Hungerbrunnen-, Sacken- und Lonetal Protected Area: Karst Valleys and Swabian Alb Landscapes

The protection site was first proposed in 2005 by the Regierungspräsidium Stuttgart under the European Union Habitats Directive (Richtlinie 92/43/EWG), commonly known as the Fauna-Flora-Habitat Directive. After a long assessment and consultation process, the official designation was completed by ordinance of the Regierungspräsidium Stuttgart dated 30 October 2018, formally establishing it as a Site of Community Importance, with legal effect from 11 January 2019. Since then it has been part of the Natura 2000 network of protected areas across Europe.

Long before formal European designation, however, parts of the area had already been protected at the state level. The whole site lies inside the landscape protection area Hungerbrunnental, while within the territory lies the nature protection area Hungerbrunnental, and the Hungerbrunnenquelle spring near Gerstetten is recognized as a natural monument. This nested system of protections reflects the long-standing regional recognition of the valley's natural value.

The landscape of Hungerbrunnen, Sacken and Lonetal is shaped by the karst geology of the eastern Swabian Alb. The Lone river and its tributaries have cut deeply into the limestone plateau over millennia, producing steep-sided valleys with terraces, rocky outcrops, scree slopes, and abrupt transitions between valley floor and plateau surface. The result is a strongly contrasting terrain where flat grassland stretches on the high plateau drop suddenly into narrow, sheltered valley arms.

A defining feature of this landscape is the periodic drying of the streams. Because water seeps easily into the karst, the Lone and its side branches can run dry during parts of the year only to return as lively meandering brooks after sustained rainfall. This hydrological rhythm helps maintain a vegetation pattern unusual for southern Germany, with dry-loving and warmth-loving species thriving alongside typical streamside vegetation.

Above the valley floor, the plateau slopes and high ground carry extensive juniper heaths and dry grasslands interrupted by patches of beech forest. Two caves within the territory highlight the karst quality of the bedrock, and limestone cliffs and rocky grasslands with rich fissure vegetation add visual structure to the side slopes. The combination of dry valley, juniper heath, rocky outcrops, and beech forest creates a layered, photogenic Swabian Alb landscape.

Ecologically, the site is a representative example of the habitat mosaic of the eastern Swabian Alb. Around a third of the area is covered by wet and mesophilic grassland, including traditionally managed meadows in the valleys. The remainder is split among deciduous forest, mainly beech on the higher ground, mixed forest, and coniferous stands, with smaller shares of improved grassland, arable land, and built-up areas.

The principal open habitat types are extensive juniper heaths on calcareous soils, semi-natural calcareous dry grasslands, and small areas of pioneer calcareous grassland on stony slopes. These are classic steppe-like vegetation formations associated with warm, dry, lime-rich sites, and they harbour many specialized plants and insects that have become rare elsewhere in central Europe.

Forest cover is dominated by a Waldmeister-type beech forest, with smaller areas of orchid-rich calcareous beech forest and ravine-slope mixed forest on the steepest, most sheltered sections. Karst features such as limestone scree slopes, calcareous rock outcrops with fissure vegetation, and small caves provide additional microhabitats. The overall ecological value comes from the tight interplay of dry, warm, open habitats and cool, shady forests in one relatively compact valley landscape.

The combination of juniper heaths, dry grasslands, karst slopes, and deciduous forest gives Hungerbrunnen, Sacken and Lonetal a habitat mosaic that supports a wide range of typical Swabian Alb fauna. Warm, dry open sites favour invertebrates that depend on calcareous grassland, including butterflies, wild bees, and other pollinators, which in turn provide food for a variety of bird species of the open countryside.

The beech forests and ravine slopes provide nesting and feeding habitat for woodland birds, while the periodic streams and meadows support amphibians, invertebrates, and small aquatic life that respond to the regularly alternating wet and dry conditions. Bats also benefit from the presence of small caves and rocky outcrops, which can serve as roosting sites.

From a conservation perspective, Hungerbrunnen, Sacken and Lonetal is significant primarily because it preserves a coherent complex of European-protected habitat types in a comparatively small area. Juniper heaths, calcareous dry grasslands, pioneer calcareous grasslands, and several Annex I beech forest types all occur within the same valley system, making the site a high-priority object for habitat conservation under the EU Habitats Directive.

The site also serves as part of a larger network of protected areas on the Swabian Alb, including the adjacent FFH areas Kuppenalb bei Laichingen und Lonetal and Härtsfeld. Its nested protection status, sitting within an existing landscape protection area, with a core nature protection area and natural monument inside it, ensures that the juniper heaths, dry grasslands, and beech forests are safeguarded at multiple administrative levels. Maintaining traditional grazing and avoiding further forest encroachment remain central to keeping the open habitats in good condition.

The visible character of the Hungerbrunnen, Sacken and Lonetal landscape is closely tied to centuries of agricultural use. The juniper heaths and dry grasslands are not purely natural; they have developed and been maintained through traditional grazing and other low-intensity land use by local communities. This long-standing interaction between people and the dry valley landscape has produced the cultural-natural mosaic that the conservation area now seeks to protect.

The Hungerbrunnenquelle spring is recognized as a local natural monument, suggesting that the area's geological features have held meaning for local communities well before modern nature conservation frameworks. Across the larger Swabian Alb region, valleys like these are part of the cultural landscape of the Lonetal and a touchstone of regional identity.

The site's main strength is its compact concentration of typical eastern Swabian Alb habitats: extensive juniper heaths, semi-natural calcareous dry grasslands, pockets of pioneer grassland on stony terrain, and a substantial share of Waldmeister-type beech forest, including small areas of orchid-rich calcareous beech forest.

A second highlight is the karst-influenced valley landscape of the Lone and its tributaries, with intermittent streams, meandering channels, limestone scree slopes, and two caves. These features together create a layered, ecologically rich picture that is more characteristic of southern European steppe-like landscapes than of southern Germany. The site's nested protection status, from Natura 2000 down to natural monument, further underlines its regional and European conservation value.

Because the site is a nature conservation area, rather than a developed visitor destination, the notion of a best time to visit is tied largely to the experience of the landscape rather than to facilities or access conditions.

Late spring and early summer, when juniper heaths, dry grasslands, and orchid-bearing beech forests are in flower, are generally the most visually rewarding periods for a walk through the valley. Late spring and early summer also bring the greatest variety of flowering plants and insect activity in the calcareous grasslands. In autumn, the beech forests take on colour and offer a quieter, more contemplative atmosphere, while the periodic drying and refilling of the Lone and its tributaries creates shifting landscape moods throughout the year.