The Communal Root System of Red Pine: Water Conduction Through Root Grafts

Abstract

Abstract Flow rates through excised root grafts of Pinus resinosa Ait. were tested under laboratory conditions. Measurable flow capacities existed between grafted roots as well as along original root axes. Flow distribution from inflow points was not strictly fixed; rather, a certain amount of water was diverted from one pathway to another depending on the tensions imposed on exiting arms. The magnitude of such diversion was often greater than could be accounted for by cross-grain conduction observed in nongrafted roots. An explanatory model postulates a mechanism for variable sharing among pathways at the junction, presumably resulting from anatomy and arrangement of tracheids in fusion tissue. Such a mechanism could similarly allow for sharing of available moisture among several interconnected trees, although this has yet to be demonstrated in the field. Forest Sci. 21:255-261.