Changes in the Range of Four Advantageous Grasshopper Habitats in the Hexi Corridor under Future Climate Conditions

Angaracris rhodopa (Fischer et Walheim), Calliptamus abbreviatus (Ikonnikov), Myrmeleotettix palpalis (Zubowsky), and Oedaleus decorus asiaticus (Bey-Bienko) are the main grasshoppers that harm the natural grassland in the Hexi Corridor in Gansu, northwest China. In this study, the MaxEnt model was employed to identify the key environmental factors affecting the distribution of the four grasshoppers' habitats and to assess their distribution under current and future climate conditions. The aim was to provide a basis for grasshopper monitoring, prediction, and precise control. In this study, distribution of suitable habitats for A. rhodopa, C. abbreviates, M. palpalis, O. decorus asiaticus were predicted under current and future climatic scenarios using the Maxent model. The average AUC (area under the ROC curve) and TSS (true skill statistic) values of the four grasshoppers were greater than 0.9, and the simulation results were excellent and highly reliable. The mean annual precipitation was the main factor limiting the current range of suitable areas for these four species. Under the current climate, A. rhodopa, C. abbreviatus, and O. decorus asiaticus were mainly distributed in the central and eastern parts of the Hexi Corridor, and M. palpalis was distributed throughout the Hexi Corridor, with a suitable area of 1.29 × 104, 1.43 × 104, 1.44 × 104, and 2.12 × 104 km2, accounting for 13.7%, 15.2%, 15.3%, and 22.5% of the total area of the grasslands in the Hexi Corridor, respectively. The highly suitable areas of A. rhodopa, C. abbreviatus, and O. decorus asiaticus were mainly distributed in the eastern-central part of Zhangye City, the western part of Wuwei City, and the western and southern parts of Jinchang City, with areas of 0.20 × 104, 0.29 × 104, and 0.35 × 104 km2, accounting for 2.2%, 3%, and 3.7% of the grassland area, respectively. The high habitat of M. palpalis was mainly distributed in the southeast of Jiuquan City, the west, middle, and east of Zhangye City, the west of Wuwei City, and the west and south of Jinchang City, with an area of 0.32 × 104 km2, accounting for 3.4% of the grassland area. In the 2030s, the range of A. rhodopa, C. abbreviatus, and O. decorus asiaticus was predicted to increase; the range of M. palpalis will decrease. The results of this study could provide a theoretical basis for the precise monitoring and control of key areas of grasshoppers in the Hexi Corridor.

[Temporal and Spatial Distributions of O3 Concentration and Potential Source Area Analysis of Hexi Corridor Based on Satellite and Ground Monitoring]

Based on 2005-2020 O3 column concentration data of OMI remote sensing satellite, combined with air pollutant data from 10 nationally controlled environmental automatic monitoring stations in the Hexi Corridor and global data assimilation system meteorological data, we used Kriging interpolation, correlation analysis, and backward trajectory (HYSPLIT) models to explore the temporal and spatial distribution characteristics, meteorological factors, transmission paths, and potential sources of O3 in the Hexi Corridor. The results showed the following:① in terms of temporal distribution, O3 column concentration showed an upward trend in 2005-2010 and 2014-2020 and downward trend in 2010-2014; the maximum and minimum values were reached in 2010 and 2014 (332.31 DU and 301.00 DU), respectively, and seasonal changes showed that those in spring and winter were significantly higher than those in summer and autumn. ② In terms of spatial distribution, O3 column concentration showed a latitudinal band distribution characteristic of increasing from southwest to northeast; the high-value areas were primarily distributed in urban areas with low terrain, and the median zone was latitudinally striped with the basic alignment of the Qilian foothills. ③ The analysis of meteorological conditions revealed that temperature, wind speed, and sunshine hours were positively correlated with O3, and relative humidity was negatively correlated with O3. ④ By simulating the airflow transportation trajectory of the receiving point in Wuwei City, it was found that the direction of the O3 conveying path was relatively singular; the dominant airflow in each season was primarily in the west and northwest; and the proportions were 71.62%, 66.85%, 61.22%, and 77.78%, respectively. There were certain seasonal differences in the source areas of O3 potential contribution:the high-value areas of O3 potential sources in spring, summer, and autumn were distributed in Baiyin City and Lanzhou City, which were southeast wind sources, and the high-value areas in winter were distributed between the Badain Jaran Desert and the Tengger Desert, which was the north wind source.

The Distribution and Influencing Factors of Hypolithic Microbial Communities in the Hexi Corridor

The Hexi Corridor is an arid region in northwestern China, where hypoliths are widely distributed, resulting from large amounts of translucent stone pavements. In this region, the water and heat distributions are uneven, with a descent gradient from east to west, which can affect the area's biological composition. The impact of environmental heterogeneity on the distribution of hypolithic microbial communities in this area is poorly understood, and this is an ideal location to investigate the factors that may influence the composition and structure of hypolithic microbial communities. An investigation of different sites with differences in precipitation between east and west revealed that the colonization rate decreased from 91.8% to 17.5% in the hypolithic community. Environmental heterogeneity influenced both the structure and function of the hypolithic community, especially total nitrogen (TN) and soil organic carbon (SOC). However, the effect on taxonomic composition was greater than that on ecological function. The dominant bacterial phyla in all sample sites were Cyanobacteria, Actinobacteria, Proteobacteria, and Deinococcus-Thermus, but the abundances varied significantly between the sampling sites. The eastern site had the highest relative abundance of Proteobacteria (18.43%) and Bacteroidetes (6.32%), while the western site had a higher relative abundance in the phyla Cyanobacteria (62%) and Firmicutes (1.45%); the middle site had a higher relative abundance of Chloroflexi (8.02%) and Gemmatimonadetes (1.87%). The dominant phylum in the fungal community is Ascomycota. Pearson correlation analysis showed that the soil's physicochemical properties were also associated with changes in community diversity at the sample sites. These results have important implications for better understanding the community assembly and ecological adaptations of hypolithic microorganisms.

Decoupling of water resources utilization and coordinated economic development in China's Hexi Corridor based on ecological water resource footprint

The rapid growth of population and economy leads to a further increase in demand for water resources. The contradiction between supply and demand of water resources has become the main bottleneck restricting sustainable development of a regional social economy. Accurate measurement of regional water usage and the harmonious balance between water consumption (WC) and economic growth (EG) are the premise of regional high-quality development. Based on this premise, this paper studied the arid oasis region, Hexi Corridor, as the research object; utilized the theory of ecological footprint to calculate the ecological footprint (EFW) and ecological carrying capacity (ECCW) of water resources from 2005 to 2019; and quantitatively analyzed the water utilization situation in Hexi Corridor in the past 15 years. Then, combining with the coordinated development decoupling evaluation model, the connection between WC and EG was evaluated. The main results of this study were as follows: (1) During the study period, EFW has shown a fluctuating downward trend, decreasing from 1.745 in 2015 to 1.588 hm²/person in 2019. The average annual EFW per capita of 10,000 yuan of GDP decreased by 10.18%, which showed that the water resources utilization efficiency was gradually increasing. However, there was still a large water deficit. The average water ecological pressure index was 16.55; water resources were under great pressure. (2) From 2005 to 2019, the relationship between WC and EG experienced stages of strong decoupling-weak decoupling-weak negative decoupling-strong decoupling in Hexi Corridor, and the coordination between the two was gradually strengthened. (3) The decoupling status of the Hexi Corridor cities was gradually optimized. Zhangye was the best and in a stable decoupling state, followed by Wuwei and Jiuquan. The number of decoupling years accounted for 85.7% and 78.6% of the evaluation period, respectively. The cities with poor decoupling status were Jiayuguan and Jinchang, and the number of decoupling years accounted for 71.4% and 57.1%, respectively. This study provides some highlights for the formulation of arid oasis regional water strategy.

[Eco-environmental effects and spatiotemporal evolution characteristics of land use change: A case study of Hexi Corridor, Northwest China.]

Based on the land use data of Hexi Corridor region from 1980 to 2020, we calculated the ecological environment quality index and analyzed the spatial and temporal evolution characteristics, change frequency, patterns, circles of the long time series land use type changes and its ecological environment quality, using the spatial analysis method of ArcGIS. The results showed that unused land was the main land use type in the study area during 1980-2020. The area of construction land, forest land, grassland, and water changed more, and the transition among land use types was obvious. The trends of deterioration and improvement of ecological environment quality in the study area occurred simultaneously and offset each other under certain conditions. The ecological environment quality index evolved in a 'U' shape, first decreasing and then increasing, with little change in overall ecological environment quality fluctuations. The spatial clustering of ecological quality was obvious, which was higher in the southeast and lower in the northwest, without high frequency and large change. The ecological quality in the southeast quadrant of the study area was the worst, followed by the southwest and northwest quadrants, while the ecological quality in the northeast quadrant was the best. The area of the continuously decline zone in ecological environment quality type conversion was larger than that of the continuously rising zone, indicating that ecological environmental protection in the Hexi Corridor had been effective during the study period. The hot spots of ecological quality change were mainly distributed in the central and southwestern part of the Hexi Corridor, and the cold spots were mainly distributed in the northwestern part.

The lifestyle of Tuyuhun royal descendants: Identification and chemical analysis of buried plants in the Chashancun cemetery, northwest China

The Tuyuhun Kingdom (AD 313-663) was one of the most famous regimes in northwest China during the early medieval period. However, the lifestyle and spiritual pursuit of their descendants who became allied with the Tang Dynasty remain enigmatic. The excavation of the Chashancun cemetery, a Tuyuhun royal descendant (AD 691) cemetery in the Qilian Mountains in northwest China, reveals a large amount of uncharred plant remains. These remains provided a rare opportunity to explore the geographical origin of the buried crops and their social implications. In total, 253,647 crops and 12,071 weeds were identified. Foxtail millet and broomcorn millet represent 61.99 and 30.83% of the total plant remains, with the rest being barley, buckwheat, beans, and hemp. The oxygen isotope and trace elements of the crop and weed remains suggest that broomcorn millet, foxtail millet, barley, buckwheat, and hemp were sourced from different regions. The assemblage of plant remains in the Chashancun cemetery suggests that millet cultivation played an important role in the livelihoods of Tuyuhun descendants, and the location of the elite Tuyuhun cemetery and multisources of different buried crops may reflect their memory of ancestors and homelands. This case study provides a unique perspective to understand the interactions among human subsistence strategy, geopolitical patterns, and local natural environments in northwest China during the late 7th century.

Assessment of Spatio-Temporal Changes for Ecosystem Health: A Case Study of Hexi Corridor, Northwest China

Ecosystem health (EH) is important for ensuring sustainable development, and the main goal of environmental protection and governance, especially for ecological fragile areas. Scientific assessment of EH can improve decision-making ability and inform sustainable development. In this paper, the effects of natural and social environment were integrated to reflect the characteristics of EH based on a comprehensive assessment system including ecosystem vigor (EV), ecosystem organization (EO), ecosystem resilience (ER), and the ratio of supply to demand of ecosystem services (ESDR) from the perspectives of ecological integrity and human demand for ecosystem services (ES). The Entire-Array-Polygon (EAP) method was applied to calculate an ecosystem health index (EHI) and analyze spatio-temporal change from 2000 to 2020 in Hexi Corridor (HC), Northwest China. The results showed that: (1) The spatial distribution of EV, EO, ER, and ESDR was generally consistent, with a low spatial distribution in the northwest and high in the southeast, the values showed an overall increasing trend from 2000 to 2020. (2) The spatial distribution of EHI was high in the northwest and central regions, and low in the southwest, reflected a moderate health level. The proportion of area with well and relatively well health was increasing, which indicated that EH showed an improving trend. (3) The significantly decrease areas of EHI were mainly located in urban areas, and the increases areas were mainly located outside of urban areas. The distribution of the EH condition has obvious orientation characteristics. The results of the study provide theoretical and practical implications for regional ecological conservation and management.

Status, Sources and Potential Risk of Polycyclic Aromatic Hydrocarbons in Soils from Hexi Corridor in Northwest China

The Hexi Corridor is the main commodity grain base in northwest China and plays a special role in ensuring food security in northwest China. However, the multiple pollution transport pathways of PAHs and complex and co-existing potential pollution sources around the study areas require a combination of pollution status, source identification, and risk assessment to explore pollution distribution and potential risks. In this study, the total PAHs concentration (∑₁₈PAHs) in soils ranged from 69.6 to 1300 ng/g. Spatially, the higher content of PAHs was detected in the Jinchang, followed by Jiayuguan, Jiuquan, Wuwei, and Zhangye, indicating a remarkable influence of different industrial activities. Although high-molecular-weight PAHs were predominated, the compositions of PAHs in most of the soil samples were varied. The isomer ratios of PAHs and principal component analysis were also revealed the PAHs probably originate from the sources different significantly. The total health risk values indicated a low health risk.

Trends and distribution of coronary heart disease mortality rate in Hexi Corridor, Gansu, China from 2006 to 2015

This study described the trend and distribution of coronary heart disease (CHD) in the Hexi Corridor region of Gansu. The CHD mortality rates from 2006-2015 were obtained through the Death Reporting System of Gansu Centers for Disease Control (CDC) for 2006-2015. The overall mortality rate of CHD in the Hexi Corridor showed a decreasing trend, increasing in winter and spring and lowest in summer. The CHD mortality rate was higher in men than in women (P < 0.05) and increased with age (P < 0.05). The mortality rate was higher in rural areas than in urban areas (P < 0.05). A ten-year mortality rate trend analysis showed that CHD mortality rate in women has significantly decreased. Specifically, women aged 18-39 years experienced increased There was little change in CHD mortality among women aged 40-59 years, and a declined in CHD mortality among women 60 years and older and women in urban areas. Further analysis showed that in the 18-39-year-old and 40-59-year-old groups and in urban areas, CHD mortality rate was higher in men than in women (P < 0.05). From 2006 to 2015, the mortality rate of CHD in the Hexi Corridor of Gansu was lower than in the national average, but in certain populations such as men, young and middle-aged group and rural areas, the CHD mortality rate was gradually increased. There has been a gradual and progressive decline in CHD mortality rate compared to the rising trend in China. This is due to fewer risk factors in the region, effective drug treatment and improvements in environmental pollution. However, there is still a need to enhance the experience of effective prevention and control for specific subgroups such as men, young people and rural residents, and to take appropriate measures to prevent the occurrence of CHD.

New insights into the fine-scale history of western-eastern admixture of the northwestern Chinese population in the Hexi Corridor via genome-wide genetic legacy

Trans-Eurasian cultural and genetic exchanges have significantly influenced the demographic dynamics of Eurasian populations. The Hexi Corridor, located along the southeastern edge of the Eurasian steppe, served as an important passage of the ancient Silk Road in Northwest China and intensified the transcontinental exchange and interaction between populations on the Central Plain and in Western Eurasia. Historical and archeological records indicate that the Western Eurasian cultural elements were largely brought into North China via this geographical corridor, but there is debate on the extent to which the spread of barley/wheat agriculture into North China and subsequent Bronze Age cultural and technological mixture/shifts were achieved by the movement of people or dissemination of ideas. Here, we presented higher-resolution genome-wide autosomal and uniparental Y/mtDNA SNP or STR data for 599 northwestern Han Chinese individuals and conducted 2 different comprehensive genetic studies among Neolithic-to-present-day Eurasians. Genetic studies based on lower-resolution STR markers via PCA, STRUCTURE, and phylogenetic trees showed that northwestern Han Chinese individuals had increased genetic homogeneity relative to northern Mongolic/Turkic/Tungusic speakers and Tibeto-Burman groups. The genomic signature constructed based on modern/ancient DNA further illustrated that the primary ancestry of the northwestern Han was derived from northern millet farmer ancestors, which was consistent with the hypothesis of Han origin in North China and more recent northwestward population expansion. This was subsequently confirmed via excess shared derived alleles in f₃/f₄ statistical analyses and by more northern East Asian-related ancestry in the qpAdm/qpGraph models. Interestingly, we identified one western Eurasian admixture signature that was present in northwestern Han but absent from southern Han, with an admixture time dated to approximately 1000 CE (Tang and Song dynasties). Generally, we provided supporting evidence that historic Trans-Eurasian communication was primarily maintained through population movement, not simply cultural diffusion. The observed population dynamics in northwestern Han Chinese not only support the North China origin hypothesis but also reflect the multiple sources of the genetic diversity observed in this population.

Sandstorm weather is a risk factor for mortality in ischemic heart disease patients in the Hexi Corridor, northwestern China

Ischemic heart disease (IHD) is one of the leading causes of mortality worldwide. Moreover, the effects of air pollution have been associated with several cardiovascular diseases (CVDs). The relationship between sandstorm weather and IHD is unknown. The Hexi Corridor is located in northwestern China and is a typical desert region comprising a large area of desert with a high incidence of sandstorms. This study aimed to explore the association between sandstorm weather and IHD-related mortality in this area. We acquired meteorological data of sandstorm weather from 2006 to 2015 from the Gansu Meteorological Bureau, and data regarding deaths due to IHD in five cities within the Hexi Corridor were collected from the death registration system of the Center for Disease Control of Gansu during the same period. Two other cities with few sandstorm events were selected as control regions. The time series method of the generalized additive model (GAM) was used to assess the association between sandstorm weather and IHD-related mortality in the Hexi Corridor. The results showed that the frequency of sandstorms in the Hexi Corridor was higher than that in the control regions (5.48% vs 1.64%, P < 0.01), and IHD-related mortality was correspondingly higher than that in the control regions (56.42/100,000 vs 45.62/100,000, P < 0.01). After stratification by gender, age, and urban/rural residence, a significant difference in IHD-related mortality was also noted (P < 0.05). Significant associations were found between sandstorm weather and IHD-related mortality, and the relative risk (RR) increased with an increasing number of days of sandstorm weather. According to the monthly and annual analyses, the mortality rate corresponded to sandstorm frequency. Our data suggest a positive association between sandstorm weather and IHD-related mortality in the Hexi Corridor of Gansu Province. The underlying mechanism requires further study.

Water Productivity Evaluation under Multi-GCM Projections of Climate Change in Oases of the Heihe River Basin, Northwest China

As the second largest inland river basin situated in the middle of the Hexi Corridor, Northwest China, the Heihe River basin (HRB) has been facing a severe water shortage problem, which seriously restricts its green and sustainable development. The evaluation of climate change impact on water productivity inferred by crop yield and actual evapotranspiration is of significant importance for water-saving in agricultural regions. In this study, the multi-model projections of climate change under the three Representative Concentration Pathways emission scenarios (RCP2.6, RCP4.5, RCP8.5) were used to drive an agro-hydrological model to evaluate the crop water productivity in the middle irrigated oases of the HRB from 2021–2050. Compared with the water productivity simulation based on field experiments during 2012–2015, the projected water productivity in the two typical agricultural areas (Gaotai and Ganzhou) both exhibited an increasing trend in the future 30 years, which was mainly attributed to the significant decrease of the crop water consumption. The water productivity in the Gaotai area under the three RCP scenarios during 2021–2050 increased by 9.2%, 14.3%, and 11.8%, while the water productivity increased by 15.4%, 21.6%, and 19.9% in the Ganzhou area, respectively. The findings can provide useful information on the Hexi Corridor and the Belt and Road to policy-makers and stakeholders for sustainable development of the water-ecosystem-economy system.

Contribution of dust in northern China to PM10 concentrations over the Hexi corridor

Four main dust sources and dust events that affected the Hexi Corridor were defined, and the HYSPLIT model was used to trace the dust that originated during the dust episodes of 2015-2017 and to quantify the contributions of dust sources to PM₁₀. On this basis, an algorithm that quantified the contribution of dust sources to PM₁₀ was proposed in this study. The results showed that the main dust sources affecting the Hexi Corridor are generally located in the northern part of Xinjiang, which is mainly dominated by the Gurbantunggut Desert (source A); the Taklimakan and Kumtag Deserts and their surrounding areas (source B); both Qaidam Basins (source C); and the Badain Jaran Desert, Tengger Desert, Hobq Desert, Ulan Buh Desert, and Mu Us Sandy Land and their surrounding areas (source D). The occurrence time of dust and the frequency of PM₁₀ exceeded the daily concentration standards and showed significant characteristics of being high in the spring and low in the autumn. The higher concentration of PM₁₀ in the winter was mainly due to anthropogenic sources from heating process. The contribution of source area D to PM₁₀ concentration was the greatest (42%). Source area B was one of the main dust sources (with a contribution rate of 23%); however, approximately 63% of the dust in this area originates from the Kumtag Desert. The contribution of source area A is lower than that of the study area due to greater precipitation and higher vegetation coverage (22% contribution rate). Source area C has the lowest contribution to the research area due to obstruction by the Qilian Mountain (13% contribution rate).

Aeolian process of the dried-up riverbeds of the Hexi Corridor, China: a wind tunnel experiment

Wind tunnel studies, which remain limited, are an important tool to understand the aeolian processes of dried-up riverbeds. The particle size, chemical composition, and the mineral contents of sediments arising from the dried river beds are poorly understood. Dried-up riverbeds cover a wide area in the Hexi Corridor, China, and comprise a complex synthesis of different land surfaces, including aeolian deposits, pavement surfaces, and Takyr crust. The results of the present wind tunnel experiment suggest that aeolian transport from the dried-up riverbeds of the Hexi Corridor ranges from 0 to 177.04 g/m²/min and that dry riverbeds could be one of the main sources of dust emissions in this region. As soon as the wind velocity reaches 16 m/s and assuming that there are abundant source materials available, aeolian transport intensity increases rapidly. The dried-up riverbed sediment and the associated aeolian transported material were composed mainly of fine and medium sands. However, the transported samples were coarser than the bed samples, because of the sorting effect of the aeolian processes on the sediment. The aeolian processes also led to regional elemental migration and mineral composition variations.

Biomass and nutrient allocation strategies in a desert ecosystem in the Hexi Corridor, northwest China

The allocation of biomass and nutrients in plants is a crucial factor in understanding the process of plant structures and dynamics to different environmental conditions. In this study, we present a comprehensive scaling analysis of data from a desert ecosystem to determine biomass and nutrient (carbon (C), nitrogen (N), and phosphorus (P)) allocation strategies of desert plants from 40 sites in the Hexi Corridor. We found that the biomass and levels of C, N, and P storage were higher in shoots than in roots. Roots biomass and nutrient storage were concentrated at a soil depth of 0-30 cm. Scaling relationships of biomass, C storage, and P storage between shoots and roots were isometric, but that of N storage was allometric. Results of a redundancy analysis (RDA) showed that soil nutrient densities were the primary factors influencing biomass and nutrient allocation, accounting for 94.5% of the explained proportion. However, mean annual precipitation was the primary factor influencing the roots biomass/shoots biomass (R/S) ratio. Furthermore, Pearson's correlations and regression analyses demonstrated that although the biomass and nutrients that associated with functional traits primarily depended on soil conditions, mean annual precipitation and mean annual temperature had greater effects on roots biomass and nutrient storage.

Groundwater level prediction using a SOM-aided stepwise cluster inference model

Accurate groundwater level (GWL) prediction can contribute to sustaining reliable water supply to domestic, agricultural and industrial uses as well as ecological services, especially in arid and semi-arid areas. In this paper, a regional GWL modeling framework was first presented through coupling both spatial and temporal clustering techniques. Specifically, the self-organizing map (SOM) was applied to identify spatially homogeneous clusters of GWL piezometers, while GWL time series forecasting was performed through developing a stepwise cluster multisite inference model with various predictors including climate conditions, well extractions, surface runoffs, reservoir operations and GWL measurements at previous steps. The proposed modeling approach was then demonstrated by a case of an arid irrigation district in the western Hexi Corridor, northwest China. Spatial clustering analysis identified 6 regionally representative central piezometers out of 30, for which sensitivity and uncertainty analysis were carried out regarding GWL predictions. As the stepwise cluster tree provided uncertain predictions, we added an AR(1) error model to the mean prediction to forecast GWL 1 month ahead. Model performance indicators suggest that the modeling system is a useful tool to aid decision-making for informed groundwater resource management in arid areas, and would have a great potential to extend its applications to more areas or regions in the future.