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Fallopia sachalinensis - Giant knotweed

Synonym: Reynoutria sachalinensis, Polygonum sachalinense
French name:  Renouée de sakhaline
Dutch name: Sachalinse duizendknoop
Family: Polygonaceae
Group: Vascular plants
Origin: Asia
Habitat: terrestrial
Introduction:  agri- and horticulture
ISEIA Score : 12
Naturalization in Belgium
First observation in the wild: 1924
Invasion stage: spread
Spatial distribution: restricted
Reproduction in the wild: yes
Dispersion potential: high
Natural habitats: high
More on invasiveness: As other Asiatic knotweeds, giant knotweed colonises a wide range of environments, with a predilection for moist and nitrogen-rich soils. It prefers sunny places or semi-shaded habitats. This pioneer plant proliferates both in ruderal and semi-natural habitats, including riparian areas and open forests. Stem and rhizomes may easily split in small pieces; fragments are able to regenerate a plant, provided a node is present. Giant knotweed produces a small amount of viable seeds, but seedlings are seldom observed in the wild. Transport of garden waste and soil contaminated with rhizomes are the major dispersal modes. Where the plant is widely consolidated on river banks it is also spread by floods and can easily colonise downstream.
Distribution in Belgium
Established populations
absent from district
isolated populations (1-5 localities per district)
widespread (>5 localities per district)
Endangered areas
low risk
medium risk
high risk

Endangered Natura 2000 habitats ():
grasslands: 643065106520
forest habitats: 91E0*91F0
Impacts on Species
Predation / Herbivory: low
Competition: high
Disease transmission: low
Genetic effects: low
Impacts on Ecosystems
Nutrient cycling: likely
Physical alteration: high
Natural successions: high
Food web alteration: low
More on impacts: Fallopia sachalinensis is able to monopolize space and to form dense and persistent populations. It can outcompete most of native herbaceous plant species thanks to early seasonal development, high growth rate and productivity, abundant leaf cover, allelochemical production and clonal spread associated with an extraordinarily high rate of proliferation of below-ground organs. It can even outcompete Fallopia japonica on alluvial riverbanks. Its development reduces plant and invertebrate species diversity, alters habitat for fish and wildlife, change ligth and energy conditions of the ecosystem and favours river bank erosion during the winter. It can also break through tarmac and thin layers of concrete and can penetrate some flood defences.
Data Source & References
Authors: Branquart Etienne, Vanderhoeven Sonia, Van Landuyt Wouter, Van Rossum Fabienne, Verloove Filip
Published on:  16 December 2010
Last update:  14 October 2011
Gerber, E., Krebs, C., Murrell, C., Moretti, M., Rocklin, R. & Schaffner, U. (2008)
Exotic invasive knotweeds (Fallopia spp.) negatively affect native plant and invertebrate assemblages in European riparian habitats.
Biological Conservation 141: 646-654.
Hejda, M., Pysek, P. & Jarosik, V. (2009)
Impact of invasive plants on the species richness, diversity and composition of invaded communities.
Journal of Ecology 97: 393–403.
Inoue, M., Nishimura, H., Li, H.H. & Mazutani, J. (1992)
Allelochemicals from Polygonum sachalinense (Polygonaceae).
Journal of Chemical Ecology 18 (10): 1833-1840.
Kappes, H., Lay, R. & Topp, W. (2007)
Changes in different trophic levels of litter-dwelling macrofauna associated with giant knotweed invasion.
Ecosystems 10: 737-744.
Krebs, C., Mahy, G., Matthies, D., Schaffner, U.,Tiébré, M.-S. & Bizoux, J.-P. (2009)
Taxa distribution and RAPD markers indicate different origin and regional differentiation of hybrids in the invasive Fallopia complex in central-western Europe.
Plant Biology
Lambinon, J., Delvosalle, L. & Duvigneaud, J. (2004)
Nouvelle fore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des régions voisines.
Editions du Patrimoine du Jardin botanique national de Belgique, Meise.
Marigo, G. & Patou, G. (2009)
Phenology, growth and ecophysiological characteristics of Fallopia sachalinensis.
Journal of Vegetation Science 9(3): 379–386.
Muller, S. (2004)
Plantes invasives en France : état des connaissances et propositions d'actions.
Publication scientifique du Museum d'Histoire naturelle, Patrimoines naturels n°62.
Sukopp, H. & Starfinger, U. (1995)
Reynoutria sachalinensis in Europe and the Far East: a comparison of the species ecology in its native and adventive distribution range.
In: Pysek et al. (eds.),Plant Invasions: general aspects and special problems. SPB Academic Publishing. Amsterdam, Netherlands: 151 - 159.
Van Landuyt, W., Hoste, I., Vanhecke, L., Van den Bremt, P. Vercruysse, W. & De Beer, D. (2006)
Atlas van de Flora van Vlaanderen en het Brussels gewest.
Nationale Plantentuin en het Instituut voor Natuur- en Bosonderzoek i.s.m. Flo.Wer vzw.
Vanderhoeven, S., Dassonville, N. & Meerts, P. (2005)
Increased topsoil mineral nutrient concentrations under exotic invasive plants in Belgium.
Pland and Soil 275: 169-179.
Verloove, F. (2006)
Catalogue of the Neophytes in Belgium (1800-2005).
Scripta Botanica Belgica 39, 89 pp.
Weber, E. & Gut, D. (2004)
Assessing the risk of potentially invasive plant species in central Europe.
Journal for Nature Conservation12: 171-179.
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