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 < 0.05). Meanwhile, the large Ψpd−Ψm was consistent with high SFR for H. rhamnoides, and the small Ψpd−Ψm was consistent with the low SFR for P. davidiana, in response to rainfall pulses. Therefore, H. rhamnoides and P. davidiana exhibited sensitive and insensitive responses to rainfall pulses, respectively. Furthermore, mixed afforestation significantly enhanced RUP, SFR, and reduced the water source proportion from the deep soil layer (100–200 cm) for both species (P < 0.05). The SFR was significantly influenced by RUP and Ψpd−Ψm for both species in the mixed plantation. Lower Ψm and higher Ψpd were adopted by H. rhamnoides and P. davidiana in mixed plantation, respectively, to enlarge Ψpd−Ψm, enhance rainwater uptake, and decrease water source competition from the deep soil layer. These results indicate that mixed afforestation enhanced the influence of rainwater uptake to water consumption after rainfall pulse, regardless of sensitivity to rainfall pulses. This study provides insights into suitable plantation species selection and management considering the link between rainwater uptake and consumption in water limited regions.
Highlights
Rainwater uptake by plant and water consumption in response to rainfall pulses drive the survival of 40 plant species and ecosystem ecohydrological processes, especially in arid and semiarid regions where rainwater is the only replenishable soil water source (Berkelhammer et al, 2020; Gebauer and Ehleringer, 2000; West et al, 2012)
These results indicate that mixed afforestation enhanced the influence of rainwater uptake to water consumption after rainfall pulse, regardless of sensitivity to rainfall pulses
The SFR was significantly influenced by rainwater uptake proportion (RUP) and Ψpd−Ψm for H. rhamnoides, but the SFR was only significantly influenced by Ψpd−Ψm for P. davidiana
Summary
Rainwater uptake by plant and water consumption in response to rainfall pulses drive the survival of 40 plant species and ecosystem ecohydrological processes, especially in arid and semiarid regions where rainwater is the only replenishable soil water source (Berkelhammer et al, 2020; Gebauer and Ehleringer, 2000; West et al, 2012). The variability and intermittency of rainfall, which plays an important role in plant water uptake and consumption (Swaffer et al, 2014; Wang et al, 2020), have been predicted to increase in water limited regions (Klein et al, 2014; Mendham et al, 2011). Clarifying the influence of rainwater uptake to plant water consumption after rainfall pulses is essential to understand the process of plant species adaptation in water limited 50 regions (Meier et al, 2018; Tfwala et al, 2019). Rainwater uptake by plant is expected to increase water consumption after a rainfall pulse (Cheng et al, 2006; Liu et al, 2019; Xu et al, 2012).
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