Physiological integration of trees through root connections

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The main objective of the proposed research program is to demonstrate physiological integration of trees that are interconnected through root grafts or parental roots (root sprouting species). We recently demonstrated that trees could affect the physiology of their neighbours through root connections, but the level on physiological integration between trees is not known. For example, we do not know to what extent (spatially and quantitatively) C reserves and resources are shared between trees, and in particular, how relationships of competition vs cooperation affect forest dynamics. We have previously shown that root connections are found in most forest stands of the boreal forest, using exploratory approaches. We found many trees grafted to live roots of dead trees; this indicates that connected trees provide energy to linked root systems to keep them alive. We will use field and lab experiments to demonstrate the «cost» of supporting large underground biomass from communal root systems, and how trees can vegetatively regenerate trees from different genotypes with root grafting. We will also examine competitive vs cooperative relationships between trees interconnected through their root system. This research has the potential to impact classical notions of forest ecology that consider trees as distinct individuals, strictly competing for resources with each other. If the level of physiological integration is found to be high, forest management practices may also need to be changed.