Growth and Water Relations of Kentucky Coffee Tree and Silver Maple Following Transplanting

Abstract

Following transplanting we monitored growth and water relations over two years in Kentucky coffee tree (Gymnocladus dioica (L.) C. Koch) and silver maple (Acer saccharinum L.). Field-grown, well-established trees transplanted in place were compared to nontransplanted control trees. Predawn water potential was measured twice each month for two growing seasons, as well as midday stomatal conductance and water potential. Shoot elongation, leaf size, diameter growth, and total leaf area were determined both years. Less total leaf area as a result of transplanting apparently moderated total tree transpiration in both species. Reduced tree transpiration allowed stomatal conductance and predawn water potential to reach levels equal to non-transplanted trees in both species during periods of high rainfall. During low-rainfall periods water relations of transplanted Kentucky coffee tree (KCT) declined more than silver maple (MAP) relative to the control trees. Compared to non-transplanted trees, transplanting reduced growth of KCT more than that of MAP the first year. In the second year, when growing-season rainfall was less than half of the first year, the relative effect of transplanting on growth of the two species was reversed, indicating that KCT was more drought tolerant. These results suggested that deciduous balled-and-burlapped trees transplanted while dormant self-regulate water loss by reducing transpiring leaf area the following growing season.