Willow Salix viminalis L. supplies oxygen into the subsurface environment. Laboratory experiments determined the willow Oxygen Transfer Capacity and its dependence on total leaf area and root wet mass. It was shown, that oxygen is released by roots under light conditions, and the rate of oxygen supplymay be greater than the rate of consumption due to respiration of roots. The mean OTC level was 195.7 [gO(2).m(-3).h(-1-)kg(rwm)(-1)]. Nonlinear relationship between OTC and both total leaf area and root wet mass was found, and confirmed by high determination coefficient (R-2) values: 0.912 and 0.936. (C) 2011 Elsevier Ltd. All rights reserved.