In 2000, Weyerhaeuser funded the Canadian Forest Service to conduct a pilot study to examine the abundance and diversity of ectomycorrhizae on operational Variable Retention (VR) settings being monitored under the Adaptive Management program. The objective of the pilot study was to compare the ectomycorrhizal fungal abundance and diversity on operationally planted seedlings, proximal and distant to forest patches in second growth and old growth stands subject to VR harvesting. We hypothesized that retention of mature trees enhances the survival of ectomycorrhizal fungal species, and increases the abundance and diversity of ectomycorrhizal fungi on the seedlings. The results of the pilot study demonstrated an influence of proximity to a forest patch as well as previous stand age on both abundance and diversity of ectomycorrhizal fungi on seedling roots (Outerbridge et al. 2001). We found that sites with planted seedling suitable for the pilot study were limited and as a result 4 of the 5 sites we used were not part of the vegetation and forest structure monitoring program. As a result in 2000 we also established an experimental study in which we planted non-mycorrhizal seedling along transects at the 5 pilot sites and on a transect at a sixth former old-growth site. We suggested that it would be useful to have vegetation cover surveyed along transects we measured in the pilot study and planted for the experimental study. Since we had observed variation in ectomycorrhizal colonization in seedling, such a survey would help determine if any of the variability observed in the seedlings within a transect or differences between harvested old-growth and second-growth areas might be due to the presence of either advanced regeneration or woody species which might serve as alternate host for the ectomycorrhizal fungi. Previous research has demonstrated inter and intra-specific sharing of the vegetative mycelium amongst host trees (Amaranthus and Perry, 1989; Molina et al., 1992). While most herbs and ferns are non-mycorrhizal, woody perennials typically form at least vesicular-arbuscular mycorrhizae (VAMs), many are ectomycorrhizal (e.g. all Pinaceae), and some species can form several types of symbiotic root-fungus associations (Harley and Smith, 1983). Evidence also exists in literature which indicates competition or inhibition amongst plants at the root level (Perry et al., 1989), which has potential for interfering with the processes of ectomycorrhizal formation and retention. Vascular plants, especially trees and woody perennials have been fairly well documented in coastal British Columbia (Henry, 1915; Straley et al., 1985; Klinka et al., 1989; Pojar et al., 1994; Lyons et al., 1995; Douglas et al., 1998-2000). Weyerhaeuser?s BC Coastal Group has also been conducting plant surveys in VR sites as part of the vegetation and forest structure monitoring program. No studies were found which investigate the correlation between ectomycorrhizal diversity and the perennial vegetation present in the proximity of the host conifer seedlings. Our objective for conducting the vegetation survey along transects of the 6 sites was to conduct a post-hoc analysis to see if variation in ectomycorrhizae on seedlings at the 5 pilot study sites could be accounted for our differences in vegetation and later use the vegetation data in the analysis of ectomycorrhizae on seedlings experimentally planted at all 6 sites.
Outerbridge, Renata, Trofymow, John Antonio. 2003. Diversity of ectomycorrhizae on planted seedlings in variable retention forestry sites: results of vegetation survey. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2003MR066