Zur Vergesellschaftung von Gentianella campestris ssp. baltica am Ostufer der Müritz (Mecklenburg-Vorpommern) und bei Ballenstedt am Nordharzrand (Sachsen-Anhalt)

Abstract

Krumbiegel, A.: Socialization of Gentianella campestris ssp. baltica at the east bank of the Müritz Lake (Mecklenburg-Western Pomerania) and near Ballenstedt at the north rim of the Harz Mountains (Saxony-Anhalt). – Hercynia N.F. 41 (2008): 219 -238.Gentianella campestris ssp. baltica is a strongly endangered species both in Germany and in Europe. The reason therefore is the intensive land use which caused the decrease of suitable sites. The remaining places of occurrence in Eastern Germany are concentrating in the Harz Mountains and the northern Harz Mountains foreland (Saxony-Anhalt). In Mecklenburg-Western Pomerania the species only occurs with few individuals in the Müritz National Park on the Spukloch enclosure. The site conditions at the northern Harz Mountains erection zone and at the eastern bank of the Müritz Lake are very different. The investigation of the phytosociological behaviour of Gentianella campestris ssp. baltica at the different sites shall contribute to a better knowledge about the species. Whereas lake sand partly with embedded peat is common on the Spukloch enclosure, which is a terrace of the Müritz Lake, Gentianella campestris ssp. baltica grows on withering substrates of Cretaceous sandstone near the Gegensteine (erection zone of the northern Harz Mountains rim). Two small partial populations of Gentianella campestris ssp. baltica are known on the Spukloch enclosure at present. They show a very broad range of phytosociologically different species. Molinietalia species, indicating moisture and changing moisture conditions, respectively are remarkable at the one place. On contrary, Festuco-Brometea species, indicating dry conditions are of interest at the other place of occurrence. Nardo-Callunetea, Molinio-Arrhenatheretea, Arrhenatheretalia, Brometalia erecti, Arrhenatherion and Cynosurion species add the species inventory on both sites. The phytosociological characterization of Gentianella campestris ssp. baltica on the Spukloch enclosure is difficult because of the very different accompanying species. The vegetation can be classified as poor Arrhenatheretalia basal community most likely and as Festuco rubrae-Cynosuretum cristati R. Tx. in Büker 1942, respectively. The moister place also shows a very diverse species composition, so that it can be characterized as Molinion-Cynosurion-Arrhenatherion mixed stand. The spatial adjacencies to the Parnassio palustris- Molinietum caeruleae suggests the belonging of Gentianella campestris ssp. baltica to this assoziation, too. However, this must still become confirmed with specific relevés. Gentianella campestris ssp. baltica occurs on dry stands around the Gegensteine at the north Harz Mountains rim. Its sites are characterized by Festuco-Brometea-, especially Mesobromion- as well as Nardo-Callunetea-species, and other common species of anthropo-zoogenic heaths and lawns with higher abundance. One of the three stands (Schierberge) can be classified as a transition between Arrhenatherion elatius and Galio-Agrostidetum Mahn 1965 with respect to the rather high amount of Arrhenatheretalia- and Molinio-Arrhenatheretea species. Secondly Gentianlla campestris ssp. baltica occurs within grass rich Euphorbio-Callunetum Schub. 1960 em. Schub. 1995 below the rock formation of the Gegensteine. At the third place (between Gegensteine and Schierberge) the species grows very scattered in denser and higher vegetation (Festuco rupicolae-Brachypodietum pinnati Mahn 1959 em. Schub. 1995). A comparison between Ellenberg indicator values and such values, determined by means of the accompanying species of the relevés showed both rather good correspondency (temperature, [light, continentality]) and clear differences (moisture, soil reaction) based on the average of al 20 vegetation relevés. The ascertained fertility value (3,5) clearly shows the species’ preference of poor stands, however an Ellenberg indicator value of fertility does not exist. Gentianella campestris ssp. baltica is a therophyte. Thus it depends on of scattered, low vegetation which allows annual reproduction from seed. This is illustrated by the one place of occurrence on the Spukloch enclosure, where Gentianella campestris ssp. baltica grows on a cattle track. Similar conditions on principle exist below the rock formation of the Gegensteine, where the grassland and heath are partly mown very near to the ground including soil damage. Extensive grazing or (occasional) mowing for nature protection purposes therefore contributes to conservation or facilitation of the species.