Functional features in the response to drought by Quercus species; inter- and intra-specific variation

Abstract

Aranda, I., Ramírez-Valiente, J.A., Rodríguez-Calcerrada, J. 2014. Functional features in the response to drought by Quercus species; inter- and intra-specific variation. Ecosistemas 23(2): 27-36. Doi.: 10.7818/ECOS.2014.23-2.05

The genus Quercus has a wide geographic distribution throughout the Northern hemisphere. Oak species spread from cold-temperate zones in Europe or North-America to sub-tropical areas in South-America. In a macro-evolutionary frame, numerous species within the genus have mechanisms to resist water stress together with functional and morphological traits to avoid dehydration of aerial tissues. In the last, these traits bring about oak species to be successful organisms in environments with high seasonal or sporadic water limitations. On the other hand, water scarcity is interacting with other resources such as light availability during forest regeneration. This inter-play between availability of resources results in a complex tuning in the expression of functional traits. In addition, and from a micro-evolutionary point of view, it is common that many Quercus species have a high level of intraspecific genetic variation in response to drought. This variation operates at different hierarchical levels, ranging from populations to maternal lines or clones.

Different mechanisms of tolerance and avoidance of drought are revised in this work aimed at explaining the success of Quercus in environments prone to water stress. The overview also covers studies of intraspecific variability in traits responding to water stress. Finally, we discuss some putative functional responses of Quercus that may occur in the future in the Mediterranea area, and for which more stressful conditions are expected.