The spatial and temporal dynamics of Asian knotweeds: expecting the unexpected

Abstract

Asian knotweed (Reynoutria spp.) has long been of concern and fascination to many botanists and managers. Having become one of the most problematic species complexes on the planet, knotweeds present spatial and temporal dynamics with subtleties of great heuristic and practical importance. This review article proposes to establish a profile of the processes and factors underlying knotweed invasions from the scale of young plant establishment to the regional scale. Like most other invasive plants, knotweed invasion dynamics consist of a hierarchy of processes occurring based on a nested scale principle. What differs from many other plants, however, and is often ignored or underestimated, is that knotweeds are clonal plants. Thus, it appears that knotweeds probably have a much wider ecological niche than is commonly accepted. Indeed, while their seeds generally have difficulty producing new individuals in the wild, fragments of knotweed seem potentially capable of causing the invasion of most temperate terrestrial habitats, if given time to do so.