Instrumental Approaches for Studying Tree-Water Relations Along Gradients of Tree Size and Forest Age

There is an increasing demand for data on tree structural and functional attributes that can be collected simultaneously at multiple sites and integrated across landscapes. Here, we present several examples of approaches applicable for measuring tree and stand structures and for characterizing spatial and temporal variation in important functions of the above- and belowground parts of both large and small trees. Special attention is given to explanations of the theoretical basis for several sap flow techniques and to the types of information that can be gleaned from carefully planned measurements of sap flow in stems and roots. A variety of approaches for characterizing the structure and function of root systems: the hidden half of trees, are also described.