Invasiveness Ranking System for Non-Native Plants of Alaska

Role of anthropogenic and natural disturbance in2establishment (0–5)Prostrate knotweed colonizes disturbed ground. Plants mayappear on sites that have been redisturbed several decades afterthe last human disturbance (Densmore et al. 2000). Prostrateknotweed was dominant on patches of soil disturbed by animalsin a study in Germany (Milton et al. 1997).Current global distribution (0–5) 5Prostrate knotweed is one of the most widespread weeds inEurope and Asia. It has been introduced into Central and SouthAfrica, South and North America, Australia, and New Zealand. Ithas been recorded in Alaska, including arctic regions (Gubanov etal. 2003, Hultén 1968).Extent of the species U.S. range and/or occurrence of5formal state or provincial listing (0–5)Prostrate knotweed is found in nearly all American states andCanadian provinces (USDA, NRCS 2006). Polygonum aviculareis listed as a noxious weed in Quebec (Rice 2006).Total for Ecological Amplitude and Distribution 16/25Feasibility of ControlScoreSeed banks (0–3) 3Chepil (1946) found that although a significant proportion ofprostrate knotweed seeds germinate in the year after they wereproduced, a smaller number of seedlings emerged 3–5 years aftersowing. Two out of 1,000 seeds sown, emerged after 5 years.Viability of seeds was 7% after 4.7 years, and