Baumberge Protected Landscape: Mapping Berlin's Rare Inland Dune and Dry Grassland Ecosystems

The history of the Baumberge is a story of repeated human use that inadvertently preserved their open character. The dunes were originally formed in the late glacial period, but by the early medieval period settlers of the nearby Heiligensee village, founded in the 13th century as Hyelegense, began clearing the surrounding forests for fields, pasture, and beekeeping. Trees were left standing only on the higher dunes, which stood out as wooded hills above cleared heathland and were already labelled Bumberg on the earliest known 1739 map of the Heiligensee field area.

This open state held throughout much of the 19th century. By around 1875 a young forest had grown up on the Baumberge, and by about 1910 they appeared indistinguishable from the surrounding Tegeler Forst on city maps. That changed in 1928 when the site was used as a sand borrow pit for construction of the Kremmener Bahn railway, opening wide forest clearings into the dunes.

During the Second World War and afterwards, the Baumberge were heavily cleared again. From the end of the war until 1994, they served as a French Allied military training ground, and tracked vehicles in particular prevented trees from re-establishing. Illegal motocross and similar uses further kept the sand open. Since 1994, formal nature protection has reduced these disturbances, although the area is still used for local recreation, and conservation management now includes deliberate removal of succession species to mimic the historical open landscape.

The Baumberge landscape is shaped almost entirely by sand. The dunes form parabolic and broader sheets aligned west-east or northwest-southeast, the classic pattern of late-glacial Aeolian deposits on the northern edge of the Berlin glacial valley. The highest crests rise to about 62 meters above sea level, while the lowest point, the Lingenpfuhl basin in the southwest, lies near 32 meters.

Sand thickness is highly variable. On most of the area it is only a few decimetres, but on the highest dunes it reaches around 20 meters. The sands are bright, fine, and mostly calcareous-deficient, with humic bands from fossil vegetation and the locally typical Osteokollen, calcified ancient root traces. In the dune valleys finer-grained valley sands appear, with carbonate layers and silty loam, and beneath the whole complex lies the glacial till that floors the wider Berlin countryside.

The visual character of the Baumberge contrasts strongly with the surrounding Tegeler Forst. Where the forest is dense and closed, the Baumberge offer open sandy expanses, low heather, scattered shrubs, exposed crests, and small dune valleys, giving the site an unusually open, almost semi-arid feeling within an otherwise urban and forested setting.

The ecological identity of the Baumberge rests on their exceptionally nutrient-poor, calcareous-deficient sand and on the persistent openness of the terrain. Four major habitat types coexist in a compact area: open dune sand colonized by pioneers, inland sand heaths dominated by heather and broom, xerothermic dry sand grasslands, and small zones of wet and moist vegetation around the Lingenpfuhl.

The most distinctive vegetation is the subcontinental Blauschillergrasflur, a dry grassland type dominated by Koeleria glauca that occurs in very few localities across Europe and is treated as a priority habitat under the EU Habitats Directive. Other characteristic communities include silver-grass and red bent grasslands, heaths of Calluna vulgaris and Genista species, and, at the margins, scattered Pine, sessile oak, and pedunculate oak stands typical of the Tegeler Forst.

Succession is a constant pressure on the site. Land-reed grass, aspen, black locust, and Scots Pine all push in from the edges and from planted stands. Conservation management therefore includes periodic removal of woody plants and controlled disturbance to maintain the open dune character on which the rare flora depends.

The Baumberge are especially significant for invertebrates that depend on dry, warm, open sand habitats. The site hosts a rich xerothermic fauna of ground beetles, spiders, grasshoppers, butterflies, and aculeate hymenopterans, many of which are highly specialised and stenotopic.

Among the most notable species are the sand earwig, adapted to life in warm sandy soils, the dune tiger beetle, a characteristic predator of open dune surfaces, and all three antlion species recorded in the Berlin region, including the rare dune antlion, which in Berlin has been documented mainly at this site, the Windmühlenberg in Gatow, and the Fichtewiese on the edge of the Spandauer Forst. The Kiesbankgrashüpfer grasshopper, nationally considered endangered, also occurs here.

Protected vertebrates include the sand lizard in dry open habitats and the garlic toad around the wet zones of the Lingenpfuhl. The general bird and mammal fauna largely mirrors the surrounding Tegeler Forst, since many species use the Baumberge as an open structure embedded within a wider forested habitat.

Conservation significance is the core reason the Baumberge exist as a protected area today. The site is designated as a European Fauna-Flora-Habitat area and is part of the transboundary Natura 2000 network. It is one of only two inland dune complexes in Berlin where open sand habitat and dry sand grassland vegetation have survived; the other is the Wilhelmshagen-Woltersdorfer Dünenzug. The priority habitat singled out for special protection is the subcontinental Blauschillergrasflur, a dry grassland type that is extremely rare across Europe.

By 1994, heavy recreational and military use had pushed many xerothermic invertebrate populations into strong decline, and several characteristic plant species survived only in small remnants. Open silver-grass grasslands and dwarf-shrub heaths were particularly affected by drifting sand and by nutrient enrichment from atmospheric deposition, which converted some sand dry grasslands into more nitrogen-loving herb communities at the site margins.

Current official management aims at preserving the open dune habitats, sustaining the Blauschillergrasrasen, heaths and thrift communities, and the silver-grass dry grasslands; promoting open pine stands on xerothermic sites with rich dry-grass understorey; and maintaining acidophilous oak forests on sandy plains where they do not threaten open dune areas. Practical measures include periodic removal of succession species such as reed grass, aspen, black locust, and invasive pine, and the controlled continuation of visitor pressure that helps keep the sands open, with sensitive zones physically fenced off.

The cultural context of the Baumberge is closely tied to the founding of Heiligensee in the early 13th century. As Ascanian margraves brought settlers into the region, those settlers cleared the surrounding forests to create agricultural fields, pasture, and heathland for beekeeping. They preserved trees only on the higher dunes, which then stood out from the cleared surroundings as distinctive wooded hills and gave the site its name: the hills with trees, the Baumberge.

This long pattern of clearance, use, and partial abandonment, followed by 20th-century sand extraction, wartime deforestation, postwar use as a French military training ground, illegal motocross, and finally formalized nature protection, has shaped not only the landscape but the local identity of the area. The site remains a popular local recreation destination, used in conjunction with the Schullandheim school camp within the reserve, and modern conservation efforts deliberately integrate some of that continued human presence into dune management rather than excluding it entirely.

Open inland dune landscape in the northwest of Berlin, within the Tegeler Forst landscape protection area. Home to one of Europe's priority subcontinental Blauschillergrasfluren dry grasslands, a habitat of European conservation concern. Hosts a specialised xerothermic invertebrate fauna including the sand earwig, dune tiger beetle, the nationally threatened Kiesbankgrashüpfer grasshopper, and all three Berlin antlion species. Combines open dune, sand heath, dry grassland, and a wet Lingenpfuhl pond basin in a compact site of roughly 47 hectares.

Late spring and summer are the most rewarding seasons for visiting the Baumberge. From May through August, the sand heaths and dry grasslands are in flower, with heather, broom, and characteristic dune species producing visible color across the open sands, and warmth-loving insects are most active. Sunny summer days also best reveal the unusual, semi-open character of the dunes against the dense surrounding forest.

Autumn and winter visits are quieter and emphasize the dune morphology itself, with bare sand, exposed crests, and sheltering pine and oak stands at the margins. The wet zone around the Lingenpfuhl is easiest to observe in spring, when groundwater conditions and growing bird activity make it more visible, while frozen or snowy conditions in winter highlight the very different microclimate of the dunes compared with the forest around them.