Measurements were made of the effects of below- and/or above-ground competition from the vines Lonicera japonica and Parthenocissus quinquefolia on availability of light water and nitrogen to the host tree Liquidambar styraciflua and the relation between resource availability and tree growth was examined. Light penetration through the tree canopy pre-dawn leaf water potential and leaf nitrogen concentration were used as predictors of respectively light water and nitrogen availability to the tree. Vine presence significantly reduced light penetration through the canopy but this reduction was not clearly related to the growth responses of trees. Vines did not reduce the pre-dawn leaf water potential of competing trees. Leaf nitrogen concentration of trees was significantly reduced by below-ground competition with L. japonica. The positive correlation between the annual average leaf nitrogen concentration and tree diameter growth suggested that competition for nitrogen mediated the effects of below-ground competition of vines on tree growth.