Naturschutzgebiet Thielenbruch und Thurner Wald

The reserve stretches between the Mutzbach and Strunde streams along the western edge of the Paffrath limestone basin. The Thurner Wald is framed by Bergisch Gladbacher Straße, Duckterather Weg, Katharinenkammerweg, Heinrich-Strünker-Straße and Waltherstraße. It is crossed by the S11 suburban railway, Paffrather Straße, and a natural-gas and a high-voltage power line. To the north lie the three sections of the Thielenbruch nature reserve.

Extensive bogs once covered the mid-terrace east of the Rhine before drainage largely destroyed them – here the wetland survived. In the east, around Katharinenkammerweg, several calcareous springs feed a fen that borders a purple moor-grass meadow. Alder carr grows near the water, drier zones carry oak and birch, and elsewhere there are reed beds, willow scrub and a transition mire with floating peat-moss surfaces. This variety of sites offers a refuge to highly endangered species such as the dainty damselfly, the desmoulin's whorl snail, broad-leaved cottongrass, the marsh helleborine, the few-flowered spike-rush, flea sedge and the lesser bladderwort.

Protection aims to preserve and develop this near-urban area – its fen, purple moor-grass meadows and wet and floodplain woodlands – as a refuge for rare species. Together with parts of the Thielenbruch reserve within Bergisch Gladbach, it forms the Thielenbruch FFH site (area number DE-5008-301).