SHARED COMPATIBILITY OF ECTOMYCORRHIZAE ON PSEUDOTSUGA-MENZIESII AND BETULA-PAPYRIFERA SEEDLINGS GROWN IN MIXTURE IN SOILS FROM SOUTHERN BRITISH-COLUMBIA

Seedlings of Pseudotsuga menziesii (Mirb.) France and Betula papyrifer a Marsh. were grown in the greenhouse in monoculture and dual culture in soils collected from a young mixed species plantation in the southe rn interior of British Columbia. The objectives of the study were (i) to evaluate the ability of P. menziesii and B. papyrifera to share com patible ectomycorrhizal fungi in order to assess their potential for h yphal linkages and (ii) to study the influence of neighboring seedling s on ectomycorrhizae occurrence. Eleven ectomycorrhizal morphotypes we re recognized, seven of which P. menziesii and B. papyrifera seedlings shared in common over 90% of their root tips. The abundance and frequ ency of Rhizopogon, E-strain I, and Tuber on P. menziesii, and the fre quency of Lactarius, Hebeloma, and Cenococcum on B. papyrifera, were a ffected by the presence of a neighboring seedling. The number of ectom ycorrhizal morphotypes shared in common and colonization of root tips by common types were slightly greater when P. menziesii and B. papyrif era were grown in dual culture rather than in monoculture.