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 ecosystems (calcareous-acidic, dry-wet) in the Netherlands. High EcM colonization, low AM colonization, and lack of differences between habitats indicate that ectomycorrhizas do not increase their importance in later successional 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, nevertheless, even these low levels contributed to covering the P demands of the plant. As a decrease in AM colonization in S. repens at the end of the season coincided with a decrease in AM inoculum potential, the seasonal decline of arbuscular mycorrhiza is caused by changes in plant demand or soil nutrient availability rather than by interference by ectomycorrhiza. Regardless of seasonal shifts and possible interaction between ectomycorrhiza and arbuscular mycorrhiza, both persist in the plant roots during seasons and throughout succession. Differences in the habitat preference of various EcM morphotypes and arbuscular mycorrhiza suggest that mycorrhizal diversity contributes to the broad ecological amplitude of S. repens.