The nature reserve is in the west of Oldenburg. It includes a section of the lower reaches of the hair and the adjacent lowland areas. The Haaren is developed with predominantly steep banks. In some sections, the banks are fortified with fascines. The Haaren lowland is characterized by damp wasteland with tall herb meadows, swamps, vineyards and reed beds, in places with islands of wood and hedgerows. Parts of the lowlands are used extensively as grassland.
Drögen-Hasen-Teich in the NSG; north of it is the Wechloy campus of the University of Oldenburg
Pedestrian bridge over the hair
The nature reserve is the habitat of numerous plants and animals. Damp and wet meadows accommodate u. a. Marsh marigold, broad-leaved marsh orchid, overlooked marsh orchid, loosestrife, common rattle, yellow meadow rue, tubular water fennel, groundwort, marsh vetch, buckbean, millet sedge, thread rush and in places also needle marsh rush. Great sedge reeds are formed by slender sedge, swamp sedge, and two-rowed sedge. In addition, reeds, canary grass and water vapor reeds are developed. Tall herb corridors are z. B. from meadowsweet, loosestrife, loosestrife, yellow meadow rue, shaggy willowherb, angelica, bindweed, groundsel, common comfrey, real valerian and marsh ziest. The area is also home to the endangered swamp fern. The area includes Water rail, moorhen, kingfisher, tree sparrow, redstart, spotted flycatcher, green and lesser woodpecker are all native. Reed beds are a habitat for reed warblers, reed buntings and warblers. Also native to the area are grasshoppers such as the marsh cricket and saber-thorn cricket, and dragonflies such as the banded demoiselle, damsel-fly bat, spotted darter and damsel-eye. The area is also the habitat of various amphibians, including the marsh frog. Haaren and Haarenniehne are hunting habitats of the bat species serotine bat, water bat, common noctule bat, pipistrelle bat and common pipistrelle.
Floating aquatic vegetation settles in the Haaren, e.g. made of crested spawning herb, water star and yellow water lily. The Haaren is home to perch, ruff, gudgeon, roach, three-spined stickleback, wolffish, ide, bream, and occasionally eel, pike, dace, white bream, burbot, rudd and bitterling, as well as the mussel species pea and painter's mussel.