Differential response of plant water consumption to rainwater uptake for dominant tree species in the semiarid Loess Plateau

Abstract. Whether uptake of rainwater can increase plant water consumption in response to rainfall pulses requires investigation to evaluate the plant adaptability, especially in water limited regions where rainwater is the only replenishable soil water source. In this study, the water sources from rainwater and three soil layers, predawn (Ψpd), midday (Ψm) and gradient (Ψpd−Ψm) of leaf water potential, and water consumption in response to rainfall pulses were analyzed for two dominant tree species, Hippophae rhamnoides and Populus davidiana, in pure and mixed plantations during the growing period (June–September). In pure plantations, the relative response of daily normalized sap flow (SFR) was significantly affected by rainwater uptake proportion (RUP) and Ψpd−Ψm for H. rhamnoides, and was only significantly influenced by Ψpd−Ψm for P. davidiana (P