Search

In July 2021, the Taklamakan Desert (TD) experienced an unprecedented rainstorm with daily precipitation exceeding 61.1 mm, triggering mudslides and landslides, highlighting the increasing frequency of extreme precipitation events even in arid regions under global warming. The water vapor sources and transport paths of this rainstorm are still puzzling due to the insufficient representation of physical processes in previous analytical models, leading to possible deviations from reality. Here, using the online Eulerian Weather Research and Forecasting model with water vapor tracer (WRF‐WVT), we aim for an improved understanding of water vapor sources of the rainfall event. Results demonstrate that the most important water source for this event is water vapor from local evapotranspiration, contributing to 32.77% of the rainstorm moisture. Water vapor from Upstream Westerlies (28.95%) and East Asian Drylands (28.54%) are transported over the precipitation area by the westerlies owing to the strong lower‐level low‐pressure system, being the second‐most important precipitation source. These sources contribute significantly more than other regions, including the Arabian Sea (5.56%), the Tibetan Plateau (2.16%), and the South Asian Monsoon (0.77%). External moisture sources collectively provide over 65.98% of the precipitation, underscoring their important role. Notably, local evapotranspiration significantly influences precipitation, exceeding the contributions from other individual sources. By comparing with the 2016 precipitation event, it is found that a low‐pressure trough extending southward to the west of the TD plays a significant role in the 2021 rainstorm event. The presence of the trough significantly enhances the moisture transport of the westerlies and the upward motion, contributing to the occurrence of extreme precipitation events. Plain Language Summary: The Taklamakan Desert (TD), widely recognized as one of the driest places on Earth, preserves records of environmental changes. However, despite the dryness and its arid conditions, rainfall is observed under the background of global warming without being completely understood so far. This study focuses on understanding the mechanisms behind rainfall in the TD. We aim to investigate a specific rainstorm event in July 2021, discovering the water vapor sources and transport pathways that transport moisture for hundreds and thousands of kilometers to the desert. Over 65.98% of the precipitation contributing water vapor inflow from outside the desert region. The water vapor originating from the evapotranspiration within the desert accounts for 32.77% of the total precipitation. By describing how and why extreme precipitation has occurred in the TD, this study facilitates understanding the mechanism of extreme precipitation in the region as well as being extrapolated to many other cases. Key Points: The source of water vapor of a rainstorm event in Taklamakan Desert is investigated using WRF‐WVTThe moisture of this rainstorm event primarily comes from external regions, being transported by the westerliesLocal evaporation contributes ∼1/3 water vapor to July 2021 extreme rainfall, whereas external moisture input contributes ∼2/3 [ABSTRACT FROM AUTHOR]

Copyright of Plateau Meteorology is the property of Plateau Meteorology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on MERRA-2 reanalysis data and the dust records at meteorological stations from 1980 to 2020， we have defined the Westerly Jet stream Position Index （JPI） and provided preliminary insights into the impact of north-south movement of westerly jet stream on dust activity in the Taklamakan Desert （TD）.By conducting a comparative analysis of the dust mixing ratio， frequency of dust events， and the atmospheric circulation fields during periods characterized by northward and southward shifts in the jet stream， we have derived the following conclusions： （1） The position of the westerly jet stream in spring exhibits obvious fluctuation between different years， and the interannual variation trend between different months is also different.The meridional movement is mainly caused by the changes of the north-south temperature gradient over the TD.When the temperature decreases in the southern regions and increases in the northern regions， the north-south temperature gradient decreases， causing the jet stream to shift northward.（2） The spring dust activity in the TD exhibits a significant correlation with the positional changes of the westerly jet stream.The dust mixing ratio within the atmospheric column experiences substantial increases （decreases） as the jet stream shifts towards the north （south）.The difference in dust mixing ratio is greater in the lower layers than in the middle to upper layers.（3） The frequency of dust events in the TD during spring is closely correlated with the north-south movement of the jet stream.The northward shift of the jet stream leads to an elevation in the average occurrence of floating dust， blowing sand， and dust storms throughout each month in spring.The difference in the number of dust weather days caused by the positional shift of the jet stream is more significant in March and May compared to April.Especially episodes of floating dust， there is an average difference of up to 3 days between northward and southward shifts of the jet stream in May.（4） The northward migration of the westerly jet stream during spring alters the atmospheric circulation fields and exerts a profound influence on the emission and transportation of dust in the hinterland of TD.The abnormal anticyclone dominates the middle and upper atmosphere of the Tibetan Plateau and TD， intensifying the westerly jet stream over the desert and augmenting downward momentum transfer.Additionally， abnormal easterly winds manifest in the lower atmosphere， leading to an increase in the surface wind speed.These new findings will be helpful for understanding the formation mechanisms of spring dust activities in the TD and provide scientific basis and reference for climate change in the arid regions of Northwest China.

Abstract Analyzing the genetic diversity and selection characteristics of sheep (Ovis aries) holds significant value in understanding their environmental adaptability, enhancing breeding efficiency, and achieving effective conservation and rational utilization of genetic resources. In this study, we utilized Illumina Ovine SNP 50 K BeadChip data from four indigenous sheep breeds from the southern margin of the Taklamakan Desert (Duolang sheep: n = 36, Hetian sheep: n = 74, Kunlun sheep: n = 27, Qira black sheep: n = 178) and three foreign meat sheep breeds (Poll Dorset sheep: n = 105, Suffolk sheep: n = 153, Texel sheep: n = 150) to investigate the population structure, genetic diversity, and genomic signals of positive selection within the indigenous sheep. According to the Principal component analysis (PCA), the Neighbor-Joining tree (NJ tree), and Admixture, we revealed distinct clustering patterns of these seven sheep breeds based on their geographical distribution. Then used Cross Population Extended Haplotype Homozygosity (XP-EHH), Fixation Index (FST), and Integrated Haplotype Score (iHS), we identified a collective set of 32 overlapping genes under positive selection across four indigenous sheep breeds. These genes are associated with wool follicle development and wool traits, desert environmental adaptability, disease resistance, reproduction, and high-altitude adaptability. This study reveals the population structure and genomic selection characteristics in the extreme desert environments of native sheep breeds from the southern edge of the Taklimakan Desert, providing new insights into the conservation and sustainable use of indigenous sheep genetic resources in extreme environments. Additionally, these findings offer valuable genetic resources for sheep and other mammals to adapt to global climate change.

Analyzing the genetic diversity and selection characteristics of sheep (Ovis aries) holds significant value in understanding their environmental adaptability, enhancing breeding efficiency, and achieving effective conservation and rational utilization of genetic resources. In this study, we utilized Illumina Ovine SNP 50 K BeadChip data from four indigenous sheep breeds from the southern margin of the Taklamakan Desert (Duolang sheep: n = 36, Hetian sheep: n = 74, Kunlun sheep: n = 27, Qira black sheep: n = 178) and three foreign meat sheep breeds (Poll Dorset sheep: n = 105, Suffolk sheep: n = 153, Texel sheep: n = 150) to investigate the population structure, genetic diversity, and genomic signals of positive selection within the indigenous sheep. According to the Principal component analysis (PCA), the Neighbor-Joining tree (NJ tree), and Admixture, we revealed distinct clustering patterns of these seven sheep breeds based on their geographical distribution. Then used Cross Population Extended Haplotype Homozygosity (XP-EHH), Fixation Index (FST), and Integrated Haplotype Score (iHS), we identified a collective set of 32 overlapping genes under positive selection across four indigenous sheep breeds. These genes are associated with wool follicle development and wool traits, desert environmental adaptability, disease resistance, reproduction, and high-altitude adaptability. This study reveals the population structure and genomic selection characteristics in the extreme desert environments of native sheep breeds from the southern edge of the Taklimakan Desert, providing new insights into the conservation and sustainable use of indigenous sheep genetic resources in extreme environments. Additionally, these findings offer valuable genetic resources for sheep and other mammals to adapt to global climate change. [ABSTRACT FROM AUTHOR]

Taklamakan Desert (TD) has been characterized by numerous heatwaves and dust storms, leading to negative effects on societies and ecosystems at regional and global scales. However, the association between heatwaves and dust storms is poorly known. In this study, we describe the association between heatwaves and dust events and propose a mechanism for such compound events in the TD. The results show that, from 1993 to 2022, the frequency and intensity of heatwaves in the TD have increased at a rate of 0.21 days year−1 and 0.02°C year−1, respectively. More than 40% of heatwaves existed with dust events, which significantly lagged behind heatwaves. Mechanically, the higher the air temperature, the hotter and drier the soil, leading to more dust emissions in the TD. In high-occurrence heatwave years, a large-scale wave train of "cyclone-anticyclone-cyclone" in the northwest-southeast direction was found, with the anticyclone of which hovered over the TD region. The anomalous anticyclones favored the formation and maintenance of heatwaves, and subsequent anomalous cyclones in the wave train triggered strong dust events followed by heatwaves. With climate warming, the compound events of heatwave and dust storm are becoming bigger hazards threatening the socioeconomic and ecological security in the TD, the profound study of which is critical to understanding regional extreme responses. [ABSTRACT FROM AUTHOR]

A fundamental challenge in soil macroecology is to understand how microbial community structure shapes ecosystem function along environmental gradients of the land surface at broad spatial scales (i.e. the horizontal dimension). However, little is known about microbial community structure–function relationships in extreme environments along environmental gradients of soil depth at finer spatial scales (i.e. the vertical dimension). Here, we propose a general spatial dimension partitioning approach for assessing the patterns and drivers of soil microbial community structure–function relationships across horizontal and vertical spatial gradients simultaneously. We leveraged a 200‐km desert soil salinity gradient created by a 12‐year saline‐water irrigation in the Tarim basin of Taklamakan Desert. Specifically, using a general linear model, hierarchical variance partitioning, and a path model, we assessed the patterns and key ecological processes controlling spatial turnover in microbial community structure (i.e. β‐diversity) and enzymatic activity relevant to carbon, nitrogen, and phosphorus cycling along soil salinity gradients across study sites (horizontal dimension) and soil depths (vertical dimension). We found a decoupled relationship between soil microbial β‐diversity and enzymatic activity. Differences in soil depth (on the scale of meters) were as important as geographic distance (on the scale of kilometers) in shaping bacterial and fungal β‐diversity. However, the vertical and horizontal turnover in enzymatic activity was largely attributed to an increase in the heterogeneity of soil properties, such as soil texture, water content, and pH. Our findings suggest that dispersal limitation controls microbial community β‐diversity and that environmental heterogeneity, rather than soil salinization, controls enzymatic activity. Taken together, this work highlights that in the face of ongoing environmental alterations, soil depth is an under‐explored spatial dimension that must be considered in soil conservation efforts as a critical factor in determining microbial community structure and function in extreme environments. [ABSTRACT FROM AUTHOR]

This study aimed to examine the spatio-temporal variations in the atmospheric boundary layer height (ABLH) over the Tarim Basin (TB). Monthly ABLH data from the ERA-Interim dataset from January 1979 to December 2018 were used. Periodicity analysis and the Mann–Kendall Abrupt Changes test were employed to identify the change cycle and abrupt change year of the boundary layer height. The Empirical Orthogonal Function (EOF) method was utilized to determine the spatial distribution of the boundary layer height, and the RF method was used to establish the relationship between the ABLH and influencing factors. The results demonstrated that the highest values of ABLH (over 1900 m) were observed in the middle parts of the study area in June, and the ABLH exhibited a significant increase over the TB throughout the study period. Abrupt changes in the ABLH were also identified in 2004, as well as in 2-, 5-, 9-, and 15-year changing cycles. The first EOF ABLH mode indicated that the middle and northeast regions are relatively high ABLH areas within the study area. Additionally, the monthly variations in ABLH show a moderately positive correlation with air temperature, while exhibiting a negative correlation with air pressure and relative humidity. [ABSTRACT FROM AUTHOR]

The lack of observational data in Taklamakan Desert makes it very difficult to study its unique boundary layer structure. As a common means of supplementing observational data, the mesoscale boundary layer parameterization scheme in the numerical model method is difficult to capture small-scale turbulent processes, which may lead to large deviations in simulation. In order to obtain more accurate simulation data of desert atmospheric boundary layer, nested LES into WRF (WRF-LES) was configured to simulate the seasonal variations in Taklamakan Desert. By comparing LES with the conventional boundary layer parameterization scheme, the error characteristics between the two schemes are analyzed. The results show that LES exhibits superior performance in solving key atmospheric features such as small-scale processes and low-level jet streams. The simulation results in winter and summer have great uncertainty due to the boundary condition errors, respectively. LES also shows the maximum and minimum optimization degree in summer and winter, respectively, while the simulation results in spring and autumn are relatively stable. In the analysis of turbulence parameters, there are clear seasonal differences in turbulence characteristics, and the intensity of turbulence in summer is significantly higher than that in other seasons. When turbulent activity is strong, the difference in potential temperature and horizontal wind speed simulated between the two schemes is closely related to intense turbulent kinetic energy in LES. More accurate turbulence reproduced in LES leads to the better potential temperature and horizontal wind speed simulations in summer. In addition, large-scale cloud systems can lead to considerable simulation bias. Neither scheme can accurately simulate the cloud emergence process, and large differences between the two schemes occur at this point. [ABSTRACT FROM AUTHOR]

Abstract The construction of hybrid power plants with renewable resources can bring significant economic benefits if it is evaluated economically and technically. The present study uses a novel optimum methodology for designing a combined solar/battery/diesel system in Yarkant, Xinjiang Uyghur Autonomous Region of China. In the desired system, the green energy combined system is designed to reduce the use of diesel generators. The diesel generator has been used in the photovoltaic, diesel, and battery to support green energy resources and batteries, as well as function as a backup generator for critical times whenever the production of green energy resources is low or the load demand is high. The amount of CO2 emitted, the probability of load shortage and the system cost on yearly basis are the major goals in the process of optimization. Here, the single‐objective problem is created by using the ε‐constraint technique to combine the many objectives. An improved Henry gas solubility optimizer handles the problem of optimization. To demonstrate the superiority of the strategy, a comparison is conducted between the simulation outcomes of the offered system, HOMER, and particle swarm optimizer ‐based optimum systems from the literature. The sensitivity of each parameter is also examined using sensitivity analysis.

Soil-derived dust emissions have been widely associated with health and environmental problems and should therefore be accurately and reliably estimated and assessed. Of these emissions, the inhalable PM10 and PM2.5 are difficult to estimate. Consequently, to calculate PM10 and PM2.5 emissions from soil erosion, an approach based on an artificial neural network (ANN) model which provides a multilayered, fully connected framework that relates input parameters and outcomes was proposed in this study. Owing to the difficulty in obtaining the actual emissions of soil-derived PM10 and PM2.5 over a broad area, the PM10 and PM2.5 simulated results of the ANN model were compared with the published results simulated by the widely used wind erosion prediction system (WEPS) model. The PM10 and PM2.5 emission results, based on the WEPS, agreed well with the field data, with R2 values of 0.93 and 0.97, respectively, indicating the potential for using the WEPS results as a reference for training the ANN model. The calculated r, RMSE and MAE for the results simulated by the WEPS and ANN were 0.78, 3.37 and 2.31 for PM10 and 0.79, 1.40 and 0.91 for PM2.5, respectively, throughout Southern Xinjiang. The uncertainty of the soil-derived PM10 and PM2.5 emissions at a 95% CI was (−66–106%) and (−75–108%), respectively, in 2016. The results indicated that by using parameters that affect soil erodibility, including the soil pH, soil cation exchange capacity, soil organic content, soil calcium carbonate, wind speed, precipitation and elevation as input factors, the ANN model could simulate soil-derived particle emissions in Southern Xinjiang. The results showed that when the study domain was reduced from the entire Southern Xinjiang region to its five administrative divisions, the performance of the ANN improved, producing average correlation coefficients of 0.88 and 0.87, respectively, for PM10 and PM2.5. The performances of the ANN differed by study period, with the best result obtained during the sand period (March to May) followed by the nonheating (June to October) and heating periods (November to February). Wind speed, precipitation and soil calcium carbonate were the predominant input factors affecting particle emissions from wind erosion sources. The results of this study can be used as a reference for the wind erosion prevention and soil conservation plans in Southern Xinjiang. [ABSTRACT FROM AUTHOR]

The construction of hybrid power plants with renewable resources can bring significant economic benefits if it is evaluated economically and technically. The present study uses a novel optimum methodology for designing a combined solar/battery/diesel system in Yarkant, Xinjiang Uyghur Autonomous Region of China. In the desired system, the green energy combined system is designed to reduce the use of diesel generators. The diesel generator has been used in the photovoltaic, diesel, and battery to support green energy resources and batteries, as well as function as a backup generator for critical times whenever the production of green energy resources is low or the load demand is high. The amount of CO2 emitted, the probability of load shortage and the system cost on yearly basis are the major goals in the process of optimization. Here, the single‐objective problem is created by using the ε‐constraint technique to combine the many objectives. An improved Henry gas solubility optimizer handles the problem of optimization. To demonstrate the superiority of the strategy, a comparison is conducted between the simulation outcomes of the offered system, HOMER, and particle swarm optimizer ‐based optimum systems from the literature. The sensitivity of each parameter is also examined using sensitivity analysis. [ABSTRACT FROM AUTHOR]

[Objectives] The windbreak efficiency of shelterbelts with different permeability on strip fields at the edge of the oasis in the Taklamakan Desert was analyzed in order to provide theoretical guidance for sustainable development of local grid strip fields. [Methods] The peri-urban shelter forest in the Qiaqikumu area of Yecheng County, Xingjiang Wei Autonomous Region on the southern edge of the Taklamakan Desert was selected as the research location. Field observations were made to quantify the windbreak effect for shelterbelts with different structures on the edge of the Taklamakan Desert oasis. [Results] ① The strip field within 10—15 m of the leeward side of the shelterbelts in the Qiaqikumu area of Yecheng County experienced the best windbreak effect. Crops with poor ability to withstand wind damage can be planted in this strip field. ② In general, the windbreak effect provided by shelterbelts was highest for plants with a height of 1.5 m and lowest for plants with a height of 2 m. Therefore, planting crops with a plant height of less than 1.5 m in the shelterbelts can effectively minimize losses caused by wind damage in this study area. ③ The sand fixation efficiency of the open-structure shelterbelt was the greatest, followed by the ventilated-structure shelterbelt. The sand fixation efficiency of the compact-structure shelterbelt was the worst. The order of sand fixation efficiency for the three kinds of structural shelterbelts followed the order of 58.39%>57.99%>36.29%, respectively. [Conclusion] In order to increase the sand-fixation efficiency of shelterbelts, open-structure shelterbelts should be recommended. This shelterbelt type can achieve the best windbreak effect. Strip fields around open-structure shelterbelts can be planted with crops having weak sand resistance.

Land–atmosphere interactions are influenced by the earth's complex underlying subsurface, which in turn indirectly affects atmospheric motion and climate change. Human activities are increasingly exerting an influence on desert ecosystems, and artificial green land with clear functional orientation has been established in many desert areas. Consequently, the previously dominant, shifting, sand-covered, underlying surface in these desert regions is gradually transforming. This transformation has significant implications for the characteristics of land–atmosphere interactions, causing them to deviate from their original state. At present, existing studies still have not presented a systematic understanding of this change and have ignored the impact of human activities on land–atmosphere interactions in artificial green land. To address these research gaps, this study specifically targets artificial green land in the Tazhong region of Taklamakan Desert. We carried out observation experiments on land–atmosphere interactions in three different functional units from outside to inside: natural shifting sands, the shelter forest, and the living area. We also analyzed the differences and attribution of land–atmosphere interactions characteristics of different functional units. Compared with the natural shifting sands, the daily average maximum values of wind speed in the shelter forest decreased by 78%, and the daily average maximum air temperature and soil (0 cm) temperature decreased by 2.6 °C and 7 °C, respectively. Additionally, the soil moisture level was significantly increased throughout the green land due to the shelter forest. The surface albedo experienced a decrease, with an annual average of 0.21. Furthermore, the aerodynamic roughness and bulk transport coefficient increased by two orders of magnitude. The daily average maximum values of sensible heat flux and soil heat flux (G05) decreased by 18.7% and 75%, respectively, and the daily average maximum value of latent heat flux increased by 70.3%. This effectively improved the microclimate environment of the green land. The living area was greatly reduced by the shelter forest coverage and influenced by the buildings. Consequently, the environmental improvement was not as large as it was inside the shelter forest. However, it still provided a good shelter for production and living in the desert area. Throughout the year, a total of 4.60 × 105 t water was consumed through evapotranspiration in the artificial green land. The findings of this study have the potential to enhance our comprehension of land–atmosphere interactions in desert regions, thereby offering valuable insights for the establishment and effective management of artificial desert green lands. [ABSTRACT FROM AUTHOR]

The main objective of this study is to present a multi-objective and optimal hybrid PV/diesel generator/ battery Renewable Energy System (HRES) to provide this reliability in the Hotan county, placed in Taklamakan Desert. This study uses the ɛ-constraint method along with a developed version of the coyote optimization algorithm to achieve the best values of the component sized to decrease the loss of load probability, CO2 emission value, and the annualized cost of the system. Sensitivity analysis also is performed to show each component’s impact on the system. The results demonstrate that the DG backup system improves the yearly cost of the system from 8347.2 $ to 9318.4 $, which shows about 10.42% increasing by increasing the fuel consumption. Here, the LLP increases from 0% to 9.19% and the CO2 emissions improve from 2531.2 kg/yr to 13257 kg/yr. Accordingly, the COE value is reduced from 0.39 $/kWh to 0.24 $/kWh over the PV penetration, reducing from 92.27% to 59.42%. This decreasing indicates that the system fuel cost has more impact than the cost of PV on the COE, which is due to the low cost required of conventional power production than the PV system. The results also indicate a noteworthy upshot on the battery storage unit size such that the size of ɛCO2has been enhanced from 27.4 kWh to 50 kWh in the range from 7000 kg/year to 25 kg/year. The results also are compared with the PSO-based optimal system and HOMER software results to show its excellence toward them.

Copyright of Bulletin of Soil & Water Conservation is the property of Bulletin of Soil & Water Conservation Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Land–atmosphere interactions are influenced by the earth’s complex underlying subsurface, which in turn indirectly affects atmospheric motion and climate change. Human activities are increasingly exerting an influence on desert ecosystems, and artificial green land with clear functional orientation has been established in many desert areas. Consequently, the previously dominant, shifting, sand-covered, underlying surface in these desert regions is gradually transforming. This transformation has significant implications for the characteristics of land–atmosphere interactions, causing them to deviate from their original state. At present, existing studies still have not presented a systematic understanding of this change and have ignored the impact of human activities on land–atmosphere interactions in artificial green land. To address these research gaps, this study specifically targets artificial green land in the Tazhong region of Taklamakan Desert. We carried out observation experiments on land–atmosphere interactions in three different functional units from outside to inside: natural shifting sands, the shelter forest, and the living area. We also analyzed the differences and attribution of land–atmosphere interactions characteristics of different functional units. Compared with the natural shifting sands, the daily average maximum values of wind speed in the shelter forest decreased by 78%, and the daily average maximum air temperature and soil (0 cm) temperature decreased by 2.6 °C and 7 °C, respectively. Additionally, the soil moisture level was significantly increased throughout the green land due to the shelter forest. The surface albedo experienced a decrease, with an annual average of 0.21. Furthermore, the aerodynamic roughness and bulk transport coefficient increased by two orders of magnitude. The daily average maximum values of sensible heat flux and soil heat flux (G05) decreased by 18.7% and 75%, respectively, and the daily average maximum value of latent heat flux increased by 70.3%. This effectively improved the microclimate environment of the green land. The living area was greatly reduced by the shelter forest coverage and influenced by the buildings. Consequently, the environmental improvement was not as large as it was inside the shelter forest. However, it still provided a good shelter for production and living in the desert area. Throughout the year, a total of 4.60 × 105 t water was consumed through evapotranspiration in the artificial green land. The findings of this study have the potential to enhance our comprehension of land–atmosphere interactions in desert regions, thereby offering valuable insights for the establishment and effective management of artificial desert green lands.

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Three hundred and twenty endophytic actinobacterial strains were isolated from psammophytes collected from Taklamakan Desert and identified. Among them, three strains already had been identified as new species of two genera and sixteen isolates showed relatively low 16S rRNA similarities < 98.6% to validly described species. Seventy-five of the isolates were selected as representative strains to screen antibacterial activity and mechanism. Forty-seven strains showed antagonistic activity against at least one of the indicator bacteria. Two Streptomyces strains produced bioactive compounds inducing DNA damage, and two Streptomyces strains produced bioactive compounds with inhibitory activity on protein biosynthesis. Notably, the strain Streptomyces sp. 8P21H-1 that demonstrated both strong antibacterial activity and inhibitory activity on protein biosynthesis was prioritized for exploring new antibiotics. Under the strategy of integrating genetics-based discovery program and MS/MS-based molecular networking, two new streptogramin-type antibiotics, i.e., acetyl-griseoviridin and desulphurizing griseoviridin, along with known griseoviridin, were isolated from the culture broth of strain 8P21H-1. Their chemical structures were determined by HR-MS, and 1D and 2D NMR. Desulphurizing griseoviridin and griseoviridin exhibited antibacterial activities by inhibiting translation.

The longest artificial highway shelterbelt flowing across the Taklamakan desert was conducted in 2005. To ensure the sustainable development of the highway and shelterbelts, scholars have carried out a large number of studies on the shelterbelt since 1991. This review is based on a 30-year monitoring program from 1991 to 2021. We find that, with the increase of shelterbelt age, some ecological and economic benefits gradually appear, such as saving transportation cost, promoting economic development in Southern Xinjiang, improving the sandy soil and microenvironment, and increasing the biodiversity. In the meanwhile, some adverse phenomena also exist, such as high maintenance costs, decrease in water tables because of irrigation, threats of the protected species, pollution from pumping oil wells, and the potential damage from highway burying as sand dunes move forward. In view of these problems, some suggestions are as follows. First, the science-policy sections of both the UNFCCC and the UNCCD should pay special attention to providing research-based guidance for the international cooperation and coordination. Second, China government should provide the necessary funding to establish the 27th China desert observation and research station to ensure long-term monitoring and slow down the pace of construction on the desert highway to allow time to develop strategies that minimize the impact on wild animals. Third, it is necessary to apply solar photovoltaic power in well irrigation and sand industry development. Fourth, the sand-blocking belt of 10 m width and 10 m away from the outside of the upwind shelterbelt can be laid every five years in view of sand-buried roads. In short, the inter-agency collaboration and coordination are both essential to ensuring the success of sustainable development and management of the Taklamakan Desert man-made ecosystem.

A new species of the genus Tachyura Motschulsky, 1862 is described: Tachyura (s. str.) yuezhisp. n. from the Ruoqiang River in the southeastern part of the Taklamakan Desert, Xinjiang Uyghur Autonomous Region of China. [ABSTRACT FROM AUTHOR]

Taklamakan desert is known as the largest dunefield in China and as the second largest shifting sand desert in the world. Although with long history and glorious culture, the Taklamakan desert remains largely unexplored and numerous microorganisms have not been harvested in culture or taxonomically identified yet. The main objective of this study is to explore the diversity, novelty, and pharmacological potential of the cultivable actinomycetes from soil samples at various sites along the Alar-Hotan desert highway in the Taklamakan desert. A total of 590 actinobacterial strains were recovered by the culture-dependent approach. Phylogenetic analysis based on 16S ribosomal RNA (rRNA) gene sequences unveiled a significant level of actinobacterial diversity with 55 genera distributed in 27 families of 12 orders. Thirty-six strains showed relatively low 16S rRNA similarities (

Three hundred and twenty endophytic actinobacterial strains were isolated from psammophytes collected from Taklamakan Desert and identified. Among them, three strains already had been identified as new species of two genera and sixteen isolates showed relatively low 16S rRNA similarities < 98.6% to validly described species. Seventy-five of the isolates were selected as representative strains to screen antibacterial activity and mechanism. Forty-seven strains showed antagonistic activity against at least one of the indicator bacteria. Two Streptomyces strains produced bioactive compounds inducing DNA damage, and two Streptomyces strains produced bioactive compounds with inhibitory activity on protein biosynthesis. Notably, the strain Streptomyces sp. 8P21H-1 that demonstrated both strong antibacterial activity and inhibitory activity on protein biosynthesis was prioritized for exploring new antibiotics. Under the strategy of integrating genetics-based discovery program and MS/MS-based molecular networking, two new streptogramin-type antibiotics, i.e., acetyl-griseoviridin and desulphurizing griseoviridin, along with known griseoviridin, were isolated from the culture broth of strain 8P21H-1. Their chemical structures were determined by HR-MS, and 1D and 2D NMR. Desulphurizing griseoviridin and griseoviridin exhibited antibacterial activities by inhibiting translation. [Display omitted] • Integrated analytic technologies break the bottleneck of metabolites rediscovery. • Two new streptogramin-type antibiotics were discovered from Streptomyces sp. 8P21H-1. • Actinobacteria from Taklamakan are promising source of novel species and compounds. [ABSTRACT FROM AUTHOR]

Taklamakan desert is known as the largest dunefield in China and as the second largest shifting sand desert in the world. Although with long history and glorious culture, the Taklamakan desert remains largely unexplored and numerous microorganisms have not been harvested in culture or taxonomically identified yet. The main objective of this study is to explore the diversity, novelty, and pharmacological potential of the cultivable actinomycetes from soil samples at various sites along the Alar-Hotan desert highway in the Taklamakan desert. A total of 590 actinobacterial strains were recovered by the culture-dependent approach. Phylogenetic analysis based on 16S ribosomal RNA (rRNA) gene sequences unveiled a significant level of actinobacterial diversity with 55 genera distributed in 27 families of 12 orders. Thirty-six strains showed relatively low 16S rRNA similarities (<98.65%) with validly described species, among which four strains had already been characterized as novel taxa by our previous research. One hundred and forty-six actinobacterial isolates were selected as representatives to evaluate the antibacterial activities and mechanism of action by the paper-disk diffusion method and a double fluorescent protein reporter "pDualrep2" system, respectively. A total of 61 isolates exhibited antagonistic activity against the tested "ESKAPE" pathogens, among which seven strains could produce bioactive metabolites either to be able to block translation machinery or to induce SOS-response in the pDualrep2 system. Notably, Saccharothrix sp. 16Sb2-4, harboring a promising antibacterial potential with the mechanism of interfering with protein translation, was analyzed in detail to gain deeper insights into its bioactive metabolites. Through ultra-performance liquid chromatography (UPLC)-quadrupole time-of-flight (QToF)-MS/MS based molecular networking analysis and databases identification, four families of compounds (1 – 16) were putatively identified. Subsequent bioassay-guided separation resulted in purification of four 16-membered macrolide antibiotics, aldgamycin H (8), aldgamycin K (9), aldgamycin G (10), and swalpamycin B (11), and their structures were elucidated by HR-electrospray ionization source (ESI)-MS and NMR spectroscopy. All compounds 8 – 11 displayed antibacterial activities by inhibiting protein synthesis in the pDualrep2 system. In conclusion, this work demonstrates that Taklamakan desert is a potentially unique reservoir of versatile actinobacteria, which can be a promising source for discovery of novel species and diverse bioactive compounds. [ABSTRACT FROM AUTHOR]

• The dust storm led to new record-low visibility observations in Chinese cities. • Taklamakan dust emissions linked to Mongolian cyclone via NLLJs for the first time. • Gobi dust affected most cities, while Taklamakan dust influenced the West of China. In mid-March 2021, one of the strongest dust storms of the last decade hit East Asia with adverse impacts on socio-economic activities and loss of life. The aim of this study is to assess the atmospheric dynamics involved in the temporal evolution of the Mongolian extra-tropical cyclone driving the dust event in different dust source regions in East Asia and to quantify to what extent the event was unusual for the first time. To that end, we use observation and model data from different sources. We identify that dust aerosols of the event primarily originated in the Gobi Desert. The anomalously strong dust-emitting winds were here associated with the passage of a cold front and exceeded the 99th percentile of the near-surface wind climatology for March 1992–2021 by far. Over the Loess Plateau, the dust deposition mostly exceeded the regional dust emission, indicative of the region being a net sink for dust aerosols, even during a high-impact event like in mid-March 2021. The formed dust aerosol layer of thousands of kilometers in extent led to sharp decreases in the air quality across China with record-high urban particulate matter concentrations, poor air quality, and low atmospheric visibility. Our results highlight that also the Taklamakan Desert contributed to the dust outbreak in the Western part of China. The dust emissions in the Taklamakan Desert were associated with nocturnal low-level jets that were favored by the cold air intrusion. It provides the first evidence for a link between different dust-emission mechanisms across East Asian Deserts during synoptic-scale dust outbreaks. [ABSTRACT FROM AUTHOR]

Monitoring, modeling and predicting the formation and movement of dust storms across the global deserts has drawn great attention in recent decades. Nevertheless, the scarcity of real-time observations of the wind-driven emission, transport and deposition of dusts has severely impeded progress in this area. In this study, we report an observational analysis of sand-dust storm samples collected at seven vertical levels from an 80-m-high flux tower located in the hinterland of the great Taklamakan Desert for ten sand-dust storm events that occurred during 2008-2010. We analyzed the vertical distribution of sandstorm particle grain sizes and horizontal sand-dust sediment fluxes from the near surface up to 80 m high in this extremely harsh but highly representative environment. The results showed that the average sandstorm grain size was in the range of 70 to 85 μm. With the natural presence of sand dunes and valleys, the horizontal dust flux appeared to increase with height within the lower surface layer, but was almost invariant above 32 m. The average flux values varied within the range of 8 to 14 kg m and the vertical distribution was dominated by the wind speed in the boundary layer. The dominant dust particle size was PM and below, which on average accounted for 60-80 % of the samples collected, with 0.9-2.5 % for PM, 3.5-7.0 % for PM, 5.0-14.0 % for PM and 20.0-40.0 % for PM. The observations suggested that on average the sand-dust vertical flux potential is about 0.29 kg m from the top of the 80 m tower to the upper planetary boundary layer and free atmosphere through the transport of particles smaller than PM. Some of our results differed from previous measurements from other desert surfaces and laboratory wind-dust experiments, and therefore provide valuable observations to support further improvement of modeling of sandstorms across different natural environmental conditions. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT The Urumqi Institute of Desert Meteorology of China Meteorological Administration carried out a scientific experiment to detect the clear-sky atmospheric boundary layer by using a wind-profiling radar and L-band radar sounding system in the hinterland and southern margin of the Taklamakan Desert in the summer of 2010 and 2011. Based on wind profile and radiosonde data collected from this experiment, this paper analyses the vertical structure features of the clear-sky daytime convective boundary layer and night-time stable boundary layer in the hinterland and southern margin of the desert, and compared the result with the boundary layer features in the Tibetan Plateau and the Dunhuang region in Gansu. The results show that: (1) the summer clear-sky convective boundary layers in the hinterland and southern margin of the Taklamakan Desert can develop thickly. The mixing layer can reach a maxiumum thickness of 3700 m, above which a significant entrainment layer exists with average thickness about 500 m. The maximum thickness of the convective boundary layer can exceed 4000 m. (2) A temperature inversion phenomenon is found to exist remarkably over the summer clear-sky nights in the hinterland and southern margin of the desert. The thickness of the night stable boundary layer is about 400-600 m, but the residual layer above it generally can reach a thickness of more than 3000 m. (3) An atmospheric boundary layer with supernormal thickness under the clear summer sky is a phenomenon of arid regions in Northwest China. [ABSTRACT FROM AUTHOR]

The characteristics of the wind regime and the development of dune morphology in the Taklamakan Desert have been the focus of scholars. In this study, we used ERA5 reanalysis wind data at a height of 10 m from 1979 to 2019 to examine the sand transport and wind regime characteristics of the entire Taklamakan Desert. We combined the two latest dune development modes, i.e., bed instability and elongation modes, and determined that: (1) Taklamakan Desert is overall characterized by a lower wind energy environment; the wind and sand activity intensities are highest in the eastern part of the desert, with a decreasing trend from the east to the west. The wind direction in the eastern region shows unimodal characteristics due to the backward easterly wind; the wind regime gradually becomes complicated from the northeast to the southwest; (2) the morphological alignments of dunes can be predicted by such modern wind regimes combined with the latest dune development modes. Large longitudinal dunes in the middle of the desert can be predicted with the elongation mode, whereas secondary transverse dunes, which derive from these composite dunes, can be predicted using the bed instability mode. Collectively, this paper fills the gap of the lack of uniform and standardized macro-scale wind data in the Taklamakan Desert, and the two modes of dune development derived from ERA5 reanalysis data can match the morphology and trend of most modern dunes. • The wind regime in Taklamakan Desert was examined using ERA5 reanalysis data. • ERA5 reanalysis wind data can be used to explain the morphology of modern dunes. • Two dune development modes can predict the alignments of most sand dunes in the desert. [ABSTRACT FROM AUTHOR]

The degree to which warming of the planet will alter Asia's water resources is an important question for food, energy, and economic security. Here we present geological evidence, underpinned by radiometric dating and dendrochronology, and bolstered by hydrological modeling, indicating that wetter-than-present conditions characterized the core of the inner Asian desert belt during the Little Ice Age, the last major Northern Hemispheric cold spell of the Holocene. These wetter conditions accompanied northern mid-latitude cooling, glacier expansion, a strengthened/southward-shifted boreal jet, and weakened south Asian monsoons. We suggest that southward migration of grasslands in response to these wetter conditions aided the spread of Mongol Empire steppe pastoralists across Asian drylands. Conversely, net drying over the 20th century has led to drought that is unprecedented for the past ∼830 years, and that could intensify with further heating of the Asian continent. [ABSTRACT FROM AUTHOR]

Populus euphratica (Euphrates poplar) is the dominant tree species of the riparian (“tugai”) forests of Central Asia, which provide important ecosystem services to a rapidly growing population. However, overuse of the forests by wood harvest (pollarding) contributes markedly to their destabilisation. At the upper reaches of the Tarim River (Xinjiang, NW China), we investigated the effects of past pollarding (in the 1970s and 1980s) on the stand structure, tree morphology, stem diameter increment and intrinsic water use efficiency (iWUE) of poplars with different pollarding intensities in the past (‘No Use’, ‘Moderate’, ‘Intense’) growing on three adjacent plots with the same distance to the groundwater level. Compared to the non-used trees, the pollarded poplars (in particular, the intensely used trees) exhibited smaller figures of the following morphological variables: ratio of tree height to diameter at breast height, vertical crown extension, crown projection area, crown volume, and tree-ring width as well as basal area increment (BAI) during the past 24 years; but a higher number of secondary shoots, a higher percentage of hollow stems and a higher degree of hollowness of the stems. The pollarded trees were capable of regenerating to a certain extent, which was obvious from the formation of secondary shoots and, in the intensely pollarded trees, from a lower iWUE (inferred by more negative δ 13 C isotopic ratios of the tree rings; most probably due to higher rates of gas exchange) as well as from their capability of re-establishing a crown efficiency similar to non-pollarded trees. However, the BAI of the main trunk and the secondary branches of the pollarded trees decreased continuously during the last 24 years of investigation. Whilst moderate intensities of pollarding seem to be sustainable for the riparian P. euphratica forests, intense pollarding reduces the growth increment of the trees and, even more importantly, results in a distinct increase in the percentage of hollow stems, which can render the trees less stable and more susceptible to secondary damaging factors. The significant correlations between BAI and morphological variables of crown projection area and crown volume are promising for developing approaches to assess the productivity of P. euphratica stands on a landscape level using methods of remote sensing. [ABSTRACT FROM AUTHOR]

A novel endophytic actinobacterium, designated strain SP28S-3, was isolated from a surface-sterilized stem of Tamarix taklamakanensis collected from the southern edge of Taklamakan desert, Xinjiang, China. Strain SP28S-3 was found to show chemotaxonomic and morphological properties consistent with its classification in the genus Prauserella. The polar lipids were found to consist of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphoglycolipid, phosphatidylcholine, phosphatidylinositol, a glycolipid, an aminolipid and unidentified phospholipids. The major fatty acids (>10 %) were identified as iso-C and C. The genomic DNA G+C content was determined to be 69.7 mol%. Phylogenetic analysis of strain SP28S-3 clearly showed that the strain had the highest similarity of 16S rRNA gene sequence with Prauserella coralliicola SCSIO 11529 (99.9 %), followed by Prauserella marina DSM 45268 (97.0 %) and is affiliated with the genus Prauserella. The low level (47.8 ± 5.5 %) of DNA-DNA relatedness between strain SP28S-3 and P. coralliicola SCSIO 11529 combined with other polyphasic taxonomic evidence clearly support the conclusion that strain SP28S-3 represents a novel Prauserella species, for which the name Prauserella endophytica sp. nov. is proposed. The type strain is SP28S-3 (=DSM 46655 = CGMCC 4.7182 ). [ABSTRACT FROM AUTHOR]

Radioactive wastes always contain radioactive substances and a lot of Pb compound and other heavy metals, which severely contaminate soils and groundwater. Thus, search for radiation-resistant microorganisms that are capable of sequestering Pb contaminants from the contaminated sites is urgently needed. However, very few such microorganisms have been found so far. In the present study, we discovered a novel Gram-negative bacterium from the arid Taklamakan desert, which can strongly resist both radiation and Pb. Phylogenetic and phenotypic analysis indicated that this bacterial strain is closely affiliated with Microvirga aerilata, and was thus referred to as Microvirga aerilata LM (=CCTCC AB 208311). We found that M. aerilata LM can effectively accumulate Pb and form intracellular precipitations. It also keeps similar ability to remove Pb under radioactive stress. Our data suggest that M. aerilata LM may offer an effective and eco-friendly in situ approach to remove soluble Pb contaminants from radioactive wastes. [ABSTRACT FROM AUTHOR]

Climate change is expected to result in an increase in the frequency and magnitude of extreme weather events. Alhagi sparsifolia is an important factor for wind prevention and sand fixation in the forelands of the Taklamakan Desert. The effects of high temperature on desert plants remain widely unknown. In this work, chlorophyll a fluorescence induction kinetics were investigated at different time stresses of 5, 20, 40, and 60 min at temperature gradients of 38-44 °C at 2 °C intervals. A pronounced K-step was found, and the values of the maximum quantum yield for primary photochemistry, the quantum yield of electron transport, the density of reaction centers and the performance index on absorption basis were lowest after 60 min at 44 °C, thus indicating that the oxygen-evolving complex was damaged, the inactivated reaction centers increased, and the activity of the photosystem II (PSII) reaction center in leaves was seriously limited. Therefore, we suggest that under normal temperature (below 42 °C), the PSII of A. sparsifolia would be unaffected. When such temperature is maintained for 40 min, the activity of PSII would be limited, and when retained for 60 min, PSII may be severely damaged. [ABSTRACT FROM AUTHOR]

To advance understanding of the provenance of the silt and clay fraction (particles <0.063 mm in diameter) in the Taklamakan Desert, where dust events occur frequently, we have investigated the spatial distribution and geochemical characteristics of the silt and clay content of surface sediment in the region. The mean PM10 (particles <0.01 mm in diameter) and PM50 (particles <0.05 mm in diameter) content of the surface sediment of the mobile desert were <0.97% and <3.98%, respectively, which was lower than for the Gobi Desert (PM10 = 2.13–6.46%, PM50 = 7.94–20.86%) and the degraded land surrounding the Taklamakan Desert (PM10 = 3.71–13.70%, PM50 = 12.33–32.29%). These results indicate that the Taklamakan Desert is surrounded by potential sources of silt and clay. The relationships between TiO2 and Fe2O3, MgO, V, and Zr confirm that the geochemical composition of the silt and clay fraction have striking spatial differences in the interior of the Taklamakan Desert. Three regions with different silt and clay fraction provenances were identified: the Southeastern (I), Northeastern (II), and Western (III) deserts. Homogeneous geochemical characteristics of the silt and clay fractions from the Southeastern (I) Desert, Gobi Desert and degraded land surrounding the Taklamakan Desert, under prevailing wind conditions, means that the same sources of silt and clay fraction source existed among these areas. The significant differences in the geochemical characteristics of the silt and clay fraction from upwind degraded land, the Western (III) Desert and the Northeastern (II) Desert, indicate that they are sourced from different locations. [ABSTRACT FROM AUTHOR]

Taking the Gramineae species Elytrigia intermedia, Avena sativa, Bromus inermis, Elymus sibiricus , Leymus tianschanicus , Elymus dahuricus , Festuca elata, Agropyron cristatum, and Puccinellia distans at the edge of Cele Oasis in southern Taklimakan Desert as test objects, this paper monitored their fast chlorophyll fluorescence kinetics after 20 minutes adaptation in darkness, compared their photosystem n ( P S n ) characteristics, and analyzed their adaptability to the local environment. Among the nine Gramineae species, L. tianschanicus and E. dahuricus had markedly higher values of maximum fluorescence yield ( Fm ) , maximum photochemical efficiency of PS n ( Fv /Fm) , and active reaction centers per cross-section ( RC/CSo) , but lower values of minimum fluorescence yield ( Fo ) , absorption flux per reaction center (ABC/ RC) , maximal trapping flux per reaction center ( TRo/RC) , flux of dissipated excitation energy per reaction center (DIo/RC) , and initial slope of fluorescence intensity ( Mo) , as compared to F. elata, A. cristatum, and P. distans , whereas E. intermedia, A. sativa, B. inermis , and E. sibiricus had a medium level of the values. These results suggested that all the test pasture species were suffered from the severe environmental conditions of Cele Oasis to some extent, as indicated by the inactivation of PS n reaction center and the depression of electron transport chain. L. tianschanicus and E. dahuricus were least impacted, while F. elata, A. cristatum, and P. distans were most impacted. [ABSTRACT FROM AUTHOR]

Abstract: To better understand the influence of Tamarix spp. (tamarisk shrubs) on soil fertility and salinity and the implication for saline soil management in northwestern China, several soil physical and chemical characteristics were measured beneath tamarisk canopies from the upper, middle, and lower regions of the Taklamakan Desert alluvial plain. The measured properties included soil organic matter (SOM), plant-available phosphorus (P), extractable soil potassium (K) soil electric conductivity (EC), sodium (Na+), total potassium (K+), and pH. The enrichment ratios for soil nutrients (i.e., available P, extractable K, and SOM) and salinity (i.e., EC, Na+, K+, and pH) were used to evaluate fertility and salinity islands in tamarisk mounds. SOM, available P, and extractable K were higher within mounds than in open, tamarisk-free land in each of the three sampled locations. The SOM enrichment ratios were highest at the middle region of the alluvial plain and lowest at the lower region of the alluvial plain, a pattern that is consistent with the growth patterns of tamarisk plants. The variation in SOM enrichment ratios in surface soils was mainly affected by the shoot biomass of tamarisk shrubs. The positive effect of tamarisk on soil fertility indicates that tamarisk may be beneficial for vegetation restoration and improving utilization of saline land. Nevertheless, soil salinity and pH increased under tamarisk canopy, especially EC and K+ in surface soil from the middle alluvial plain. The EC enrichment ratio was highest in the middle alluvial plain and, depending on soil depth, lowest in the upper and lower alluvial plain. These results reflect negative effects of tamarisk on soil chemical characteristics. [ABSTRACT FROM AUTHOR]

Alhagi sparsifolia is a leguminous perennial desert species that is plays an important role in dune stabilization and revegetation of degraded desert ecosystems. We investigated the effects of three different levels of salinity (50, 150, 250 mmol/L NaCl) on the growth, shoot photosynthetic parameters and salt distribution amongst different plant organs in one-year-old A. sparsifolia seedlings in a pot experiment over a 50 d period. The minimum (predawn) and maximum (midday) water potentials of A. sparsifolia seedlings decreased with the increase of external NaCl concentrations as a consequence of the osmotic or water deficit effect of saline solutions outside the roots. Salinity also reduced gas exchange parameters in A. sparsifolia, with seedlings subjected to salinity having lower photosynthesis rates and reduced stomatal conductances compared to the control. The reductions in photosynthetic rates in high salinity treatments of the A. sparsifolia seedlings were mainly caused by stomatal limitation. Consequently plants growing at greater external NaCl concentrations had significantly lower biomass accumulation compared to the control grown at 50 mmol/L. However, plants exposed to higher salinity were able to maintain growth throughout the experiment but allocated a greater proportion of biomass belowground. Plants exposed to higher external salinity levels had increased concentrations of Na+ and Cl- ions in shoots and roots, suggesting that A. sparsifolia seedlings were utilizing Na+ and Cl- as osmolytes to increase the cellular osmolality and decrease their water potential. We observed the greatest NaCl concentrations in the plants treated with 150 mmol/L NaCl indicating that there may be a threshold level of NaCl that can be tolerated by the plants. In conclusion our results indicate that A. sparsifolia seedlings are moderately salt tolerant. Photosynthetic gas exchange parameters were reduced by greater external salinity but the seedlings maintained substantial photosynthetic rates even under high salinity stress, were able to maintain growth over the 50 d experimental period and showed no signs of salinity toxicity or damage. [ABSTRACT FROM AUTHOR]

Copyright of Basic & Applied Ecology is the property of Urban & Fischer Verlag and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

After conducting many laboratory and field experiments, several key technical issues related to the construction of China’s Taklamakan Desert Highway have been satisfactorily resolved. In particular, considerable progress has been made on the dry compaction of a sand sub-base, road design parameters, the creation of a structure that combines a sub-grade and asphalt pavement, analysis of the stability of a sand sub-base strengthened with geotextiles, and on the development of a complete set of construction techniques. The achievements of this research were successfully applied for the first time in the Taklamakan Desert, where the environmental conditions are extremely harsh. The results suggest that the construction of this highway was economical and that the simple construction methods produced a reliable highway. The resulting highway is believed to be the world’s first long-distance graded highway running through a huge desert with migrating dunes. [ABSTRACT FROM AUTHOR]

Little is known of the mechanisms employed by woody plants to acquire key resources such as water and nutrients in hyperarid environments. For phreatophytic plants, deep roots are necessary to access the water table, but given that most nutrients in many desert ecosystems are stored in the upper soil layers, viable shallow roots may be equally necessary for nutrient uptake. We sought to better understand the interaction between water and nutrient uptake from soil horizons differing in the relative abundance of these resources. To this end, we monitored plant water and nutrient status before and after applying flood irrigation to four phreatophytic perennial plant species in the remote hyperarid Taklamakan desert in western China. Sap flow in the roots of five plants of the perennial desert species Alhagi sparsifolia Shap., Karelina caspica (Pall.) Less., Calligonum caput medusea Schrenk, and Eleagnus angustifolia Hill. was monitored using the heat ratio method (HRM). Additionally we measured predawn and midday water potential, foliar nitrate reductase activity (NRA), xylem sap nutrient concentration and the concentration of total solutes in the leaves before, 12 and 96 h after flooding to investigate possible short-term physiological effects on water and nutrient status. Rates of sap flow measured during the day and at night in the absence of transpiration did not change after flooding. Moderately high rates of sap flow (HRM heat pulse velocity, 5–25 cm h−1) detected during the day in soils that had a near zero water content at the surface indicated that all species had contact to groundwater. There was no evidence from sap flow data that plants had utilised flood water to increase maximum rates of transpiration under similar climatic conditions, and there was no evidence of a process to improve the efficiency of water or nutrient uptake, such as hydraulic redistribution (i.e. the passive movement of water from moist soil to very dry soil via roots). Measurements of plant water status, xylem sap nutrient status, foliar NRA and the concentration of osmotically active substances were also unaffected by flood irrigation. Our results clearly show that groundwater acts as the major source of water and nutrients for these plants. The inability of plants to utilise abundant surface soil–water or newly available nutrients following irrigation was attributed to the absence of fine roots in the topsoil layer. [ABSTRACT FROM AUTHOR]