Neophytenbekämpfung an Gewässern im Spannungsfeld gesetzlicher Zielkonflikte (Essay)

Abstract

Control of non-native plant species along streams: an area of conflict caused by legal trade-offs (essay) Driven by global trade and supported by climate change, we increasingly encounter new species in our ecosystems. Certain of these species, for example Asian Knotweeds (Reynoutria japonica, R. sachalinensis, R. × bohemica), exhibit immense growth rates and thereby suppress existing vegetation in revitalized reaches and biotopes deserving particular protection. The ecological damage accompanying the loss of biodiversity can only be contained by effective and efficient control measures. Contradictory legal guidelines at Federal level lead in practice to a conflict of aims, making goal-oriented control impossible. On the one hand the Chemical Risk Reduction Ordinance prohibits the use of pesticides in a 3-m strip along water stretches. On the other hand, numerous laws – such as the Federal Act on the Protection of Nature and Cultural Heritage, the Water Protection Law and the Ordinance on the Handling of Organisms in the Environment infer that it is a responsibility to protect riparian zones and river banks as ecologically valuable habitats, and to take measures against invasive neophytes. As long-term investigations in the Canton of Aargau have shown, chemical control sustainably weakens the Asian Knotweed. Further, a fluorescent tracer experiment demonstrated that with careful implementation, the use of pesticides along a 3-m strip along riverbanks poses no threat to the stretch of water. Therefore the Canton of Aargau hopes that these findings contribute to the fastest possible resolution of this conflict of aims, so that investments made over the past years towards restoring stretches of water may be protected promptly from the threat of Asian Knotweed.