Weed occurrence on pavements in five North European towns

Weeds on pavements in urban areas are unwanted mainly because they cause an untidy appearance or sometimes structural damage. Glyphosate has been the principal weed control method for years, but policies in several European towns have changed to lower dependence on herbicides. Instead, less effective and more species-dependent non-chemical methods are used, but little is known about the pavement flora. Consequently, we surveyed the flora on pavements in five North European towns [Braunschweig (DE), Malmö (SE), Næstved (DK), Royal Leamington Spa (UK) and Wageningen (NL)] by recording weed species and their coverage in 56 recording points randomly placed in each town. Weeds were recorded at several dates in 2005 and 2006 and no weed control was applied apart from sweeping. Weed coverage increased during the survey (averaging 1.4% in late 2006) and was highest in the towns having the strictest policies limiting herbicide use. Most coverage (averaging 2%) was found along the pavement edge away from the road. Poa annua was the most frequently recorded species, followed by bryophytes (mainly mosses), Sagina procumbens and perennial grasses. Grasses and some other species frequently found, notably Taraxacum officinale, should receive particular attention when planning a non-chemical weed control campaign on pavements.