheep grazing. This study analyses the success of restoration measures taken at two Natura 2000 sites. Based on vegetation relevés from 70 sites with different land use histories, we investigate the influence of the successional status of the woodlands prior to clear-cutting and the time period of subsequent grazing on the actual vegetation. The results suggest that both factors influence species composition. On formerly dense pine woodland sites, it takes at least five years of grazing until the number of target species increases. On formerly more sparsely wooded sites, target species establish faster after reintroduction of grazing. Our results show that keeping sites open by tree and shrub removal followed by seasonal grazing are important measures to maintain and restore plant communities of calcareous grasslands in the Franconian Jura.
To examine the necessity of livestock grazing for managing threatened sand vegetation so as to en-sure and develop its nature-conservation value, we investigated a grazing system in a model nature reserve (German upper Rhine valley) characterized by threatened steppic sandy grassland (Allio-Stipetum vegetation complex: Habitats Directive Annex I, priority type 6240, additionally Koelerion glaucae: priority type 6120). The area has been grazed by sheep and additionally by donkeys since late summer of the year 2000. We established ungrazed (Au) and grazed plots (Ag) in the Allio-Stipetum complex in a systematic grid-plot design before grazing impact started. We sampled phytosociological relevés yearly in the Au/Ag plots for 12 vegetation periods. Addi-tionally, we sampled relevés on former farmland adjacent to the Allio-Stipetum complex (systematic grid-plot design) over ten vegetation periods. These former fields (Fg) were integrated in the grazing system since the beginning of the study. A constancy table was produced for Au, Ag, Fg. To determine the portions of target species (Koelerio-Corynephoretea, Festuco-Brometea species) we calculated target-species ratios (proportion of target species in comparison with the total species number; qualitative or quantitative approach: TSRqual/quant). We tested the effects of grazing, year and interactions on structural and phytodiversity characteristics of the relevés by mixed linear models. The results of the long-term experiment confirmed significant beneficial effects of grazing on habi-tat-typical structure and phytodiversity: e. g. reduction of litter, support of species which are short in height (< 20 cm), reduction of taller species (> 50 cm), support of the diversity of all plant species, of non-graminoid herbs and of target plant species, reduction of Calamagrostis epigejos, positive effects on TSRqual and TSRquant values. Similar developments, e.g. for phytodiversity and Calamagrostis epigejos cover, were observed on the former fields, but there are still seed limitations and high ruderal-plant dominances. In general TSRqual/quant show remarkable increases, but do not reach the values of the Ag plots. Concerning aims of nature conservation, the habitat-typical vegetation structure and phytodiversity of the Allio-Stipetum shows an excellent development as a consequence of the used grazing manage-ment. However, occasionally small populations of target species did not increase (e.g. Koeleria glauca). The former fields show a development towards valuable sandy grassland.