| Recent studies have indicated that sand dune vegetational patterns are caused by soil pathogens. However, they have ignored possible influences of beneficial soil organisms like arbuscular mycorrhizal (AM) fungi. Since plant-parasitic nematodes are ubiquitous in soils from many habitats, including sand dunes, I investigated the possible influences of these two microorganisms on the vegetation.;Results showed that plant-parasitic nematode infections and AM fungi colonizations followed a spatial pattern corresponding to the plant community composition. A controlled experiment showed that sand burial and AM fungi interacted to increase the root biomass. Plant-parasitic nematodes only affected the plants when they were combined with either sand burial or AM fungi, when both burial and AM fungi were present no nematode effects were evident.;I concluded that although plant-parasitic nematodes are associated with the plant community composition, it is likely that they are not the primary determinants affecting vegetation composition. |
