Stomata regulate plant carbon gain, water loss and other physiological determinants of forest productivity. Our ability to assess impacts of reduced soil moisture and other global changes on forest ecosystems relies heavily, therefore, on understanding of stomatal function and control. A new paradigm is emerging in stomatal physiology, one that challenges the traditional view that drought affects stomatal behavior initially and chiefly via leaf dehydration. It now appears that stomata of plants in drying soil may be controlled by both nonhydraulic and hydraulic factors, with hormonal root-sourced signals having as much or more influence as leaf dehydration in closing stomates during soil drying. This nonhydraulic, Whole-plant mechanism for perceiving and responding to gradual declines in soil moisture had yet to be investigated in forest ecosystems. we investigated the significance of this process in deciduous forests and tested whether species sensitivity to nonhydraulic signaling is allied with drought avoidance and tolerance profiles.