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The implementation of large-scale vegetation restoration over the Chinese Loess Plateau has achieved clear improvements in vegetation fraction, as evidenced by large areas of slopes and plains being restored to grassland or forest. However, such large-scale vegetation restoration has altered land-atmosphere exchanges of water and energy, as the land surface characteristics have changed. These variations could affect regional climate, especially local precipitation. Quantitatively evaluating this feedback is an important scientific question in hydrometeorology. This study constructs a coupled land-atmosphere model incorporating vegetation dynamics, and analyzes the spatio-temporal changes of different land use types and land surface parameters over the Loess Plateau. By considering the impacts of vegetation restoration on the water-energy cycle and on land-atmosphere interactions, we quantified the feedback effect of vegetation restoration on local precipitation across the Loess Plateau, and discussed the important underlying processes. To achieve a quantitative evaluation, we designed two simulation experiments, comprising a real scenario with vegetation restoration and a hypothetical scenario without vegetation restoration. These enabled a comparison and analysis of the net impact of vegetation restoration on local precipitation. The results show that vegetation restoration had a positive effect on local precipitation over the Loess Plateau. Observations show that precipitation on the Loess Plateau increased significantly, at a rate of 7.84 mm yr −2 , from 2000 to 2015. The simulations show that the contribution of large-scale vegetation restoration to the precipitation increase was about 37.4%, while external atmospheric circulation changes beyond the Loess Plateau contributed the other 62.6%. The average annual precipitation under the vegetation restoration scenario over the Loess Plateau was 12.4% higher than that under the scenario without vegetation restoration. The above research results have important theoretical and practical significance for the ecological protection and optimal development of the Loess Plateau, as well as the sustainable management of vegetation restoration.

Increased human water use combined with climate change have aggravated water scarcity from the regional to global scales. However, the lack of spatially detailed datasets limits our understanding of the historical water use trend and its key drivers. Here, we present a survey-based reconstruction of China’s sectoral water use in 341 prefectures during 1965 to 2013. The data indicate that water use has doubled during the entire study period, yet with a widespread slowdown of the growth rates from 10.66 km³·y−2 before 1975 to 6.23 km³·y−2 in 1975 to 1992, and further down to 3.59 km³·y−2 afterward. These decelerations were attributed to reduced water use intensities of irrigation and industry, which partly offset the increase driven by pronounced socioeconomic development (i.e., economic growth, population growth, and structural transitions) by 55% in 1975 to 1992 and 83% after 1992. Adoptions for highly efficient irrigation and industrial water recycling technologies explained most of the observed reduction of water use intensities across China. These findings challenge conventional views about an acceleration in water use in China and highlight the opposing roles of different drivers for water use projections.

Background and aims Understanding the variability in water availability in agroforestry systems in rain-fed orchards is vital for optimizing orchard management in semiarid areas. However, few studies have examined the soil capacity of water stock and supply in these systems over multiple years. We aim at (i) characterizing several soil physical properties related to water availability and inter-annual dynamics of soil water content and (ii) exploring their response to meteorological conditions and root distribution. Methods Jujube ( Ziziphus jujuba Mill.) intercropped with the fodder species canola ( Brassica napus L.) (JFCS), jujube intercropped with daylily ( Hemerocallis fulva L.) (JDLS), and a jujube orchard with clean tillage (JCS) were established on the Loess Plateau, China. Soil physical properties (including soil bulk density, soil hydraulic conductivity, soil field capacity, and soil porosity), soil water content and fine root data were collected over the period 2014–2017. Results Compared to JCS-Tree, the field capacity was significantly increased both in the JFCS-Tree and JDLS-Tree treatments, while soil capillary porosity increased significantly only in the JFCS-Tree. Compared to JCS-Inter-row, the JFCS-Inter-row and JDLS-Inter-row exhibited significantly decreased soil bulk density, and increased field capacity, saturated hydraulic conductivity, and improved soil porosity, but the non-capillary porosity in the JDLS-Inter-row treatment were not significantly modified. Compare to JCS-Tree treatment, the soil water at 0–60 cm significantly increased under JFCS-Tree and JDLS-Tree in four years. However, due to the deeper fine root distribution for both tree and crop under JDLS-Inter-row, the soil water content at 60–180 cm in JDLS-Inter-row significantly decreased more than JFCS-Inter-row and JCS-Inter-row. Conclusions The introduced crop modified the soil physical properties and soil water content, indirectly under trees and directly between inter-rows through the role of fine roots, thereby changing the orchard environment in semiarid areas. Agroforests can generally improve water condition at shallow soil layers compared to monocultural plantations, although such an effect may be accompanied with lower water stock at deeper soil layers in inter-rows, depending on crop species chosen.

Aims Intercropping in plantations can improve ecosystem services, but its potential effects on trees’ water use and production are concerns due to increases in water scarcity related to climate change. The aim of this study was to address these concerns by exploring water uptake responses of jujube ( Ziziphus jujuba Mill.) trees to intercropping and extremely dry periods on the semi-arid Loess Plateau of China. Methods Natural stable isotopes ( 2 H and 18 O) were analysed to characterize water use patterns of jujube trees and intercrops in the main tree and crop root overlap layer (ROL, 0–120 cm). 10% stable deuterated water was injected at three targeted depths (2, 3 and 4 m) to characterize the water uptake of jujube trees below the main root overlap layers (BOL). Results In ROL, intercropped jujube trees obtained higher proportions of water in shallower and deeper layers than monocultured jujube trees during wet and dry periods, respectively. Proportional contributions of soil layers to the trees’ water uptake were positively correlated with the layers’ water amount ratios (relative to the entire profile) in intercropped orchards but not in monoculture. In some extremely dry periods, intercropping resulted in jujube trees absorbing deeper water (up to 3 m) in BOL. Conclusions At the early stage of land-use change from plantation to agroforestry, intercrops induce jujube trees to absorb higher proportions of water from soil layers with high proportions of total water contents in ROL. The soil water in BOL is an important buffer for maintaining water supplies for tree growth in agroforestry systems in case of extreme drought.

Increasing evidence reports hydrogen isotopic offset (HIO) between plant stem and source soil water, which introduces considerable uncertainties in estimating plant water sources. However, it remains unknown how HIO varies along precipitation gradients and its effect on quantification of plant water sources. We sampled soil water and apple tree samples at five sites along a precipitation gradient (420–610 mm) on China's Loess Plateau to characterize HIO's climatic drivers and hydrological implication. Clear and negative stem‐soil water HIO was observed at all sites, with magnitude increasing with mean annual precipitation (MAP). The overestimation of deep soil water use caused by HIO was clearly higher in sites with MAP > 500 mm (14.42%) than those with MAP < 500 mm (0.76%), indicating overestimation of deep soil water use by stable water isotopes is more susceptible in wetter regions. This study emphasizes the necessity of incorporating climate‐related HIO for accurate regional ecohydrological assessments.

Analyzing deep soil water use (DSWU) response to precipitation change and its impact on tree physiology is necessary to understand tree mortality mechanisms, especially in drylands. Using a process‐based model parameterized with in situ measured fine root distribution data for 0–2,000 cm depth, along with a root‐cutting (below 200 cm depth) numerical experiment, this study explored DSWU strategies and their contribution to total water consumption during different precipitation years, as well as their relationship to tree gas exchange traits, in mature apple (Malus pumila Mill) tree and black locust (Robinia pseudoacacia L.) plantations in both wetter (Changwu, 583 mm) and drier (Yan'an, 534 mm) sites on China's Loess Plateau. Results showed that DSWU at 200–2,000 cm depth in different precipitation years of both species mainly occurred during the early growing seasons. On average, DSWU contributed 22.9% and 25.1% to the total water consumption of apple trees and black locust, respectively, and its contribution increased to 26.0% and 36.7% in extremely dry years. Moreover, the lack of DSWU significantly decreased (p < 0.05) stomatal conductance (by 16.9%, 16.9%, 47.4%, and 11.4%, respectively) and photosynthetic rates (by 37.1%, 20.1%, 28.5%, and 16.4%, respectively) of Changwu apple trees, Yan'an apple trees, Changwu black locust and Yan'an black locust in extremely dry years. Similar reductions occurred only in Yan'an for both tree species in normal years. In contrast, no significant differences were found in gas exchange traits in extremely wet years. Our results highlight that DSWU is an important strategy for plantations in the deep vadose zone region to resist extreme drought. Key Points A process‐based model parameterized with measured fine root data for 0–20 m was used to explore DSWU and its relationship to tree gas exchange traits Deep (2–20 m) soil water contributed 20.3%–26.0% and 14.4%–36.7% to total water consumption for apple tree and black locust, respectively DWSU can compensate for the drought effect on gas exchange in dry years better than in wet years for dryland tree plantations

Ciprofol, a novel intravenous anesthetic, provides rapid recovery in patients undergoing colonoscopy. We aimed to examine the efficacy and safety of ciprofol in comparison with propofol for sedation or anesthesia in non-operating room settings including endoscopic submucosal dissection, endoscopic retrograde cholangiopancreatography, and flexible bronchoscopy (FB). Prospective, randomized, double-blind, parallel-group clinical trial. University-affiliated teaching hospital. We recruited 207 patients scheduled for an endoscopic procedure from October 2021 to December 2021. Patients were randomized into three groups according to the dose during induction (n = 69 each): 1) ciprofol 6 mg/kg/h, 2) ciprofol 8 mg/kg/h, or 3) propofol 40 mg/kg/h. Ciprofol or propofol was administered throughout the procedure. The primary outcome was the success rate of sedation or anesthesia for the procedures. Secondary outcomes included induction time, endoscope insertion time, recovery time, discharge time, incidence of drug-related adverse events (AEs), neurological and inflammatory outcomes. The procedure success rates in the three groups were 100%. The induction time in the 6 (3.3 ± 1.0 min) and 8 mg/kg/h (2.9 ± 0.6 min) ciprofol groups was longer than that in the propofol group (2.5 ± 0.6 min) only in patients undergoing FB (p = 0.004). The time for patients to be fully alert and discharged from the post-anesthesia care unit was comparable across the three groups (p > 0.05). The incidence of drug-related AEs in the propofol and 6 and 8 mg/kg/h ciprofol groups was 84.1%, 76.8%, and 79.7%. No pain on injection was reported by ciprofol groups. Neurological outcomes and inflammatory responses were comparable among the three groups. Ciprofol induced a level of sedation or anesthesia equivalent to that induced by propofol in non-operating room settings except for a prolonged induction time in patients undergoing FB. Ciprofol had a safety profile similar to that of propofol. No pain on injection was reported by ciprofol. •Ciprofol, a novel intravenous anesthetic, and propofol induced equivalent sedation or anesthesia in non-operating room settings.•Ciprofol had a similar safety profile to that of propofol.•No pain on injection was reported by the ciprofol groups.•Ciprofol and propofol anesthesia had similar neurological outcomes and inflammatory parameters.

Elevated atmospheric CO 2 concentrations ([eCO 2 ]) and soil water deficits significantly influence gas exchange in plant leaves, affecting the carbon-water cycle in terrestrial ecosystems. However, it remains unclear how the soil water deficit modulates the plant CO 2 fertilization effect, especially for gas exchange and leaf-level water use efficiency (WUE). Here, we synthesized a comprehensive dataset including 554 observations from 54 individual studies and quantified the responses for leaf gas exchange induced by e[CO 2 ] under water deficit. Moreover, we investigated the contribution of plant net photosynthesis rate ( P n ) and transpiration rates ( T r ) toward WUE in water deficit conditions and e[CO 2 ] using graphical vector analysis (GVA). In summary, e[CO 2 ] significantly increased P n and WUE by 11.9 and 29.3% under well-watered conditions, respectively, whereas the interaction of water deficit and e[CO 2 ] slightly decreased P n by 8.3%. Plants grown under light in an open environment were stimulated to a greater degree compared with plants grown under a lamp in a closed environment. Meanwhile, water deficit reduced P n by 40.5 and 37.8%, while increasing WUE by 24.5 and 21.5% under ambient CO 2 concentration (a[CO 2 ]) and e[CO 2 ], respectively. The e[CO 2 ]-induced stimulation of WUE was attributed to the common effect of P n and T r , whereas a water deficit induced increase in WUE was linked to the decrease in T r . These results suggested that water deficit lowered the stimulation of e[CO 2 ] induced in plants. Therefore, fumigation conditions that closely mimic field conditions and multi-factorial experiments such as water availability are needed to predict the response of plants to future climate change.

In water-limited areas, planted trees can extract substantial amounts of soil water from deep layers (> 200 cm) to meet their high water demand, resulting in deep soil desiccation, which influences not only regional water cycling but also the sustainability of trees per se in drylands. However, the specific dimensions of deep soil desiccation in relation to both the soil moisture limitation and the maximum root water uptake (RWU) depth are still not well determined. Whether the dimensions depend on tree species and how they will affect trees' xylem hydraulic conductivity are also unclear, restricting our ability to predict the fate of dryland tree plantations. Therefore, we studied the spatiotemporal distribution of deep soil moisture deficit (DSMD) for two typical planted trees, apple (Malus pumila Mill.) and black locust (Robinia pseudoacacia L.), based on published data and multiple field samplings on China's Loess Plateau. The results indicated that the lowest deep soil moisture (DSM; units of gravimetric percent, i.e., grav-%) occurred under the planted trees aged 24–28 years at all sites. The lowest DSMD varied around −0.6, which was close to the DSMD at the permanent wilting point (PWP, grav-%), regardless of tree species and site, although shallow (< 200 cm) soil moisture was not reduced to the point of limitation. This suggests that PWP is a reliable indicator of the moisture limitation of deep-layer soil desiccation for the tree species examined. The corresponding depth of soil moisture use reached 18.0–22.0 m for these old planted trees at different sites, while it was more than 25 m for R. pseudoacacia in the drier site of Mizhi. Furthermore, the mean values of native percentage loss of hydraulic conductivity of planted trees' branches xylem reached 74.9 %–96.5 % in the plantations sampled in this study, indicating that tree mortality may occur. The findings help predict the sustainability of planted trees in semi-arid regions with a thick vadose zone.

Comprehensive assessment of the long-term evolution of water stress and its driving factors is essential for designing effective water resource management strategies. However, the roles of water withdrawal and water availability components in determining water stress and potential mitigating measures in large water-scarce basins are poorly understood. Here, an integrated analytical framework was applied to the Yellow River basin (YRB), where the water crisis has been a core issue for sustainable development. The analysis suggests that the YRB has experienced unfavorable changes in critical water stress indicators over the past 56 years. Compared to the period from 1965 to 1980, the regional water stress index (WSI) and the frequency and duration of water scarcity increased by 76 %, 100 %, and 92 %, respectively, over the most recent 2 decades. Water withdrawal was the primary driver of the increased WSI before 2000; however, it has since contributed as much as water availability. Meanwhile, local water management and climate change adaptation were shown to be important in determining total water availability at the sub-basin scale. Water demand in the 2030s is predicted to be 6.5 % higher than during 2001–2020 (34.2 km3) based on the trajectory of historical irrigation water use and corrected socio-economic data under different Shared Socioeconomic Pathways (SSPs). To meet all sectoral water needs, a surface water deficit of 8.36 km3 is projected. Potential improvements in irrigation efficiency could address 25 % of this deficit, thereby alleviating the pressure on external water transfer projects. Such efficiency gains would enable the WSI of the YRB in the 2030s to be maintained at the current level (0.95), which would worsen conditions for 44.9 % of the total population while easing them for 10.7 % compared to in the 2000s. Our results have vital implications for water resource management in basins facing similar water crises to that in the YRB.