Ecohydrology of arid and semiarid ecosystems: An introduction

Ecohydrology has been recently defined as the science, which seeks to describe the hydrologic mechanisms that underlie ecologic patterns and processes (Rodriguez-Iturbe, 2000; p. 1). This type of inquiry is fundamental to the understanding of the coupling existing between ecosystem dynamics and the water cycle, in particular in arid and semiarid environments, where water is an important limiting resource not only for its scarcity but also for its intermittency and unpredictable presence (Porporato and Rodriguez-Iturbe, 2002; Rodriguez-Iturbe and Porporato, 2005). The biogeoscience community has been recently trying to establish stronger connections between research in the physical and the natural sciences to provide a process-based understanding of the interactions existing between the hydrosphere and the biosphere. Thus, the research area at the border between hydrology and ecology is recently receiving a considerable attention. The term Ecohydrology itself, is becoming increasingly popular in the scientific literature. Nuttle (2002) provides a thorough analysis of this new and combined approach to hydrological and ecological studies: Eco-hydrology emerges as an engaging topic with multiple facets and deep roots in the history of hydrologic science. It is the subdiscipline shared by the ecological and hydrological sciences that is concerned with the effects of hydrological processes on the distribution, structure, and function of ecosystems, and on the effects of the biotic processes on the elements of the water cycle. The same author notices that in this new context previously unrelated areas of scientific inquiry are now coming together. This approach is fundamental to the analysis of ecosystem dynamics, of their response to different hydrologic and climatic regimes as well as of their impact on regional and global climate. This book represents an effort exactly in this direction, in that it provides a background for a synthesis of new research approaches and recent results in the study of ecological and hydrological processes characteristic of arid environments.