Thirty-minute averages of temperature difference data were computed and stored in data loggers. Using tree sapwood area,stand LAI and stand tree density , Js was scaled and convered to a tree-scale average transpiration per unit leaf area. At the Piedmont natural site,stand characteristics,including LAI and sapwood area per unit ground area were taken in a 6.25 ha area surrounding the eddy covariance tower . At the Piedmont lopblolly pine plantation LAI and sapwood area were determined from four 30-m diameter plots.