| This dissertation investigated the prevalence and select ecological impacts of root grafting in lodgepole pine. To document the frequency of root grafting, groups of trees were hydraulically excavated and the root systems were examined. Results indicate that root grafting frequency was controlled by tree density, tree age and tree diameter; as these variables increased, the rate of grafting also increased. The greatest distance recorded between grafted trees was 109 cm, which suggests that grafting would not be a common occurrence in stands with less than 8,500 stems per hectare (based on even tree distribution).; We also examined whether root grafts can transfer sufficient carbohydrate reserves among trees to affect the vigour of grafted trees growing in light-limited environments. At each plot, one tree in a grafted pair and one non-grafted tree were shaded for one growing season. Results indicate that shaded trees had significantly lower carbohydrate reserves and smaller crowns relative to non-shaded trees. However, root grafts appeared to partially offset the effects of shading as grafted shaded trees had significantly higher root carbohydrate reserves than non-grafted shaded trees. This implies that root grafts can transfer enough photosynthate to affect the carbon economy of subordinate trees, which may allow grafted trees to persist longer under shaded conditions than non-grafted trees.; The longevity of live roots on snags and stumps grafted to living trees and the impact of these roots on the growth of live trees were investigated. Grafted tree pairs composed of one live tree and one snag and leave trees that had their grafted partners cut two growing seasons previously were assessed. Results demonstrate that the percentage of live roots on snags or stumps grafted to living trees gradually decreased until virtually no live roots remained 15 years after death of the crown. Also, diameter increment in the living trees significantly increased following manual thinning, but was unaffected when the grafted partner died naturally. From these results, it appears that the improved growing conditions following thinning were more important for tree growth than the inheritance of a large neighbouring root system connected by a graft. |
