Urgenson et al 2009 giant knotweed implications

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Urgenson, L.S., Reichard, S.H. and Halpern, C.B., 2009. Community and ecosystem consequences of giant knotweed (Polygonum sachalinense) invasion into riparian forests of western Washington, USA. Biological Conservation, 142(7), pp.1536-1541.


  • Knotweed excludes native ground vegetation
  • Nitrogen recovery from stems to roots at the end of the growing season is extremely efficient (70%) compared to 5-33% in native vegetation.
  • Knotweed litter has a higher C:N ratio of 50:1 compared to 30-40:1 among native trees, while fresh leaves have a high C:N ratio (~13:1)