Author(s): Mijke Van Oorschot; Maarten Kleinhans; Gertjan Geerling; Gregory Egger; Rob S. E. W. Leuven; Hans Middelkoop
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Abstract: Invasive alien plant species cause severe damage in their introduced range. Especially river systems are vulnerable, since waterways serve as invasion corridors. Development of cost-effective management strategies requires understanding of interactions between alien invaders and native species, and of their combined effects on river dynamics. This study investigates how an alien plant invasion affects native vegetation and hydromorphodynamic processes, using a numerical model including dynamic interactions between riparian vegetation and river-morphodynamics. We explored the long-term effect of an invading perennial herb with characteristics based on Japanese knotweed (Fallopia japonica) on the native willow and poplar cover and river hydromorphodynamics. Invaders with high propagule pressure out-compete native vegetation, shift accessible colonization sites towards lower floodplain elevations and increase hydro-morphodynamic pressures at these sites. However, less abundant alien species increase native vegetation cover by creating more suitable colonization sites. Moreover, seasonal invader properties determine hydro-morphodynamic invasion effects.
Year: 2018