Importance of soil characteristics for plant-parasitic nematode communities in European coastal foredunes
Résumé
Plant-parasitic nematodes are involved in soil fatigue processes in coastal foredunes and, therefore, have an impact on the growth of plants such as marram grass (Ammophila arenaria) that enhance sand accretion and the stabilisation of dunes. Transects were sampled in European Atlantic and Mediterranean foredunes at different locations. Plant-parasitic nematode communities and physico-chemical soil properties were analysed, and multivariate techniques were used to link them. Although all the dunes are of sandy texture, the Atlantic and Mediterranean dunes mainly differ by their ratio of coarse and fine sands. Mediterranean dunes, although more disturbed by storms than the Atlantic dunes, have fine-textured soils that can accumulate organic matter. They trap a large amount of minerals and have a high carbonate concentration due to the salinity of the Mediterranean Sea. As a result of the higher content of coarse sand in the top horizons, probably due to a higher accretion of sand, Atlantic foredune soils are low in organic matter and minerals. Soils from North and Irish Sea dunes have intermediate characteristics. These soil contrasts lead to specific plant-parasitic nematode communities. Thus, nematodes such as Hemicycliophora spp., Neodolichorhynchus spp., Longidorus spp. and Merlinius spp. generally colonise the carbonated and mineralised soils of the Mediterranean dunes, and do not seem to be affected by high salinity. Conversely, populations of Meloidogyne spp. and Pratylenchus spp. nematodes are more commonly found in coarse textured soils and the oligotrophic conditions that occur in Atlantic dunes. Specific local conditions such as the presence of paleosols do not seem to disturb them. Considering that both nematode species are major pests in cropping systems, higher population levels due to their fit to such soil characteristics can explain their contribution to soil fatigue encountered in Atlantic dunes.