Control of Japanese knotweed through goat grazing in Mayenne's wetland area, research and management aspects

Abstract

In 2011, a preliminary experiment with goats (Chèvre des fossés) was carried out in a wetland with the aim of controlling Japanese knotweed. First results showed that this management led to lower biomass of Japanese knotweed. Experiments with a similar protocol were then carried out over a period of three years. As in the previous study, significant decreases were observed at any given time in Japanese knotweed cover, height of stems and dry biomass at the end of the knotweed's lifecycle. Results are more mitigated for cumulative cover of other species. They do not allow revealing benefits in terms of increasing species richness. In the grazed places, there is no increase of number of species neither within Japanese knotweed stands nor outside them. This management does not lead to a decrease in stem density at the end of the knotweed life cycle.