Himalayan balsam control on the forest streams of the Thurauen

When you think of watercourses in the Thurauen, you think of the slowly meandering Thur, which flows into the Rhine at Thurspitz. But in the Thurauen area, two streams also flow into the Thur. The Mederbach and the Schüepbach flow through the forests of the Thurauen and are home to the beaver.

The Mederbach flows into the Thurauen with a small waterfall at Riselibuck and then winds slowly to the north bank of the Thur. Along the way it is dammed up in some places by beaver dams and overflows its banks into the adjacent forest area during floods. Visitors can cross the Mederbach at four different points over a small bridge. From these bridges you can also admire the beavers' structures and the labyrinth of branches and tree trunks above the stream.

The Schüepbach flows through the Thurauen in a somewhat more secret way. At the Wehri it meanders along a hedge and then enters a small forest. In a long curve it then turns towards the Thur and flows into the Thur opposite the Eggrank.

Since 2016, Himalayan balsam ( Impatiens glandulifera ), an invasive neophyte, has been controlled on both streams. Thanks to the beavers' damming work, there were always wet spots and areas along the streams where Himalayan balsam seeds were washed in and could thrive perfectly. This control is important because the Thurauen is a nature reserve of national importance and is home to many rare animal and plant species.

The control measures along the streams prevent the Himalayan balsam seeds from being carried into the Thur, as the natural network also controls invasive neophytes there. This protects the valuable gravel banks and riverbanks of the Thur and the habitats of the kingfisher and the little ringed plover.

In the first few years, very dense stands of Himalayan balsam could be found along the forest streams, but thanks to consistent and precise control measures, these are now only represented by a few specimens. Control of Himalayan balsam in recent years has been so successful that the control perimeter has been able to be expanded over the last three years. The entire forest section on the Schüepbach can now be cleared of Himalayan balsam, and in one place on the Mederbach, work has begun on controlling other invasive neophytes, such as goldenrod ( Solidago ).

The control measures along the forest streams in the Thurauen region show that regular and precise control of neophytes leads to success and that dense stands consist only of individual plants after just a few years. This gives native plants more space and the beaver's food supply becomes larger and more diverse.