Synopsis/Abstract top ↑
One outcome of the numerically based subdivision of the class Festuco-Brometea is that many of the associations described by various authors as occuring in the study area, can be fused into a small number of well-defined associations. For example, all relevés of continental fairly dry swards (Cirsio-Brachypodion) can be assigned to the Adonido-Brachypodietum. Continental arid swards of the Festucion valesiacae are represented by the Stipetum capillatae and the suboceanic fairly dry swards of the alliance Mesobromion belong the the Gentiano-Koelerietum. Out of the pale fescue rocky outcrop communities (Festucion pallentis) only the Teucrio-Festucetum was investigated in the study area, although the alliance comprises some further associations in central and eastern Germany. For some relevés of the acid soil fairly dry swards (Koelerio-Phleion) from northeastern Germany an assignment to the Sileno-Fetucetum trachyphyllae is discussed, but this evaluation isonly based on a small number of relevés. Likewise, the final assignment of relevés of the suboceanic arid swards (Xerobromion) was postponed to the future due to insufficient data in the database. Stands with Sesleria varia that do not belong to any of the alliances of the Festuco-Brometea were compiled to a large extent to the Polygalo-Seslerietum, which, following the tradition, was assigned to the Mesobromion although the species characterizing the alliance are not present in most of the relevés. For some other classes (Molinio-Arrhenatheretea, Koelerio-Corynephoretea, Calluno-Ulicetea) only vegetation types with transitions to the calcareous grasslands were studied. Consequently, the demarcation of these types can only be provisionally proposed, due to the geographical limitation of the vegetation database.
The classification scheme which was calculated and defined within the extended regional database was applied unmodified to 350 own relevés from the gypsum Karst area at the southern Harz and the Kyffäuser. The resulting vegetation units were evaluated with regard to site conditions based on soil analyses (pH, contents in carbonates, C and N, soil depth, humus form etc.), on measurements of the micro climate and data of the macroclimate.
Within the gypsum Karst area the stands of the order Festucetalia valesiacae (Cirsio-Brachypodion, Festucion valesiacae and Festucion pallentis) reach the western limit of their distribution. This coincides with a higher amount of precipitation and the slightly cooler climate in the western part of this area. The distribution of the order Brometalia overlaps with the area of the Festucetalia valesiacae and reaches much further to the east. The climatic gradient within the investigation area also corresponds to a floristic gradient which, moreover, represents a gradient in species richness with a maximum in the Kyffhäuser area.
A chorological analysis of the flora of the study area shows that the species limited to the eastern parts of the gypsum Karst area have a (sub)meridional to temperate distribution and, independent of their zonal distribution, have a continental to subcontinental range. Species of both types of distribution are concentrated on the warmest and dryest sites within the study area. This fact contributes to the explanation of problems in delimiting the orders Brometalia and Festucetalia valesiacae.
One section of this publication deals with the actual situation of nature conservation in the gypsum Karst areas of the southern Harz and the Kyffhäuser. One of the major problems is the increase in the number of fallow grasslands. In the recent past nature conservation agencies have designed maintenance grazing and management plans to counteract this problem. Nevertheless, the most acute threat for the preservation of the calcareous grasslands of the gypsum Karst areas comes from the increasing exploitation of the gypsum resulting in an irretrievable destruction of the existing vegetation. As a result of the mining activities, many species have become much moe rare in comparison to the past and some are currently even threatened by extinction.