Naturschutzgebiet Schatthangwald Röhre Nature Reserve and Protected Limestone Landscape Atlas

Schatthangwald Röhre is best known for its shaded limestone slope forest and for protecting the entrance zone of the Große Sunderner Höhle, one of the few significant cave systems in the Lower Carboniferous limestone of the region. The reserve combines calcareous beech woodland, hornbeam coppice, and a former quarry with calcium-loving vegetation, creating an unusually diverse habitat mosaic in a very small area. The cave itself is also notable: roughly 250 metres of branching, partly water-bearing passages, with geological evidence of former ice infill and biological records of specialized cave-dwelling invertebrates such as the groundwater shrimp Niphargus fontanus. Historically the cave was also used as a bat winter roost, adding a further dimension to its conservation value.

The protected status of Schatthangwald Röhre dates to 1993, when the area was first designated as a nature reserve under the Sundern landscape plan adopted by the Hochsauerlandkreis, initially covering about 3.3 hectares. The designation was renewed when the same landscape plan was revised some years later, at which point the protected surface was enlarged to approximately 5.6 hectares.

The natural features of the site are significantly older. The Große Sunderner Höhle, whose entrance within the reserve is one of the principal reasons the area was protected, was discovered only in 1961, even though the surrounding limestone had been worked in the small quarry far earlier. Research published in 1998 by K. H. Pielsticker examined the cave's sinter formations and internal sediments, discussing evidence that parts of the cave system had once been filled with ice, a reminder that the subterranean environment has its own long climatic and geological history independent of the surface reserve.

A further milestone came in 2005, when the area was incorporated into the EU Natura 2000 network through the Fauna-Flora-Habitat designation of the Große Sunderner Höhle site. This inclusion tied the small German nature reserve into a broader European framework for the protection of habitats and species and emphasized the importance of the underground system alongside the surface forest.

The reserve sits on a small limestone ridge that rises above the Röhr valley near Sundern. The ridge has a clear gradient from west to east: its western end tapers gently, while the eastern side breaks off in a steep slope down toward the Röhr river. This asymmetry gives the protected area a strongly three-dimensional character despite its modest size.

In the eastern part of the reserve lies the floor of a former limestone quarry. The quarry has two working levels cut into the local Hellefelder Kalk, with gently inclined, structurally simple rock faces. Near the top of the quarry wall sits the sealed entrance of the Große Sunderner Höhle, and lower down, on the steep east-facing slope above the Röhr, an additional small cave opening is hidden within the hornbeam coppice.

Around the quarry, the slopes are a mixture of rocky outcrops, loose block fields, and stepped cliffs. Soil is frequently thin, especially on the east- and northeast-facing slopes where individual rock faces and steps interrupt the woodland cover. In the western half of the reserve, in contrast, much of the surface is dominated by shrubby regrowth and former clearing areas partly replanted with wild cherry, giving a more open, regenerating woodland character. The combination of steep slope, shallow soil, and exposed limestone is the defining physical setting of the area.

Despite its small area, the reserve encompasses a striking range of calcareous habitats. On the floor of the disused quarry grows a thin, species-rich vegetation close in character to nutrient-poor calcareous grassland, marked by lime-loving plants such as the blue-green sedge. Around the edges of the quarry floor, where the rock walls and block-strewn slopes meet, more diverse pioneer-woodland stages have established themselves.

The forests above represent the ecological heart of the reserve. The eastern part is dominated by a mature hornbeam coppice enriched with other tree species and underlain by the typical herb layer of calcareous beech woodland. Small relicts of an older limestone beech forest persist in favored spots, while lower on the slope a thinned-out ash stand has developed features of a ravine-style forest. Toward the west the canopy opens into heavily shrubby regrowth on former clearing areas, with wild cherry plantations in places.

The underground habitat provided by the Große Sunderner Höhle adds a fundamentally different ecological dimension. The cave offers a stable, sheltered environment with its own microclimate, and parts of its passage system are water-bearing, sustaining the conditions that allow specialized cave invertebrates to survive. The combination of dry calcareous forest on the surface and a damp, cool limestone cave below makes the reserve an unusually compact example of integrated above-ground and below-ground habitat protection.

The headline wildlife interest of the reserve lies underground, in the Große Sunderner Höhle. The cave system, with about 250 metres of branching, partly water-bearing galleries, is one of only a few caves in the region's Lower Carboniferous limestone and provides a specialized habitat for cave-dwelling invertebrates. Among the species documented is the groundwater shrimp Niphargus fontanus, recorded within the cave and indicative of the clean subterranean water conditions the system maintains.

Historically the cave was also used as a winter roost by bats, although current data on the bat species present is lacking. The combination of suitable cave microclimate and the surrounding forested landscape means that bats remain part of the site's ecological profile even where modern surveys have not yet been completed.

Above ground, the value of the reserve for wildlife lies less in rare individual species than in the habitat mosaic itself: the calcareous beech forest, the hornbeam coppice, and the thin-soil ash stands provide shelter and continuity for woodland invertebrates and small woodland fauna, while the open quarry floor adds flowering plants and associated pollinators typical of nutrient-poor calcareous grassland.

The conservation purpose of Schatthangwald Röhre is framed by the standard German criteria for nature reserves: the area was designated because of the rarity, particular character, and beauty of the site. In practical terms this translates into protecting a combination of calcareous woodland types, a former quarry habitat, and the entrance zone of a regionally important cave, alongside the plant and animal communities associated with each.

Since 2005 the reserve has formed part of the Fauna-Flora-Habitat site Große Sunderner Höhle (DE-4614-306), embedding it in the EU Natura 2000 network. This linkage gives the reserve additional international recognition and obliges its management to take account both of the surface habitats and of the subterranean cave system as a single ecological entity. The protection of the cave fauna, in particular groundwater-dependent invertebrates such as Niphargus fontanus, is a central concern that depends on maintaining clean water conditions and undisturbed passages.

The reserve also serves as a local example of how small, steep, geologically distinctive sites can be integrated into broader landscape planning. It adjoins the Sundern landscape protection area and is one of many individual nature reserves in the Hochsauerlandkreis that together maintain a network of calcareous and forest habitats across the otherwise largely siliceous Sauerland uplands.

Schatthangwald Röhre is best understood in the context of the long history of small-scale limestone working in the Hellefeld area. The disused quarry within the reserve is a direct artifact of that working tradition and is one of the visible human imprints on the landscape. The discovery of the Große Sunderner Höhle in 1961 reflects local speleological interest and later scientific research into the region's caves, exemplified by K. H. Pielsticker's work on the cave's internal formations and ice-fill history.

Today, the reserve sits in close proximity to modern industrial life: the Sundern municipal utilities and the Severin Elektrogeräte headquarters lie immediately to the east and north, reflecting Sundern's identity as a long-established center of electrical appliance manufacturing. That juxtaposition of a small protected calcareous woodland and cave system with active urban and industrial surroundings gives the reserve a particular cultural character as a piece of retained natural heritage within a working town.

The reserve's strongest single feature is its compressed mosaic of calcareous habitats: limestone beech forest, hornbeam coppice with ravine-forest tendencies, open quarry floor with lime-loving plants, and the entrance zone of the Große Sunderner Höhle all within a few hectares.

A second highlight is the cave itself, which combines geological interest (Lower Carboniferous limestone, evidence of former ice infill, sinter formations) with biological importance as a habitat for specialized cave invertebrates and, historically, for wintering bats.

The reserve is valued primarily for its quiet woodland and its concealed geological features rather than for a seasonal display, so it can be rewarding to visit at any time of year outside heavy snow or leafless midwinter conditions. Late spring and early summer bring the most visible herb-layer development in the calcareous beech forest and the flowering of calcium-loving plants on the former quarry floor, while autumn highlights the structural contrast between the mature hornbeam coppice on the steep eastern slope and the more open, regenerating woodland on the western side of the ridge. Because the entrance of the cave is sealed, visits are essentially confined to the surface landscape and the surrounding woodland paths.