Ectomycorrhizas of regenerating stands of lodgepole pine (Pinus contorta)

Abstract

The ectomycorrhizal community associated with regenerating lodgepole pine (Pinus contorta Loud.) after clear-cutting in southwestern Alberta was investigated in 6-, 10-, and 19-year-old cut blocks and their adjacent 90-year-old undisturbed control stands. Twenty different mycorrhizal taxa were found in the 90-year-old undisturbed stands. Of these 20, 13 mycorrhizal taxa were found in the 6-year-old cut blocks, and 15 mycorrhizal taxa were found in both the 10- and 19-year-old cut blocks. The most common associate of all stand ages was Mycelium radicis atrovirens Melin (MRA), which overall colonized 29% (weighted average) of the root tips. Species or groups accounting for greater than 10% of the mycorrhizas in one or more age classes included Piloderma fallax (Karst.) Jül. (15% overall), Piloderma byssinum (Karst.) Jül. (11%), Cenococcum geophilum L. (8%), Russula-like (8%), Suillus brevipes (Pk.) Kuntze (5%), Suillus tomentosus (Kauff.) Sing., Snell & Dick (5%), and Lactarius deliciosus (L.:Fr.) S.F. Gray (2%). Although several mycorrhizal fungi exhibited significant differences in percent relative abundance of root tips colonized, when comparing cut blocks to their controls, there was no evidence to suggest that the suite of mycorrhizal fungi colonizing roots of young lodgepole pine trees was replaced by a different suite of mycorrhizal fungi in mature stands. Extensive fruit body collections, totalling 43 species of ectomycorrhizal fungi, throughout the study sites support this contention.Key words: Pinus contorta ectomycorrhizas, clear-cutting, second-rotation forests, succession.