Patterns of arbuscular- and ecto- mycorrhizal colonization of Eucalyptus dunnii in southern Brazil

Abstract

After planting Eucalyptus dunnii, virtually free of mycorrhizal colonization, at six sites in southern Brazil, three distinctive patterns of root colonization by arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi were discerned during the ensuing 13 months which seemed to be very strongly related to previous cropping: 1) pattern A followed the AM-forming soya bean: the relatively large incidence of AM 5 months after planting progressively decreased while that of ECM increased; 2) pattern B followed the AM/ECMforming Eucalyptus viminalis: the incidence of AM remained minimal while that of ECM relatively rapidly reached a high plateau: and 3) pattern C followed the ECM-forming Pinus taeda: both AM and ECM progressively increased but were never abundant. Although the results do not fully explain the three patterns of colonization, it is suggested that the inoculum potential and the specificity fungi host are implicated.