Dynamics of a weed community in a cereal field created after ploughing a seminatural meadow: Roles of the permanent seed bank

Very few studies have been carried out on the ecological restoration of arable weed communities because farmers consider these species as competitors with the cultivated species. However, such restoration projects are interesting to be undertaken in south-eastern France (Parc Naturel Regional du Luberon) because there are still enough of the arable weed species specifically growing in cereal fields (segetal species), whereas they decrease in other regions of France. This study over three years (1999-2001) assessed the above-ground vegetation and the permanent seed bank of a field (0.2 ha) cultivated with cereals on a ploughed 10 year-old meadow. Our results show that among the 113 species recorded, only two segetal species germinated from permanent seed bank (Galeopsis angustifolium, Papaver rhoeas), while ten segetal species were recorded in above-ground vegetation (1/4 of typical segetal species in Pare Naturel Regional du Luberon). Arable weed vegetation was dominated by grassland or ruderal species. This suggests that, segetal populations are not resilient after 10 years of putting the arable fields under grass and that restoration cannot occur from permanent seed bank. Thus, in order to preserve species-rich segetal communities, fields should be cultivated with cereals and should not be included in a rotation with a long meadow phase.