Characterization and seasonal ecology of ectomycorrhizae associated with Sitka alder and lodgepole pine from naturally regeneraing young and mature spruce forests in the sub-boreal spruce zone of British Columbia

摘要

Prior to this thesis project, our understanding of the influence of stand age and season on in vivo ectomycorrhizal communities of Sitka alder growing with Lodgepole pine within the Sub-Boreal Spruce biogeoclimatic zone was limited. The magnitude of ectomycorrhizal associates present on Sitka alder and Lodgepole pine was not known. In addition, it was of ecological interest to assess if the two host species, common to early-successional, post-harvest forest communities, were directly linked via common ectomycorrhizal fungi with reference to ecosystem interactions and possible nutrient translocation. Stemming from this general lack of knowledge, the purpose of this thesis project was to strengthen our ecological understanding of these two ectomycorrhizal communities. Two complementary methodologies were implemented in order to assess the ectomycorrhizal communities. Traditional morphological assessments offered one perspective of the mycorrhizal associates and permitted morphological description and mycobiont identification when possible, as well as richness, abundance, diversity, and evenness comparisons with respect to host, stand age, and season. It was found that mycorrhizal richness was greatest for Lodgepole pine. Seral and seasonal effects were shown to significantly impact certain Sitka alder and Lodgepole pine ectomycorrhizae. Seral and seasonal effects also significantly impacted alder ectomycorrhizal diversity and evenness assessments, however, no similar impact was observed for pine. Several possible genera of fungal symbionts were identified that may link Sitka alder and Lodgepole pine. The resolution of ectomycorrhizal taxa comprising the belowground communities were improved over morphological assessments through the use of molecular techniques, specifically PCR-RFLP analyses, the second technique applied. Molecular datasets further confirmed some morpholog_ical assessments and defined morphological descriptions allowing for identification of some mycobionts mostly to the genus level, but also to the species level, as well as determining inter- and intraspecific variation of the int!'lrnal transcribed spacer region of rONA within certain morphotypes. Two mycobiont genera (Cortinarius and Lactarius) were identified on both hosts which suggest the possibility of direct mycorrhizal linkage. In this study, molecular diversity assessments, when used in conjunction with defined morphological techniques (such as morphotyping), offered a complementary synopsis of the diversity and dynamics of ectomycorrhizal communities. Taxa were distinguished to a finer taxonomic level and could be identified using PCR-RFLP analysis while the abundance of ectomycorrhizal morphotypes was best described using morphological techniques. The research indicated that stand age and season can significantly influence alder and pine ectomycorrhizae.