MYCORRHIZAL FUNGUS COLONIZATION OF PINUS-RESINOSA AIT TRANSPLANTED ON NORTHERN HARDWOOD CLEARCUTS

An ordered succession in mycorrhizal fungus colonization occurred on red pine (Pinus resinosa Ait.) root systems transplanted on three recently-cleared northern hardwood sites in northern Michigan, U.S.A. Ordered changes were related to tree age from transplanting, and were demonstrated experimentally by quantification of mycorrhizal morpho-types, laboratory isolation of fungi from mycorrhizae, physiological categorization of fungi recovered from mycorrhizae and surveys of fruiting bodies associated with seedlings and transplants. With increasing plantation age, (1) the number of non-mycorrhizal root tips encountered declined to zero, (2) the common nursery mycorrhizae decreased in abundance, (3) new mycorrhizal types especially Cenococcum and Suillus) became more abundant, (4) cellulolytic fungi and ectendomycorrhizal fungi were isolated from mycorrhizae less frequently, and (5) ectomycorrhizal fungi were isolated from mycorrhizae more frequently. The number of apparently different mycorrhizal fungus species isolated from mycorrhizae increased from five in the first year after transplanting to 22 in the fourth year.