The heathland „Oranienbaumer Heide“, former used by Soviet troops as a military training area, is located near Dessau (Saxony- Anhalt, Eastern Germany). As a result, valuable habitat types with rare and endangered plant and animal species have developed and survived there. Today, the area is one of the most habitat and species rich territories in Saxony-Anhalt. The occurrence of habitat types, as according to the European Habitats Directive, such as European dry heathlands, Xeric sand calcareous grasslands (= dry basophilic grasslands), Inland dunes with open Corynephorus and Agrostis grasslands, dry sand heaths with Calluna and Genista as well as the occurrence of bird species like European nightjar, woodlark and red-backed shrike, led to it being designated as a NATURA 2000 region.
As a result of the military abandonment after the political change and the ongoing succession, the valuable habitats and communities were in danger of disappearance. At the beginning of the project in 2008, all protected habitat types showed an unfavorable conservation status, characterized by a lack of gaps (safe-sites) and bare soil, mature and degenerate age stages of heather (Calluna vulgaris), scrub or forest encroachment, invasion of grasses and an increase of ruderal species. The invasive alien tree species black cherry (Prunus serotina) has partly recolonized the heathland.
The aim of the DBU pilot project is the development and implementation of a long-term and sustainable management to maintain the (semi-) open habitat types and their characteristic communities. Therefore, the total area of habitat types has to be preserved according to their status in 2008; changes in the expansion of each habitat are acceptable. A further aim is to improve the conservation status of all habitat types within the area. Thus, we formulated management goals for each habitat type in appropriate time intervals with respect to typical habitat structures, species compositions and the acceptable degree of adverse effects (e.g. scrub encroachment, coverage of grasses). In addition, the further spread of black cherry should be prevented by management measures.
Due to the large-scale area and the danger of munition, in cooperation with the Primigenius Köthener Naturschutz und Landschaftspflege gGmbH (http://www.primigenius.de/ ) we decided for an all-year grazing system with large herbivores (Heck cattle and Konik horses). With an area of approximately 800 ha the Oranienbaumer Heide currently contains the largest year-round pasture in Saxony-Anhalt. Moreover, we tested an all-year grazing in subcontinental heathlands and dry basophilic grasslands in Central Germany for the first time. The target stocking rate is about 0.2 live-stock units per hectare, which will be reached in autumn 2015. Due to the nutrient poor site conditions a higher stocking rate is unrewarding to maintain the habitat types for the long term.
In autumn and wintertime between 2009 and 2015 shrubs and trees were cleared on approximately 550 hectares in all to improve the conservation status of the habitat types. Different concepts and target densities of the tree cover were pursued. The densities depending on the improvement of habitat structures as well as on the habitat requirements of target bird species like woodlark, barred warbler or European nightjar. Furthermore, in 2010, 2012 and 2013 mowing of degenerate heather was carried out on approximately 25 hectares in all to promote their rejuvenation.
To prevent undesirable developments, all management measures are scientifically investigated and evaluated according to nature conservation objectives. A control system has been designed, which is adapted for large-scale areas. On permanent plots (macroplots, size of 1 hectare), appropriate indicators for vegetation structure as well as selected species groups (flora, fauna: butterflies, grasshoppers) are recorded (Figure 1). Survey data of vegetation structure are not only suitable for the evaluation of the impacts of management measures but also for the assessment of the conservation status of habitat types according to the guidelines for mapping of Natura 2000 habitats in Saxony-Anhalt. At regular intervals, all indicators are subjected to analysis of change. In the case of deviation from the objectives, the management has to be optimized, e.g. by adaptation of the stocking rate, changes of the ratio between cattle and horses or application of further supplementary management measures.
Breeding bird species (SPA, red list species) are also investigated for the whole grazing area. Furthermore, habitat selection and feeding preferences of the grazing animals, forage quality of habitat types and nutrient conditions of the soil are examined. Due to the sensitivity of the habitat types towards nitrogen, the local atmospheric nitrogen depositions were recorded between 2009 and 2012. The data were compared with other heathlands in Germany as well as with critical loads for these types of ecosystems.
The grazing management caused rapidly positive trends and dynamic processes. Especially winter grazing led to strong effects on vegetation structure, because grazing animals also use old or dead plant parts.
After 3 years of grazing, the following positive effects could be observed for all habitat types: a substantial reduction of litter material, grasses (in particular Calamagrostis epigejos) and ruderal species as well as a clear increase of gaps consisting of bare soil (safe-sites) due to treading and wallowing of the grazing animals (Figure 1). As a consequence of the varied intensities of use, the grazing animals created a highly diverse vegetation structure. As a result of the very intensive and deep grazing by horses, typical short-grass meadows have developed in some parts of the pasture.
Less competitive species, for instance endangered Ophioglossum or Botrychium species, which require more light, already benefit from the opening of more gaps (Figure 2). The dry basophilic grasslands are more flowery and species rich than at the beginning of the project. Furthermore, an increase of species numbers, especially target species and species adapted to nutrient poor site conditions, was observed for all habitat types (Figure 3).
Whereas the grazing effects in grasslands have been occurred very rapidly, the regeneration of Calluna vulgaris is proceeding slower. First Calluna regenerated in habitats with small-scale mosaics of grasslands and heather. The large-scale heather dominated stands were used by grazing animals only in winter time when other food sources are not available. To initiate Calluna regeneration by treading, animals are attracted in the over-aged heather stands by mineral licks. In addition, heather was mown in some parts of the pasture to accelerate the regeneration and enhance the food quality for the grazing animals. Cattle use more frequently trees, like Silver Birch (Betula pendula) and Aspen (Populus tremula), especially in winter time. Even Scots pine (Pinus sylvestris) is occasionally browsed (Figure 4). The shoots of black cherry, which were cleared before the implementation of grazing, are completely browsed by cattle (Figure 5, 6). Therefore, a further spread of this alien species is likely prevented.
The number of breeding territories of characteristic bird species clearly increased since the implementation of grazing, whereby the highest abundances were recorded on tree cleared parts of the pasture with the longest grazing history. The nutrient poor site conditions of the study area could be preserved as well as reduced in European dry heath and mosaics of heather and dry basophilic grasslands by grazing and additional management measures. The total soil nitrogen content decreased in comparison to the starting conditions without management. This is likely caused by nutrient shifts.
The successive extension of the pasture in 2012 resulted in a temporary under-grazing, which led to a short-term stagnation of grazing effects. Further positive trends are expected by the currently increasing stocking density.
The grazing management is ensured by use of agri-environmental schemes on partial areas until end of 2019. In future years the mowing of degenerated heather should be conducted successively to improve the conservation status of the dry heathlands. Since the end of the DBU-Project in 2011 the management measures are still be scientifically studied and evaluated according to nature conservation objectives until September 2015, funded by ELER Sachsen-Anhalt. Further investigations will focus on vegetative and generative rejuvenation of heather, the impact of grazing on plant species with high nature conservation value and selected animal species groups (birds, butterflies, grasshoppers). In addition, the efficiency of the continuously pasture management regarding to the regrown shoots of pioneer tree species will controlled in cooperation with the manager of the study area.
Further need for research
Further investigations regarding the effectiveness of management measures to maintain European dry heathlands by rejuvenating heather and combat the further spread of black cherry are necessary. Furthermore, there is an urgent need for research with respect to the impact of the grazing management at the landscape scale as well as the effects of the rising groundwater level on the flora and fauna of the Oranienbaumer Heide. In addition to the management with cattle and horses also other agricultural usages, like the production and marketing of heather honey, are conceivable. To this end, studies of the effects of honey bees on wild bee populations of the heathland are required.
Arrival by car
The heathland "Oranienbaumer Heide" is located between Dessau-Rosslau and Oranienbaum-Wörlitz. Coming from Dessau-Rosslau you can get there following the road B107 heading towards Oranienbaum-Wörlitz. You have to pass the traffic light crossing at the Dessora-Park (industrial area) and follow the B107 for further 400 m. Then you will have to turn right to reach a parking area (without liability), followed by a straight forest path. After parking you car you have to follow the forest path on foot or by bicycle for about 1 km. You will finally arrive at the northern boundary of the grazed open-landscape of the Oranienbaumer Heide (Figure 1: northern access, upper red point). Alternatively you can park your car at the railway station "Bahnhof Oranienbaum" and reach the pasture according to the map at the right.
Access on food and by bicycle
Furthermore, the heathland can be reached on food or by bicycle from Jüdenberg or Möhlau following the bikeable walking path Jüdenberger Weg (Figure 1: eastern and southern access, red points).
Project leaders: Prof. Dr. Birgit Felinks (2008 - 2011), Prof. Dr. Sabine Tischew (2008 - 2015)
Researchers: Dipl.-Ing. (FH) Antje Lorenz, M. Sc. René Seifert, M. Sc. Katrin Henning, B. Sc. Susanne Osterloh (2008 bis 2015), B. Eng. Nadine Blume (2011 bis 2013)
Funded by: Deutsche Bundesstiftung Umwelt (2008 - 2011), ELER Sachsen-Anhalt (2009 - 2011, 2011 - 2013, 2013 - 2015), Stiftung Umwelt, Natur - und Klimaschutz Sachsen-Anhalt,
Project partners: Primigenius – Köthener Naturschutz und Landschaftspflege gGmbH,
Cooperation partners: Biosphärenreservatsverwaltung "Mittelelbe", Förder- und Landschaftspflegeverein "Mittelelbe" e.V., Bundesanstalt für Immobilienaufgaben, Bundesforstbetrieb "Mittelelbe", Naturstiftung David