Mat-grass swards (Festuco-Genistelletum sagittalis) of the montane level in the southern Black Forest: Changes of an endangered plant community in the last 40 years Summary We investigated stands of the Festuco-Genistelletum sagittalis in the Black Forest. We were able to compare 60 phytosociological relevés with an average size of 21 m2 for two time windows: 1977–1978 and 2016–2020. The old relevés had been sampled by one of the authors (A.S.). The old relevés were re-sampled considering the topographical situ ation (‘quasi-permanent plots’). Stands of the Festuco-Genistelletum sagittalis belong to Nardetalia communities, which are generally highly endangered. The species-rich types had been classified as priority habitats of the Fauna-Flora-Habitats Directive of the Eu ropean Union (Code 6230). In the south-western part of the Black Forest, the Festuco Genistelletum sagittalis is found mainly in common pasture land. To minimise the parameters for the comparison of Festuco-Genistelletum sagittalis, we re-sampled only those plots which were still characterised by a Nardetalia community. Among the 174 plots that were sampled in 1977–1978, many had developed into other types: they had been, e.g., fertilized or afforested. Once the material was sampled, we compiled the relevés in a presence table, using a classical approach. Additionally, for comparison, we included older relevés from about 1930 to 1975 in separate columns in the same table. In further steps, we compiled the relevés in multivariate ordinations (Detrended Correspondence Analysis, DCA). For dif ferent parameters (also including Ellenberg indicator values), we applied statistical tests (paired exact Wilcoxon rank test in R) and showed the most important results for both time windows in boxplot diagrams. The DCA demonstrates that the new relevés are mostly clearly separated from the old ones, mainly because of the increase in indicator species of nutrient-rich conditions. We elaborated these figures for the south-western Black Forest and separately for the south eastern Black Forest. The ‘Target Species Ratio’ (TSR) is a sensitive indicator for changes in the floristic struc ture, showing the ratio between the target species and all other species. TSR decreased overall, especially with high level of significance in the south-western Black Forest. Montane Borstgrasrasen (Festuco-Genistelletum sagittalis) im südlichen Schwarzwald 341 The following developments could be detected for the 60 plots: • Absence of Antennaria dioica and Jasione laevis in the plots (although sparce pre sence remains in the investigated area) • Change of the ratio between target species and other species (decrease in proporti on, to the disadvantage of target species) • Decrease of the presence and cover of the acidophytic moss Pleurozium schreberi • Increase of indicator species for nutrient rich conditions in all areas and for the south western Black Forest increase of cover of indicator species for nutrients and the moss Rhytidiadelphus squarrosus • Increase of the Ellenberg indicator value for nutrients (N), i.e., increase of indicator species for nutrients • Increase of the cover of Agrostis capillaris • Increase of the Ellenberg indicator value for soil reaction (R) in the south-western Black Forest, i.e., decrease of indicator species for acidity • Occurence in the new relevés of the invasive species Lupinus polyphyllus (alien spe cies: still with small populations and in the study area only locally), a species with N fixing bacteria, which contributes to nutrient enrichments. The increases of Agrostis capillaris and of different nutrient indicator species corres pond to the subtle transition into a new level of eutrophication. Actually a coexistence of most of the Nardetalia target species and the nutrient indicator species is still possible. Some sites remain, either sheltered at the edges of pastures or perfectly managed, whe re Festuco-Genistelletum stands still reflect nutrient poor conditions comparable to the years 1977–1978. We found no clearly provable indications for floristic changes caused by new climate-change processes. Despite these changes, the floristic structure of the Festuco-Genistelletum sagittalis re mains highly valuable for nature conservation as compared with the conditions in other parts of Germany. This still remarkable status with, e.g., large populations of Arnica mon tana and an average number of target species of 9–10 per plot was realised through the efforts of farmers, local government authorities and the successful work of different nature conservation institutions (including management plans and diverse financial sup ports). Grazed sites of the Festuco-Genistelletum fulfill all criteria for ‘high nature value farmland’ and have to be managed mainly by extensive cattle grazing. As a rule manuring is not allowed in the case of such valuable sites in nature protection areas. Nevertheless, nearly hidden developments do exist; e.g., by nutrient transfers of cattle (after additional feeding or when changing from nutrient-rich pastures) or by edge effects by application of liquid manure. This may be strengthened by atmospheric N immissions, which are within the lower zone (8–10 kg N ha-1 a-1, period 2013–15) of the range compared to Germany as a whole. A management plan that considers the nutrient flows carefully should be increasingly integrated to protect those communities that are restricted to nutrient-poor sites.
Keywords Ellenberg indicator values, grazing, mat-grass swards, quasi-permanent plots, target species