Mycorrhizal facilitation of kin recognition in interior Douglas-fir (Pseudotsuga menziesii var. glauca)

Insight into influences on successful seedling establishment could be essential to future regeneration of British Columbia’s interior Douglas-fir (Pseudotsuga menziesii var. glauca) forests, particularly as climate changes. Areas of harsh climatic conditions have low regenerative capacity and require management decisions leading to enhanced seedling establishment. Variable retention harvesting and natural regeneration from residual trees, for example, may become increasingly important for their locally adaptive traits as climate changes. Kin recognition, mycorrhizal networks, or the combination of the two may be important mechanisms for enhanced seedling establishment in these regions. We examined the effects of relationship (kin vs. non-kin) and mycorrhizal networks on regeneration from seed in greenhouse and field settings. In the greenhouse, kin recognition was evident in differing foliar microelement (Fe, Mo, Al and Cu) and growth variables (total leaf area, volume and stem length) according to relationships between seedlings. Kin recognition was also weakly evident in the field, where it was expressed as differential survivorship among kin versus non-kin seedlings. Kin selection was evident in the greenhouse, where microelement content of kin was greater than non-kin. Greater mycorrhizal colonization of kin compared to non-kin as well as greater donor total leaf area, volume and stem length also suggest kin selection, although not consistently in all experiments. In the field, survivorship was greater among non-kin; however, detection of kin recognition may have been masked by the large effects of site and seed origin on germination and survival. Mycorrhizal networks and carbon transfer occurred within all greenhouse seedling pairs, and enhanced mycorrhization of kin suggests network colonization was involved in kin selection, but our data does not strongly support our hypothesis that kin recognition was facilitated by mycorrhizal networks. While the mechanism of kin recognition is still not well understood, we provided evidence of kin recognition in interior Douglas-fir seedlings, particularly those that originate from harsh climates, and observed subtle indicators of kin selection or reduction of competition due to a close genetic relationship. Accounting for these phenomena in forest management could be helpful to successful regeneration of interior Douglas-fir forests as stresses associated with climate change increase.Forestry, Faculty ofGraduat