The hydraulic architecture of trees and other woody plants

Abstract

summary In this paper, we have reviewed how the hydraulic design of trees influences the movement of water from roots to leaves. The hydraulic architecture of trees can limit their water relations, gas exchange throughout the crown of trees, the distribution of trees over different habitats and, perhaps, even the maximum height that a particular species can achieve. Parameters of particular importance include: (1) the vulnerability of stems to drought‐induced cavitation events because cavitation reduces the hydraulic conductance of stems, (2) the leaf specific conductivity‐of stems because it determines the pressure gradients and most negative water potentials needed to sustain evaporation from leaves, (3) the water storage capacity of tissues because this might determine the ability of trees to survive long drought periods. All of these parameters are determined by the structure and function of anatomical components of trees. Some of the ecological and physiological trade‐offs of specific structures are discussed.

Change in Hydraulic Resistance and Shoot Morphology of Napiergrass (Pennisetum purpureumSchumach.) under Shaded Condition

“…Hydraulic resistance of a stem is generally regulated by stem length and cross-sectional area (Tyree and Ewers, 1991). In this study, normalization of R stem by stem cross-sectional area (R S stem ) decreased the difference in R stem among treatments, although there was still signifi cant difference among treatments (R stem , Table 3).…”

“…These fi ndings indicate that SF plants were superior in both the capacity and the effi ciency of water conductance in the stem. In woody plant, R SP stem decreased with the increase in conduit diameter (Tyree and Ewers, 1991). Thicker stem included wider diameter (Shultz and Matthews, 1993;Lovisolo and Schubert, 1998), therefore a thicker stem is considered to have a lower R SP stem .…”

Water acquisition patterns of two wet tropical canopy tree species of French Guiana as inferred from H218O extraction profiles

“…Several characteristics have been proposed to explain these differences, among which, differences in CO 2 assimilation rates [1,6,7,29], stomatal regulation [7,9,23,26,29] or hydraulic conductivity [9,39,41]. Differences in water acquisition strategies among species and the ability of some species to explore deep soil layers could also explain these differences.…”

Hydraulic properties and embolism in small-diameter roots of five temperate broad-leaved tree species with contrasting drought tolerance

“…It is assumed that about half of a plant's total hydraulic resistance is located belowground, which emphasizes the crucial role played by the root system in water flux control (Passioura 1988;Tyree and Ewers 1991). Surface roots may function like valves in the soil-plant-atmosphere flow path by enabling rapid water transport when the soil is wet, but disconnecting the plant from the driest soil patches through the development of drought-induced embolism (Alder et al 1996;Martínez-Vilalta et al 2002).…”