Plants in water-controlled ecosystems: active role in hydrologic processesand response to water stress - I. Scope and general outline

This series of four papers studies the complex dynamics of water-controlled ecosystems from the hydro-ecological point of view [e.g., I. Rodriguez-Itu rbe, Water Resour. Res. 36 (1) (2000) 3-9]. After this general outline, the role of climate, soil, and vegetation is modeled in Part II [F. Laio, A. P orporato, L. Ridolfi, I. Rodriguez-Iturbe, Adv. Water Res. 24 (7) (2001) 70 7-723] to investigate the probabilistic structure of soil moisture dynamics and the water balance. Particular attention is given to the impact of timi ng and amount of rainfall, plant physiology, and soil properties. From the statistical characterization of the crossing properties of arbitrary levels of soil moisture, Part III develops an expression for vegetation water str ess [A. Porporato, F. Laio, L. Ridolfi, I. Rodriguez-Iturbe, Adv. Water Res . 24 (7) (2001) 725-744]. This measure of stress is then employed to quanti fy the response of plants to soil moisture deficit as well as to infer plan t suitability to given environmental conditions and understand some of the reasons for possible coexistence of different species. Detailed application s of these concepts are developed in Part IV [F. Laio, A. Porporato, C.P. F ernandez-Illescas, I. Rodriguez-Iturbe, Adv. Water Res. 24 (7) (2001) 745-7 62], where we investigate the dynamics of three different water-controlled ecosystems. (C) 2001 Elsevier Science Ltd. All rights reserved.