Open Collections

Abstract

The overall objective of this thesis was to assess the influence of different clear-cut sizes on the survival of ectomycorrhizal fungi one and two growing seasons after logging. A comparative study involving a greenhouse bioassay and a survey of ectomycorrhizal roots from soil cores detected very different assemblages of the ectomycorrhizal fungal community one growing season after host removal. These differences are thought to be the result of variation in fungal activity and differences in epidemiology. Two growing seasons after host removal, a survey of ectomycorrhizal roots from soil cores revealed that both the numbers of active ectomycorrhizae and the diversity of ectomycorrhizae were significantly reduced at clear-cut plots relative to the undisturbed forest. Specifically, there was a significant decrease in diversity with increasing distance from the block edge. There were no differences in diversity at the same distance from the edge of different sized clear-cuts. A field bioassay showed that the diversity of ectomycorrhizal fungi capable of colonizing young spruce seedlings two growing seasons after host removal was significantly reduced with distance from the block edge. The critical distance beyond which diversity decreased was 16 - 25m. As with the results of the survey of ectomycorrhizae from soil cores, there were no differences in diversity at the same distance from the edge of different sized clear-cuts. These results suggest that, in clear-cuts ranging in size from 0.1 to 10 ha, distance from the edge, or proximity to overstory trees, is more important to patterns of ectomycorrhizal persistence and diversity than opening size. The use of vital stains revealed that fungal tissue associated with 'active' mycorrhizae is viable yet not metabolically active.