Mehlem In addition to a beautiful view, the Rhine bank near Mehlem also offers a variety of ecological features. These include goldenrod and scabious, but also nightingale and marsh warbler.
What other arguments would one need to suggest a hike along the Rhine near Mehlem than the magnificent view of the Siebengebirge and the relaxed flow of the water? Ornithologist Peter Tröltzsch of the Bonn/Rhein-Erft Biological Station can think of other reasons, which he explains on a tour.
This walk can start anywhere in Mehlem, Tröltzsch chooses the corner of Im Frankenkeller and Im Vogelsang as the meeting point. From there, you can get directly to the banks of the Rhine. The path leads through an overwater area, according to the expert these are relics of the former floodplains. "The water is allowed to overflow its banks here." This has consequences: "Due to the overwatering in spring and the drying afterwards, certain plant communities can establish themselves.“
Large woody plants are found only sporadically, predominantly herbaceous plants, "so-called stream valley species that always have to live with the water dynamics," explains Tröltzsch. Goldenrod is one of them, as are scabious, horsetail and two-toothed species. They spread by being carried away by floodwaters after the snow melts and find good soil on the groynes, the dams built vertically from the bank into the Rhine.
At these times, says the ornithologist, migratory birds on their way to their breeding grounds, such as the little ringed plover and the sandpiper, can also be found there. Theoretically, the conditions would also be good for them to breed there, but they would be disturbed too often, because on nice days the groynes and the fine sandy bays in between are popular destinations for excursions, and dogs are often let off the leash there. "At certain times, it would be nice if some groynes were not open to the public," Tröltzsch wishes.
Good breeding conditions also come from the willows that stick out of the water. When the Rhine is at low water for a long time - and that has often been the case in the past three dry years - they settle there on the bank. But whether they can hold on is uncertain, because the rising Rhine water washes out the roots. Some trees from this family have made it in previous years. Tröltzsch shows an unusual silver willow: it is rooted in the more stable bank, but projects out over the water at an almost impossible angle.
Nearby, a moorhen is looking for food, not necessarily the rarest water bird, but Tröltzsch is happy about this sighting. A little further upstream, there are better conditions for some bird species: a large gray heron colony lives on Nonnenwerth Island, and the common merganser, a duck species, can also be observed there in winter. But also the cormorant and the black harrier as well as the kingfisher and some species of gulls. This is made possible by a special feature of this island: "It is one of the few Rhine islands that are left natural on the south side." This, he says, allows material to be deposited there that creates good conditions for birds.
Back to the riverside path: In the hedge there with hawthorn and rosehip, birds find food even in winter. The clapper warbler breeds there, and it's one of the few places in Bonn where you can still hear the nightingale singing, says Tröltzsch. Hops are a typical floodplain species, and the yellow-flowering toadflax loves rubble deposits in floodplains. Behind the hedge begins the Genienaue with the campground of the same name. The lush meadow further south is also part of it, a retention area for the settlement; in spring it is sometimes flooded. "We need something like that," says Tröltzsch, also referring to the floods in the Eifel: "Open spaces where the power is taken away from the flow."
We pass a large scrub area with lots of stinging nettles that stretches all the way to the border with Rhineland-Palatinate. The marsh warbler feels at home in it. You can continue on the path almost at will, if you want, even to Rolandsbogen for coffee and cake - and then back over the Rodderberg, a long distance. Or you can choose the field path that leads past a meadow orchard - which, according to Tröltzsch, is in urgent need of pruning - and past the campground back to Mehlem. There is the beer garden Waidmannsruh for a stop. Perhaps one has also begun the hike in the wine cottage at the Mehlemer ferry and wants to end it there.
The landscape in Bad Godesberg and Wachtberg is impressive: you walk through sunken paths, over a volcanic crater rim, across a lively pastureland in the Kottenforst, hike along the apple route and past a special biotope. The GA series, which ends with the tour along the Rhine, has shown that it is also worth taking a look at the depths of these nature hotspots.
Original text: Stefan Knopp
Translation: Mareike Graepel