Neophyte control in Niderholz
Realized:
2019
performed by:
Naturnetz Nordostschweiz
Four years ago, a pleasant but precarious situation arose in the Niderholz forest area near Marthalen in the Zurich wine country: Due to the structural influence of the recently arrived beavers, the Mederbach had dammed up to form a six-hectare body of standing water, the Bibersee. This caused local tree populations to die and led to a natural renaturation and ecological improvement of the area. Unfortunately, an invasive neophyte, Himalayan balsam ( Impatiens glandulifera ), also took a liking to the changed light conditions on the ground and experienced an explosive growth.
The Niderholz forest area borders on the Thurauen, which, at almost 400 hectares, is the largest floodplain area in the Swiss Mittelland and a protected area of national importance. Along the Mederbach, which flows through the Thurauen after the Niderholz and finally flows into the Thur, there is a high exchange and entry of potentially harmful plant material downstream. In 2016, the situation at the Bibersee was the decisive factor in us starting the strategic control of neophytes in the Niderholz on behalf of the Forest Department of the Canton of Zurich. This project indirectly protects the Thurauen and its unique fauna from problematic entries of neophytes.
A total of eight core zones were defined in which we are primarily fighting Himalayan balsam, but also Canadian goldenrod ( Solidago canadensis ) and annual fleabane ( Erigeron annuus ). The focus is on areas near bodies of water such as the Bibersee or the Mederbach. But large areas that were reforested with oak after Hurricane Lothar in December 1999 are also heavily infested with goldenrod and are also being tackled. In cooperation with the forestry service, which is responsible for large-scale mowing on open areas, we are targeting the more inaccessible areas of the water or forest and are fighting the stocks by hand. Thanks to immediate success, the eight core zones were able to be expanded annually and the control perimeter almost tripled over four years. Today, the neophytes in the original core zones have largely been eliminated or reduced to a minimum. Niderholz is therefore a success story both in our eyes and in those of the beavers!