Variation in xylem structure and function in stems and roots of trees to 20 m depth

To assess hydraulic architecture and limitations to water transport across whole trees, we compared xylem anatomy, vulnerability to cavitation (Y50), and specific hydraulic conductivity (Ks) of stems, shallow roots, and deep roots (from caves to 20 m depth) for four species: Juniperus ashei, Bumelia lanuginosa, Quercus fusiformis and Quercus sinuata. Mean, maximum, and hydraulically-weighted (Dh) conduit diameters and Ks were largest in deep roots, intermediate in shallow roots, and smallest in stems (P

See also commentary by Gretchen North (New Phytologist 163: 447-449) np04north.pdf