15 - Structure-function relationships in sapwood water transport and storage

Abstract

Primary production by plants requires the loss of substantial quantities of water when the stomata are open for carbon assimilation. The delivery of that water to the leaves occurs through the xylem. The structure, condition, and quantity of the xylem control not only the transport efficiency but also the release of water from storage. For example, if there is high resistance to water flow in the stem, then less water is available to the leaves, so less primary production can occur. High resistance can result from wood material with low conductivity, from having only a small amount of conductive wood, or from having very slow release of stored water to the transpiration stream. This chapter focuses on the efficiency with which different parts of the sapwood transport, store, and release water, and how the structure of the wood affects these processes. Particularly, it describes the radial patterns of axial water transport, their anatomical and physiological causes, the effect that sapwood width and wood structure, especially density, have on water transport, and determinants of sapwood water storage properties.