Teufelsseemoor Köpenick: A Glacial Kettle Bog and Protected Nature Reserve in Berlin, Germany

The geological history of Teufelsseemoor Köpenick reaches back to the Weichselian glaciation, when advancing ice sheets reshaped the terrain south of present-day Berlin. Pressure from the ice created push moraines that today form the Müggelberge ridge to the south, while a block of ice buried in the landscape later melted in place to leave a deep kettle hole. Over time, this depression filled with meltwater and gradually shifted from a water-filled basin into a fen, then an intermediate bog, and eventually a peat-forming system with peat layers reaching up to roughly 13 meters thick in places.

The more recent, human history of the site is largely a story of damage and subsequent restoration. After the Second World War, approximately 8,000 tons of construction rubble, slag, and tar were deposited in parts of the moor to extend the local toboggan run toward the Teufelssee. These pollutants remained for decades before being removed in 2003 at a cost of about 371,000 euros, marking a major turning point in the site's recovery.

Formal protection followed more than a decade later. On 12 September 2016, the area was designated as a nature reserve under Berlin law ("Verordnung über das Naturschutzgebiet Teufelsseemoor Köpenick") and recognized as part of the European Natura 2000 network. Since then, it has been managed as both a protected landscape and an educational site, including the reconstruction of a boardwalk that had existed for around 25 years before being replaced in 2015. The new boardwalk rests on 240 larch piles driven up to eight meters into the ground and represents a significant investment in making the fragile peatland accessible without compromising its conservation.

Ecologically, Teufelsseemoor Köpenick is a textbook example of a kettle-bog succession in a glacial landscape. The system lacks a natural surface outflow, and its water chemistry has shifted over time from groundwater-fed conditions to a more rain-fed, nutrient-poor, oligotrophic state, supporting the growth of peat mosses and small sedges characteristic of intermediate bog environments. Peat moss cushions and small-sedge communities dominate the open central areas, while peripheral zones host reedbeds, alder swamp forest fragments, and, where groundwater once reached higher, patches of wet woodland.

The combined presence of open water, reedbeds, peat-forming mats, and swamp forest within roughly six hectares gives the reserve an unusually high habitat density for its size. The bog surface is also a habitat for moisture- and light-dependent species such as sundews, and the surrounding transitional zones provide conditions suited to amphibians and dragonflies that depend on cool, fish-poor or carefully balanced waters. Management actions, particularly the thinning of successional trees and shrubs, are explicitly aimed at maintaining open bog conditions and at keeping these specialized habitats from closing over.

The wildlife of Teufelsseemoor Köpenick is shaped strongly by the bog's cold, nutrient-poor water and its mosaic of aquatic, wetland, and swamp forest habitats. The Teufelssee itself supports a population of bitterling, a small freshwater fish typically associated with clean, well-vegetated waters, while the shoreline reedbeds and shallow marsh areas provide breeding habitat for amphibians such as the northern crested newt, the moor frog, and the garlic toad.

Insect life is also a notable feature of the reserve. The large white-faced dragonfly, a dragonfly species closely tied to peatland and bog pool environments, has been recorded in the area, alongside other bog-associated invertebrate communities. Reptiles such as the grass snake are protected within the site, as are ground beetles that depend on the particular microhabitats created by the bog's surface structure. Together, these species illustrate how a small, well-protected kettle bog can function as an important refugium for moisture-loving wildlife even within a densely populated metropolitan region.

The conservation significance of Teufelsseemoor Köpenick lies in the fact that it preserves an almost complete kettle-bog habitat sequence inside the city of Berlin, a setting where such landscapes are extremely scarce. Its dual designation as a Berlin nature reserve (Naturschutzgebiet) and as a Natura 2000 site (DE3547302) recognizes the European-scale value of its habitats, particularly the peat-forming communities, the oligotrophic bog vegetation, and the wildlife they support.

The site also embodies an active conservation case study. The earlier dumping of construction waste into the bog, and its subsequent removal in 2003, demonstrated the seriousness of contamination threats to urban wetlands and helped justify the formal protection that followed. Today, management focuses on resisting succession: maintaining water tables, removing encroaching trees and shrubs to slow forest overgrowth, and preserving the open conditions that bog-dependent species like sundews, moor frogs, and dragonflies require. In this sense, Teufelsseemoor Köpenick functions both as a surviving natural relic of the last ice age and as a working example of small-scale urban peatland restoration.

Although Teufelsseemoor Köpenick is primarily valued for its natural character, it also reflects a distinctive relationship between Berlin residents and the surrounding glacial landscape. The name "Teufelssee," meaning "Devil's Lake," and the broader presence of "devil" place names in the Müggelberge area hint at an older folk tradition of naming unusual, dark, or mysterious local waters and bogs. The postwar use of the bog as informal dumping ground, followed by modern cleanup, conservation, and the construction of an educational trail and forest education cabin, also illustrates how this landscape has shifted, over the span of a single lifetime, from a neglected urban backwater into a recognized piece of protected natural heritage.

Among the most distinctive features of Teufelsseemoor Köpenick are its glacial origins, visible in the kettle hole that became the Teufelssee and in the push-moraine ridge of the Müggelberge rising immediately to the south. Within the reserve, the transition from open water through reedbeds into sedge and peat-moss communities, and then into alder swamp forest, provides an unusually compact cross-section of peatland habitats. The presence of specialist species such as sundews, moor frogs, northern crested newts, and the large white-faced dragonfly gives the site a wildlife profile well beyond what its size might suggest.

Equally notable is the active conservation story: the removal of wartime debris in 2003, the formal nature reserve designation in 2016, and the ongoing forestry work to keep the bog open and wet. Visitors can experience this landscape directly via a roughly 300-meter boardwalk and the surrounding nature trail maintained by the Berlin Forestry Office, making the reserve an accessible example of urban peatland protection.

Teufelsseemoor Köpenick can be visited across much of the year, with each season offering a slightly different experience. Spring and early summer bring active amphibian breeding in and around the Teufelssee and growing reed vegetation, while warm summer days offer the fullest sense of the bog's lush green character and the best chance to observe dragonflies and other wetland insects. Autumn can be a quieter, atmospherically rich time to walk the boardwalk, when sedges and bog vegetation take on warmer tones. In winter, frozen sections of the bog and bare deciduous vegetation offer clearer views of the underlying landforms, though visitors should expect cold conditions in an exposed wetland setting.