Subjects: Geosciences >> Geography submitted time 2025-07-17 Cooperative journals: 《干旱区科学》
Abstract： The Loess Plateau (LP), one of the most ecologically fragile regions in China, is affected by severe soil erosion and environmental degradation. Despite large-scale ecological restoration efforts made by Chinese government in recent years, the region continues to face significant ecological challenges due to the combined impact of climate change and human activities. In this context, we developed a kernal Remote Sensing Ecological Index (kRSEI) using Moderate Resolution Imaging Spectroradiometer (MODIS) products on the Google Earth Engine (GEE) platform to analyze the spatiotemporal patterns and trends in ecological environmental quality (EEQ) across the LP from 2000 to 2022 and project future trajectories. Then, we applied partial correlation analysis and multivariate regression residual analysis to further quantify the relative contributions of climate change and human activities to EEQ. During the study period, the kRSEI values exhibited significant spatial heterogeneity, with a stepwise degradation pattern in the southeast to northwest across the LP. The maximum (0.51) and minimum (0.46) values of the kRSEI were observed in 2007 and 2021, respectively. Trend analyses revealed a decline in EEQ across the LP. Hurst exponent analysis predicted a trend of weak anti-persistent development in most of the plateau areas in the future. A positive correlation was identified between kRSEI and precipitation, particularly in the central and western regions; although, improvements were limited by a precipitation threshold of 837.66 mm/a. A moderate increase in temperature was shown to potentially benefit the ecological environment within a certain range; however, temperature of –1.00°C–7.95°C often had a negative impact on the ecosystem. Climate change and human activities jointly influenced 65.78% of LP area on EEQ, primarily having a negative impact. In terms of contribution, human activities played a dominant role in driving changes in EEQ across the plateau. These findings provide crucial insights for accurately assessing the ecological state of the LP and suggest the design of future restoration strategies.
Subjects: Geosciences >> Geography submitted time 2025-07-17 Cooperative journals: 《干旱区科学》
JIN Zizhen
QIN Xiang
LI Xiaoying
ZHAO Qiudong
ZHANG Jingtian
MA Xinxin
WANG Chunlin
HE Rui
WANG Renjun
Abstract： Understanding the impact of meteorological and topographical factors on snow cover fraction (SCF) is crucial for water resource management in the Qilian Mountains (QLM), China. However, there is still a lack of adequate quantitative analysis of the impact of these factors. This study investigated the spatiotemporal characteristics and trends of SCF in the QLM based on the cloud-removed Moderate Resolution Imaging Spectroradiometer (MODIS) SCF dataset during 2000–2021 and conducted a quantitative analysis of the drivers using a histogram-based gradient boosting regression tree (HGBRT) model. The results indicated that the monthly distribution of SCF exhibited a bimodal pattern. The SCF showed a pattern of higher values in the western regions and lower values in the eastern regions. Overall, the SCF showed a decreasing trend during 2000–2021. The decrease in SCF occurred at higher elevations, while an increase was observed at lower elevations. At the annual scale, the SCF showed a downward trend in the western regions affected by westerly (52.84% of the QLM). However, the opposite trend was observed in the eastern regions affected by monsoon (45.73% of the QLM). The SCF displayed broadly similar spatial patterns in autumn and winter, with a significant decrease in the western regions and a slight increase in the central and eastern regions. The effect of spring SCF on spring surface runoff was more pronounced than that of winter SCF. Furthermore, compared with meteorological factors, a variation of 46.53% in spring surface runoff can be attributed to changes in spring SCF. At the annual scale, temperature and relative humidity were the most important drivers of SCF change. An increase in temperature exceeding 0.04°C/a was observed to result in a decline in SCF, with a maximum decrease of 0.22%/a. An increase in relative humidity of more than 0.02%/a stabilized the rise in SCF (about 0.06%/a). The impacts of slope and aspect were found to be minimal. At the seasonal scale, the primary factors impacting SCF change varied. In spring, precipitation and wind speed emerged as the primary drivers. In autumn, precipitation and temperature were identified as the primary drivers. In winter, relative humidity and precipitation were the most important drivers. In contrast to the other seasons, slope exerted the strongest influence on SCF change in summer. This study facilitates a detailed quantitative description of SCF change in the QLM, enhancing the effectiveness of watershed water resource management and ecological conservation efforts in this region.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2025-07-17 Cooperative journals: 《干旱区科学》
Suellen Teixeira Nobre GONÇALVES
Francisco das Chagas VASCONCELOS JÚNIOR
Cleiton da Silva SILVEIRA
José Micael Ferreira da COSTA
Abstract： Precipitation is scarce in semi-arid areas, which results in serious drought. Occurrence of flash drought is quite often in these areas, and flash drought may also cause significant disasters. However, monitoring flash drought is still weak and remains a challenge. This study aims to identify, evaluate, and monitor flash drought events that occurred from 1961 to 2020 in reservoirs of the Ceará State, Brazil. The Christian's method, standardized precipitation index (SPI), standardized precipitation evapotranspiration index (SPEI), and evaporative demand drought index (EDDI) were used to assess the severity and persistence of flash drought. Moreover, analyses conducted in 2001, 2008, 2011, 2012, 2016, and 2020 revealed the complexity and interaction of flash drought with environmental and meteorological factors. The results indicated that in dry years such as 2001, 2012, and 2016, drought indices pointed to the intensification of drought conditions, with impacts on major reservoirs in the area, such as Banabuiú, Castanhão, and Orós. Low precipitation, associated with high evaporative demand, intensified water stress, reducing water availability for the population and local ecosystems. In wet years such as 2008, 2011, and 2020, SPEI and EDDI indicated higher moisture levels and drought relief, favoring the recovery of reservoirs. It was also observed that most flash drought episodes evolved into conventional droughts, highlighting their persistence and potential long-term impact. Moreover, the months of May and November presented a higher frequency of flash drought during the wet and dry periods, respectively, negatively impacting most of the studied reservoirs. These findings underscore the need for effective drought monitoring and mitigation strategies to reduce its impacts on agriculture and water resources in the semi-arid area. Early detection and analysis of flash drought are important for improving water resource management and for continuous adaptation to changing drought conditions.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： As the scarcity of global water intensifies, accurate assessments of water resource carrying capacity (WRCC) have become essential for sustainably managing regional water resources and combating the adverse effects of climate change. However, the water resources-ecology-society system is highly complex, involving multidimensional interactions and dynamic internal changes that cannot be fully captured by a single evaluation method. This paper reviews the application status and research progress of coupled-model methods for WRCC evaluation. A systematic comparative analysis reveals the strengths and limitations of the major evaluation methods—systems analysis, comprehensive evaluation, and machine learning—in WRCC evaluation. Particular attention is devoted to the challenges of these methods in arid regions. The dynamic feedback mechanisms, nonlinear modeling capabilities, data-driven characteristics, and applicabilities of different methods are analyzed through a horizontal comparison study. The review also analyzes the suitabilities and limitations of each method in arid regions and explores the feasibility of coupled models, providing new insights for resolving WRCC issues in these areas. Multimodel integration and data-driven optimization will enhance the generalizability and applicability of models in future, facilitating the transition of water resource management from static evaluation to dynamic simulation and precise prediction. These developments will offer scientific support for sustainable water resource utilization in arid regions and worldwide.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： The ongoing decline in biodiversity adversely effects ecosystem services. Investigating spatiotemporal changes in land use and habitat quality in the Three River Source Region is crucial for ecological protection and restoration. This study, based on the PLUS model and the InVEST model’s habitat quality module, conducts multi-scenario simulations to predict land use changes and estimate habitat quality. The results are as follows: (1) During the historical period, 9663.53 km2 of grassland converted to unused land, represented the largest proportion of total land conversion, whereas unused land converted to grassland only covered 3659.27 km2 , the grassland degraded into unused land to a relatively serious extent in the Three River Source Region. (2) Multi-scenario predictions for 2030 reveal that the biodiversity conservation scenario performs best, followed by the grassland protection scenario, then the water resources protection scenario, and finally the natural development scenario. (3) Among conversion types, the contribution rate of converting unused land to grassland in enhancing habitat quality is highest at 0.7167, followed by that of converting unused land to water bodies, at 0.2603. Implementing biodiversity protection strategies, resolving the grass-livestock conflict, and enhancing management of unused land, while reducing grassland-to-unused land conversion will help mitigate the decline in habitat quality.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： This study examines cotton growth affected by soil temperature under the condition of phosphate fertilizer drip application. It also explores the role and mechanism of soil temperature regulation of cotton root growth on improving the utilization rate of cotton phosphate fertilizer. Using potted tests, three soil temperature gradients were examined: low temperature (LT: 11℃–18℃); medium temperature (MT: 22℃–26℃); and high temperature (HT: 30℃–34℃). Single factor testing with water bath temperature control was utilized. The effects of various soil temperatures on the growth traits, biomass, root distribution, effective soil phosphorus distribution, and phosphate utilization efficiency in cotton were assessed. As soil temperature increased, cotton plant height, stem thickness, leaf number and biomass all showed parabolic changes that peaked in the medium temperature (22℃–26℃) group. Additionally, root length in the 0 to 5 cm soil layer increased with soil temperature, most notably with high temperature treatment, followed by low temperature and medium temperature treatments increasing by 5.2%–126.9% and 4.9%–62.3%, respectively. Below the 5 cm soil layer, root length decreased with increasing temperature, with the medium temperature treatment having the longest root length, 81.68%–98.43%, which was 170.17%–218.35% longer than the low temperature and high temperature treatment, respectively. The effective P content of each treatment increased with lower temperatures, with the medium and high temperature treatment content being 13.7% and 20.5% lower than the low temperature treatment, respectively. Phosphorus absorption and phosphate utilization were maximized in the medium temperature cotton, followed by the low temperature cotton. With the lowest high temperature , the total phosphorus absorption in the medium temperature cotton increased relatively by 49.69% and 89.36% compared with low temperature and high temperature treatments, respectively. Furthermore, the phosphate utilization rate was twice and 50% higher than the high and low temperature treatments, respectively. These findings indicate that based on the effects of soil temperature on cotton growth, root and soil effective phosphorus distribution, phosphorus absorption, and phosphate utilization, the most suitable soil temperature for cotton growth is 22℃–26℃.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： Incorporating agricultural irrigation water into the global trade chain and determining its sustainability is vital for ensuring water and food security. However, the issue of sustainability in the virtual water footprint of crop trade has received limited attention, due to the conflict between economic benefits and water resource utilization. Thus, based on the crop production and trade matrix data from the Food and Agriculture Organization, this study conducted physical trade flow and spatial correlation analyses as well as multiscale geographically weighted regression to systematically analyze the spatiotemporal distribution, the spatial correlation characteristics, and the driving factors of net exported virtual water sustainability in global crop trade from 2000 to 2019. Based on the findings, the sustainable and unsustainable net exported virtual water volumes in global crop trade (especially cotton) exhibited a fluctuating upward trend (approximately 0.20 Gm3 per year) over the past two decades. However, due to agricultural technological advancements, the proportion of unsustainable virtual water in the total virtual water trade volume decreased from 42.31% to 41.40%. Although the spatial analysis revealed considerable spatial clustering of unsustainable net exported virtual water volumes between 2000 and 2009, as shown by global and local Moran’s I statistics, this clustering trend weakened and became more dispersed over the past decade. Moreover, the increase in net exported virtual water was mainly driven by changes in cultivated land area, with agricultural value-added having a significant negative impact on virtual water in trade. Overall, these results highlight the importance of implementing stringent food security policies in order to facilitate the sustainable development of the global virtual water trade in crops and to further reduce the proportion of unsustainable water use.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： Water resources form the foundation for maintaining ecosystem balance and ensuring human life and economic development. Simulating hydrological processes in arid and semi-arid ecosystems promotes the effective utilization of local water resources. This paper analyzed the applicability of two models—the Distributed Hydrology Soil Vegetation Model (DHSVM) and the Soil and Water Assessment Tool (SWAT)—in different types of watersheds in semi-arid regions by performing: (1) sensitivity analysis and parameter calibration; (2) simulation of monthly runoff for the upper reaches of the Xar Moron River and the Laoha River during the growing seasons of 2011–2012 and 2017–2019. The upper reaches of the Xar Moron River are dominated by grasslands, while those of the Laoha River are dominated by forestland and farmland. The results show that DHSVM exhibits 7 primary sensitive parameters in the Xar Moron River and 6 in the Laoha River, whereas SWAT identifies 11 and 12 sensitive parameters, respectively. Following parameter calibration, in the upper reaches of the Xar Moron River the Nash–Sutcliffe efficiency coefficient for DHSVM is 0.70 during calibration and 0.11 during validation, while for SWAT it is 0.43 and 0.04, respectively. In the upper reaches of the Laoha River, the Nash–Sutcliffe efficiency coefficients for DHSVM are 0.56 and 0.70 during the two periods, compared with 0.86 and 0.54 for SWAT. The findings indicate that both models are applicable for simulating hydrological processes in the study area, with DHSVM more accurately simulating overall runoff and SWAT more accurately simulating peak monthly runoff.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
LI Shuaifei
LIU Changyi
HU Xiasong
TANG Binyuan
WU Zhijie
DENG Taiguo
XING Guangyan
ZHAO Jimei
LEI Haochuan.
Abstract： This study examines the surface deformation characteristics and deformation rate prediction of large-scale landslides in the upper regions of the Yellow River between the Longyang and Jishi Gorge riverbanks. The study area was the Xijitan giant landslide within the Guide region of the upper Yellow River. The Small Baseline Subset Interferometric Synthetic Aperture Rader（SBAS-InSAR）technology was employed to monitor the surface deformation of the Xijitan giant landslide and analyze, its deformation rates and variation characteristics for the period 2019—2022.The results show that the following. (1)The maximum surface deformation rate of the land- slide body was -96 mm·a−1,with a maximum cumulative deformation of 464.71 mm. Distinct deformation zones were observed along the front and rear edges of the landslide body, with surface deformation rates ranging across−96~16 mm·a−1.(2)The cumulative deformation of characteristic points on a landslide body, determined using SBAS-InSAR technology, exhibited a maximum cumulative deformation of -140.50 mm. (3)The long short-term memory (LSTM) neural network model was used to predict the cumulative deformation of these points, and the results were compared with those obtained using support vector machine（SVM）and back propagation（BP）neu-ral network models. The LSTM model demonstrated high prediction accuracy, with an absolute error within 5mm and a goodness-of-fit (R2)greater than 0.8.This confirmed the effectiveness of the LSTM model in predicting the cumulative surface deformation of landslides. Thus, the findings of this study provide data support and practical guidance for the enhanced monitoring of giant landslide deformation in the upper Yellow River regionand the early detection of potential landslides.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： To obtain more accurate precipitation distribution in remote areas, this paper combines the high-resolution advantages of radar and the wide-coverage detection of satellites. By integrating radar and satellite-derived precipitation, we generate high-precision quantitative precipitation estimation (QPE) products. Taking the strong convective events in Xinjiang on August 12 and 13, 2023, as an example, we use radar reflectivity for precipitation inversion based on cloud classification and Z-R relationships. We input Himawari 9 satellite brightness temperature and IMERG precipitation into a BP neural network model to establish the relationship between average brightness temperature and average rainfall intensity. Subsequently, we use the instantaneous brightness temperature of the Himawari 9 satellite to invert momentary precipitation through the BP neural network model. We also propose two precipitation data fusion schemes: Scheme I uses a uniform correction value to integrate radar and satellite precipitation, while Scheme II further considers precipitation intensity levels for comparison. Finally, we obtain high-precision precipitation inversion products for Xinjiang. The results show that: (1) Cloud classification based on brightness temperature can finely estimate precipitation within the radar range, and brightness temperature differences can reduce the impact of non-precipitating clouds to some extent. (2) The root mean square errors (RMSE) of satellite precipitation inversion is 1.793 mm·h–1, with coefficient of determination (R2) of 0.572, indicating reasonable model accuracy. The binary classification score results show that the model can accurately invert precipitation in over 70% of the areas. (3) The fusion of precipitation by the two schemes has limited improvement in the accuracy of short-duration light rain. Scheme II outperforms Scheme I for short-duration moderate rain but shows a slight decline for short-duration heavy rain compared to Scheme I, indicating that the asynchrony between satellite observation and near-surface precipitation has some impact. (4) Under a 95% confidence interval, the P values for the RMSE and R2 differences between the two schemes and satellite inversion are all less than 0.005, while the P value for Scheme II compared to Scheme I is greater than 0.05. Both fusion schemes significantly improve the accuracy of satellite precipitation, but the improvement of Scheme II, which considers precipitation intensity levels, over Scheme I is minimal.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： Assessing climate comfort in the Shaanxi-Gansu-Ningxia region is crucial for developing red tourism resources and promoting ecological sustainability. Based on daily meteorological data from 1953 to 2020, including average temperature, wind speed, and relative humidity, this study employs a comprehensive climate comfort evaluation model, integrated with GIS spatial interpolation and comprehensive zoning methods, to systematically analyze the spatiotemporal distribution characteristics of climate comfort in the region. The results indicate that, temporally, the climate in the region is generally comfortable from May to September, whereas from December to February of the following year, it is predominantly characterized by discomfort. Spatially, northern Shaanxi exhibits relatively comfortable climatic conditions, while the southwestern Xihaigu region is less suitable in terms of climate comfort. Against the backdrop of global warming, the annual average number of comfortable days has shown an increasing trend, while the number of uncomfortable days has significantly decreased since 2000. Comprehensive zoning results indicate that southwestern and central high-altitude areas experience lower comfort levels, while other regions remain relatively favorable. Further analysis demonstrates that for every unit change in the climate comfort index, the red tourism visitor flow index correspondingly changes by 0.593%. Notably, Yan’an, due to its abundant red tourism resources and favorable climate conditions, exhibits a significantly higher attractiveness index compared to other regions. Moving forward, red tourism planning should be dynamically optimized to accommodate climate change and evolving tourist demands. This study provides a scientific reference for regional tourism development and the sustainable advancement of red tourism activities.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： This study explores the community structure and function of generalized and specialized fungal species (GFS and SFS) in the soil and roots of Pinus sylvestris var. mongolica forests, and their relationship with soil physicochemical properties, aiming to unravel key microbiological mechanisms affecting ecosystem functioning in P. sylvestris fores. Using high-throughput sequencing technology, we analyzed the differences in community structure and functional groups of GFS and SFS in the soil and roots of natural forests and plantations (24a, 35a, 44a) of P. sylvestris var. mongolica in Hulunbuir desert. The results showed that: (1) the soil and root-associated GFS totally retained 169 OTUs, The soil SFS retained 603 OTUs, the root-associated SFS retained 216 OTUs. As well as Tricholoma and Suillus for soil GFS and Tricholoma, Suillus and Cadophora for root-associated GFS, Penicillium, for soil SFS and for Acephala root-associated SFS. (2) The relative abundance of symbiotic nutritive fungi of soil GFS accounted for 28.49% to 47.21%, and the dominant ecological functional group was ectomycorrhizal fungi, which showed a trend of increasing and then decreasing with forest age; the saprophytic nutritive fungi of soil SFS accounted for 17.01% to 40.01%, compared with natural forests, the relative abundance of saprophytic nutritive fungi in plantation forests was lower than that in natural forests, and the saprophytic nutritive fungi showed a tendency of increasing and decreasing followed by increasing with forest age; The symbiotic trophic type of root-associated GFS accounted for 43.25% to 54.45%, with the dominant ecological functional group was ectomycorrhizal fungi, which showed an increasing trend with the increase of forest age, and the relative abundance of ectomycorrhizal fungi in natural forests was higher than that in plantation forests. (3) The soil organic matter and available phosphorus content of natural P. sylvestris forests were significantly higher than that of plantation forests (P<0.05). With the increase of forest age, the soil organic matter(SOM); total phosphorus(TP); available nitrogen(AN); and available phosphorus(AP) in the soil of plantation forests increased significantly(P<0.05); while the soil pH decreased but not significantly (P>0.05). GFS were mainly dominated by soil SOM, NH+4-N and TP (P<0.05); whereas the community variability of root-associated SFS was further regulated by total nitrogen(TN) (P<0.05); and soil SFS were significantly associated only with TP, AN and NO3--N (P<0.05). The drivers of fungal community structure showed significant ecological niche differentiation, the research contributes to a deeper understanding of the ecological functions of fungi in the soil and roots of P. sylvestris forest, providing scientific support for the sustainable management and protection of P. sylvestris forests in the Hulunbuir desert.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： Located at the convergence zone of the Qinghai-Tibet Plateau Ecological Barrier and the Northern Sand Control Belt, Babusha region serves as a frontline defense against the southward encroachment of the Tengger Desert. Assessing the changes in its ecological environment quality holds significant guidance value for evaluating regional desertification control effectiveness and advancing the "Three-North" Shelterbelt Development Program. This study utilized data from the Google Earth Engine (GEE) platform to investigate land use pattern changes in the Babusha region from 1986 to 2021. A comprehensive assessment of spatiotemporal changes in regional ecological environment quality was conducted using the Normalized Difference Vegetation Index (NDVI); Desertification Index (DI); and Remote Sensing Ecological Index (RSEI). The results indicate that: (1) Temporally, the desert area in Babusha region has continued to decrease, grassland area has progressively increased, and vegetation coverage has improved. From 1986 to 2021, both NDVI and RSEI showed fluctuating upward trends, with NDVI increasing from 0.14 to 0.31 (more than doubling) and RSEI rising from 0.22 to 0.24 (9.39% increase). Meanwhile, DI exhibited a fluctuating downward trend, decreasing from 0.79 to 0.57 with a cumulative reduction of 27.85%. (2) Spatially, high-value areas of NDVI and RSEI were concentrated in the southern and northwestern parts of the study region, dominated by woodland and cultivated land, while low-value areas were distributed in the northern region characterized by extremely low vegetation coverage and desert. (3) The trend analysis revealed that NDVI and RSEI changes were primarily characterized by non-significant/significant increases, whereas DI mainly showed non-significant decreases. Specifically, 12.12% and 61.10% of the study area exhibited non-significant and significant NDVI increases respectively, while 5.06% and 38.63% showed non-significant and significant RSEI increases. Ecological improvement areas were concentrated in the northwestern and southeastern regions with higher human activity. From 1986 to 2021, Babusha region demonstrated remarkable vegetation restoration, continuous ecological environment improvement, and significant desertification control achievements, establishing a replicable Babusha model.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： Nitrous oxide (N2O) a remarkable greenhouse gas in the atmosphere, exerts a pronounced effect on global climate warming. Changes in land use types critically affects N2O emissions, particularly in ecologically fragile semiarid regions with more complex underlying mechanisms. However, there is still a lack of systematic research on how complex and diverse land use types affect soil N2O emissions in semiarid regions of China and the key driving factors involved. To address this, this study focused on four typical land use types in the semiarid Loess Plateau of central Gansu Province: Picea asperata forest (Piceaasperata); Medicago sativa grassland (Medicago sativa); abandoned land (Abandoned land); and wheat field (Wheat field). Soil N2O fluxes were monitored using the static chamber-gas chromatography method, combined with soil physicochemical property data,to elucidate the key drivers regulating soil N2O emissions under different land use types. Compared to the abandoned land, the Picea asperata forest and Medicago sativa grassland had significantly increased soil water content, while wheat fields exhibited elevated ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N) concentrations. Compared to the abandoned land, the Medicago sativa grassland and wheat fields exhibited markedly enhanced nitrate reductase and nitrite reductase activities, which decreased with an increase in soil depth across all treatments. Soil N2O fluxes under different land use types exhibited an initial increase followed by a decline during the vegetation growth stages. The total soil N2O emissions decreased by 34.2% and 23.3% in the Picea asperata forest and Medicago sativa grassland, respectively, and increased by 32.47% in the wheat fields, compared to the abandoned land. Random forest analysis identified soil temperature as the most influential factor affecting the soil N2O flux. Overall, compared to the abandoned land and wheat fields, the artificial forest and grassland systems in the study area demonstr
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
ZHANG Xiuxia
HAN Lisha
DANG Xinghai
WANG Xiaoxian
LIN Qingrun
DENG Lingzhi
YANG Minghang
ZHANG Xilai
Abstract： The arid region of Northwest China is an area of notable vegetation vulnerability, where vegetation cover plays a crucial role in sustaining unique terrestrial ecosystems. This study utilized Landsat data and the pixel dichotomy model to analyze spatiotemporal variation patterns of Fractional Vegetation Cover (FVC) in the arid region of Northwest China from 1990−2022. Integrating land use data, the research employed Sen’s slope estimation, the Mann-Kendall test, and correlation analysis to investigate FVC characteristics across different vegetation types and their responses to climatic factors. The results indicate that: (1) FVC exhibited a fluctuating upward trend, with an annual increase rate of 0.98×10 − 4 ; spatial heterogeneity was significant, with areas predominantly characterized by very low vegetation coverage, while river basin regions displayed higher FVC values. (2) Land use transformation has driven the evolution of FVC patterns, with increases in forestland and cultivated land contributing to the expansion of areas with very high FVC coverage (increasing by 3.0% and 18.8%, respectively); grassland remains the dominant cover across all levels, with an average proportion exceeding 47.7%. (3) Average precipitation during the vegetation growing season ranks as follows: shrubland>forestland>grassland>cropland,whereas temperature trends are reversed; evapotranspiration follows the order: forestland>cropland>grassland>shrubland; the average annual humid area proportion is 61.03% in shrubland regions, compared to less than 5% in cropland regions. FVC shows negative correlations with precipitation (52.0%); temperature (60.2%); evapotranspiration, and aridity index (63%). Vegetation demonstrates significant sensitivity to climate change. The findings provide an important basis for ecological management and restoration in the arid regions of Northwest China.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： The success of sand fixation projects in deserts is dependent on soil hydrothermal conditions, which are essential for the healthy growth of sand fixation plants. Vertical pipe surface drip irrigation is a new water-saving and temperature-control conservation technology focused on combating soil drought and surface heat stress on seedlings. However, the mechanisms regulating hydrothermal distribution and migration status remain unclear, and its widespread application in sand-fixing areas lacks a theoretical formulation. Thus, this study constructed a mathematical model of soil water–heat migration for vertical tube surface drip irrigation using HYDRUS-2D software. The study investigated the effects of key irrigation parameters (drip head flow rate and irrigation water temperature) and vertical tube parameters (tube diameter and burial depth) on soil water–heat distribution and migration. The accuracy of the constructed model was confirmed through indoor experiments. Consequently, a single-factor analysis was conducted involving nine simulation scenarios to study the impacts of four influencing factors—drip head flow rate (1, 2, and 3 L·h−1); irrigation water temperatures (10, 20, and 30 °C); riser diameter (9.6, 11.6, and 13.2 cm); and riser depth (15, 20, and 25 cm) to obtain the distributions and migration patterns of the soil hydrothermal properties. The results showed the following. (1) Soil hydrothermal changes during irrigation occurred through water-heat coupling influenced by irrigation water temperature. Dynamic changes were most pronounced in the early stage of irrigation, particularly in the inner surface layer of the tube. Over time, these changes stabilized. Water infiltration from the bottom holes of the tube into the surrounding soil increased the soil moisture rapidly before stabilizing. Further, the soil temperature was affected by the irrigation water temperature, exhibiting slight increases or decreases. (2) The diameter of the vertical tube had a minimal effect on the soil hydrothermal changes during drip irrigation. However, the burial depth had a significant influence on the soil moisture but minimal impact on the thermal environment. Outside the tube, the soil moisture distribution around the tube formed a distinct pattern, with the bottom of the tube functioning as a dividing line. Above this line, the soil moisture content at the same point decreased as the burial depth increased, while below this line, the soil moisture content increased with greater burial depth. (3) The drip head flow was a critical factor in determining the soil moisture status although its impact on the soil temperature distribution was limited. The larger the drip head flow, the higher the soil moisture content at the same points outside the pipe. (4) The influence of the irrigation water temperature on the soil moisture distribution was relatively weak; however, it directly influenced the soil temperature. Higher irrigation water temperatures resulted in increased soil temperature at the same points inside and outside the pipe. (5) When adjustments to the vertical tube's diameter and burial depth were not feasible, soil hydrothermal conditions in the root zone could be effectively regulated by adjusting the drip head flow rate and irrigation water temperature. Thus, this study offers a scientific basis for the design, operation, and management of a vertical pipe surface drip irrigation project for sand fixation plants.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： Pixel-based classification struggles with the accurate identification of glacier changes in areas with similar spectral characteristics, particularly in debris-covered areas where spectral features closely resemble the surrounding mountains and rocks, thereby resulting in low extraction accuracy. This study investigates the Yinsugaiti and Yalong Glaciers using Google Earth Engine to integrate spectral indices, microwave texture features, and topographic data. An object-based(OB) machine learning algorithm is applied for automated glacier extraction and compared to pixel-based(PB) classification methods. The results show the following. (1) The OB classification approach, integrating multi-feature fusion, significantly improved the glacier extraction accuracy. The OB_RF classifier achieved an overall accuracy of 98.1%, a Kappa coefficient of 0.97, and an F1-score of 98.67%, outperforming the OB_CART and OB_GTB classifiers. When compared to PB_RF, the overall accuracy, Kappa coefficient, and F1-score increased by 1.7%, 0.024, and 5.57%, respectively. (2) Between 2001–2022, the Yinsugaiti and Yalong Glaciers retreated at average annual rates of 0.08% and 0.13%, respectively. (3) Supraglacial debris was primarily distributed below 5,000 and 4,800 m on the Yinsugaiti and Yalong Glacier, respectively. Over the same period, debris-covered areas on both glaciers expanded upward.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： The Loess Plateau (LP) in China is highly sensitive to climate change, making it an ideal region for understanding temperature dynamics under global warming. This study analyzed the spatio-temporal variations of integrated temperature indicators for ≥0 ℃ and ≥10 ℃—including the first date (FD); ending data (ED); duration (DD); and active integrated temperature (AIT)—using daily average temperature data from 55 meteorological stations on the LP spanning 1960 to 2019. Methods such as linear fitting, mutation tests, and dominance analysis were employed. The results indicate that, from 1960 to 2019, the indicators for both thresholds changed synchronously, with an advancing FD, a delayed ED, a prolonged DD, and an increasing AIT (P<0.01). Notably, most interdecadal shifts occurred in the 1990s, with abrupt changes concentrated from the late 1990s to the early 2000s. The spatial distribution of mean values for both thresholds was similar, showing that FD advanced, ED delayed, DD prolonged, and AIT increased from northwest to southeast. However, the spatial trends differed: the magnitude of the ED delay followed an east-west pattern with alternating phases, while the increase in AIT was higher in the east and lower in the west. For the ≥0 ℃ threshold, changes in FD, ED, and DD were influenced jointly by latitude and altitude, whereas changes in the other indicators were mainly driven by altitude, with contribution rates between 65.59% and 72.17%. The contribution of FD changes to DD changes was 65.1% for ≥0 ℃ and 68.4% for ≥10 ℃, each exhibiting opposite spatial distribution patterns. Compared with 1960-1989, most indicators—except DD and AIT for ≥0 ℃ and FD for ≥10 ℃—showed significant shifts (in terms of earlier or delayed timing, extended duration, or increased magnitude) during 1990-2019, with more pronounced changes at the ≥0 ℃ threshold. Furthermore, the contribution of FD change to DD change decreased by 2.3% for ≥0 ℃ but increased by 15.2% for ≥10 ℃. Spatially, the variation in contribution rates exhibited a“higher-lower-higher”pattern along the south-to-west axis and a contrast with higher values in the southeast and lower in the northwest. Overall, the integrated temperature indicators for both thresholds on the LP show significant responses to climate warming, with distinct regional and temporal characteristics.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： Using hourly precipitation data collected from automatic weather stations (AWS) in eastern Gansu Province during the summer months from 2010 to 2021, a total of 50 regional heavy rain showers were identified.An analysis was then conducted to examine the spatiotemporal distribution and intensity of such events in eastern Gansu Province. The obtained results can be summarized as follows: (1) The intensity of the heavy rain showers primarily ranged between 20 and 30 mm·h- 1, which accounted for more than 60% of such events. Intensities exceeding 40 mm·h−1 represented less than 10% of such events. Notably, short bouts of intense precipitation with in-tensities exceeding 50 mm·h−1 occurred in 74% of the heavy rain showers in the studied region. (2) In the studied region, heavy rain showers mainly occur from mid-June to late August, peaking in the period from late July to mid-August. While such events occur throughout the year, the interannual variability in their occurrence is significant and closely associated with the position of the Western Pacific subtropical high, the transport of abnormally warm water vapor from the South China Sea or East China Sea, and significant baroclinic features resulting from the interaction of weather systems at mid and low latitudes. (3) The area typically affected by heavy rain showers in eastern Gansu Province accounts for only 3.17% of its total area. However, there are notable regional variations in the spatial distribution of these events, with areas struck by high-intensity rainfall being primarily located in the Taizishan region, the western section of the Qinling Mountain, Liupan Mountain, and Ziwu Mountain. Additionally, areas affected by rainfall of extreme intensity, exceeding 40 mm·h−1, are concentrated in these high-in-cidence centers. (4) There is a clear pattern in the distribution of stations recording heavy rain showers under different circulation patterns. Stations associated with the eastward- moving plateau trough type are dispersed and most abundant. Meanwhile, stations related to the subtropical high’s southwestern airflow type record the lowest median number of such events. Finally, stations experiencing shear between two high-pressure systems are concentrated, while those associated with the northwest airflow type are the least numerous. There was no significant difference in the distribution of the events with heavy rainfall intensity among these circulation types. However,rainfall intensities between 30 and 50 mm·h−1 are more likely to occur in the two high-shear types.
Subjects: Geosciences >> Geography submitted time 2025-07-14 Cooperative journals: 《干旱区研究》
Abstract： Accurate identification for ecological restoration is essential for promoting sustainable ecological development. Longnan City, as a crucial water source conservation area and ecological security barrier in the upper reaches of the Yangtze River, plays a critical role in maintaining the regional ecological balance. This study used the InVEST model to evaluate ecosystem services and combined the morphological spatial pattern analysis (MSPA) method with circuit theory to construct the ecological security pattern of Longnan City, then analyze its evolution. The results showed: (1) From 2000 to 2022, the number of ecological source areas increased, primarily distributed in the Kang, Hui, and Cheng Counties. The spatial distribution exhibited a pattern of higher density in the south and lower in the north. (2) The average resistance value first decreased then increased, while the length of ecological corridors initially increased and later decreased, with a net reduction of approximately 508.94 km. Spatially, the corridors shifted from central to southeastern regions. (3) Ecological bottleneck areas, primarily dominated by forests, croplands, and grasslands, were concentrated in low-resistance zones. Their total area decreased annually, with a net reduction of about 144.84 km² over the study period. Ecological obstacles also decreased in both number and area, mainly clustered in Wudu, Li, and Tanchang counties. Thus, the research results provide a scientific foundation for the formulation of ecological restoration plans and promotion of high-quality regional economic development in Longnan City. The findings provide scientific support for formulating ecological restoration plans and promoting highquality economic development in Longnan City.
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