Vegetalization test

First observations

  • Vegetalization test zones unweeded
  • Philippe FERARD
About diversity
  • 105 vascular species have been observed on the 13 inventories performed in 2007, which represents close to 6% of the local flora. Species settling on Nantes pavement are mainly indigenous (90%).
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  • Among those species, a few are pretty rare or can be found at the northern limit of our region. 10% of the observed species are exotic plants. One of them (Conyza canadensis, Canadian Fleabane) is among the three species most frequently observed on the pavements. In additions, it has been observed that pavements flora was influenced by neighbouring natural environment or cultivation areas.
Evolutive aspect of pavements vegetalisation
  • Analyse of inventories performed on sand surfaces show that annual plants settle more quickly than perennial plants (see graph above). However, perennial plants, though not numerous in the first phase of the colonization process, end up completing with annual plants when soil occupation rate reaches 70%. Vegetation on Cobblestones and Tarmac surfaces exhibit roughly the same dynamic as on sand surfaces.
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  • Moreover, we have observed with an increasing frequency, the emergence of tree seedling. This phenomenon must be considered with great care: indeed, if no intervention was done during a sustained period of time, a “urban forest” could invest public space, on building fronts or gutters.