Floods affect the abundance of invasive Impatiens glandulifera and its spread from river corridors

Abstract

Aim Riparian habitats are amongst the most invaded ecosystems world-wide. The great abundance of invasive species in river corridors is attributed to the efficient transport of alien species' propagules and reduced competition from native plants due to regular flooding. Once an invasive species has become established, river corridors can serve as stepping stones for spread into other habitats. We have chosen the Himalayan balsam Impatiens glandulifera Royle, highly invasive annual in riparian areas, as a model for spread of invasive species from linear river corridors. Location Central Europe.Methods We mapped its distribution and recorded its abundance in over 1200 patches along four rivers in central Europe, differing in the time of balsam's introduction . The patches were characterized in terms of the distance from the riverbank, height above the river surface, degree of soil disturbance and flooding regime. ResultsThe patches at sites subject to flooding had twice as many individuals as those that were not subject to flooding, regardless of their distance from the riverbank and height above the river surface. There was a strong effect of the river identity, with river invaded 20 years ago being less infested than those invaded earlier. The distance from the riverbank at which the populations occurred differed and did not depend on river identity/residence time. The patches in tributaries were on average two times further from the bank of the main river than those located elsewhere.Main conclusions Flooding is an important factor affecting the abundance of I. glandulifera, and accounts for its spread and dominance along river corridors probably due to spreading the seeds, increasing nutrient availability and disturbing native vegetation. It is likely that the number of I. glandulifera populations will increase in the future, especially along small water courses.

Species- and developmental stage-specific effects of allelopathy and competition of invasive Impatiens glandulifera on co-occurring plants

“…This moderate ranking was justified with the mixed results from field studies on the impact of I . glandulifera on native plant communities [ 11 , 16 – 19 ]. Thus, a deeper understanding of the interaction between I .…”

Giant hogweed at its northern distribution limit in North America: Experiments for a better understanding of its dispersal dynamics along rivers

“…We suggest that late fall, and especially spring floods when water flow of FBk is about 9 times that of the summer (Ministère du Développement durable, de l'Environnement et de la Lutte contre les changements climatiques du Québec, ), is the most efficient dispersal vectors for GH seeds. This is the case for a large number of riparian plant species with dormant seeds (Boedeltje, Bakker, Ten Brinke, Van Groenendael, & Soesbergen, ; Soomers et al, ; Catford & Jansson, ; Čuda, Rumlerová, Brůna, Skálová, & Pyšek, ). Floods can potentially carry thousands of seeds deposited near the parent plants, and spread them much farther than during the summer because of the velocity of flood waters.…”

“…Nesom, and tree‐of‐heaven ( Ailanthus altissima (Miller) Swingle). In all cases, floods contribute to the long‐distance dispersal of diaspores (up to 8 km), and thus to the acceleration of the invasion process (Čuda et al, ; Kaproth & McGraw, ; Kowarik & Saümel, ; Schmiedel & Tackenberg, ; Thébaud & Debussche, ; Truscott et al, ).…”

Principal Threats to the Conservation of Running Water Habitats in the Continental Biogeographical Region of Central Europe

“…Running water habitats such as river floodplains are one of the most dynamic ecosystems in Central Europe; may contain a wide array of habitats, from vegetated lowlands to forests to freshwater marshes; and serve important ecological roles for numerous plant and animal species. They fulfil numerous functions in the landscape and their ecological research, therefore, has a long tradition (e.g., Tockner & Stanford, 2002;Pataki et al, 2013;Hein et al, 2016;Blakey et al, 2017;Čuda et al, 2017). These ecosystems harbor unique biodiversity (Schröter et al, 2005;Wilk-Woźniak et al, 2019) and are the most threatened ecosystems worldwide (MEA, 2005).…”