Hunshandake Sandy Land Research Articles

Effects of different sand fixation plantations on soil properties in the Hunshandake Sandy Land, Eastern Inner Mongolia, China.

Planting forests is an effective way to improve desertification. In order to elucidate the impacts of different vegetation types on soil development and restoration of degraded lands, we compared the properties of soils at different depths in three plantation forests in the Hunsandak Sandy Land in the Chinese agro-pastoral ecotone (Ulmus pumila, Pinus sylvestris var. mongolica, and Populus simonii). The results show that all three plantation forests were able to significantly improve the soil properties, and they resulted in soil nutrient enrichment in the surface layer. As the soil depth increased, the soil became progressively poorer in nutrients, the fine particle content decreased, and the bulk density and water content increased. The orders of the fractal dimension characterization and soil improvement effects of the different tree species were as follows: U. pumila > P. sylvestris var. mongolica > P. simonii. Compared with the bare sand, the soil bulk density under the U. pumila plantation was 19% lower; the soil water content was 74% higher; the soil organic matter, total N, P, and K were 336%, 207%, 106%, and 31% higher; the available N, P, and K were 41%, 125%, and 21% higher; and the clay and silt contents were 498% and 387% higher, respectively. The ranges of the soil fractal dimension were 1.67-2.08 for the bare sandy land and 2.14-2.32 for the planted forests. The soil fractal dimension was strongly correlated with the soil physicochemical properties, especially with the soil nutrients and fine particle content, which exhibited highly significant correlations (p < 0.01), and the correlation coefficients were all greater than 0.8. Therefore, we believe that U. pumila is a suitable sand-fixing plant species in this area. In addition, the soil fractal dimension can be used as an important reference index for characterizing soil properties in sandy areas.

Microtopography-Guided precision restoration of sandy lands through UAV: A case study in Hunshandake Sandy Land, China

Increasing desertification rates have adversely affected biodiversity and ecosystem functioning in sandy lands. Ecological restoration is an effective way to combat desertification. Specific microtopographic characteristics may facilitate vegetation growth, enhancing the success of restoration efforts. However, limited research to date has explored how microtopography may guide the “precision restoration” of sandy lands by supporting spatially continuous patterns of vegetation growth. Here, high-resolution unmanned aerial vehicle (UAV) multispectral data were used to identify individual species and extract microtopographic variables, and the relationships between vegetation growth and microtopography were characterized for the Hunshandake Sandy Land in China. The distribution of three dominant shrub species and grasses was investigated by comparing the performance of five popular machine-learning methods. An auto-marking watershed algorithm was then developed to discriminate individual semi-shrubs (Artemisia desertorum). Finally, a new vegetation growth index (VGI), calculated from the UAV-derived crown area, normalized difference vegetation index (NDVI), and canopy height, was used to characterize the relationships between vegetation growth and several microtopographic variables (aspect, slope, and a topographic wetness index [TWI]). With the highest species classification accuracy (94.36%) and individual discrimination rate (81%), areas with high humidity (TWI), gentle and shady slopes were found to most strongly support vegetation growth; for grasses, VGI was lower in artificially-restored regions than naturally-developed regions with similar microtopographic characteristics. These findings provide valuable guidance on the use of UAV to support diverse ecological restoration solutions in sandy lands with a “precision restoration” strategy, thereby improving the survival of key vegetation for sand restoration, especially in remote areas.

Vegetation Growth and Physiological Adaptation of Pioneer Plants on Mobile Sand Dunes

The Hunshandake Sandy Land is one of the largest sandy areas in China and the closest source of sand dust to the Beijing and Tianjing areas. Sand fixation by vegetation is considered the most efficient strategy for sand control and sustainable development, so clarifying the vegetation coverage and plant adaptation characteristics in the Hunshandake Sandy Land is helpful in guiding restoration and improving local sustainability. Here, we investigated the vegetation growth on the mobile sand dunes in the Hunshandake Sandy Land and specified the photosynthesis and stomatal characteristics of the pioneer plants for sand fixation. The vegetation survey showed that the windward slopes of the mobile sand dunes had far lower plant coverage (6.3%) and plant biodiversity (two species m−2) than the leeward ones (41.0% and eight species m−2, respectively). Elymus sibiricus L. and Agriophyllum squarrosum (L.) Moq. were the only two sand-fixing pioneer plants that grew on both the windward and leeward slopes of the mobile sand dunes and had higher plant heights, greater abundance, and more biomass than other plants. Physiological measurements revealed that Elymus sibiricus L. and Agriophyllum squarrosum (L.) Moq. also had higher photosynthetic rates, transpiration rates, and water use efficiency. In addition, the stomata density (151–197 number mm−2), length (18–29 μm), and area index (13–19%) of these two pioneer species were smaller than those of the common grassland species in Inner Mongolia, suggesting that they were better adapted to the dry habitat of the mobile sand dunes. These findings not only help in understanding the adaptive strategies of pioneer plants on mobile sand dunes, but also provide practical guidance for sand dune restoration and the sustainable development of local areas. Pioneer sand-fixing plant species that are well adapted to sand dunes can be used for sowing or aerial seeding in sand fixation during ecosystem restoration.

A Risk Assessment of the Vegetation Ecological Degradation in Hunshandake Sandy Land, China: A Case Study of Dabusennur Watershed

In the context of climate change, it is essential for sustainable development to assess the risks associated with climate change and human-induced vegetation degradation. The Hunshandake Sandy Land provides a variety of ecosystem services and is a substantial ecological security barrier in the Beijing–Tianjin–Hebei area of China. This study used the Normalized Difference Vegetation Index (NDVI) to analyze the spatiotemporal variation trend in vegetation in the Dabusennur Watershed using linear trend analysis and the GeoDetector model to identify the main drivers of vegetation change in the watershed. Finally, the study assessed the risk of ecological degradation in the vegetation of the watershed. The results show that the NDVI in the study area has had a fluctuating trend in the last 22 years, and the change has been small. Precipitation and groundwater depth are the key factors affecting vegetation change. The NDVI reaches its maximum value when the groundwater depth is at 2.75 m. The vegetation ecology of the basin is relatively fragile, mainly with medium risk and large risk. To cope with the ecological risk of vegetation degradation caused by climate change, appropriate water use strategies should be formulated to ensure ecological water use. The present study’s outcomes provide the basis for developing ecological engineering solutions in the arid and semi-arid parts of northern China.

Biomass Allocation and Allometric Relationship of Salix gordejevii Branches in Sandy Habitats Heterogeneity in Northern China

The patterns of biomass allocation are crucial for understanding the growth, reproduction, and community functions of plant individuals. We investigated the allometric growth characteristics and biomass allocation patterns of Salix gordejevii fascicular branches in various habitats of the Hunshandake Sandy Land to delve into their adaptability to environmental changes and role in the carbon cycle. We discovered the following: (1) The base diameter-to-branch length of S. gordejevii fascicular branches exhibited allometric growth relationships in mobile dunes and interdune lowlands, whereas it showed isometric growth relationships in semifixed and fixed dunes. As the soil moisture gradient increased, the length growth rate of S. gordejevii fascicular branches became faster than the base diameter growth rate in mobile dunes, demonstrated isometric growth in semifixed and fixed dunes, and was slow in interdune lowlands. (2) The biomasses of S. gordejevii fascicular branches significantly varied across different habitats, with the biomass of each component showing an increasing trend as habitat conditions improved. This study revealed the resource utilization strategies and adaptability of S. gordejevii fascicular branches in different habitats, providing new insights into the carbon sink function of desert ecosystems in semiarid regions.

Quantification of Holocene temperatures in the eastern Hunshandake Sandy Land using δ13C of loess organic matter

The soil organic carbon isotope indicator (δ13Corg) is widely used in paleoecology and paleoclimate reconstruction due to its ability to record the history of paleovegetation change. Although it has been used as a proxy for precipitation reconstruction, increasing evidence suggests that temperature has played a crucial role in influencing the relative abundance of C3/C4 plants in the mid-latitudes during the interglacial period. This opens up the possibility of reconstructing Holocene temperature using δ13Corg. In this study, the variation of δ13Corg values in a Holocene loess profile (GLH profile), located in the eastern Hunshandake Sandy Land, China, was investigated. And we analyzed the correlation between δ13Corg values and modern temperatures for a total of 792 surface soil samples from mid-latitudes of the Northern Hemisphere, which had thermal conditions comparable to the GLH profile. Strong positive correlations were found between δ13Corg values of surface soil samples and both summer temperatures (r = 0.672, p < 0.001) and growing season temperatures (r = 0.669, p < 0.001). Additionally, δ13Corg values showed significant positive correlations with accumulated temperatures above 10 °C (r = 0.641, p < 0.001) and above 0 °C (r = 0.527, p < 0.001). However, the correlation with mean annual temperature was weak (r = 0.280, p < 0.001). The δ13Corg variation in the GLH profile recorded a mixed C3/C4 vegetation composition, with C4 plants comprising between 23.40% and 1.70% of the total abundance during the Holocene. The combined evidence from modern processes and profile variations confirms that warm-season temperature was the main factor driving variations in the δ13Corg values in the GLH profile. Therefore, we used δ13Corg–temperature conversion equations to quantify Holocene seasonal and accumulated temperatures based on the GLH profile. The reconstructed summer temperatures peaked at 9.3 ka, followed by a fluctuating downward trend during the mid- and late-Holocene, which is consistent with variations in summer solar insolation. Mean summer temperatures were relatively high at 23.3 °C and 22.5 °C in the early and mid-Holocene, respectively, while the lowest mean summer temperature of 20.5 °C occurred in the late Holocene. Accumulated temperatures above 10 °C and above 0 °C in the early Holocene were 3722 °C·d and 4641 °C·d, respectively, similar to modern observations in the Beijing area, indicating a southward shift of the temperature zone by nearly three degrees of latitude since the early Holocene. These reconstruction results are supported by modern observations, TraCE21 simulations, and other studies. This study is significant for extending the application of the δ13Corg indicator for quantitative paleoclimate reconstructions. It verifies its effectiveness in quantifying Holocene temperatures in the marginal zone of the East Asian summer monsoon.

Magnetoclimatological Record of Late Pleistocene Loess in the Southern Hunshandake Sandy Land, Inner Mongolia: A Threshold Response to the East Asian Summer Monsoon Variations

AbstractWe report the first complete loess–paleosol record spanning the last 130 kyr from the southern extremity of the Hunshandake Sandy Land (HSL) in central‐eastern Mongolia. Our combined mineral magnetic and geochemical results demonstrate that during the last interglacial, the front of the East Asian summer monsoon (EASM) extended to central‐eastern Inner Mongolia, consistent with modern observations of climate change. However, during the last glacial, typical magnetic parameters (e.g., magnetic susceptibility and anhysteretic remanent magnetization and their ratios), which have been successfully adopted to denote the EASM variations on the Chinese Loess Plateau (CLP), show only muted temporal variations and cannot be readily correlated with equivalent records from the main body of the CLP. Remarkably, the Zr/Rb ratio, a robust geochemical indictor of the winter monsoon, is positively correlated with saturation isothermal remanent magnetization and saturation magnetization during the last glacial, demonstrating the strong control of wind vigor on high‐field magnetization signals dominated by lithogenic ferrimagnetic minerals. In contrast to the variable response of magnetic parameters to regional paleoclimatic fluctuations, the Rb/Sr and Ba/Sr ratios (two summer monsoon indicators) faithfully track weak chemical weathering processes and fine‐scale monsoon oscillations, especially during the last glacial. Additionally, we found that higher proportions of pedogenic high‐coercivity magnetic minerals were formed during the last interglacial, which may reflect relatively low rainfall but higher evapotranspiration in the southern extremity of the HSL compared with the CLP. We therefore attribute this complex magnetic record to a threshold response to the EASM variations in eastern Inner Mongolia.

An Improved YOLO Model for UAV Fuzzy Small Target Image Detection

High-altitude UAV photography presents several challenges, including blurry images, low image resolution, and small targets, which can cause low detection performance of existing object detection algorithms. Therefore, this study proposes an improved small-object detection algorithm based on the YOLOv5s computer vision model. First, the original convolution in the network framework was replaced with the SPD-Convolution module to eliminate the impact of pooling operations on feature information and to enhance the model’s capability to extract features from low-resolution and small targets. Second, a coordinate attention mechanism was added after the convolution operation to improve model detection accuracy with small targets under image blurring. Third, the nearest-neighbor interpolation in the original network upsampling was replaced with transposed convolution to increase the receptive field range of the neck and reduce detail loss. Finally, the CIoU loss function was replaced with the Alpha-IoU loss function to solve the problem of the slow convergence of gradients during training on small target images. Using the images of Artemisia salina, taken in Hunshandake sandy land in China, as a dataset, the experimental results demonstrated that the proposed algorithm provides significantly improved results (average precision = 80.17%, accuracy = 73.45% and recall rate = 76.97%, i.e., improvements by 14.96%, 6.24%, and 7.21%, respectively, compared with the original model) and also outperforms other detection algorithms. The detection of small objects and blurry images has been significantly improved.

Optically stimulated luminescence dating and paleoclimatic implications of the Holocene dune sands in the Hunshandake Sandy Land, Northeast China

Aeolian sediments are important geological archives of paleoclimate changes. Due to the fragile ecosystem of desert, sand dune mobility is particularly sensitive to climate change, and is thus important for revealing the stabilization and mobilization processes of dunes during the geological past. In northeastern China, several sandy lands are located in the East Asian monsoonal region, and desert evolution has been used to infer the waxing and waning of monsoonal climate. However, the relationship between dynamic aeolian landscapes and forcing mechanisms is still under debate due to the complex nature of the aeolian dune systems. In this study, we analyse two aeolian sand dune sections in the Hunshandake Sandy Land, northeast China, located at the northern edge of the East Asian summer monsoon, explore regional paleoclimatic changes during the Holocene. We carried out high-resolution optically stimulated luminescence (OSL) dating to develop a well-constrained chronology for the dune sands, as well as analyses of multiple climatic proxies including magnetic susceptibility, particle size, and color parameters, to obtain knowledge about dune mobility and climatic changes. Our results indicate that the early Holocene was characterized by the accumulation of aeolian dune sands, implying an arid climate, driven by an enhanced East Asian winter monsoon. Paleosols were generally developed in the mid-Holocene (∼8 and 4 ka) when the sand dunes were stabilized by vegetation under a relatively warm and humid climate driven by an enhanced East Asian summer monsoon. In the late Holocene, from ∼4 ka to the present, climate returned to an arid and semi-arid phase, marked by aeolian dune sands with some weakly-developed paleosols. Through comparison of the aeolian record with the other East Asian monsoonal records and the sea-surface temperature of the North Pacific, we suggest that the evolution of the East Asian monsoon, which was paced by both the melting and expansion from the Northern Hemisphere ice sheet as well as the changes of solar radiation, played an important role in driving climate change in the Hunshandake Sandy Land during the Holocene.

Responses of NDVI evolution to climate change and human activities in the Hunshandake Sandy Land and its ecotones

Responses of NDVI evolution to climate change and human activities in the Hunshandake Sandy Land and its ecotones

Southward migration of the monsoonal rainbelt hinders paleosol development and preservation in north-central China dunefield after the Middle-Late Holocene Transition

The Asian summer monsoon (ASM), including the intensity and range limits of it's associated rainfall belt, is relevant to ecosystems, agriculture, natural hazards and water availability for millions of people in this region. However, understanding of the pattern of dunefield changes near the northern limit of the East Asian summer monsoon (EASM) since Middle to Late Holocene Transition (MLHT, ∼6 to 4 ka) is still lacking. Here, we compile and analyze the sedimentology and chronology of regional dune and lake records in the Hunshandake Sandy Land (HSL). Based on prior work and confirmed by additional OSL and 14C ages, paleosol development intercalated with dune sand is found southeastern and central parts of the HSL after 4 ka. However, based on new chronological data, a paleosol complex is generally absent in the northwestern HSL after 4 ka. Together with independent high-resolution transient model simulations of summer rainfall change, we interpret a shift of the far northwestern HSL dunefield system approximately coincided with the mid-summer limit of the EASM rainbelt that retreated southward after 4 ka. Thus, we hypothesize that the southward migration of the northernmost monsoonal rainbelt after the MLHT was a first-order control on dunefields change over the far northwestern HSL. Coupled with a southward migrating rainbelt, we interpret a decrease in external sand supply (due to covering by clay) and an increase in contemporaneous seasonal eolian deflation caused by the drier hydroclimatic conditions. This climatic-driven dune system shift in the far northwestern HSL is shortly after the more globally recognized 4.2 ka event, which marks the boundary between the Middle Holocene and Late Holocene.

Salix gordejevii females exhibit more resistance against wind erosion than males under aeolian environment.

Effects of wind erosion on growth and adaptability have been widely reported in many plants, but little attention has been paid to dioecious plants. Recent studies have shown that sex-specific responses to environmental changes in many plants exist. To explore sexual differences in response to wind erosion, female and male Salix gordejevii saplings growing on inter-dune land (no erosion) and on the windward slope of the dune (20cm wind erosion) in Hunshandake Sandy Land were chosen and their morphology, biomass and physiological traits were investigated, respectively. Wind erosion significantly reduced plant growth, biomass accumulation, gas exchange and chlorophyll fluorescence, and obviously disrupted osmotic regulation function and antioxidant enzyme system in both sexes, especially in males. Under wind erosion condition, females exhibited higher sapling height (SH), basal diameter (BD), leaf dry mass (LDM), root dry mass (RDM), total dry mass (TDM), root percentage in total dry mass, net photosynthesis rate (P n), maximum efficiency of photosystem II (F v/F m), effective quantum yield of PSII (Φ PSII), relative water content (RWC) of leaves, superoxide dismutase (SOD) and peroxidase (POD) activities, but lower malondialdehyde (MDA), proline as well as soluble sugar content than did males. However, no significant sexual differences in most of these traits were observed under no erosion condition. Our results demonstrated that females possess a greater resistance to wind erosion than do males, with females having a better photosynthetic capacity, stronger water retention capacity and more efficient antioxidant system to alleviate negative effects caused by aeolian environment.

Dust amount reaching typical cities from dust emissions due to soil wind erosion in Beijing-Tianjin sandstorm source regions and its source analysis

<p indent="0mm">Dust emissions caused by soil wind erosion are a significant and concerning source of respirable particles in the atmospheric environment. Accurately estimating the contribution of dust emissions resulting from soil wind erosion to inhalable particulate matter in the urban atmospheric environment is required for the central government to formulate atmospheric environmental governance plans and decisions. By combining ground investigation, field observation, remote sensing image interpretation and other strategies, this paper first estimated the dust amount of four different particle sizes of 0–2.5, 2.5–5, 5–10, and <sc>10–20 μm</sc> arriving in Beijing, Zhangjiakou, Chifeng, Datong, Huhehaote, Xilinhaote, Baotou and Yulin, which derived from dust emissions caused by soil wind erosion due to wind force in Beijing-Tianjin sandstorm source regions. The total dust amounts reaching above cities were 274.49×10⁴, 146.96×10⁴, 151.83×10⁴, 91.03×10⁴, 68.61×10⁴, 65.42×10⁴, 41.46×10⁴, and <sc>26.21×10⁴ t,</sc> respectively. Among these dust amounts, PM_2.5 and PM₁₀ accounted for 35.40% and 84.16%, respectively. To improve the living environment, the Beijing-Tianjin sandstorm source control project targets both PM₁₀ and PM_2.5, with an emphasis on PM_2.5. Second, the contributions of subregions in the Beijing-Tianjin sandstorm source to dust amounts of different particle sizes for each city were distinctly different. For the contributions of each subregion to the total dust amount for above eight cities, the maximum came from the subregion of interlaced belt of agriculture and animal husbandry, followed by the subregions of desert steppe, the Yanshan Hills water source reserve, the mountainous and hilly areas in northern Shanxi, Hunshandake sandy land, the Greater Khingan Mountains, Kubuqi desert, Horqin sandy land, the typical steppe and Mu Us Sandy Land. The cumulative contributions for the first three subregions and four deserts (of sandy land) were 80.52% and 9.84%, respectively. The former’s cumulative contributions to the dust amounts of four particle sizes ranged from 73.06% to 83.40%, respectively, while the latter’s cumulative contributions were only between 5.56% and 12.42%. These indicated that the management of the Beijing-Tianjin sandstorm sources should focus on the subregions of the interlaced belt agriculture and animal husbandry, desert steppe and the Yanshan Hills water source reserve rather than desert (of sandy land) subregions. Third, the contributions of the cultivated land, desert (or sandy land) and grass and shrub land to the total dust amounts for above eight cities were 576.27×10⁴, 186.30×10⁴, and <sc>103.44×10⁴ t,</sc> respectively. At the same time, their contributions to the dust amounts of 0–2.5, 2.5–5, 5–10, and <sc>10–20 μm</sc> were 138.18×10⁴, 94.42×10⁴, 182.54×10⁴ and <sc>161.14×10⁴ t;</sc> 23.16×10⁴, 12.44×10⁴, 41.89×10⁴ and <sc>8.81×10⁴ t;</sc> and 28.94×10⁴, 20.79×10⁴, 42.65×10⁴, <sc>11.06×10⁴ t,</sc> respectively. Hence, the management of the Beijing-Tianjin sandstorm sources should focus on the management of cultivated land, followed by desert (or sandy land) and finally grass and shrub land. In addition, the dust amounts reaching above eight cities mainly derived from the westward wind direction, such as SW, WSW, W, WNW, NW, and NNW, although a few came from N and NNE directions. 85.15%–93.28% of dust in Baotou, Beijing, Datong, Huhehaote and Zhangjiakou originated from W, WNW, and NW; 96.16% of dust in Chifeng originated from W, WNW, and WSW; 93.68% of dust in Xilinhaote originated from WSW, W, SW, and WNW; and 81.16% of dust in Chifeng originated from NW, NNW, and NNE. There were obvious differences in the contribution of wind direction to the dust amount in different particle size groups in each city. These results provide a basis for the optimization and adjustment of the Beijing-Tianjin sandstorm source control project.

Using 137Cs and 210Pbex to Investigate the Soil Erosion Moduli of the Sandy Area of Typical Grasslands in Northern China

Soil erosion results in land degradation and desertification in northern China. The Xilingol League of Inner Mongolia is an important part of the “Two Barriers and Three Belts”, and has been given the main function of “a windbreak and sand-fixing belt of northern China”. Accurate measuring of soil erosion moduli, analyzing the differences in soil erosion moduli across different periods and regions, are the basis for carrying out soil conservation and evaluating the effectiveness of ecological governance. Some radioisotopes are good environmental tracers because they are closely combined with the fine particles of the surface soil and are only affected by the mechanical movement of soil particles. In this paper, Taipusi Banner and Zhengxiangbai Banner, which are in the farming–pastoral ecotone in northern China, were selected as the study area. A regional reference inventory, that is, the activity of 137Cs and 210Pbex in the sample without any soil erosion, accumulation/deposition, or any kind of manual disturbances, as well as the soil erosion moduli, were determined by 137Cs and 210Pbex composite tracing technology and multiple lines of evidence. The results are as follows: (1) The regional 137Cs reference inventory was 1928 Bq∙m−2, and the regional 210Pbex reference inventory was 10,041 Bq∙m−2. (2) On a 50-year time scale, the soil erosion moduli in the study area ranged from 140 t∙km−2∙a−1 to 1030 t∙km−2∙a−1; on a 100-year scale, the soil erosion moduli in the study area ranged from 35 t∙km−2∙a−1 to 2637 t∙km−2∙a−1; the entire study area was in a lightly eroded state. (3) Compared with two periods before and after the 1970s, the southern parts (cultivated land and grassland) experienced an increasing trend in soil erosion moduli due to land reclamation, grassland grazing, and other activities. Due to weakening wind and increasing precipitation, soil erosion moduli in the northern parts (southern margin of the Hunshandake Sandy Land) slowed down. The study also discussed the uncertainty and application potential of isotope-tracing technology in sandy land of typical grasslands in northern China.

Dust emissions in the Beijing-Tianjin sandstorm source and their regional differentiation

<p indent="0mm">Dust emissions caused by soil wind erosion are the primary natural source of inhalable particulate matter in dust source areas and downwind atmospheric environments. Accurate estimations of dust emissions are foundational for understanding the mechanism of sandstorm occurrences and their transport processes. They are also the basis on which planning and decision-making for sand control and atmospheric environment governance are made. Based on field surveys, surface soil collections, laboratory experiments, remote sensing images, meteorological data, and model simulation, this paper estimated the amount of dust emissions for four different particle size groups (0–2.5, 2.5–5, 5–10, <sc>10–20 μm)</sc> in four different periods (2000, 2005, 2010, 2015), revealed the temporal and spatial distributions of dust emissions from Beijing-Tianjin sandstorm sources and their responses to particle size changes, and clarified the contributions to dust emissions by different land uses. The main conclusions are as follows: (1) Due to climate change, the amount of dust emissions in the Beijing-Tianjin sandstorm source has fluctuated since the implementation of the Beijing-Tianjin sandstorm source control project. In 2000, 2005, 2010 and 2015, dust emissions were 3.24 × 10⁷, 2.76 × 10⁷, 3.44 × 10⁷, and 3.26 × <sc>10⁷ t,</sc> respectively. These emissions demonstrated a clear pattern throughout the year. From January to April, they increased monthly, peaked in April, decreased throughout May, maintained the lowest yearly value from June to September, and increased again in November. These results indicate that dust emissions in Beijing-Tianjin sandstorm sources have obvious seasonal characteristics. The emission amounts descended in the following order: spring, winter, autumn and summer. Their average proportions were 45.45%, 28.14%, 15.99% and 10.42%, respectively. (2) The three subareas, such as the agricultural and animal husbandry interlaced belt subarea, the desert steppe, and the northern Shanxi mountain hills subarea, were the main source of dust emission in Beijing-Tianjin sandstorm sources, accounting for 55.29% of the total amount. The total amount of dust emissions for the above three subareas was 2.64 times those of the four deserts or sandy land in Beijing-Tianjin sandstorm sources, which included the Kubuqi Desert, the Mu Us Sandy Land, the Hunshandake Sandy Land and the Horqin Sandy Land. (3) Although the proportion of cultivated land in Beijing-Tianjin sandstorm sources was only between 13.89% and 14.81%, dust emissions from cultivated land accounted for 71.56% of the total emissions in Beijing-Tianjin sandstorm sources. The corresponding proportions for deserts (or sandy land) and other vegetation surface covers (such as grassland, shrubland, etc.) were 19.78% and 8.66%, respectively. (4) In order to control both dust emissions in Beijing-Tianjin sandstorm sources and their impacts on atmospheric inhalable particulate matter, especially in the Beijing-Tianjin area, this paper showed that the key areas are the agriculture and animal husbandry interlaced belt subarea, the Yanshan Hills Water Source Reserve subarea, the desert steppe, and the northern Shanxi mountain hills subarea, and the core of land use in governance is cultivated land, not sandy land. The results in this paper would provide basic data for accurately assessing the benefits of the Beijing-Tianjin sandstorm source control project and also present a scientific basis for its optimal layout.

Spatial distributions of salt-based ions, a case study from the Hunshandake Sandy Land, China.

Soil water soluble base ion salt-based ion concentrations are critical parameters for estimating soil buffer capacity and vegetation productivity. Ionic content clearly covaries with the distribution of plant communities. Previous studies on salt-based ions in soils focused primarily on ion migration and its relationships with vegetation growth. Few studies have sought to characterize larger scale spatial distribution of salt-based ions or correlation with climatic and plant community characteristics. This study used ion chromatography to analyze the salt-based ion content (Ca2+, Mg2+, Na+ and K+) of surface soils from the Hunshandake sandy lands. Statistical methods were used interpret spatial variation. Results showed that the average content of salt-based ions in Hunshandake sandy land was 86.57 mg/kg. Average values ranked as Ca2+ > Na+ > K+ > Mg2+ but concentrations also exhibited uneven spatial distributions. Horizontal spatial variation in Ca2+, Mg2+ and Na+ ions showed these ions gradually decrease from northwest to southeast. Potassium ions (K+) showed no obvious spatial variation trends. Ions varied significantly across different soil layers but their average concentrations ranked as K+>Na+>Ca2+>Mg2+ (from shallow to deep). The 20–30 cm soil layer contained the highest salt ion concentrations. Of the four base ions, only K+ ions appeared in surface samples. In terms of water soluble base ion available salt-based ions, Ca2+ occurred in the highest concentrations along the north and west side of the study area. K+ ions occurred in the highest concentrations along the south and east sides of the study area. Na+ concentrations did not show a consistent spatial pattern. Statistical analysis detected significant correlations of normalized ion concentration parameters (Ca2+/CECT, K+/CEC, effective water soluble base ion salt-based ions) and the total species number, average species number and total biomass of the plant communities (P <0.05). This study can help inform understanding of soil water transport in sandy areas and provide a reference for interpreting ecosystems in arid regions.

Spatial and temporal evolution of soil wind erosion in the Beijing-Tianjin sandstorm sources

<p indent="0mm">Dust emissions due to soil wind erosion and its transport are the most important natural sources of inhalable particulate matter in the atmospheric environment of sandstorm sources and the regions where sandstorms occur. To control the impact of dust emissions caused by soil wind erosion on the atmospheric environment in the Beijing-Tianjin resources, the Chinese government implemented a strategic significance ecological governance project in the Beijing-Tianjin sandstorm sources at the beginning of this century. However, there is still much controversy about soil wind erosion in the Beijing-Tianjin sandstorm sources and the resulting dust emissions. Based on field surveys, laboratory tests, remote sensing images and meteorological data, this paper calculated soil wind erosion in the Beijing-Tianjin sandstorm sources under three conditions, including the typical years of 2000, 2005, 2010, and 2015, land-use change conditions (land use in 2000, 2005, 2010, and 2015 but other factors with 2015), and climate change conditions (land use in 2015 but other factors with 2000, 2005, 2010, and 2015), by using the specified soil wind erosion model in the National Plan for Dynamic Monitoring of Soil and Water Loss from 2018 to 2022 and the Technical Regulations for Dynamic Monitoring of Regional Soil and Water Loss (Trial Version). In 2000, 2005, 2010, and 2015, the fluctuation in wind erosion modulus in the Beijing-Tianjin sandstorm sources decreased. Wind erosion modulus gradually decreased from northwest to southeast, and the value in desert or sandy land was higher than that in the surrounding areas. With the advancement of governance projects in the Beijing-Tianjin sandstorm sources, the distribution of wind erosion modulus changed significantly. Wind erosion modulus in the desert steppe was the largest and was approximately 2.67–2.98 times that of the Beijing-Tianjin sandstorm sources. Wind erosion modulus in the Hetao Plain and Hunshandake Sandy Land, were roughly the same as that in the Beijing-Tianjin sandstorm sources. Wind erosion modulus in other subregions was 42.69% of that in the Beijing-Tianjin sandstorm sources. Wind erosion area and variability in the above years in the Beijing-Tianjin sandstorm sources were <sc>385800–464500 km²</sc> and −9.35%–9.14%, respectively. The area of ​​mild and moderate wind erosion accounted for 91.56%. Overall, wind erosion area in the northwestern Beijing-Tianjin sandstorm sources was large, and its area proportion was high, followed by that in the middle area, and the southeast area had the smallest area. The wind erosion area in ​​desert steppe accounted for the largest proportion, with a value of 25.88%, and that in the southern part of the Greater Khingan Mountains was only 3.18%. Intense and extremely intense soil wind erosion was concentrated in the desert steppe and the western part of the Hetao Plain. Intense soil wind erosion was mainly distributed in the Kubuqi Desert and Hunshandake Sandy Land. Moderate and mild erosion involved each subregion in the Beijing-Tianjin sandstorm sources. There were obvious differences in the changes in the wind erosion area and intensity in each subregion during 2000–2005, 2005–2010, and 2010–2015. Climate change and land-use change had important impacts on soil wind erosion in the Beijing-Tianjin sandstorm sources. The variability of the wind erosion modulus and the area affected by climate change was equivalent to the corresponding variability of the year but greater than the influence of land-use change. In addition, the area of wind erosion under land-use change generally decreased, especially from 2010 to 2015, which had a decrease of 4.10%, indicating that the Beijing-Tianjin sandstorm source control project played an important role. These results provide a scientific basis for the evaluation of the benefits of the Beijing-Tianjin sandstorm source control project and the optimization of its layout.

Analyses of the Dust Storm Sources, Affected Areas, and Moving Paths in Mongolia and China in Early Spring

Dust storms are common in Mongolia and northern China, this is a serious threat to the ecological security and socioeconomic development of both countries and the surrounding areas. However, a complete quantitative study of the source area, affected area, and moving path of dust storm events (DSEs) in Mongolia and China is still lacking. In this study, we monitored and analyzed the spatiotemporal characteristics of the source area and affected areas of DSEs in Mongolia and China using the high-spatiotemporal-resolution images taken by the Himawari-8 satellite from March to June 2016–2020. In addition, we calculated the moving path of dusty weather using the HYSPLIT model. The results show that (1) temporality, a total of 605 DSEs occurred in the study area, with most of them occurring in April (232 DSEs), followed by May (173 DSEs). Spatially, the dust storm sources were concentrated in the arid inland areas such as the Taklimakan Desert (TK, 138 DSEs) and Badain Jaran Desert (BJ, 87 DSEs) in the western, and the Mongolian Gobi Desert (GD, 69 DSEs) in the central parts of the study area. (2) From the affected areas of the DSEs, about 60% of the DSEs in Mongolia started locally and then affected downwind China, as approximately 55% of the DSEs in the Inner Mongolia Desert Steppe and Hunshandake Sandy Land came from Mongolia. However, the DSEs in the TK located in the Tarim Basin of northwest China affected the entire study area, with only 31.3% belonging to the local dust. (3) From the moving path of the dusty weather, the dusty weather at the three meteorological stations (Dalanzadgad, Erlian, and Beijing), all located on the main transmission path of DSEs, was mainly transported from the windward area in the northwest, accounting for about 65.5% of the total path. This study provides a reliable scientific basis for disaster prevention and control, and has practical significance for protecting and improving human settlements.

Optically Stimulated Luminescence Dating and Paleoclimatic Implications of the Holocene Dune Sands in the Hunshandake Sandy Land, Ne China

Optically Stimulated Luminescence Dating and Paleoclimatic Implications of the Holocene Dune Sands in the Hunshandake Sandy Land, Ne China

Water use characteristics of artificial sand-fixing vegetation on the southern edge of Hunshandake Sandy Land, Inner Mongolia, China

We examined the characteristics of water use in typical tree species of arbor and shrub in Hunshandake Sandy Land, Populus cathayana and Salix gordejevii, in the different seasons, with the aim to provide theoretical basis for the structural optimization of the artificial shelterbelt. Samples of precipitation, soil water, groundwater and stem water of the two vegetation were collected, and their distribution characteristics of δD-δ18O were analyzed by hydrogen and oxygen stable isotope technology. The contribution rate of these potential water source to the arbor and shrub species were calculated using multi-source linear mixing model. The precipitation equation line in the study area was δD=7.84δ18O+9.12, while soil moisture lines in the dry and wet season were δD=3.56δ18O-41.28 and δD=4.30δ18O-42.02, respectively. The δD-δ18O of soil water and stem water in the two seasons were lower than the precipitation δD-δ18O, indicating that both of them were strongly affected by the evaporation. Soil water contents in the shallow layer were strongly affected by rainfall and evaporation, with substantial fluctuation. With the increases of soil depth, soil water content tended to be stable, and the hydrogen and oxygen isotope in each soil layer showed significant differences. In the dry season, P. cathayana mainly utilized soil water in 0-40 cm and 120-200 cm layers, with contribution rates of 50.2% and 31.5%, respectively. S. gordejevii mainly absorbed soil water in 20-40 cm and 60-100 cm layers, and the contribution rates were 53.2% and 22.9%, respectively. In the wet season, the greatest contribution of soil water to P. cathayana was mainly in the 0-40 cm soil layer, accounting for 72.8%. S. gordejevii was mainly in the 0-20 cm soil water, evenly utilized the deeper soil water and groundwater. Due to the differences in root depth and distribution of the arbor and shrub, their water use strategies differed in different seasons, which was conducive to the stability of the shelterbelt community and tree species coexistence in Hunshandake Sandy Land. We proposed that the mixed planting species with different root depth should be considered in the future planting of artificial shelterbelt, which would help rationally utilize water resources and maintain the stability of sandy land ecosystem.