ARBUSCULAR MYCORRHIZAE IN SAND DUNE PLANTS OF THE NORTH-ATLANTIC COAST OF THE US - FIELD AND GREENHOUSE INOCULATION AND PRESENCE OF MYCORRHIZAE IN PLANTING STOCK

The ability of several sand dune-inhabiting plant species to successfu lly colonize dune sites appears to depend upon the presence in the soi l of arbuscular mycorrhizal fungi (AR IF) that form mutualistic associ ations with roots. Dune sites barren of vegetation lack these fungi wh ose large spores are not readily dispersed to the root zones. Despite the absence of these beneficial fungi from barren sites, however, plan tings made in AMF-free dune soils eventually form the mycorrhizal asso ciation. Examination of planting stock of several species of plants th at are used to vegetate barren sand dunes and dune flats of the easter n seaboard of the U.S.A. revealed that AMF were routinely present in t he planting materials prior to outplanting. AMF occurred in planting s tock of seven varieties of Ammophila breviligulata, and in Prunus mari tima, Rosa rugosa, and Spartina patens, but were absent from Myrica pe nsylvanica. In a field planting in a previously barren deflation zone in the large parabolic dunes of Cape Cod National Seashore, Massachuse tts, culms of A. breviligulata that were inoculated with native specie s of AMF produced more tillers and inflorescences than did non-inocula ted plants, even though 78% of the latter had become mycorrhizal 47 we eks after planting. In greenhouse experiments, P. maritima was found t o have an absolute requirement for AMF and Solidago sempervirens was n ot. The significance of the presence of AMF in planting stock for reve getation and restoration of previously unvegetated sites lacking in AM F is discussed. (C) 1997 Academic Press Limited.