Arbuscular mycorrhizae of Leymus arenarius on coastal sands and reclamation sites in Iceland and response to inoculation

The occurrence of arbuscular mycorrhizae fungi (AMF) was examined in natural and reclaimed sand dunes in Iceland. On the coastal sand-plain of Myrdalssandur no spores of AMF were found on barren sand, and very few were found in 1- and 5-year-old reclamation sites of Leymus arenarius (lymegrass). A significantly higher number of AMF spores and root colonization were found in a 10-year-old reclamation site and in a natural old dune system of L. arenarius. AMF spores showed seasonal variation with higher occurrence in the fall than in the spring. On the volcanic island Surtsey, no AMF spores or root colonization were found on L. arenarius in 6- and 10-year-old dunes. However, AMF spores and root colonization were found in the 22-year-old Leymus dune. On Surtsey, a colonization pattern was found where AMF non-dependent plants were the first colonizers followed by AMF facultative plants, then by AMF-dependent plants. Today AMF facultative plants have the highest number of species but AMF non-dependent plants have the largest population size. Three different AMF inocula were tested on L. arenarius; growth of seedlings was improved significantly by an indigenous AMF inoculum compared with commercial inocula. Inoculation of nursery grown seedlings of L. arenarius followed by transplantation into barren sand seeded with L. arenarius is recommended because this method will ensure establishment of the plant and enhance succession.