Methods:
A. Matheny's Methods Statement: At UMBS I will install and monitor 60 Granier type (1985) sap flux sensors (30 at Ameriflux and 30 at FASET). Sensors are installed at breast height and data is recorded every minute. Gas exchange and leaf water potential will be measured throughout the day for some trees. We will quantify hydraulic conductance as a function of water potential for both leaves and terminal branch sample from all three sites. Xylem hydraulic conductivity of 1-3 year old canopy branches will be measured using standard hydraulic techniques, taking into account effects due to the ionic composition of the perfusing solution. 6-10 fully illuminated branches, sampled from a minimum of five individuals per species will be measured. The hydraulic architecture and allometry of the tree species in which sap flux is measured will be determined using digital images of the tree, ground-based lidar scan of the tree for 3-D leaf density distribution, and manual measurement of stem and branch diameters combined with maps of branch splitting points, branch angles after each split, and the total conductive diameter before and after each branch split. Species specific and site specific allometric relationships for the number of branch splits as a function of tree height, the scaling of branch diameter with height and branch splitting, branch angles and leaf area per branch diameter at each height level of the tree will be determined from these observations. An allometric relationship between active xylem and branch diameter as a function of height and branching order in the tree will be determined. High resolution airborne lidar scans and ground based portable lidar scans will be ground-truthed and matched with individual tree-crown. We will develop empirical relationships between observed crown diameter, top tree height and the allometric hydraulic scaling parameters.