Species-specific water use by forest tree species: From the tree to the stand

Forests play a critical role in the hydrological cycle making the study of water use by trees and forest stands of prime importance in the global change context .Very negative effects of increasing and more intense droughts on forest vegetation have been described over the last decades. Symptoms of disease and decline have been associated with changed precipitation patterns in many forests particularly in European temperate and Mediterranean regions. Intra- and inter-specific differences in both physiology and morphology exert a large but not well understood influence on the water balance of forest ecosystems, further affecting their vulnerability to drought. Stand structure and composition influences rainfall interception, runoff and water fluxes of the whole ecosystem. Both expanding plantations of renovated interest for biofuel industry and natural and semi-natural forests must be managed in a sustainable way on the basis of their water consumption. We review the role of key drivers on forest water use such as species composition, tree canopy status of each of them and species specific sensitivity to soil water scarcity. Specifically we discuss the role of these factors for natural forest, but with references also to forest plantations. Water scarcity is expected to be one of the largest societal problems worldwide in the near future, so water use by natural and planted forest ecosystems has become a central subject in current research agendas.