Mycorrhizal associations of Salix repens L. communities in succession of dune ecosystems. II. Mycorrhizal dynamics and interactions of ectomycorrhizal and arbuscular mycorrhizal fungi

Ectomycorrhizal (EcM) and arbuscular mycorrhizal (AM) associations of Salix repens were studied at 16 sites in different successional stages of dune e cosystems (calcareous-acidic, dry-wet) in the Netherlands. High EcM coloniz ation, low AM colonization, and lack of differences between habitats indica te that ectomycorrhizas do not increase their importance in later successio nal stages. EcM and AM colonization and plant-nutrient status indicate that the relative importance of P and N does not change during succession, but during seasons. Salix repens showed low levels of AM colonization but, neve rtheless, even these low levels contributed to covering the P demands of th e plant. As a decrease in AM colonization in S. repens at the end of the se ason coincided with a decrease in AM inoculum potential, the seasonal decli ne of arbuscular mycorrhiza is caused by changes in plant demand or soil nu trient availability rather than by interference by ectomycorrhiza. Regardle ss of seasonal shifts and possible interaction between ectomycorrhiza and a rbuscular mycorrhiza, both persist in the plant roots during seasons and th roughout succession. Differences in the habitat preference of various EcM m orphotypes and arbuscular mycorrhiza suggest that mycorrhizal diversity con tributes to the broad ecological amplitude of S. repens.