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Analyzing the ecological and behavioral effects of changes in irrigation practices in oases provides valuable insights for water resource management and the sustainable development of oasis agriculture in arid regions. Taking the Yanqi Basin as a case study, this research draws on long-term empirical data and remote sensing information to evaluate the ecological and irrigation behavior effects resulting from shifts in irrigation methods. And explores the deep societal causes behind these behavioral changes. The findings demonstrate: (1). Between 2000 and 2010, the rapid adoption of groundwater extraction and mulched drip irrigation (MDI) technology temporarily alleviated the water supply-demand contradiction. However, from 2010 to 2020, as the adoption of water-saving practices significantly expanded and agricultural irrigation areas grew substantially, the irrigation paradox emerged, where increased efficiency paradoxically led to greater water consumption. (2). From 2000 to 2020, the groundwater table depth in the irrigation district dropped by 8–16 m, total soluble salt content decreased by 2–5 g/L, and soil salinity decreased by 4–12 g/kg. The proportion of severely salinized and saline soil areas fell from 21.74% in 1999 to 9.75% in 2020. The longstanding salinization issues that had plagued the irrigation district were effectively mitigated with the widespread adoption of MDI. (3). The irrigation district’s vegetation ecological quality index ( VEQI ) showed a slow but steady upward trend in cultivated areas over the years. In contrast, natural vegetation areas such as forests and grasslands exhibited an initial increase followed by a decline. The trends in VEQI responded well to changes in irrigation practices. (4). The economic benefits driven by water-saving technologies and the expansion of cultivated land are deep societal factors behind the changes in irrigation behavior. These benefits also fostered improvements in users’ understanding and awareness of irrigation practices. The shift in irrigation methods in the Yanqi Basin has led to a decline in groundwater levels, an irrigation paradox, and moderate damage to natural vegetation. However, it has had a significant positive impact on improving regional groundwater quality and mitigating soil salinization. Furthermore, it facilitates the further exploration of regional water conservation potential, enhancing the research on the regional water and soil resource management system.

This study aimed to understand the response of vegetation community characteristics in the degraded alpine meadow of the Source Zone of the Yellow River to exclosure of various lengths. Artificial fences were erected to prevent livestock grazing and let the degraded meadow recover naturally as a means of restoration. The research focused on a typical degraded alpine meadow in which four plots were fenced off for three periods of 1 year (E1), 4 years (E4), and 10 years (E10), plus a freely grazed plot as the control. The study compared and analyzed the differences in plant community characteristics, carbon (C), nitrogen (N), and phosphorus (P) reserves, as well as the stoichiometric characteristics of main functional groups in the alpine meadow over different exclosure durations. The results indicated that E10 long-term exclosure significantly increased the aboveground biomass of gramineous plants but reduced the aboveground biomass of miscellaneous grasses. However, when compared to E4 short-term exclosure, E10 resulted in a reduction in the aboveground biomass of Cyperaceae plants. On the other hand, E4 medium-term exclosure significantly increased the aboveground biomass of Gramineae and Cyperaceae. Exclosure significantly increased the nitrogen (N) and phosphorus (P) reserves of the aboveground plant communities. Among these communities, the plant communities in the E10 long-term exclosure had the highest N and P reserves. However, this exclosure length also led to a significant reduction in plant diversity. Furthermore, except for Cyperaceae, all functional groups were observed in E10 and E4 plots. The carbon–nitrogen ratio and carbon–phosphorus ratio of these groups were significantly lower than those of groups G and E1. Medium-term exclosure (E4) has a positive impact on the aboveground biomass as well as plants’ nitrogen and phosphorus reserves. However, long-term exclosure (E10) has been observed to decrease species diversity and nutrient utilization efficiency of alpine meadow vegetation, which can be detrimental to the sustainable development of the alpine meadow ecosystem. Therefore, it is not recommended to implement long-term exclosure. Instead, a moderate level of grazing should be adopted after 4 years of exclosure.

Plant diversity plays an important role in maintaining the stability of ecosystem functioning. Based on field surveys and indoor analyses, this study investigated the relationship between species diversity and community stability at different stages of bare patch succession in degraded alpine meadow ecosystems. Results show that: (1) Using the ICV (the Inverse of the Coefficient of Variation) method to analyze changes in plant community stability, community stability was generally ranked as follows: Long-term recovered patches > Healthy alpine meadow > Degraded alpine meadow > Short-term recovered patch > Bare Patches. (2) Using factor analysis to construct an evaluation system, the stability ranking based on species diversity was as follows: Healthy alpine meadow > Long-term recovered patches > Degraded alpine meadow > Short-term recovered patches > Bare Patches. (3) The community stability index was significantly positively correlated with vegetation coverage, height, biomass, species richness, Shannon–Wiener diversity index, species evenness, and Simpson’s diversity index (p < 0.05). Therefore, a positive correlation exists between plant diversity and community stability, such that plant communities with a higher species diversity tend to be more stable. To maintain the plant diversity and community stability of alpine meadow ecosystems, it is necessary to consider the characteristics of grassland plant composition and community structure, as well as their influencing factors, and promote the positive succession process of grasslands.

The solid scramjet has become one of the most promising engine types. In this paper, we report the first direct-connect test of a solid scramjet with symmetrical structure, carried out using boron-based fuel-rich solid propellant as fuel. During the test, which simulated a flight environment at Mach 5.6 and 25 km, the performance of the solid scramjet was obtained by measuring the pressure, thrust, and mass flow. The results show that, due to the change in the combustion area of the propellant and the deposition of the throat in the gas generator during the test, the equivalence ratio gradually increased from 0.54 to 0.63. In a solid scramjet, it is possible to obtain a symmetrical distribution of the flow field within the combustor. Moreover, in a multi-cavity combustor, the combustion state expands from the cavity to the center of the flow channel. The performance of the solid scramjet increased during the test, reaching a combustion efficiency of about 42%, a total pressure recovery coefficient of 0.35, and a thrust gain specific impulse of about 418 s. The solid scramjet with symmetrical structure is feasible. The cavity configuration adopted in this paper can reduce the ignition delay time of fuel-rich gas and improve the combustion efficiency of gas-phase combustible components. The shock trains in the isolator are conducive to the recovery of the total pressure. The performance of the solid scramjet is limited by the low combustion efficiency of the particles.

To achieve sustainable conservation and management of wetlands, this study investigates the influence of water balance dynamics in Baiyangdian (BYD) on the cyclical evolution of wetland landscapes from 1980 to 2020, as well as elucidates the driving role of key hydrological processes in wetland degradation. To accomplish this, a “process analysis–driver identification–uncertainty assessment” research framework was established. This framework facilitates a systematic investigation into how hydrological processes induce changes in landscape patterns and enables a quantitative evaluation of uncertainties associated with water balance states. This approach enhances our understanding of the mechanisms regulating water in wetlands and the factors contributing to their degradation. The results show that between 1980 and 2020, the wetland landscape underwent staged changes of contraction, recovery, decline, and stabilization, with the dominant mudflat gradually transitioning into marsh ecosystems. PLS-SEM analysis revealed that wetland landscape patterns were predominantly influenced by water balance dynamics: Recharge factors significantly promoted lake storage variation increases and wetland expansion, thereby enhancing landscape indices, while discharge factors suppressed lake storage variation, leading to wetland contraction and diminished landscape indices. Notably, Inflow emerged as the most substantial positive driver. Across distinct phases, both recharge and discharge factors exhibited marked uncertainties, with the uncertainty in lake storage variation reaching its maximum when levels were elevated alongside reduced inputs from precipitation and evapotranspiration. The cyclical responses of wetland landscapes offer a foundation for elucidating uncertainties in hydrological driver interactions and establish critical linkages between water balance dynamics and wetland landscape evolution. These findings highlight the necessity of integrating basin management with multi-source hydrological replenishment strategies in water resource allocation and wetland conservation efforts, thereby ensuring the long-term sustainability and ecological integrity of wetland ecosystems.

A simple and efficient flow field visualization method (based on shadow imaging) was applied in a direct-connect test to explore the influence of the momentum flux ratio and the jet angle on the formation and evolution of nitrogen jets in supersonic combustion chambers. The test setup adopts a rectangular flow passage to simulate a flight condition with Mach number of 6 and altitude of 25 km. The experimental results showed that (a) the flow field visualization method adopted in this paper can clearly register the formation and evolution of the shock wave structure in the flow field and the windward shear vortex on the jet surface. (b) The evolution process of the windward shear vortex is significantly affected by the jet angle. In particular, the stretching position of the windward shear vortex changed when the jet angle was obtuse. (c) The bow shocks showed local distortion due to the periodic generation of large-scale shear vortexes. (d) Under the working conditions of the test, the largest instability of the flow field was found for a jet angle of 120°. This work provides, on one hand, the experimental basis for clarifying the formation and evolution mechanism of transverse gas jets, and on the other, valuable data that can be used to validate numerical simulations.

The Xinjiang Region in Northwest China is known as the “dust center” of the Eurasian mainland. Dust on the leaf surface affects overall plant development. While emphasis was on studying the impacts of industrial dust particles on crop development, the effect of natural dust deposition on the physiological parameters of cotton had not been studied before. The objective of this study was to examine the effects of dust deposits on cotton leaves and to estimate their impact on crop development and yield. For this purpose, an experiment was set up having two treatments and a control. In Treatment 1, cotton leaves were cleaned with water at three-day intervals or after a natural dust fall. In Treatment 2, 100 g·m−2 of dust was applied at 10-day intervals. The control received neither additional dust nor cleaning. In all of the treatments, stomatal conductance, leaf temperature, biomass and yield were measured. The results show a 28% reduction in yield and 30% reduction in stomatal conductance of the dust treatment compared to the control treatment. This indicates blocking of the stomata on the top of the leaf surface. In addition, the canopy temperature of the dust-applied leaves was always higher than the control and treatment.

In this paper, a modular solid scramjet combustor with multicavity was proposed. The influence of multicavity shape on the performance of solid scramjet was investigated by the direct-connected tests. The experiments simulated a flight Mach 5.5 at 25 km. The boron-based fuel-rich propellant was used. The microstructure of combustion products was analyzed by SEM. The experimental results show that the fuel-rich mixture produced by the gas generator would ignite rapidly in the solid scramjet combustor. The combustion process showed a typical characteristic of establishment-development-maintenance-attenuation. Compared to the flame-holding cavity, the other shapes of cavities, e.g., narrow and lobe, can improve mixing and combustion. In our experiment, the combustion efficiency increased from 0.41 to 0.48, and the total pressure recovery was 0.36. In summary, the proposed solid scramjet combustor can effectively solve the ignition delay problem of the fuel-rich mixture, and the narrow/lobe cavity shows the ability to improve the mixing and combustion of the fuel-rich mixture.

Winter irrigation is one of the water and salt management practices widely adopted in arid irrigated areas in the Tarim Basin located in the Xinjiang Uygur Autonomous Region in the People’s Republic of China. A winter irrigation study was carried out from November 2013 to March 2014 in Korla City. A cotton field was divided into 18 plots with a size of 3 m × 3 m and five winter irrigation treatments (1200 m3/ha, 1800 m3/ha, 2400 m3/ha, 3000 m3/ha, and 3600 m3/ha) and one non-irrigation as a control were designed. The results showed that the higher winter irrigation volumes allowed the significant short-term difference after the irrigation in the fields with the higher soil moisture content. Therefore, the soil moisture in the next sowing season could be maintained at the level which was slightly lower than field capacity and four times that in the non-irrigation treatment. The desalination effect of winter irrigation increased with the increase of water irrigation volume, but its efficiency decreased with the increase of water irrigation volume. The desalination effect was characterized by short-term desalination, long-term salt accumulation, and the time-dependent gradually decreasing trend. During the winter irrigation period, air temperature was the most important external influencing factor of the soil temperature. During the period of the decrease in winter temperatures from December to January, soil temperature in the 5-cm depth showed no significant difference in all the treatments and the control. However, during the period of rising temperatures from January to March, soil temperature in the control increased significantly, faster than that in all treatments. Under the same irrigation volume, the temperature difference between the upper soil layer and the lower soil layer increased during the temperature drop period and decreased during the temperature rise period. In this paper, we proposed the proper winter irrigation volume of 1800–3000 m3/ha and suggested that the irrigation timing should be delayed to early December or performed in several stages in the fields with the drainage system. Under the current strict water management and fixed water supply quota situation, the methods are of great practical significance.

【目的】快速、有效地监测新疆干旱区的土壤盐渍化信息。【方法】以新疆渭干河流域作为研究区域，采用Sentinel-2卫星遥感影像和同步采集的0~30 cm实测土壤含盐量数据，基于决策树模型（DT）、梯度提升决策树模型（GBDT）以及随机森林模型（RF），优选最佳土壤含盐量反演模型，探求研究区土壤盐渍化分布特征。【结果】研究区土壤反射率光谱指数与土壤含盐量间存在较高的相关性，部分指数（NDVI、SRSI、SI）相关系数＞0.6，可提升Sentinel-2影像数据反演土壤含盐量的性能；基于随机森林模型（RF）构建的土壤含盐量反演模型具有最高的验证集决定系数（R2=0.613）和最低的平均绝对误差（MAE）和均方根误差（RMSE），分别为2.951 g/kg和4.524 g/kg；研究区非盐土面积增加2 404.17 km2，中度盐土与盐土面积分别减少2 856.21、2 518.06 km2，而轻度盐土与重度盐土面积分别增加1 935.51、1 034.59 km2，整体土壤盐渍化程度降低，流域盐渍化防治工作仍需坚持。【结论】实现了新疆渭干河流域土壤盐渍化程度的有效反演，Sentinel-2卫星多光谱遥感影像的光谱指数数据可作为研究区土壤盐渍化监测的重要数据源，RF模型在处理土壤盐分与遥感数据之间复杂线性关系时具有强适应性，能够有效提升土壤盐渍化监测的精度，可为流域内土壤盐渍化治理与防治提供技术参考。