Search

Heavy metal pollutants can be effectively removed from soil through phytoremediation using root exudates. Herein, experiments were conducted to assess the phytoremediation capabilities of Rumex acetosa L. and Rumex K-1 root exudates for copper (Cu) and lead (Pb) contamination. Results indicated that these root exudates effectively adsorbed Cu and Pb. Furthermore, the optimal adsorption conditions of Cu by the root exudates of both plants were as follows: light duration of 36 h, light intensity of 8000 Lx, temperature of 25 °C and CO(NH2)2 concentration of 0 %. Moreover, the optimal adsorption conditions of Pb by Rumex acetosa L. and Rumex K-1 root exudates were light duration of 48 h and 24 h, respectively, light intensity of 8000 Lx, temperature of 25 °C and CO(NH2)2 concentration of 0 %. In addition, the root exudates from both plants enhanced the enrichment and transport of Cu and Pb. Moreover, the root was found to be the main accumulation site of Pb, while the stems and leaves were the main accumulation sites of Cu. With the application of root exudates, plant growth increased, with growth indices in Rumex acetosa L. and Rumex K-1 groups treated with exudates being 1.08–1.81-fold and 1.06–1.9-fold higher, respectively, compared with the untreated ones; physiological indexes showed 1.14–2.62-fold and 1.14–2.71-fold improvements, respectively. Remediation efficiency indexes showed 1.05–1.62-fold and 1.10–1.89-fold improvements, respectively. Rumex acetosa L. and Rumex K-1 exhibited promising potential for the phytoremediation of Cu and Pb, with root exudates playing a critical role in metal adsorption and stabilisation, suggesting their potential for enhancing remediation capabilities. This study sheds light on the mechanisms of root exudate–assisted phytoremediation and provides insights into alleviating heavy metal pollution.

Palmer Drought Severity Index (PDSI) is a widely used indicator to assess the intensity of drought based on a similar two-layer bucket (TLB) model, especially in arid and semi-arid regions. However, the TLB model cannot quantify surface water balance, effectively, which may lead to the mis-assessment of drought. Therefore, an optimized PDSI indicator named RW-PDSI based on the water balance is constructed. RW-PDSI is developed using the output of a newly proposed remote-sensing-based water balance assessment tool (RWBAT) model. The RWBAT model is constructed to depict the detailed hydrological processes on a fine spatial scale using high-resolution remote sensing data. To test its performance, we collected tree-ring data on the Loess Plateau (LP) to show the drought conditions in past decades (1991–2020). Tree-ring data provide a useful continuous multi-year data archive for drought assessment. Our results showed that the correlation between RW-PDSI and tree-ring data was statistically significant (p

Optimizing nitrogen (N) management based on the critical N dilution curve (NCDC) has been proven a precision fertilization strategy to diagnose crop N nutrition status. However, few explorations have been done to establish a NCDC for dryland maize under double ridge-furrow mulching, a planting system that has been widely adopted in semi-arid areas. Moreover, the influences of various rainfall conditions on NCDC remain unclear. Therefore, a 9-yr field nitrogen fertilization experiment from 2013 to 2021 (five nitrogen rates: 0, 75, 150, 225, and 300 kg N ha–1, respectively, represented by N0, N0.25, N0.50, N0.75, and N1) was applied to established the NCDC under two planting systems (Flatting without mulching, CK; Double ridge-furrow with mulching, DRFM) and two rainfall types (rainfall season and drought season). Compared with CK, DRFM significantly increased plant dry matter (PDM, 5.5–12.8%) and N concentration (4.2–6.9%), ultimately improved grain yield (+16.9%), cumulative nitrogen recovery efficiency (CNRE, +9.8%) and crop water productivity (WPc, +26.3%). Rainfall from jointing to silking stage was an important contributor to grain yield. Compared with rainy season, drought season triggered a 51.7% yield loss and 17.1% reduction in NRE, respectively. The NCDC of the CK and DRFM were Nc=36.6×PDM−0.37 and Nc=38.4×PDM−0.36 in rainy season, respectively; the NCDC of the CK and DRFM were Nc =34.5×PDM−0.27 and Nc=37.3×PDM−0.30 in drought season, respectively. The nitrogen nutrition index (NNI) and plant nitrogen requirement (PNR) based on the NCDC intuitively recorded the N nutritional status. The improved soil micro-environment, PDM and N uptake was recorded in N0.75 (225 kg N ha–1 yr–1) under wet season and in N0.50 (150 kg N ha–1 yr–1) under drought season, respectively, which brought an increase in crop productivity with a suitable N nutrition status. The findings highlight an accurate and effective method for assessing the N nutrition status of rainfed maize, and optimize fertilization strategy for sustainable production in semi-arid regions.

Abstract Topography is an important factor affecting soil erosion and is measured as a combination of the slope length and slope steepness (LS-factor) in erosion models, like the Chinese Soil Loss Equation. However, global high-resolution LS-factor datasets have rarely been published. Challenges arise when attempting to extract the LS-factor on a global scale. Furthermore, existing LS-factor estimation methods necessitate projecting data from a spherical trapezoidal grid to a planar rectangle, resulting in grid size errors and high time complexity. Here, we present a global 1-arcsec resolution LS-factor dataset (DS-LS-GS1) with an improved method for estimating the LS-factor without projection conversion (LS-WPC), and we integrate it into a software tool (LS-TOOL). Validation of the Himmelblau–Orlandini mathematical surface shows that errors are less than 1%. We assess the LS-WPC method on 20 regions encompassing 5 landform types, and R2 of LS-factor are 0.82, 0.82, 0.83, 0.83, and 0.84. Moreover, the computational efficiency can be enhanced by up to 25.52%. DS-LS-GS1 can be used as high-quality input data for global soil erosion assessment.

Since the implementation of the Grain for Green Project, the vegetation coverage of Loess Plateau has been greatly improved. However, the contradiction between the increasing vegetation water demand (VWD) and the regional rainwater utilization potential (RUP) has become an important factor threatening the sustainable development of vegetation. In order to figure out whether the available water can support the water consumption of vegetation restoration, it is necessary to quantitatively explore the balance between the RUP and the VWD. Based on these, this study utilized the Soil and Water Assessment Tool (SWAT) and Penman–Monteith (PM) method to quantitatively evaluate the vegetation–water mutual suitability of a typical area in the Loess Plateau’s Helong Region (HLR). The results showed that both RUP and VWD exhibited significant increasing trends (95 % confidence level) from 1982 to 2018, with a rate of 18.19 mm/10a and 25.22 mm/10a, respectively. Spatially, RUP was lower in the northwest and higher in the southeast and south regions, whereas VWD decreased from the southeast to the northwest. According to the evaluation results, the annual average vegetation–water mutual suitability matching degree was 0.64 in Period I (1982–1999) and 0.67 in Period II (2000–2018). The matching degree was higher in the northwest and middle regions, lower in the southeast, and above 0.60 in most regions. Under the future climate scenarios of RCP 2.6 and RCP 8.5, the matching degree of water supply and demand also improved to 0.69 and 0.72. Overall, the available water resources can basically support vegetation growth in the HLR. Future vegetation restoration in HLR should try to select annual herbaceous plants that consume less water, and it is not recommended to continue vegetation restoration in the southeast. The results of this study can provide scientific guidance and reference for vegetation restoration policies in HLR.

The purposes of this study were to explore the impact of obesity on postoperative cognitive dysfunction (POCD) and to investigate the underlying mechanism by which obesity exacerbates POCD. In this study, fifteen-month-old male C57BL/6 J mice were fed a High-fat diet for three months to establish obesity models. Internal fixation of tibial fractures under isoflurane inhalation was performed to construct a POCD animal model. Three days after surgery, mice were subjected to the Morris water maze (MWM) experiment to evaluate their learning and memory abilities. The findings from the MWM experiment revealed that in comparison to the Ad Libitum Surgical group (ALS), mice in the High-fat Surgical group (HFS) exhibited prolonged escape latencies and reduced platform crossings. These outcomes suggest the potential exacerbating role of obesity in cognitive impairment within the POCD mouse models. Immunofluorescence (IF) findings demonstrate that obesity intensifies anesthesia and surgery-induced oxidative stress levels within the hippocampus. Compared to the Ad Libitum Control group (ALC), an elevation in PARP1 expression and a reduction in the NAD+/NADH ratio and SIRT1 expression were observed in the hippocampus of mice from the ALS. Moreover, when contrasting the HFS group with the ALS group, increased PARP1 expression along with decreased NAD+/NADH ratio and SIRT1 expression were evident. In vitro studies found that compared with the Control group (CON), oil red staining and BODIPY probe staining showed significant lipid droplet aggregation in the palmitic acid (PA) group. IF results demonstrated that HT22 cells in the PA group experienced oxidative stress and activation of the PARP1/NAD+/SIRT1 axis in contrast to the CON group. Moreover, manipulation of PARP1 expression in HT22 cells through PARP1 lentivirus-based silencing or overexpression revealed a converse relationship between PARP1 expression levels and the NAD+/NADH ratio as well as SIRT1 expression levels. This study concludes that obesity may exacerbate POCD by triggering activation of the oxidative stress-induced PARP1/NAD+/SIRT1 axis.

Study region: The Yulin Region in the Northern China. Study focus: There is an urgent need to balance supply and demand in respond to water shortages in arid and semi-arid areas. A new water-adaptable allocation framework is used to simulate different allocation scenarios. Firstly, the supply-demand was analyzed to determine whether an imbalance existed. Then, the structure of grain and energy of Yulin was optimized. In order to produce new water-adaptable boundary of industry demand. Finally, the allocation of water resources was optimized based on the target of minimizing the water shortage rate. New hydrological insights for the region: The new scheme results highlight that by 2025, it is predicted that in a BAU (business as usual) scenario, there will be an imbalance between the water supply and water demand in Yulin Region. Following the optimization of the grain and energy industrial structure (GES), and the WAS (water allocation and simulation) model used to create a water resources allocation scheme and tested its applicability using two rainfall guarantee rates scenarios, it was determined that the total water demand established for the both scenarios decreased, and the economic benefit increased by 12.43 %. Also, 87.41∼99.93 % of potable water is satisfied to the initial water needs.

Abstract China's Loess Plateau (LOP) contains around 22% of all the world's apple trees, mainly on smallholdings run by farmers. However, business‐as‐usual (BAU) intensification has reduced the ecological resilience of orchards. Agroforestry is considered to be an important method of realizing sustainable intensification of agroecosystems. However, the design of practical agroforestry systems in drylands remains poorly researched. We hypothesized that crop density is a key factor in designing dryland apple tree‐based agroforestry systems. We carried out an experiment in apple orchards in the semiarid LOP, where the bioenergy crop canola (Brassica napus L.) was intercropped at low, medium, and high densities with row spacings of 25, 50, and 100 cm, respectively, to study its effects on water, carbon, and production. We found that intercropping of canola at different densities clearly decreased soil water content (SWC) in the top 60 cm soil layer at all sampling locations, reduced midday leaf water potential (Ψm) and leaf water content (LWC), and caused apple trees to produce more fine roots at greater depths. However, intercropping did not affect SWC in soil layers below 60 cm. The SWC profiles, Ψm and LWC, progressively recovered over the mulching period. Introduction of canola also significantly (p

Background We quantified and evaluated the allocation of soil and water resources in the Aksu River Basin to measure the consequences of climate change on an agricultural irrigation system. Methods We first simulated future climate scenarios in the Aksu River Basin by using a statistical downscaling model (SDSM). We then formulated the optimal allocation scheme of agricultural water as a multiobjective optimization problem and obtained the Pareto optimal solution using the multi-objective grey wolf optimizer (MOGWO). Finally, optimal allocations of water and land resources in the basin at different times were obtained using an analytic hierarchy process (AHP). Results (1) The SDSM is able to simulate future climate change scenarios in the Aksu River Basin. Evapotranspiration (ET0) will increase significantly with variation as will the amount of available water albeit slightly. (2) To alleviate water pressure, the area of cropland should be reduced by 127.5 km2 under RCP4.5 and 377.2 km2 under RCP8.5 scenarios. (3) To be sustainable, the allocation ratio of forest land and water body should increase to 39% of the total water resource in the Aksu River Basin by 2050.

In order to study whether jujube trees can grow normally under rain-fed conditions in loess hilly areas, we planted jujube trees (Ziziphus jujuba Mill.) 4 years after felling a 23-year-old apple orchard. The growth process of the jujube trees and the variation in soil water content (SWC) were monitored for three consecutive years following planting in order to study the effects of the water-saving pruning (WSP) technique. Results showed the following. (1) The soil at a depth of 0–1,000 cm had been desiccated when the area was an apple orchard. (2) Under rain-fed conditions, the jujube trees with the WSP technique were always able to maintain normal growth while the jujube trees with conventional pruning method had a normal growth stage of only 4 years. The water use efficiency of the jujube trees with the WSP technique was much higher than that of the jujube trees with conventional pruning. We recommend WSP in jujube orchard management, because the jujube trees with WSP could maintain normal growth in the deep dried soils of the loess hilly region, as WSP can reduce the water consumption of the jujube trees and may have a positive effect on soil moisture restoration. HIGHLIGHTS We proposed water-saving pruning for the growth of jujube trees planted in dry soil.; Water-saving pruning can significantly improve water use efficiency of jujube trees planted in dry soil.; Water-saving pruning may have a positive impact on the restoration of soil water in dry soil.;

Since the 1990s, global warming has substantially affected the dynamic responses of forest ecosystems to drought by altering tree growth and ecosystems carbon cycling. The Loess Plateau is a typical vegetation recovery region with an arid and semiarid climate. However, the responses of the vegetation in this region to drought have not been fully studied. We therefore aimed to characterize these responses in tree-ring samples, which were obtained by drilling tree cores with a growth cone, for establishing the tree-ring width chronologies. In addition, we investigated the main factors controlling the radial growth of Chinese pine (Pinus tabulaeformis) and its dynamic responses to drought in the Loess Plateau using correlation analysis. Our results show that radial growth in Chinese pine had a positive correlation with precipitation during the last growing season, pre-growing season, and entire current growing season. The correlation between the radial growth and temperature was inconsistent between different sampling sites and time periods. These suggest that precipitation was more likely to affect radial vegetation growth than temperature. Moreover, the drought indices calculated using data before the year 2000 more accurately reflected the vegetation drought situation in Loess Plateau than data from the last 20 years. The drier the place, the more accurately the drought indices represented the responses of vegetation to drought. However, these indices cannot satisfactorily capture the drought responses of vegetation in wet regions. Furthermore, the PDSI was more accurate than the SPEI at capturing the effects of drought on radial vegetation growth. Understanding the response mechanism of the radial growth of Chinese pine to drought can provide theoretical support for ecological protection, forest management, and ecological construction under climate change.

Accurate spatio-temporal quantifying of ecosystem services (ESs) supply and social demand and their coordination dynamics, and determining which factors affect such coordination and the spatial distribution patterns of these effects, is essential to guide targeted ecosystem management decisions. Unfortunately, quantitative data demonstrating the explicit spatial relationships between the biophysical supply and social demand for ESs, as well as identifying the spatial non-stationary response of such relationships to influencing factors, is currently inadequate. To this end, this study employed China’s Loess Plateau (LP) as an example to quantify ES supply and social demand in 2000 and 2015, during which the society and ecology in this region have undergone tremendous changes. Then, the coupling coordination degree model was used to explore the coordination relationships between ES supply and social demand. Also, we analyzed the spatial correlations between such coordination relationships and various natural factors, policy factors and socio-economic factors, using geographically weighted regression. The results showed that ES supply and social demand had great spatio-temporal variations, and both the ES supply and social demand increased from 2000 to 2015. Although the incoordination between ES supply and social demand was great, such incoordination did improve from 2000 to 2015 with positive transitions from the lower coordination grades to the higher coordination grades. The occurrence of coordination between ES supply and social demand was highly correlated with vegetation cover driven by the “Grain for Green” Program, followed by slope (a natural factor) and socio-economic factors. This study helps deepen our understanding of the incoordination between the ES supply and social demand of the LP and the spatially explicit drivers of such incoordination, and could support auxiliary decision-making for regional ecosystem management.

Objective. Preoperative malnutrition is an independent risk factor for postoperative complications and survival for gastric cancer patients. The study is aimed at investigating the prevalence of malnutrition, perioperative nutritional support, and the risk factors associated with delayed discharge of geriatric patients undergoing gastrectomy. Methods. A retrospective study of gastric cancer patients (age≥65) who underwent gastrectomy at Zhongshan Hospital from January 2018 to May 2020 was conducted. Clinical data, including demographic information, medical history, surgery-related factors, and perioperative nutritional management, were collected and analyzed. Postoperative complications were assessed according to the Clavien-Dindo grading system, and the prognostic nutritional index (PNI) was calculated. The risk factors affecting the prolongation of postoperative hospital stay were analyzed. Results. A total of 783 patients were reviewed. The overall frequency of malnutrition was 31.3% (249/783). The albumin, prealbumin, and hemoglobin levels were lower in the malnutrition group than in the well-nourished group. The proportion of patients who received preoperative total parenteral nutritional support in the malnutrition group was significantly higher than in the well-nourished group (12.4% vs. 3.7%, P0.05). The malnutrition group was associated with a higher rate of postoperative complications (P70 years (OR=1.216, 95% CI 1.048-1.411, P=0.010), operation time>180 min (OR=1.431, 95% CI 1.237-1.656, P

Elevated atmospheric CO2 concentrations ([eCO2]) 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 CO2 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[CO2] under water deficit. Moreover, we investigated the contribution of plant net photosynthesis rate (Pn) and transpiration rates (Tr) toward WUE in water deficit conditions and e[CO2] using graphical vector analysis (GVA). In summary, e[CO2] significantly increased Pn and WUE by 11.9 and 29.3% under well-watered conditions, respectively, whereas the interaction of water deficit and e[CO2] slightly decreased Pn 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 Pn by 40.5 and 37.8%, while increasing WUE by 24.5 and 21.5% under ambient CO2 concentration (a[CO2]) and e[CO2], respectively. The e[CO2]-induced stimulation of WUE was attributed to the common effect of Pn and Tr, whereas a water deficit induced increase in WUE was linked to the decrease in Tr. These results suggested that water deficit lowered the stimulation of e[CO2] 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.

Despite its wide application across arid land types, furrow irrigation is often associated with numerous environmental problems related to deep percolation, runoff, and soil erosion. In this study, a straightforward approach was proposed to achieve higher uniformity and reduce erosion. Here, the impacts that a moveable “plug” has on the behavior of irrigation water in the furrow were simulated using FLOW-3D and HYDRUS-2D, where three plug heights and two flow rates were set. The effect of inflow rate and plug height on the water advance, water level, cumulative infiltration in the furrow, and uniformity coefficient was determined. Results indicate that the plug was able to slow water velocity by approximately 60% in the furrow and increase the furrow advance time by 3–4 times; the water level was increased by nearly 10 cm compared with no plug. Moreover, an irrigation uniformity range of 90.18–99.22% was associated with this plugging. The addition of a plug in the furrow irrigation practices for smallholder farmers in developing countries demonstrates great potential in reducing the probability of erosion under large slopes and can effectively improve irrigation uniformity.

Exploring the coupling characteristics of regional water resources and food security helps to promote the sustainable development of grain production and is of great significance for achieving global food security. From the aspects of regional “water supply”, “water use” and “water demand”, the coupling characteristics of water resources and food security were systematically revealed; the new challenges faced by regional food security from the perspective of water resources were clarified; and effective ways to promote the utilization of regional water resources and the sustainable development of grain production were explored. This paper took Northwest China, which is the most arid region, where water-resource utilization and food security are in contradiction, as the research area. The water-resource load index, the water footprint of grain production and the water-consumption footprint were used to quantify the regional water-resource pressure index, as well as the residential grain-consumption types, population urbanization, the industrial-grain-processing industry and their corresponding water-consumption footprints from 2000 to 2020. The coupling characteristics of water resources and food security were systematically revealed. The results showed the following: (1) In 2000–2020, the water-resource load index increased from 4.0 to 10.7, and the load level increased from III to I. At the same time, agricultural water resources were largely allocated elsewhere. (2) During the period, the food rations showed a significant decreasing trend, and the average annual reduction was 3.4% (p < 0.01). The water footprint of animal products increased, particularly for beef and poultry (the average annual growth rates were 9.9% and 6.3%, respectively). In addition, the water footprint of industrial food consumption increased by 297.1%. (3) With the improvement of the urbanization level, the water-consumption footprint increased by 85.9%. It is expected that the water footprint of grain consumption will increase by 39.4% and 52.3% by 2030 and 2040, respectively. Exploring how to take effective measures to reduce the water footprint to meet food-security needs is imperative. This study proposed measures to improve the utilization efficiency of blue and green water and reduce gray water and the grain-consumption water footprint from the aspects of regional planting-structure optimization potential, water-saving irrigation technology, dietary-structure transformation and virtual water trade; these measures could better relieve the water-resource pressure and promote the sustainable development of grain production and water-resource utilization.

Interspecific interactions and recovery growth play an important role in crop growth, development and ultimately yield in intercropping systems. However, the impact of different water and nitrogen levels on intercropping production, interspecific interactions between intercrops, and the recovery growth of late-maturing crops is still unclear. A two-year field experiment was conducted in Yangling, Shaanxi province, to investigate the dynamics of interspecific interactions, and the effects of interspecific interactions on crop growth and yield. The experiment consisted of three factors, including three cropping systems (wheat/maize intercropping, sole wheat, sole maize), three nitrogen (N) levels and two water applications (supplementary irrigation and rainfed). The results demonstrated that, during the co-growth period, intercropped wheat was more competitive than intercropped maize; so, intercropped wheat showed a yield advantage. Intercropping increased maize yield under irrigated conditions, and this was attributed to the full recovery growth of intercropped maize after wheat harvest. However, rainfed and nil nitrogen aggravated the interspecific competition, and water deficit under maize rows, in turn, limited the recovery growth of intercropped maize, leading to yield reduction. However, compared with sole maize, the yield of intercropped maize decreased, indicating nitrogen deficiency limited the recovery growth of intercropped maize. Among all treatments, the intercropping of medium nitrogen fertilizer with irrigation had the best yield improvement and land use advantages, the total yield of intercropping was 14.8% higher than that of sole cropping, and the land use efficiency increased 16%. These results confirmed that supplementary irrigation and optimal nitrogen application alleviated the interspecific competition, promoted the recovery growth of intercropped maize and improved the yield of wheat/maize intercropping system.

Soil water and root distribution following revegetation are key research topics in water-limited ecosystems. However, little is known about the interaction between soil water and root distribution in deep soils under different precipitation conditions. Knowledge of the root–soil water relationship of revegetated land and its response to precipitation is crucial for the management of water resources and ecological restoration worldwide, including on the Chinese Loess Plateau. In this study, we investigated soil water and root distribution under apple orchard and black locust down a 10 m soil profile and exposed to different amounts of annual precipitation on the Loess Plateau. The results showed that soil water content (SWC) under two typical planted forests both significantly decreased as the mean annual precipitation (MAP) decreased. SWC spatial variation is demarcated by a 500–550 mm precipitation threshold, being relatively high when MAP > 550 mm but extremely low when MAP < 500 mm. In apple orchards, the depth above which 50% of the roots were present increased with increasing precipitation, but in black locust it became shallower. The results of a linear mixed model revealed a significant relationship between fine root length density and SWC depletion degree for black locust irrespective of the amount of precipitation, but it was only found in the 200–1000 cm soil layers with MAP > 550 mm and the 0–200 cm soil layers with MAP < 550 mm for apple orchards. The MAP × depth interaction was significant with respect to SWC depletion degree for MAP > 550 mm, but not for MAP < 550 mm in both vegetation types. These findings add to our current understanding of the root–soil water relationship of species used for revegetation and highlight the need to assess the long-term effect of revegetation on soil water consumption in water-limited ecosystems.

Since the implementation of the Grain for Green Project (GFGP) in the 1990s, the warming and wetting trend in the Loess Plateau is becoming statistically significant in the context of climate change. However, the correlation between precipitation increase and the regional vegetation restoration is still controversial. To explore the main factors influencing the regional precipitation change, this study selected five potential influencing factors including potential evapotranspiration (PET), normalized difference vegetation index (NDVI), precipitable water (PW), surface temperature (ST), and water vapor transport (WVT). We used the statistical methods to analyze the spatial-temporal distribution of precipitation before and after the GFGP and to quantify the relative influence degree of different factors to precipitation change. The results show that: (1) The precipitation increased significantly (95% confidence level) after the GFGP, with an increase rate of 4.96 mm a−1; (2) from the perspective of spatial-temporal distribution, the precipitation in the southern part of the Loess plateau was significantly increasing with an increase rate of 20–50 mm in the period of 2000–2014; (3) the relative influence degree of NDVI to precipitation increased after the GFGP, and the annual precipitation (PREA) and summer precipitation (PRES) was more influenced by NDVI (relative influence degree of 30.18% and 31.37%, respectively) compared with winter precipitation. In winter, the PW and the PET are the main influencing factors for the precipitation change with relative influence degrees of 30.13% and 27.64%, respectively. Based on this study, we speculate that the warming and wetting trend of the Loess Plateau in recent years is not only closely related to global climate change, but also significantly affected by local climate change brought by vegetation restoration. The above conclusions are important for future ecological restoration and water resources management in the water-scarce Loess Plateau.

Revealing the characteristics of soil moisture and temperature under typical sloping land uses in the loess hilly region is of great significance for the efficient and sustainable use of sloping land resources. In this study, the soil moisture content in the 0–160 cm soil layer and the soil temperature in the 0–100 cm soil layer under soybean sloping field, maize terraced field, jujube orchard, and grassland were continuously observed during the 2014 and 2015 growing seasons (May to October). Traditional statistical analysis and wavelet fractal dimension method were used to study the characteristics and complexity of soil moisture and temperature changes under different sloping land uses. The main findings are as follows: (1) Maize terraced field obtained high soil moisture content in the 0–160 cm soil layer, showing the outstanding effect of soil moisture conservation, especially in the drought growing season. Maize terraced field minimized the changing amplitude (Ka), variation degree (Cv), and active layer of soil moisture in the 0–160 cm soil layer and the Ka and Cv of soil temperature in the 0−100 cm soil layer. The maize terraced field had the minimum fractal dimensions of soil moisture and temperature both in normal precipitation and drought growing seasons, indicating that the maize terraced field minimized the complexity of soil moisture and temperature changes. (2) The jujube orchard obtained the minimum soil moisture content in the 0−160 cm soil layer, and greatly increased the Ka, Cv, and active layer of soil moisture both in normal precipitation and drought growing seasons. The jujube orchard obtained the maximum soil temperature in the 0–100 cm soil layer, and greatly increased the Ka and Cv of soil temperature. The jujube orchard also had the maximum fractal dimensions of soil moisture and temperature, indicating that soil moisture and temperature changes in jujube orchard were the most complex. (3) Compared to jujube orchard, soybean sloping field and grassland increased soil moisture content, reduced the Ka and Cv of soil moisture and temperature, and weakened the complexity of soil moisture and temperature changes. (4) The analysis results of the complexity of soil moisture and temperature changes under the experimental sloping land uses based on the wavelet fractal dimension method were consistent with the traditional statistical analysis results, indicating that it is feasible to evaluate the complexity of soil moisture and temperature changes under the typical sloping land uses in the loess hilly region by using wavelet fractal dimension method. In summary, terraced fields were conducive to improving soil moisture content and maintaining the stability of soil moisture and temperature. It is recommended that the project of changing sloping fields into terraced fields should be popularized in the loess hilly region to effectively utilize limited natural precipitation. In order to prevent the jujube orchard from degenerating and dying due to long-term drought and water shortage, effective water management measures need to be taken to achieve the sustainable development of dry farming jujube orchard.

Jointly influenced by natural factors and artificial protection measures in recent years, the vegetation coverage of the Loess Plateau has significantly increased. However, extensive vegetation recovery can result in massive water consumption and a severe soil water deficit, which poses a great threat to the sustainable development of the regional ecological system. Maintaining the balance between precipitation and water consumption is an important foundation of ecological security in the Loess Plateau. Based on this, the present study used the GRACE (Gravity Recovery and Climate Experiment) gravity satellite data to simulate the annual actual water consumption from 2003 to 2014 and to analyze the temporal and spatial evolution of the regional precipitation and the actual evapotranspiration (AET). This study also applied the newly developed rainwater utilization potential index (IRUP) to quantify the sustainability of the water balance in the Loess Plateau. The spatial-temporal patterns of precipitation, potential evapotranspiration, and AET from 2003 to 2014 in the Loess Plateau were all analyzed in this study. Based on the results, the annual average precipitation (AAP) and AET in the entire Loess Plateau had significant increasing trends. The analysis of the spatial distribution reveals that the AET was decreasing from the southeast to the northwest in the Loess Plateau. However, the average values of potential evapotranspiration did not obviously change. Based on the estimated AET result, it was determined that the average IRUP had an increasing trend. The increase in the IRUP is due to an increased rate of precipitation that is statistically higher than that of the AET. Consequently, the Loess Plateau experienced a wetting trend during the period of 2003⁻2014, especially after the Grain for Green project was implemented. The results in this paper were proven by using three different depths of ERA-Interim (a global atmospheric reanalysis product created by the European Centre for Medium-Range Weather Forecasts) soil water content data from the same period and the observed runoff data from 18 different hydrological sites. Consequently, it seems that the vegetation could maintain a sustainable growth with the implementation of the Grain for Green Project.

To evaluate the spatial and temporal soil water availability (SWA) and improve the soil water use efficiency in agriculture, this study established a new index system for SWA evaluation considering the soil storage capacity, the temporal and spatial matching degree between soil water supply and crop water demand, and the soil water transformation and utilization efficiency. To quantitatively calculate the indexes, a self-developed hydrological model (MODCYCLE) was introduced and applied in Handan City. The results show that MODCYCLE performed well in simulating the soil hydrological processes. A comparison of the observed soil moisture data and the simulated values revealed relative errors below 10% and correlation coefficients all above 0.7. According to the evaluation results, the SWA for different typical years was very unevenly distributed in Handan City. The average SWA in a normal year is 0.71, which is higher than that in dry years at 0.62 and in wet years at 0.65. Regarding different regions, the average SWA was generally much higher in the eastern plain area than that in the western mountainous area. Generally, there is a great potential for improving SWA and further the sustainable development of soil water resource, particularly for dryland farming in similar areas.

Locally resonant metamaterial beams made from flexible substrates with piezoelectric layers can exhibit bandgap and vibration attenuation properties. However, the bandgap properties of the electromechanical metamaterials are limited by the electromechanical coupling coefficient. In order to effectively overcome this limitation of the locally resonant bandgaps, a locally resonant electromechanical metamaterial beam with piezoelectric actuators and sensors is presented, and the piezoelectric shunting technique and negative proportional feedback control strategy are combined. In this design, both negative capacitance (NC) and inductance (L) are incorporated into the shunt circuits. Then, the classical root locus method is employed to obtain single/multiple bandgaps and particular structural response by arranging the poles and zeros. Finally, the influences of the feedback control gain, the shunt circuit type, and the damping ratio on the bandgap properties and wave propagation behaviors are analyzed. Numerical results demonstrate that the single/multiple bandgaps can be obviously broadened by properly increasing the control gain. Specifically, adding negative capacitance in series to pure inductive circuit can generate wider absolute bandgaps at lower frequencies. The comparison of the frequency response and the bandgap characteristics reveals a very good agreement. Summarily speaking, combining the piezoelectric shunting technique and negative proportional feedback control strategy can effectively tune the vibration and wave propagation behavior. [ABSTRACT FROM AUTHOR]