Semiarid Region Of Northwest China Research Articles

Effects of Film Mulching on Soil Microbial Diversity and Community Structure in the Maize Root Zone under Drip Irrigation in Northwest China

Mulching is a widely used agricultural water conservation measure in the semiarid regions of Northwest China. In order to explore the response process of different film mulching methods to soil microorganisms, we characterized the effect of different film mulching methods on soil microbial diversity and community structure characteristics in the root zone of drip-irrigated maize during the heading and maturity stages using high-throughput sequencing of 16SrDNA and ITS amplicons combined with bioinformatics analysis. Full mulching (FM) was contrasted to controls of no mulching (NM) and half-mulching (HM), yielding an order of microbial diversity, abundance, and evenness scores of HM > FM > NM. The HM and FM treatments reduced the relative abundance of Proteobacteria and Actinobacteria (the most abundant bacteria) in the bacterial community structure but increased that of Acidobacteria and Chloroflexi. In the fungal community structure, HM decreased the abundance of Sordariomycetes but increased that of Eurotiomycetes (the most abundant fungi). The abundance and community structure of bacteria were significantly correlated with soil temperature and those of fungi with pH. HM improved network complexity and competitive relationships among bacteria, while FM increased the relationship between fungal groups and the symbiosis of fungal communities. HM significantly increased maize yield (20.37% and 6.01% above NM and FM, respectively). In summary, full mulching was more favorable than no mulching for soil microbial diversity and community structure composition, but soil microbial diversity and yield responded better to half-mulching. These results provide a background for improving the yield of drip-irrigated maize and protecting the microbial ecosystems of farmland soils.

Mapping quantitative trait loci associated with self-(in)compatibility in goji berries (Lycium barbarum)

BackgroundGoji (Lycium barbarum L.) is a perennial deciduous shrub widely distributed in arid and semiarid regions of Northwest China. It is highly valued for its medicinal and functional properties. Most goji varieties are naturally self-incompatible, posing challenges in breeding and cultivation. Self-incompatibility is a complex genetic trait, with ongoing debates regarding the number of self-incompatible loci. To date, no genetic mappings has been conducted for S loci or other loci related to self-incompatibility in goji.ResultsWe used genome resequencing to create a high-resolution map for detecting de novo single-nucleotide polymorphisms (SNP) in goji. We focused on 229 F1 individuals from self-compatible ‘13–19’ and self-incompatible ‘new 9’ varieties. Subsequently, we conducted a quantitative trait locus (QTL) analysis on traits associated with self-compatibility in goji berries. The genetic map consisted of 249,327 SNPs distributed across 12 linkage groups (LGs), spanning a total distance of 1243.74 cM, with an average interval of 0.002 cM. Phenotypic data related to self-incompatibility, such as average fruit weight, fruit rate, compatibility index, and comparable compatibility index after self-pollination and geitonogamy, were collected for the years 2021–2022, as well as for an extra year representing the mean data from 2021 to 2022 (2021/22). A total of 43 significant QTL, corresponding to multiple traits were identified, accounting for more than 11% of the observed phenotypic variation. Notably, a specific QTL on chromosome 2 consistently appeared across different years, irrespective of the relationship between self-pollination and geitonogamy. Within the localization interval, 1180 genes were annotated, including Lba02g01102 (annotated as an S-RNase gene), which showed pistil-specific expression. Cloning of S-RNase genes revealed that the parents had two different S-RNase alleles, namely S1S11 and S2S8. S-genotype identification of the F1 population indicated segregation of the four S-alleles from the parents in the offspring, with the type of S-RNase gene significantly associated with self-compatibility.ConclusionsIn summary, our study provides valuable insights into the genetic mechanism underlying self-compatibility in goji berries. This highlights the importance of further positional cloning investigations and emphasizes the importance of integration of marker-assisted selection in goji breeding programs.

Impacts of Climate Change on the Habitat Suitability and Natural Product Accumulation of the Medicinal Plant Sophora alopecuroides L. Based on the MaxEnt Model.

Sophora alopecuroides L., a perennial herb in the arid and semi-arid regions of northwest China, has the ecological functions of windbreaking and sand fixation and high medicinal value. In recent years, global warming and human activities have led to changes in suitable habitats for S. alopecuroides, which may affect the accumulation of natural products. In this study, MaxEnt 3.4 and ArcGIS 10.4 software were used to predict the distribution of potentially suitable habitats for S. alopecuroides in China under climate change. Furthermore, the geographical distribution of S. alopecuroides as affected by human activities, the differences in the content of natural products of S. alopecuroides between different suitable habitats, and the correlation between natural products and environmental factors were analyzed. The results showed that suitable habitats for S. alopecuroides were projected to expand in the future, and the major environmental factors were temperature (Bio1), rainfall (Bio18), and soil pH (pH). When Bio1, Bio18, and pH were 8.4283 °C, 7.1968 mm, and 9.9331, respectively, the distribution probability (P) of S. alopecuroides was the highest. After adding a human activity factor, the accuracy of the model prediction results was improved, and the area of suitable habitats was greatly reduced, showing a fragmented pattern. Meanwhile, habitat suitability had a specific effect on the content of natural products in S. alopecuroides. Specifically, the content of natural products in S. alopecuroides in wild habitats was higher than that in artificial cultivation, and highly suitable habitats showed higher contents than those in non-highly suitable habitats. The contents of total alkaloids and total flavonoids were positively correlated with human activities and negatively correlated with land use types. Among them, total alkaloids were negatively correlated with aspect, and total flavonoids were positively correlated with aspect. In addition, it is suggested that Xinjiang should be the priority planting area for S. alopecuroides in China, and priority should be given to protection measures in the Alashan area. Overall, this study provides an important foundation for the determination of priority planting areas and resource protection for S. alopecuroides.

Minor straw return enhances net income in a maize-wheat rotation system

Straw returning to the field is a common agricultural practice in China. Nevertheless, in the maize-wheat rotation system of the semi-arid region in Northwest China, it is essential to investigate the optimal approach for coupling straw return and fertilization in order to enhance soil quality and crop yield. A field trial conducted in the semi-arid region of northwest China from 2019 to 2021 examined eight different combinations of straw return and fertilization rates. The results indicated that while straw return had minimal impact on soil total nitrogen in the 0–60 cm layer, it did increase soil available phosphorus and potassium in the 0–40 cm layer. Additionally, all straw return treatments notably improved soil organic matter and humus content compared to the untreated control (CK). Specifically, applying N and P fertilizers in combination with returning 1/3 of the straw (NP+1/3S) produced in that season significantly boosted soil organic matter and humus content compared to the CK. Moreover, the NP+1/3S treatment led to a substantial enhancement in the grain yield of wheat and maize, as well as their yield components, including an increase in the number of ears/spikes per square meter, the number of grains per ear/spike, and the 100 or 1000-grain weight. The results may be attributed to a combination of factors, including improved nutrient availability, enhanced soil structure, and increased microbial activity due to the incorporation of straw. Economic analysis showed that NP+1/3S had the highest production to investment ratio (ROI), indicating its potential suitability for the region. This study highlights the significance of carefully selecting combinations of straw return and fertilization to maximize soil fertility, crop yield, and economic benefits in agricultural systems.

Why does a decrease in cloud amount increase terrestrial evapotranspiration in a monsoon transition zone?

Terrestrial evapotranspiration plays a critical role in drought monitoring and water resource management. Changes in evapotranspiration are significantly influenced by cloud-related precipitation and radiation effects. However, the impact of cloud amount (CA) on evapotranspiration through its influence on precipitation remains uncertain, especially in the transition zone affected by the East Asian summer monsoon (EASM), which limits the understanding of the water cycle. Therefore, this study deeply explores the impact of CA on evapotranspiration and its potential physical mechanisms in Northwest China. The results show that the correlation between 31-year average evapotranspiration and CA is negative only in the semi-arid region and is positive in other climatic regions of Northwest China. This unique negative correlation is related to the change of precipitation pattern in the semi-arid region caused by the weak EASM. Smaller CA in weak monsoons results in more short-wave radiation reaching the surface, larger sensible heat, and weaker convective inhibition. Consequently, the proportion of convective clouds (CCs) increases and precipitation from these CCs enhances evapotranspiration. Less CA increases evapotranspiration and potentially exacerbates aridity in the semi-arid region of Northwest China. These results emphasize the role of cloud type in evapotranspiration. It is well known that global warming can change cloud type with more CCs. Therefore, this study sheds new light on evapotranspiration change under global warming.

Comparison of the Differences in Tolerance to Drought Stress across Five Clematis Species Based on Seed Germination and Seedling Growth

Plants of the Clematis genus are attractive ornamental plants due to their various flower colors and patterns, and they play an important role as ground cover plants in landscaping. However, the application of Clematis plants in landscaping in arid and semi-arid areas is limited. This study used five common wild Clematis species in Gansu Province as experimental materials, including Clematistangutica, Clematis glauca, Clematis intricata, Clematis nannophylla, and Clematis fruticosa. By simulating different intensities of drought stress with polyethylene glycol (PEG), the germination behavior of seeds and the physiological and biochemical responses of seedlings of these five species to drought stress were observed. The results showed that 15% PEG stress significantly inhibited the seed germination of the five species, which was also the drought threshold for seed germination of C. fruticosa. C. tangutica exhibited the strongest tolerance to drought stress in seed germination. Seedlings of the five Clematis plants showed different levels of tolerance to drought stress, mainly demonstrating higher tolerance to 10% and 20% concentrations of PEG stress, while a 30% concentration of PEG stress caused varying degrees of damage to the seedlings of the five Clematis species. PCA analysis indicated that seedlings of C. intricata and C. glauca had higher scores under drought stress. These findings can provide a theoretical basis for the selection of urban landscaping plant species in arid and semi-arid regions of northwest China.

Migration patterns of heavy metals from solid waste stockpile soils by native plants for ecological restoration in arid and semi-arid regions of Northwest China

Ecological remediation with native plants is the main measure to control the pollution of solid waste in Northwest China. However, the heavy metal transport characteristics of these native plants are still unidentified. This study analyzed the distribution of 16 heavy metals in native plants in the desulfurization gypsum yard (DGY), the gangue yard (GY) and the fly ash yard (FAY). The results showed that the soil contained many heavy metals in high concentrations. For instance, As concentrations were comparable to the global soil background values, whereas Cr and Mn concentrations in the area were 2–3 times greater than the global soil background values. The content of heavy metals in the plant root system increased first, then decreased as the distance from the yard increased. Ni, Pb, and Cd migrated well in Artemisia frigida Willd and Artemisia sieversiana Ehrhart ex Willd, with A. sieversiana showing a particularly strong migration in GY. A. sieversiana, on the other hand, was more successful at migrating Cd at DGY and had a similar capability for Mg migration in all three locations. Festuca rubra L was potentially suitable for planting in GY for Ni removal. In conclusion, the migration patterns of different heavy metals were not alike for plants in the three landfills. The results provided a basis for plant selection for ecological restoration in arid and semi-arid regions.

Identification and characterization of a novel Cytorhabdovirus associated with goji berry (Lycium barbarum L.) crinkle disease.

Goji berry (Lycium barbarum L.) is a traditional Chinese herbal medicinal plant that is extensively cultivated in the arid and semiarid regions of northwest China. In this study, a novel cytorhabdovirus, tentatively named "goji cytorhabdovirus A (GCVA)," was identified from the goji berry plant exhibiting leaf crinkle symptoms through high-throughput sequencing (HTS). GCVA contains a linear, negative sense single-stranded RNA genome of 14,812 nucleotides and encodes six open reading frames in the order of 3' leader-N-P-P4-M-G-L-5' trailer. The genome of GCVA shares the highest nucleotide (nt) identity of 65.80% (16% query coverage) with yerba mate virus A (YmVA) (NC_076472). The N and L proteins also share low amino acid (aa) identities (<35.42 and < 41.23%, respectively) with known cytorhabdoviruses. Typical features of the viruses in the genus Cytorhabdovirus include a highly conserved consensus sequence in the intergenic regions and extensive complementation of the 5' non-coding trailer and the 3' leader. These features were also found in GCVA. These data in combination with a phylogenetic analysis that was based on the aa sequences of the N and L proteins support the proposal that GCVA is a new species in the genus Cytorhabdovirus.

Impacts of re-vegetation on soil water dynamics in a semiarid region of Northwest China

Understanding how vegetation (shrub) cover in drylands affects local-to-regional soil water dynamics and associated water balances is of immense importance because of the abundance of afforestation projects worldwide. Vegetation's role in the control of soil water presents a particular challenge to soil water storage (SWS) management in the drylands of China. To address this knowledge gap, we conducted a two-year study in the Mu Us Desert of northwest China. The study involved the acquisition of in-situ soil water measurements within the first 180 cm of soil at three sand dune sites characterized by their differences in % shrub cover. The sand dunes varied from a vegetation-free, bare-ground sand dune site (BF) and two partly vegetated sites, one with medium-level (40 %) and another with high shrub cover (80 %; MF and HF, respectively). Results revealed that the site with the high shrub cover (HF) suffered a net reduction in soil water content (SWC) by up to 32.7 and 39.8 % in the shallow and deep subsoil (0–100 and 100–180 cm), respectively, when compared to corresponding changes at the BF site. Soil water content was shown to be largely influenced by site properties, namely shrub biomass and litter density (p < 0.05). Due to aboveground vegetation and rainfall interception by the litter, 32.2 mm of effective rainfall was reduced to the soil for every 10 %-increase in shrub cover. Bands of soil water depletion during the dry year did not fully recover during the following wet year, resulting in the development of a dried soil layer with an average SWC of 4.6–7.8 %. Increased evapotranspiration (ETtotal) led to a decrease in SWS and relative extractable soil water (REW), which caused ETtotal at HF to be lower than the rate observed at MF. These findings highlight the need for improvements in current restoration strategies, meant at striking a balance between vegetation restoration and SWC by developing optimal plant-community cover and mosaicked vegetation systems.

Correlation between Landscape Pattern and Net Primary Productivity of Vegetation: A Case Study in the Arid and Semi-Arid Regions of Northwest China

Human activities and environmental changes have influenced the changes in landscape patterns, which in turn profoundly impact the variation in net primary productivity (NPP) of vegetation. Understanding the relationship between landscape patterns and NPP is of significant importance for maintaining ecosystem stability and improving the ecological environment. In this study, six land use types in the arid and semi-arid regions of Northwest China were selected, and five landscape pattern indices at the landscape level and four landscape pattern indices at the class level were used. Pearson correlation and multiple linear regression models were employed to analyze the relationship between landscape indices and NPP at a 100 km × 100 km grid scale. The results indicate that there are varying degrees of correlation between landscape pattern indices and NPP from 2001 to 2020, with different levels of variation over the 20-year period. The correlation between indices and NPP is higher at the class level than at the landscape level, and the increase in landscape abundance and fragmentation promotes an increase in NPP. At the landscape level, three landscape indices, namely NP (Number of Patches), PR (Patch Richness), and SHDI (Shannon’s Diversity Index), explain 45.4% of the variation in NPP. At the class level, NP, TE (Total Edge Length), and IJI (Dispersion and Juxtaposition Index) are the main influencing factors for NPP in cropland, forestland, and grassland. Therefore, in ecological governance, it is necessary to consider landscape pattern changes appropriately to maintain ecosystem stability.

Assessing resource utilization, food production and ecosystem service value from spring wheat farmland under reduced irrigation and N fertilization management using a process simulation-based framework

Excessive irrigation and nitrogen (N) fertilization have caused severe reductions in farmland water and N productivity, and functional degradation of agroecosystems in arid to semi-arid regions. Thus, a process simulation-based framework for resource, food, and ecology (RFE) trade-offs was used to optimize the irrigation and N fertilization strategy (IRNF). A scenario study was conducted based on the framework that was developed in our previous companion study in the arid to semi-arid regions of Northwest China. Based on the local IRNF (i.e., 450 mm irrigation and 340 kg ha−1 N fertilization), reduced irrigation and N fertilization management scenarios were proposed considering eleven irrigation depth reduction cases and ten N fertilization reduction cases in three hydrological years (wet, normal, and dry). The integrated responses of spring wheat yield, water and N productivity, and ecosystem service value (ESV) to various IRNFs were quantified and assessed. The results showed that the local IRNF obtained higher yields and positive ESVs, but was also produced higher greenhouse gas (GHG) emissions, N losses, and water consumption, thus resulting in lower water and N productivity and higher negative ESVs. Among the negative ESVs, GHG emission value accounted for the largest proportion of the total negative ESV (75–80 %), followed by water consumption and fertilizer loss values. Compared with the local IRNF, the scenarios with 210 mm irrigation and 240 kg ha–1 N fertilization in wet years, 240 mm irrigation and 200 kg ha–1 N fertilization in normal years, and 300 mm irrigation and 200 kg ha–1 N fertilization in dry years could not only reduce negative ESVs, improve water and N productivity, and save water and fertilizer resources, but also maintain acceptable yields and positive ESVs. These recommendations reduced the total negative ESV by 4.8–7.7 %, increased water and N productivity by 4.0–8.9 % and 44–69 %, and saved irrigation water and N fertilizer resources by 33.3–53.3 % and 29.4–41.2 % in three hydrological years in relation to the local IRNF, respectively. This study indicates that the framework is a reliable tool for achieving farmland RFE trade-offs and generating appropriate IRNFs for different hydrological years in arid to semi-arid regions. Therefore, sustainable development goals in RFE systems may be achieved by optimizing irrigation and fertilization management.

Hydrochemical analysis and groundwater suitability for drinking and irrigation in an arid agricultural area of the Northwest China

Groundwater is the foremost water source in the arid and semiarid regions of Northwest China. Assessing groundwater's drinking and irrigation quality is essential for protecting these valuable groundwater resources. In this study, a total of 24 confined groundwater samples and 54 phreatic groundwater samples were collected in the southern and central Ningxia area for hydrochemical analysis and quality assessment. The hydrochemical results revealed that hydrochemical types of phreatic and confined groundwater consistently belonged to Na-SO4-Cl and Na-Mg-SO4-Cl types. The driving forces of groundwater chemistry were determined by gypsum dissolution, silicate dissolution, and positive cation exchange for phreatic and confined aquifers. The entropy-weighted water quality index (EWQI) and irrigation water quality index (IWQI) showed that the drinking water quality and irrigation quality were better in phreatic groundwater than in confined groundwater due to the Neogene-Paleogene groundwater system recharge and strong evaporation. Measures such as controlling groundwater extraction and optimizing well placement need to be implemented. The achievements would be helpful for groundwater management and protection in agricultural areas under semi-arid and arid climates.

Strategy matters: Phytoremediation potential of native halophytes is jointly associated with their distinct salt tolerances

Halophytes are effective candidates for phytoremediation of heavy metal-contaminated saline soils. Still, little is known about the relationships between their potential for metal enrichment and salt-tolerance strategies. This study comprehensively investigated the plant community and concentrations and accumulation characteristics of heavy metals (As, Cd, Cr, Cu, Pb, and Zn) in the soil and dominant native plants with different salt-tolerance strategy groups, namely salt-dilution (SD), salt-excretion (SE), salt-exclusion (SC), and non-halophyte, in a semiarid region of Northwest China. The results showed that the soil in this area was primarily polluted by As and Cd, which were 5.80 and 21.18 times higher than the corresponding background values, respectively. The primary vegetation was desert steppe, and 95 species of 34 families were investigated, most of which were herbaceous (64.2%) with the Asteraceae dominating. Eleven of the thirteen dominant plants, except Zea mays and Helianthus annuus, were halophytes with distinct salt tolerances, exhibiting differing metal accumulation and transport capacities. All the bioconcentration factors of the selected species for six metals were lower than 1, and their accumulation ability decreased in the order of Cu (0.466) > Cr (0.315) ≈ Cd (0.093) ≈ Zn (0.082) ≈ As (0.076) > Pb (0.049). Salt-tolerance strategies were significantly correlated with As and Cd accumulations in the soil-plant environment, but in diametrically opposite directions. Also, metal accumulations and translocations partly depended on plant salt resistance strategies. Salt-diluting halophytes such as Suaeda glauca and Kochia scoparia seem applicable for phytoextraction of single or mixed metal pollution, particularly Cd. In comparison, salt-excreting halophytes such as Chenopodium glaucum and Salsola collina would be more suited to As phytostabilization due to the potential for second pollution. In conclusion, SD halophytes could be used in various metal-contaminated soils in salt-affected regions, while SE halophytes would be well suited for phytostabilization. This study would enhance the exploitation advantages of halophyte germplasms with different salt tolerances in multiple-stressed environments.

Assessing the Spatiotemporal Evolution and Drivers of Ecological Environment Quality Using an Enhanced Remote Sensing Ecological Index in Lanzhou City, China

Lanzhou City is located in the semi-arid region of northwest China, which experiences serious desertification. Moreover, the high intensity of land development, with the accelerated industrialization and urbanization, causes increasingly aggravated conflict between humans and the environment. Exploring the response of the ecological environment quality to the natural environment and anthropogenic activities is important to protect the sustainable development of urban economic construction and the environment. Based on the Google Earth Engine (GEE) platform, this paper constructed a modified Remote Sensing Ecological Index (MRSEI) model which could reflect the ecological environment quality by integrating the desertification index (DI) into the Remote Sensing Ecological index (RSEI) model. This paper explores the spatiotemporal variation in the environmental quality from 2000 to 2020 in Lanzhou, China, and analyzes the natural and anthropogenic factors affecting the environment quality in terms of temperature, precipitation, gross domestic product (GDP), land use, night lighting, and population. The results showed that the mean value of MRSEI ranged from 0.254 to 0.400. The area undergoing fast growth in ecological quality was in the northwestern part of Lanzhou, and the area of decrease was in the central part. Various factors have different degrees of influence on the ecosystem, with temperature, precipitation, and land use having a greater impact, and GDP and population having a limited impact. Precipitation and temperature showed a strong impact when interacting with other factors, demonstrating that precipitation and temperature were also key factors affecting MRSEI. Overall, climate change and the implementation of ecological restoration projects have led to an improvement in the quality of the ecological environment in Lanzhou. This study provides a reference for understanding the spatiotemporal changes in the ecological environment in semi-arid Lanzhou and is conducive to formulating proper protection strategies.

Effect of Ambient Temperature on Hospital Admissions for Respiratory Disease in Suburban Rural Villages of a Semi-Arid Region in Northwest China.

This study evaluated the effects of extreme temperatures on hospital admissions for respiratory diseases (RDs) in a semi-arid region in the Northwest of China. Distributed lag nonlinear model was constructed, and stratified analysis by gender and age was performed. The exposure-response curve between temperature and RD hospital admissions was almost W-shaped. Either extremely cold temperatures or moderately cold temperatures presented a short-term acute harmful effect, and the relative risks were higher among males (1.976, 95% confidence interval [CI]: 1.773-2.203; 1.242, 95% CI: 1.203-1.282) and the elderly (2.363, 95% CI: 1.724-3.240; 1.267, 95% CI: 1.154-1.390). Both extreme and moderately hot temperatures had higher risks among females (2.040, 95% CI: 1.815-2.292; 1.328, 95% CI: 1.276-1.381). The relationship between air temperature and RD hospital admissions was nonlinear. Vulnerable populations varied according to extreme temperature conditions.

Distribution areas and monthly dynamic distribution changes of three Aedes species in China: Aedes aegypti, Aedes albopictus and Aedes vexans.

Mosquitoes play an absolute role in the spread of epidemic arbovirus diseases. Worldwide, Aedes aegypti and Aedes albopictus are the main vectors responsible for the spread of these mosquito-borne diseases. Aedes vexans, a mosquito species native to China, also carries mosquito-borne viruses, such as dengue fever virus and Japanese encephalitis virus, but research on this mosquito has been inadequate. Mapping the potential distribution range of and monthly change in the distribution of these three Aedes species is of particular importance for mosquito surveillance, eradication and disease control. Monitoring data were collected for the three Aedes species in China. Long-term temperature and precipitation data (2001-2021) and land cover data were used to represent various climate and environmental conditions. An ecological niche model was developed using a maximum entropy modeling method to predict the current optimum habitat areas for the three Aedes species and to obtain important variables influencing their monthly distribution. The distribution model for the three Aedes species performed well, with an area under the receiver operating characteristic curve value of 0.991 for Ae. aegypti, 0.928 for Ae. albopictus and 0.940 for Ae. vexans. Analysis of the distribution change and mapping of the optimum habitat range for each Aedes species for each month demonstrated that temperature, precipitation and construction land were important factors influencing the distribution of these three Aedes species. In China, Aedes aegypti is mainly concentrated in a few tropical regions and along the Yunnan border; Aedes albopictus is widely distributed throughout most of the country, except for the arid and semi-arid regions of northwest China; and Aedes vexans is mainly found in the northern regions. Our results provide a basis for the timing and location of surveillance efforts for high-priority mosquitoes.

Unraveling the connection between vegetation greening and terrestrial water storage decline in the arid and semi-arid regions of northwest China

Study RegionArid and semi-arid regions of Northwest China (NWC) Study FocusWater scarcity poses a significant challenge to the development of NWC. Although the climate is getting warmer and wetter in NWC, there is a clear intensification in the trend of regional hydrological aridification. However, the connection between these factors continues to remain elusive to our comprehension. This study investigated the impacts of vegetation changes on terrestrial water storage (TWS) and explored their underlying causes using the Lund-Potsdam-Jena (LPJ) Dynamic Global Vegetation Model based on long-term hydrometeorological data, TWS anomaly data, and Normalized Difference Vegetation Index (NDVI) data. New Hydrological Insights for the RegionThis study unveils a significant upsurge in NDVI and actual evaporation (E) within NWC during 1982–2019, with distinct prominence observed in cultivated regions. This heightened E emerges as a central driver behind the reduction in surface soil water, root zone soil water, and the continuous decline of TWS across the NWC. The research discerns the amplified E, influenced by both climatic and human activities, as a key contributor to the diminution of TWS within the region. Notably, the contribution of cultivated land E exhibits consistent expansion, while grassland E remains pivotal in TWS reduction. Transpiration (Et) and bare-soil evaporation (Eb) surface as the predominant elements of terrestrial E. The degradation of grasslands leads to intensified Eb, thereby further augmenting E.

An Approach for Monitoring Shallow Surface Outcrop Mining Activities Based on Multisource Satellite Remote Sensing Data

Monitoring mine activities can help management track the status of mineral resource exploration and mine rehabilitation. It is crucial to the sustainable development of the mining industry and the protection of the geological environment in mining areas. To monitor the mining activities of shallow surface outcrops in the arid and semi-arid regions of northwest China, this paper proposes a remote sensing monitoring approach of mining activities based on deep learning and integrated interferometric synthetic aperture radar technique. This approach uses the DeepLabV3-ResNet model to identify and extract the spatial location of the mine patches and then uses object-oriented analysis and spatial analysis methods to optimize the mine patch boundaries. SBAS-InSAR technique is used to obtain the time-series deformation information of the mine patches and is combined with the multi-temporal optical imagery to analyze the mining activities in the study area. The proposed approach has a recognition accuracy of 95.80% for the identification and extraction of mine patches, with an F1-score of 0.727 at the pixel level, and the average area similarity for all patches is 0.78 at the object-oriented level. The proposed approach possesses the capability to analyze mining activities, indicating promising prospects for engineering applications. It provides a reference for monitoring mining activities using multisource satellite remote sensing.

Nitrogen inhibitors improve soil ecosystem multifunctionality by enhancing soil quality and alleviating microbial nitrogen limitation

Soil quality (SQI) is a comprehensive indicator reflecting the agricultural productivity of soil, and soil ecosystem multifunctionality (performing multiple functions simultaneously; EMF) can reflect complex biogeochemical processes. However, the effects of enhanced efficiency nitrogen fertilizers (EENFs; urease inhibitors (NBPT), nitrification inhibitors (DCD), and coated controlled-release urea (RCN)) application on the SQI and soil EMF and their relationships are still unclear. Therefore, we conducted a field experiment to study the effects of different EENFs on the SQI, enzyme stoichiometry and soil EMF in semiarid areas of Northwest China (Gansu, Ningxia, Shaanxi, Shanxi). Across the four study sites, DCD and NBPT increased SQI by 7.61–16.80 % and 2.61 %–23.20 % compared to mineral fertilizer, respectively. N fertilizer application (N200 and EENFs) alleviated microbial N limitation, and EENFs alleviated microbial N and C limitations to a greater extent in Gansu and Shanxi. Moreover, nitrogen inhibitors (Nis; DCD and NBPT) improved the soil EMF to a greater extent than N200 and RCN, DCD increased by 205.82–340.00 % and 145.00–215.47 % in Gansu and Shanxi, respectively; NBPT increased by 332.75–778.59 % and 364.44–929.62 % in Ningxia and Shanxi, respectively. A random forest model showed that the microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and soil water content (SWC) of the SQI factors were the main driving forces of soil EMF. Moreover, SQI improvement could alleviate microbial C and N limitations and promote the improvement of soil EMF. It is worth noting that soil EMF was mainly affected by microbial N limitation rather than C limitation. Overall, NIs application is an effective way to improve the SQI and soil EMF in the semiarid region of Northwest China.

Evaluation of Surface Crack Development and Soil Damage Based on UAV Images of Coal Mining Areas

Coal mining is necessary for the development of society but at the same time causes ecological damage that must also be repaired based on science. In the arid and semi-arid regions of northwest China, surface cracks are one of the major geo-environmental problems caused by coal mining, and studies are urgently needed to determine how to effectively repair them in a scientific manner. The rapid development of unmanned aerial vehicle (UAV) remote sensing technology in recent years has resulted in a good source of data for acquiring feature information on surface cracks. Existing studies mainly focus on high-precision crack extraction methods, and there are few studies on the methods for evaluating cracks. However, clarifying the degree of cracks requiring repair and what repair measures are required through scientific and reasonable evaluation methods is necessary to formulate effective crack repair and land reclamation plans. Given these considerations, in this study, the degree of both crack development and soil damage were evaluated based on the crack extraction results of UAV images. Based on the results of indoor experiments and field measurements, the grading criteria for the degree of crack development and soil damage were constructed. Crack density was used as the evaluation index for the degree of crack development (slight: &lt;0.4%, moderate: 0.4–2%, severe: &gt;2%). The distance between soil and cracks was the basis of the evaluation index for the soil damage degree (severe damage area: &lt;0.6 m; slight damage area: 0.6–1.2 m; no obvious damage area: &gt;1.2 m). Through the results from evaluating the degree of both crack development and soil damage in the study area, it was found that the degree of crack development was mainly moderate and located in the northern crack zone of the study area, with the cracks and damaged soil showing a striped pattern in the east-west direction. Combining the evaluation results of crack development and soil damage, the ecological restoration model of “natural restoration + crack filling + water supplementing + vegetation planting” is proposed. We conclude that crack repair should be applied in areas where moderate and severe cracks have developed, whereas soil repair should target the soil within 1.2 m of the cracks in the above area. This study is the first attempt to construct and evaluate the classification criteria of crack development degree and soil damage degree from the perspective of cracks and soil, and the results are of guiding significance for land reclamation in mining areas.