FLORON is the organization that maps the distribution and numbers of vascular plants occurring in the Netherlands. According to FLORON’s distribution atlas, 10,992 locations in the Netherlands are now infected with Japanese knotweed. Quite a few municipalities have measured exactly how many square meters of Japanese knotweed proliferate within their own municipal boundaries.
Tibach has investigated the surface area of these municipalities and calculated the average contaminated surface of Japanese knotweed per square kilometre.
Tibach calculated an average of 440m2 per square kilometre. According to Floron’s distribution atlas, the number of sources of infection is the same throughout the Netherlands.
If we take the total surface area of the Netherlands and subtract the water surface, we are left with a land area of 33,893km2 x the average of 440m2 per km2 = 14.93km2
The Japanese knotweed new contamination sites in particular can grow rapidly. It is therefore important to treat Japanese knotweed at the earliest possible stage. Rhizomes of this invasive exotic grow through small gaps in asphalt and concrete, damaging buildings and infrastructure.
