Arid Regions Of Central Asia Research Articles

Monitoring of Glacier Area Changes in the Ili River Basin during 1992–2020 Based on Google Earth Engine

The Ili River Basin, a crucial transboundary river in the arid region of Central Asia, plays a significant role in the region’s ecology and water resources. However, current methods for monitoring glacier area changes in this region face challenges in automation and accuracy due to the complex terrain and climatic conditions. This study aims to evaluate the effectiveness of the Google Earth Engine (GEE) platform for monitoring glacier area changes in the Ili River Basin from 1992 to 2020, with a focus on improving data accuracy and processing efficiency. Utilizing the Landsat data series, we employed the random forest (RF) classification algorithm within the GEE platform to extract glacier areas, optimizing a multidimensional feature set using the Jeffries–Matusita (JM) distance method, and applied visual interpretation for data refinement. Our results demonstrated that the GEE platform, combined with the RF algorithm, provided high accuracy in glacier monitoring, achieving an overall accuracy of 89% and a kappa coefficient of 0.85. During the study period, the glacier area in the Ili River Basin decreased by 184.76 km2, with an average annual retreat rate of 6.84 km2, most notably between 3800 and 4400 m in elevation. The analysis revealed that temperature changes had a more pronounced impact on glacier dynamics than precipitation. This approach significantly enhances image utilization efficiency and data processing speed, offering a reliable tool for monitoring glacier dynamics. Future research should focus on integrating additional environmental variables and extending the temporal scope to further refine glacier dynamics modeling and predictions.

Future challenges of terrestrial water storage over the arid regions of Central Asia

Since the arid regions of Central Asia (ACA) are located in the interior of Eurasia, water resources play a vital role in the stability of its ecosystem and economic development. Based on the terrestrial water storage anomaly (TWSA) of the Gravity Recovery and Climate Experiment (GRACE), we analyze the observed characteristics of the TWSA over the ACA during 2003–2014. Results indicate that the terrestrial water storage (TWS) in the region showed an overall declining trend from 2003 to 2014, and the autumn TWS in this region is the smallest compared to other seasons and exhibits a strong decreasing trend at least −4.5 cm/decade. This means water resources over the ACA are scarcer and more vulnerable in autumn. The Distance between Indices of Simulation and Observation (DISO) method is employed to evaluate the performance of the sixth phase of the Coupled Model Intercomparison Project (CMIP6) models in simulating the autumn TWSA over the ACA. Compared with observational results, the autumn TWSA values captured by CMIP6 models are larger and the declining TWS trends are weaker. Using the optimal CMIP6 models, the statistical downscaling method constrains the projection results of autumn TWSA values over the ACA using the GRACE datasets. It shows autumn TWS will continue to decrease in most parts of the ACA in the future, and water scarcity will be the most severe in Tajikistan and southwestern Kazakhstan. Under SSP126, Tajikistan’s TWSA is projected to decrease by 11.0 cm in the long term. This study reveals the current situation and possible future changes in TWS over the ACA in autumn, providing references for water resource management and sustainable development policies in this area to avoid losses caused by water scarcity.

Spatial characteristics and trade-offs of ecosystem services in arid central asia

Ecosystem services (ESs) research is crucial for comprehending the intricate interplay between humans activities and the environment, particularly in ecologically sensitive regions like Central Asia, which straddles the transition from semi-arid to arid climates. Despite the ecological significance of these arid regions, research on ESs remains limited. In this study, we applied the InVEST model to analyze the spatial characteristics of multiple ESs, including water yield (WY), soil retention (SR), carbon storage (CS), and habitat quality (HQ), in Central Asia. Our findings unveil significant zonal disparities in the distribution of ESs and trade-offs across the region. WY, SR and WY-SR display distinct vertical zonation patterns, while CS and HQ exhibit both latitudinal and vertical zonation patterns. Trade-offs, with the exception of WY-SR, mostly exhibit a striped distribution pattern. Additionally, based on the GeoDetector approach, we identified key influencing factors, encompassing land use type, precipitation, evapotranspiration, temperature, vegetation coverage, soil depth, and soil organic matter. Notably, we discovered that the relationship between these factors and ESs, as well as trade-offs, is non-linear, with certain factors exhibiting optimal thresholds for maintaining either high or low levels of ESs and trade-offs.This study advances our understanding of ESs in the arid regions of Central Asia, offering valuable insights for regional ecosystem management and coordinated development. By shedding light on the non-linear dynamics of ESs and their response to influencing factors, it underscores the importance of further research to support sustainable development efforts in these regions. Future research can build upon these findings to develop policies and interventions that harness ESs for the benefit of the environment and local communities.

Downscale Inversion of Soil Moisture during Vegetation Growth Period in Ebinur Lake Watershed

Soil moisture content is an important measure of soil health, and high-precision soil moisture trend analysis is essential for understanding regional ecological quality in the context of climate change, flood monitoring, and water cycle processes. However, in the arid regions of Central Asia, where data are severely lacking, obtaining high-spatial-resolution, continuous soil moisture data is difficult due to the scarcity of stations. Moreover, because soil moisture is easily affected by evaporation time, surface morphology, and anthropogenic factors, mature theoretical models or empirical or semiempirical models to measure soil moisture are also lacking. To investigate the distribution and trend of soil moisture in the Ebinur Lake water, in this study, microwave remote sensing and visible remote sensing data were selected as inputs, and the Global Land Data Assimilation System (GLDAS-2.2) data products were downscaled using the GTWR model, which increased the spatial scale from 27,830 m × 27,830 m to 30 m × 30 m. The phenomena involved in the soil moisture change cycle, spatial distribution, temporal variation, and internal randomness distance were analyzed in the study area through wavelet analysis, Theil–Sen trend analysis, the Mann–Kendall (MK) test, and a variogram. This study obtained high-resolution continuous soil moisture data in the arid and data-scarce region in Central Asia, thus broadening the field of multisource remote sensing analysis and providing a theoretical basis for the construction of precision agriculture in northwest China.

Combined Effects of Meteorological Factors, Terrain, and Greenhouse Gases on Vegetation Phenology in Arid Areas of Central Asia from 1982 to 2021

Spatiotemporal variations in Central Asian vegetation phenology provide insights into arid ecosystem behavior and its response to environmental cues. Nevertheless, comprehensive research on the integrated impact of meteorological factors (temperature, precipitation, soil moisture, saturation vapor pressure deficit), topography (slope, aspect, elevation), and greenhouse gases (carbon dioxide, methane, nitrous oxide) on the phenology of Central Asian vegetation remains insufficient. Utilizing methods such as partial correlation and structural equation modeling, this study delves into the direct and indirect influences of climate, topography, and greenhouse gases on the phenology of vegetation. The results reveal that the start of the season decreased by 0.239 days annually, the length of the season increased by 0.044 days annually, and the end of the season decreased by 0.125 days annually from 1982 to 2021 in the arid regions of Central Asia. Compared with topography and greenhouse gases, meteorological factors are the dominant environmental factors affecting interannual phenological changes. Temperature and vapor pressure deficits (VPD) have become the principal meteorological elements influencing interannual dynamic changes in vegetation phenology. Elevation and slope primarily regulate phenological variation by influencing the VPD and soil moisture, whereas aspect mainly affects the spatiotemporal patterns of vegetation phenology by influencing precipitation and temperature. The findings of this study contribute to a deeper understanding of how various environmental factors collectively influence the phenology of vegetation, thereby fostering a more profound exploration of the intricate response relationships of terrestrial ecosystems to environmental changes.

Radiocarbon chronology of sediments with implications for climatic events in Lop Nur, NW China

Radiocarbon dating has played a pivotal role in paleoclimate research, particularly in establishing chronological sequences for lake sediment. However, the persistent challenge of the radiocarbon reservoir effect has remained a notable concern when using 14C dating. While several methods have been developed address this issue, the spatiotemporal variability of the lake reservoir and their climatic implications on the occurrence of anomalous 14C dating results have frequently been overlooked in previous studies. Especially when dealing with lake sediments in arid regions of Central Asia, the impact of climate-induced sediment sources and watershed hydrology poses substantial challenges for 14C dating. In this study, we focused on sediment profile in the Lop Nur and established a reliable chronological framework for the late Holocene using a piecewise linear regression approach. By integrating climate data from the surrounding region and archaeological evidence, we reconstructed the hydrological and aeolian processes of Lop Nur spanning from 670 BCE to 1300 CE. Our findings suggest that the anomalies observed in dating results were closely associated with the presence of sand component with a reduced organic matter content. And the record reveals the occurrence of sandstorm events around 500 BCE and 300 BCE, with a significant increase in strength after 200 CE. This indicates a decrease in reservoir effects during the lake regression, due to increased aeolian inputs. Therefore, we proposed that the deposition of larger-sized sandstorm particles during lake regression is predominant reason for reduced absorption of surrounding aged organic matter, leading to the younger age observed.

Soil bacteria mediate organic carbon stability during alpine wetland biogeomorphic succession in the arid region of Central Asia

Soil bacteria mediate organic carbon stability during alpine wetland biogeomorphic succession in the arid region of Central Asia

Surface deformation detection and attribution in the Mountain-Oasis-Desert Landscape in north Tianshan Mountains

ABSTRACT The Mountain-Oasis-Desert System (MODS) is the fundamental landscape component within the vast arid region of Central Asia. Human activities and natural processes cause surface displacement in the MODS, resulting in geoenvironmental issues and hazards. However, surface displacement and its driving mechanisms in the MODS are not understood. In this study, we used the time-series interferometric synthetic aperture radar (InSAR) method to detect deformation in the MODS in north Tianshan Mountain, Xinjiang and investigated its attribution from the geological conditions, groundwater level changes, and climate variability. The results along the vertical gradient indicate that decorrelation is severe in the high mountain areas with ice-marginal environments (over 3600 m above sea level (a.s.l.)) and the forest-covered mid-mountainous belt (1700–2800 m asl), rendering effective detection unfeasible. Dynamic characteristics are identified in subalpine areas with an elevation of 2800–3600 m asl, with maximum horizontal and vertical displacements of −80.2 mm/year and −58.6 mm/year, respectively. The seasonal acceleration is influenced by the combined effects of temperature and precipitation changes. We observed dense subsidence funnels and ground fissures associated with coal mining in the foreland hills (700–1700 m asl). Ground displacements here exceeded −50 mm/year two years after mining activities had ceased. Subsidence has expanded in the oases with elevations of less than 700 m asl, due to extensive groundwater extraction for agricultural irrigation. The correlation coefficient between groundwater level and displacement was 0.89 and 0.45 at wells in the agricultural and desert areas, respectively. The deformation exhibited seasonal variations associated with groundwater level. The deformation remains relatively stable in the surrounding oasis-affected desert areas, with weak fluctuations influenced by seasonal variations in groundwater level.

Proteomic Analysis of the Cold Stress Response of Ammopiptanthus mongolicus Reveals the Role of AmCHIA in Its Cold Tolerance

Ammopiptanthus mongolicus, a traditional ethnic medicinal herb, is a rare broad-leaved evergreen shrub in the arid region of central Asia that can survive under extremely low temperatures during winter. In this study, we investigated the cold stress response of A. mongolicus leaves using physiological and proteomic approaches. Cold stress treatment increased the relative electrolyte leakage, proline, and soluble sugar levels and decreased the chlorophyll content in A. mongolicus leaves. Moreover, 93 differentially abundant proteins (DAPs) were identified using two-dimensional electrophoresis, of which 79 were further confirmed via tandem mass spectrometric analysis. The predicted functions of DAPs were mainly associated with photosynthesis in chloroplasts, reactive oxygen species scavenging, defense, and protein synthesis, folding, and degradation. A. mongolicus chitinase A (AmCHIA) is a cold-induced apoplast protein whose transcription is upregulated under cold, osmotic, high-salinity, and mechanical stresses. Recombinant AmCHIA expressed in Escherichia coli exhibits chitinase activity. Here, AmCHIA expression enhanced the cold tolerance of E. coli cells, suggesting that it may contribute to the cold adaptation of A. mongolicus after cold treatment. The present study not only provides important data for understanding the cold stress responses in plants but also serves as a basis for further exploration of the biological functions of cold-induced proteins in A. mongolicus using genetic approaches.

Different patterns of changes in glacier mass balance and glacier runoff over the Tarim Basin, Central Asia

AbstractThe climate change impacted glacio‐hydrological regime and thus the availability of water resources in arid region of Central Asia. The effects of climate change in the magnitude or seasonality of regional glacier runoff were still poorly understood in Central Asia. In this study, the glacier runoff, components of glacier runoff, equilibrium line altitude (ELA) and Glacier Mass Balance (GMB) during 1959–2017 are evaluated by elevation‐dependent Degree‐Day glacier melt model in eight sub‐basins of Tarim Basin over Central Asia. The impacts of climate change on glacier and hydrology are assessed. The results suggested that climatic regime shifted to more warm‐wet pattern on glacier zone after 1990 in study area. The ablation and accumulation of glaciers showed different patterns in eight sub‐basins. All sub‐basins showed a glacier mass deficit and GMB displayed a marked decreasing trend, but also exhibiting discrepancy. The mean ELA and rising rate of ELA were higher in the southern region. The glacier runoff increased significantly after 1990 in Tarim Basin, with obviously temporal and spatial variations in sub‐basins. The mean annual volume of glacier runoff was 175.8 × 108 m3. The ice melt was a larger component of glacial runoff in Tarim Basin. The influence of rainfall runoff on glacier runoff was more obviously than snow melt runoff as more precipitation fell as rain in northern region. The larger proportions of snow melt runoff imply more precipitation fell as snowfall in southern region. The elevation‐dependent contributions in glacier runoff showed differences in individual basins. Temperature and precipitation played different role for the glacier runoff increases among the sub‐basins. Differences in sensitivity of GMB and glacier runoff were distinct and vary considerably. A thorough assessment of the spatially and temporally varying melt water originated by glaciers is crucial for the success of water scarcity adaptation under climate change.

Dynamic Changes of Terrestrial Water Cycle Components over Central Asia in the Last Two Decades from 2003 to 2020

The terrestrial water cycle is important for the arid regions of central Asia (CA). In this study, the spatiotemporal variations in the three climate variables [temperature (TMP), precipitation (PRE), and potential evapotranspiration (PET)] and terrestrial water cycle components [soil moisture (SM), snow water equivalent (SWE), runoff, terrestrial water storage (TWS), and groundwater storage (GWS)] of CA are comprehensively analyzed based on multiple datasets from 2003 to 2020. The major results are as follows: (1) Significant decreasing trends were observed for the TWS anomaly (TWSA) and GWS anomaly (GWSA) during 2003–2020, indicating serious water resource depletion. The annual linear trend values of TWSA and GWSA are −0.31 and −0.27 mm/a, respectively. The depletion centers are distributed over most areas of western and southern Kazakhstan (KAZ) and nearly all areas of Uzbekistan (UZB), Kyrgyzstan (KGZ), and Tajikistan (TJK). (2) TMP and PET have the largest significant negative impacts on SM and SWE. The PRE has a positive impact on terrestrial water variations. (3) During 1999–2019, water withdrawal did not significantly increase, whereas TWS showed a significant decreasing trend. Our results provide a comprehensive analysis of the basic TWS variation that plays a significant role in the water resource management of CA.

Uncertainties of Climate Change on Suitable Habitat of Calligonum mongolicum Turcz. (Polygonaceae) in Desert Areas of Central Asia

Understanding the climatically suitable habitat of species plays a vital role in the sustainable use and management of target species. Calligonum mongolicum Turcz., a native shrub species found in desert areas of Central Asia, is generally considered as one of the top four tree species for desertification control. However, previous works on suitable habitat simulation had focused mainly on either the national or specific geographical scales rather than entire biota scales, which have underestimated the climatic tolerance of the species. Furthermore, the uncertainty outcomes of climate change were largely ignored. With these questions, the arid regions of Central Asia were selected as our research background area. Occurrence data of C. mongolicum were obtained from various sources, such as the Global Biodiversity Information Facility, the Chinese Virtual Herbarium, and the iPlant website. The maximum entropy model (MaxEnt) was used to simulate the suitable habitat change dynamics under various climate change scenarios [5 general circulation models (GCMs) × 3 shared socioeconomic pathways (SSPs)]. The uncertainty of climate change induced by GCMs and SSPs were decomposed by the two-way ANOVA method. Our results show that hydrological-related variables are more important for the species’ habitat suitability than thermal-related variables. The climatic threshold for the core suitable habitat was 1–30 mm for precipitation of the coldest quarter, 14–401 mm for annual precipitation, −16.01–12.42 °C for mean temperature of the driest quarter, 9.48–32.63 °C for mean temperature of the wettest quarter, and −25.01–−9.77 °C for the minimum temperature of the coldest month. The size of suitable habitat was about 287.4 × 104 km2 under the current climate condition, located in China and Mongolia. Climate change has less impact on the total area size, but it has bigger impacts on the gain area and loss area sizes. The loss area is mainly located in the southeast boundaries, whereas the gain area is mainly located in Mongolia and the Qinghai-Tibet Plateau. The decomposition uncertainty of climate change indicates that GCMs could explain 14.5%, 66.4%, and 97.0% of total variation, respectively, and SSPs could explain 85.5%, 33.6%, and 3.0% of the total variation for gain, loss, and total habitat sizes, respectively. Our work clearly demonstrates that while C. mongolicum has great planting potential in Central Asia under various climate change scenarios, the sensitive areas possess large uncertainties requiring long-term climate monitoring for afforestation projects.

Temporal and spatial variation of cloud cover in arid regions of Central Asia in the last 40 years

Water resources are one of the key factors restricting the development of arid areas, and cloud water resources is an important part of water resources. The arid region of central Asia is the core region of the current national green silk road construction, and is the largest arid region in the world. Based on cloud cover data of ECMWF, the current study analyzed temporal and spatial characteristics of cloud properties in arid regions of Central Asia between 1980 and 2019. Our findings show that: (1) From the point of view of spatial distribution, total cloudiness in arid regions of Central Asia was low in the south and high in the north. The distribution of high cloud frequency and medium cloud frequency was higher in the south and lower in the north, while low cloud frequency distribution was low in the south and high in the north. (2) In terms of time, the variation of cloud cover and cloud type frequency had obvious seasonal characteristics. From winter to spring, cloud cover increased, and the change of cloud type frequency increased. From spring to summer, cloud cover continued to increase and the change of cloud type frequency increased further. Cloud cover began to decrease from summer to autumn, and the change of cloud type frequency also decreased. (3) Generally, average total cloud cover decreased in most of central Asia, and high and medium cloud cover increased while low cloud cover decreased. This study provides a reference for the rational development of cloud resources in the region.

Provenances of the Oldest Xiashu loess and Xuancheng loess in southern China: Implications for dust transport and dust proxies of the East Asian winter monsoon

The loess-paleosol sequences of southern China are valuable paleoclimatic archives since the Middle Pleistocene, on the regional and global scales. Knowledge of loess provenance can shed light on dust transport and the development of paleoclimatic proxies for loess deposits. However, there is a research gap regarding the provenance of the Oldest (∼0.9 Ma) Xiashu loess near the Yangtze River valley. The precise source area of the Xuancheng loess in southern China remains to be unidentified. In this study, we used elemental geochemistry and detrital zircon UPb ages to identify the sources of the Oldest Xiashu loess and Xuancheng loess in southern China. The Oldest Xiashu loess is dominantly derived from Yangtze River sediments, and part of its fine-grained dust component originates from the arid regions of Central Asia or northern China. The elemental compositions of the size-fractionated silicates and detrital zircon UPb ages of the Xuancheng loess are like those of the Shuiyang River sediments in the Xuancheng region. These results demonstrate that the Xuancheng loess is mainly the product of local dust activity in the Xuancheng regions, and thus that the Xiashu and Xuancheng loess are the products of independent dust transport processes. This spatial differentiation of loess provenance may be a widespread phenomenon in southern China, and consequently, the grain size compositions of the various loess sections in southern China cannot be used to recover paleo-wind directions on a regional scale. Overall, our study shows that when the grain size compositions from the southern China loess are used to reconstruct East Asian winter monsoon intensity, the signals from local wind fields should first be removed.

Multivariate drives and their interactive effects on the ratio of transpiration to evapotranspiration over Central Asia ecosystems

The ratio of vegetation transpiration to evapotranspiration (T/ET) characterizes the role of vegetation in surface-atmosphere interactions, affecting ecosystem productivity and the global carbon and water balances. Therefore, isolating and identifying the spatiotemporal characteristics of T/ET and its response to the individual and interactive effects of climatic factors will help us better understand the carbon and water cycle characteristics of ecosystems. The arid region of Central Asia has always been in the restricted area of ​​carbon-water cycle observations due to scarce station observations, harsh climatic conditions, and severe anthropogenic disturbances. Using a specific Arid Ecosystem Model (AEM), this study explored the temporal and spatial dynamic patterns of T/ET of different plant functional types (PFTs) in drylands of Central Asia based on multi-climate scenarios, and separated and quantified the independent and interactive effects of different environmental factors. The result indicated that precipitation dominated the areas of 86% (ET, evapotranspiration), 77% (T, transpiration), and 71% (the ratio of T/ET) in the arid region of Central Asia, respectively. The effect of temperature on the ratio of T/ET was negative and slight. And the temperature increase effect is only 9.7% of the negative effect of precipitation. Affected by the insignificant effect of CO2 enrichment on T, the interactive effect between climate change and CO2 effect appear to be little and negative. According to the vegetation growth and the spatial distribution of precipitation, we found that the southern Xinjiang region and the Turgay Plateau in northwestern Kazakhstan are the ecologically vulnerable areas in Central Asian. The results also indicated that general warming in this region may not have a direct and significant impact on vegetation T/ET in the future. We may need to pay more attention to the indirect effect of enhanced evaporation and reduced moisture on T/ET caused by future warming.

Variations in precipitation and temperature in Xinjiang (Northwest China) and their connection to atmospheric circulation

As one of the most vulnerable types of global ecosystems and water resource systems, arid regions are most sensitive to climate change. The Xinjiang (XJ) region is an important part of the arid region in Central Asia and is representative of global arid regions. The complex topography and underlying surface result in distinct climate change characteristics in XJ. In this study, XJ was divided into five sub-regions: the Irtysh River Basin (IRB), the economic belt on the northern slope of the Tianshan Mountains (NSTM), the Ili River Basin (ILRB), the Turpan-Hami Basin (THB), and the Tarim River Basin (TRB). The change in temperature and precipitation over XJ and its sub-regions were investigated from 1960 to 2019 using the Mann-Kendall method and cross-wavelet analysis. Moreover, the multi-timescale correlations between the variations in temperature and precipitation and the atmospheric circulation indices were explored. The results show significant warming and wetting trends in XJ from 1960 to 2019. The warming rate was 0.32°C/10 a (p < 0.01), with an abrupt change during the mid-1990s. The increasing rate of precipitation was 9.24 mm/10 a (p < 0.01), with an abrupt change during the middle to late 1990s. In terms of seasonal variation, the greatest warming rate was during winter (0.37°C/10 a), whereas the precipitation increase was concentrated in summer (3.48 mm/10 a). In terms of spatial variation, a significant warming trend was observed in THB, IRB, ILRB, and NSTM, and precipitation increased significantly in ILRB, NSTM, and the western TRB in southern XJ. The Hurst index analysis indicated that the warming and wetting trends in XJ will slow in the future. Climate change in XJ was closely related to atmospheric circulation at multiple timescales. The subtropical high, Northern-Hemisphere polar vortex activities and the Tibetan Plateau have a significant impact on climate change in XJ. The annual mean temperature in XJ was positively correlated with the area and intensity index of the subtropical high over North Africa, Atlantic, and North America, and negatively correlated with the area and intensity index of the Asia polar vortex. The XJ annual precipitation was positively correlated with the index of the Tibet Plateau Region one and negatively correlated with the intensity index of the Atlantic and European polar vortex, and the area and intensity index of the Northern Hemisphere polar vortex. The results of this study can provide some references for the scientific assessment and accurate prediction of climate change in XJ.

Characteristics and physical mechanisms of a rainstorm in Hotan, Xinjiang, China

Owing to global warming, extreme precipitation events in the arid regions of Central Asia have increased, resulting in significant consequences for water resources and ecosystems. Hence, to address the features and corresponding physical mechanisms of these rainstorms, we examined the rainstorm that occurred in Hotan, Xinjiang in June 2021 as a case study. We employed multiple datasets, including meteorological stations, sounding observations, satellite precipitation data, and reanalysis datasets. The results indicate that the Global Precipitation Measurement satellite precipitation product accurately captured the temporal and spatial variations in this rainstorm, as verified against hourly in situ observation data. Some meteorological stations recorded values greater than twice their historical records, such as Luopu, Pishan, Moyu, and Hotan. Moreover, the duration of the precipitation was longer than 2 days. For the physical mechanisms of this rainstorm, the water vapor in this rainstorm is sourced from the 45°–65°N region of the North Atlantic Ocean crosses the Ural Mountains and the West Siberian Plain to southern Xinjiang. The low-pressure levels (e.g., 700 hPa and 850 hPa) have the more water vapor flux and specific humidity than the high-pressure levels. Our findings can aid the understanding of extreme precipitation events in Central Asia and provide a reference for dealing with meteorological disasters, including extreme precipitation, in the context of global climate change.

Temporal and Spatial Distribution of Cloud Water Content in Arid Region of Central Asia

To evaluate the distribution characteristics of water vapor content (WVC), cloud liquid water content (CLWC) and cloud ice water content (CIWC) in arid areas of central Asia from 1980 to 2019 were analyzed by using average data of ERA5 in the European Centre for Medium-Range Weather Forecasts. The results show that: On the spatial scale, the WVC in the arid area of central Asia is mainly between 2 and 26 kg·m−2. The area of maximum water vapor content is distributed in southwestern Kazakhstan and southwestern Tajikistan, with a maximum value of 26 kg·m−2. The minimum areas are distributed in eastern Tajikistan, central Kyrgyzstan, central Tajikistan, and western Xinjiang, China, with the lowest WVC of 2 kg·m−2. The maximum of CLWC areas were mainly distributed in northwest Kazakhstan, with a maximum value of 0.08 kg·m−2, while the minimum areas were distributed in Tajikistan, eastern Kyrgyzstan, and northwest China, with a minimum value of 0.02 kg·m−2. The maximum areas of CIWC were distributed in the north of Tajikistan and the west of Kyrgyzstan, possessing a maximum value of 0.06 kg·m−2. The minimum area is distributed in the western part of Central Asia with a minimum value of 0.01 kg·m−2. From 1980 to 2019, the WVC generally increased, while the annual average CIWC and CLWC appeared a downward trend.

Adaptation to low nitrogen and salt stresses in the desert poplar by effective regulation of nitrogen assimilation and ion balance

As a main desert plant from arid regions of Central Asia, Populus euphratica always encounters with nitrogen shortage in its long life, apart from salt or drought stress. However, it remains unknown how this species responds to low nitrogen and combined stresses of low nitrogen and salinity. Thus, saplings of P. euphratica with uniform size were exposed to normal or low nitrogen condition (150 and 15 ppm ammonium nitrate separately) individually or in combination with salinity. Under low nitrogen conditions we found a positive effect on P. euphratica root growth, which could be associated to high level of nitrogen allocation to support root growth and effective regulation of nitrogen assimilation in comparison with the other poplar species reported before. Under salt stress the root growth of P. euphratica was significantly inhibited, with the side effects of oxidative stress, as saplings stored higher Na+ and Cl− contents in roots. Under the combined stressors of both salinity and low nitrogen, P. euphratica undergo a risky strategy, as stimulated root growth is accompanied by further oxidative stress.The concentrations of root K+ and whole plant NO3− were increased to support the tolerance of the combined stressors in P. euphratica, showing same characteristics with halophytes. Overall, our results provide evidence that the desert poplar can adapt to the salt stress/low nitrogen bundle, by effective regulation of nitrogen assimilation and ion homoeostasis.

Spatial Variation in Desert Spring Vegetation Biomass, Richness and Their Environmental Controls in the Arid Region of Central Asia

A precise evaluation of spatial patterns in desert vegetation biomass, species richness and their environmental controls is essential for a deeper comprehension of the potential carbon preservation and sustainability of grassland ecosystems. There are widespread reports suggesting robust associations among biomass, species richness and mean annual precipitation (MAP) or temperature (MAT) at different scales. However, these reports were inconsistent, and knowledge on the desert grasslands of Central Asia remains limited. In this study, we showed that spatial patterns of biomass and species richness along the zonal climate of the northern Tianshan Mountains exhibited substantial regional differences and the relationship among biomass, richness and elevation exhibited a substantial exponential decline. We discovered that functional groups of biomass, total biomass and species richness in the desert exhibited exponential growth along the MAP gradient and a quadratic relationship with MAT. Furthermore, the biomass–species richness relationships were bell-shaped in the desert zone. Accordingly, the biomass and species richness had spatial differences. At a regional scale, the spatial variation in the desert biomass and species richness was primarily dependent on climate. Our results demonstrated the specificity between the desert vegetation and climate in arid regions of Central Asia and revealed the regularity between biomass and species richness in desert areas. The research results emphasized the impact of precipitation on desert vegetation in arid regions of Central Asia and the relationship between biomass and plant species richness, which is of great significance for understanding desert ecosystems and protecting the ecological environment.