Climate change significantly affects the arid/humid processes and patterns in China,directly impacting management decisions related to adaptive agriculture and water resources management,desertification control,and sp...Climate change significantly affects the arid/humid processes and patterns in China,directly impacting management decisions related to adaptive agriculture and water resources management,desertification control,and spatial ecological restoration.However,current studies primarily focus on changes in arid/humid climate variables,lacking quantitative characterization of the dynamic evolution of areal systems and their nonlinear responses.Based on the data of national meteorological stations from 1961 to 2020,we systematically quantified the nonlinear response of arid/humid patterns to climate change.The results revealed that 6.98%of eco-geographical arid/humid regions underwent type shifts over the past six decades,with 4.95%transitioning toward wetter conditions.Humid and semi-arid regions expanded significantly while sub-humid and arid regions contracted significantly.In the late 1990s,trends of the humid and sub-humid region shifted.Humid region contraction in northern China was driven primarily by precipitation decline,whereas the Tibetan Plateau responded to increasing potential evapotranspiration.During the same period,the retreat rate of the arid region slowed,linked to intensified aridification in the west part of northern China and a decelerating wetting trend in northwest China,both primarily driven by precipitation trends.Our study reveals the nonlinear response of the arid/humid patterns under climate change,providing a scientific basis for the improvement of regional climate resilience.展开更多
Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis t...Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.展开更多
Under arid and semi-arid bioclimates,steppes are increasingly threatened by anthropogenic disturbance and climatic variability,which strongly affects ecosystem functioning and subsequently leads to desertification.We ...Under arid and semi-arid bioclimates,steppes are increasingly threatened by anthropogenic disturbance and climatic variability,which strongly affects ecosystem functioning and subsequently leads to desertification.We investigated the morphological and physiological responses of Stipa tenacissima L.across three disturbance levels(undisturbed,slightly disturbed,and highly disturbed)in three Tunisian steppe areas(Kasserine,Sidi Bouzid,and Sfax).Morphological and physiological traits were monitored over one year,together with microclimatic variables.Result showed that disturbance was a strong driver of plant functional dynamics,with significant effects on all traits and strong interactions with site and season.Disturbance reduced photosynthetic activity and water use efficiency,particularly in Sfax,where plants adopted conservative strategies(i.e.,higher leaf dry matter content and reduced leaf area).In contrast,undisturbed populations maintained a stronger coordination between physiological and morphological traits.Seasonal analyses revealed that disturbance amplified physiological stress with limited recovery.Heatmap analyses further showed that disturbance weakened trait coordination and reshaped trade-offs between acquisitive and conservative traits.Partial least squares-path modeling showed that morphology strongly drove physiological performance(path coefficient=0.48).Disturbance(path coefficient=0.41)and tussock cover(path coefficient=0.47)influenced morphology both directly and indirectly through their effects on physiology.In conclusion,S.tenacissima adjusts physiological and morphological traits under disturbance,favoring stress tolerance,while undisturbed sites maintain high physiological efficiency and coordinated trait integration,reflecting a trade-off between survival and performance while overriding local site differences.Disturbance strongly restructures trait networks,drives site-specific adjustments,and modulates the seasonal balance between morphological stability and physiological flexibility.展开更多
This study presents a multi-physical modeling approach to analyze the dynamics of moisture potential and stress-deformation features near deep desiccation cracks in clayey soils under three consecutive years’climate ...This study presents a multi-physical modeling approach to analyze the dynamics of moisture potential and stress-deformation features near deep desiccation cracks in clayey soils under three consecutive years’climate variability in an arid region.A triple research approach of statistical analysis,analytical framework,and numerical modeling was used to investigate the complex thermo-hydro-mechanical behavior of desiccation-cracked soil,incorporating realistic climatic data of Qom,Iran.The results revealed the interplay between stress,strain,and pore water pressure over time,demonstrating that soil experiences significant swelling and shrinkage due to cyclic wetting and drying.The horizontal stress distribution shows compressive stress concentration at crack tips during wetting,transitioning to tensile stresses uniformly across the soil surface during drying paths.Similarly,vertical stress distributions exhibit localized compressive stresses along crack boundaries during wetting and tensile stresses during drying,highlighting the critical stress conditions at crack tips.The model differentiates between microstructural and macrostructural changes in porosity.Annual trends in micro-porosity revealed cyclic-dependent behavior,with significant volumetric changes occurring in the first year,stabilizing with successive cycles.The results also indicated that part of the volumetric changes are irreversible,with volumetric plastic strain increasing exponentially but at a decreasing rate over three years.Principal stress analysis indicates a shift from compressive to tensile stress states around cracks,driven by climate-induced wetting and drying cycles.These findings underscore the critical role of climate variability in shaping cracked soil behavior in arid regions,providing insights into the heterogeneous behavior of cracked soil surfFicial layers.展开更多
Arid and semi-arid ecosystems are prone to extensive fires due to specific climatic conditions,sparse vegetation cover,and high density of fine fuels.Understanding the flammability characteristics of land covers is es...Arid and semi-arid ecosystems are prone to extensive fires due to specific climatic conditions,sparse vegetation cover,and high density of fine fuels.Understanding the flammability characteristics of land covers is essential for fire management and designing land restoration programs in arid and semi-arid ecosystems.This study provided a new approach to evaluate the flammability of shrublands and woodlands using flammability indices(FIs)including time to ignition(TI),duration of combustion(DC),and flame height(FH)of plant species and their relative frequencies in the Dalfard Basin of southeastern Iran.The results showed that there was a significant difference in FIs between land covers.Shrublands had higher flammability potential compared with woodlands.Plant moisture content had a negative relationship with TI(P<0.010)and no significant relationship with DC and FH(P>0.050).Artemisia spp.,Astragalus gossypinus Fischer,Amygdalus scoparia Spach,and Cymbopogon jwarancusa(Jones)Schult.had the highest FI.Tree species such as Rhazya stricta Decne.,and Pistacia atlantica Desf.showed greater resistance to fire.Using principal component analysis,the relationship between species and FIs was examined,and TI of wet fuel was the most important FI in relation to species.Structural equation model showed that life form(P<0.001)was the most important flammability driver.Precipitation(P<0.010)and legume species(P<0.010)were significantly related to the flammability in arid land.This study emphasizes the importance of managing high-risk species and using resistant species in vegetation restoration and shows that combining species FIs with their abundance is an effective tool for assessing fire risk and fuel management at the plant community scale.展开更多
Surface water plays an essential role in the ecohydrological cycle,especially in water-scarce regions.Changes in surface water restrict social,economic,and agricultural development.However,the patterns and underlying ...Surface water plays an essential role in the ecohydrological cycle,especially in water-scarce regions.Changes in surface water restrict social,economic,and agricultural development.However,the patterns and underlying causes of surface water changes over varying frequencies in global arid regions remain unclear.Thus,this study investigated the changes in surface water and the underlying causes using the trend analysis and Spearman correlation coefficient on the basis of multi-source remote sensing and climate datasets across global arid regions during 2000–2020.The surface water was divided into temporary surface water(TSW),seasonal surface water(SSW),and permanent surface water(PSW)by calculating the surface water inundation frequency.Considering that surface water may be influenced by precipitation in the upper basins,we analyzed the response of surface water area to climatic factors at the basin scale.The area of all surface water(ASW)increased dramatically in global arid regions from 2000 to 2020,increasing from 61.88×104 to 67.40×104 km^(2);however,this increase was accompanied by a decrease in surface water inundation frequency.TSW increased by 55.46%relative to its area in 2000,with a net change rate of 3284.00 km^(2)/a.Changes in surface water were predominantly observed in the Kyzylkum Desert in Central Asia,the Thar Desert in southwestern Asia,and the deserts in Oceania.Precipitation had a significant effect on SSW and TSW at the basin scale.The correlation between precipitation and SSW area can reach 0.808 in the Indus River Basin of the Thar Desert(P<0.01).The findings provide a more comprehensive understanding of surface water variability in global arid regions,carrying significant practical implications for the scientific management of surface water at different frequencies.展开更多
High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective he...High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective heat dissipation is critical to prevent performance degradation and structural failure.This study investigates the thermal performance and design optimization of an enhanced HCPV module,integrating numerical,analytical,and experimental methods.A coupled optical-thermal-electrical model was developed to simulate ray tracing,heat transfer,and temperature-dependent electrical behaviour,with predictions validated under real-world desert conditions.Compared to a baseline commercial module operating at 106℃,the optimized design achieved a peak temperature reduction of 16℃,lowering the cell temperature to 90℃under a concentration ratio of 961×and direct normal irradiance(DNI)of 950 W/m^(2).The total thermal resistance was reduced from 0.25 to 0.15 K/W(a 40%improvement),and the electrical efficiency increased from 37.5%to 38.6%,representing a relative gain of approximately 3.1%.The system consistently maintained a fill factor exceeding 78%,underscoring stable performance under high thermal load.These findings demonstrate that targeted thermal design,informed by integrated modeling,is essential for unlocking the reliability and efficiency of high-flux solar energy systems.展开更多
Within the context of global climate change and rapid urbanization,increasing urban resilience(UR)is especially important in the arid region of Northwest China(ANC),where fragile ecosystems and an uneven water distrib...Within the context of global climate change and rapid urbanization,increasing urban resilience(UR)is especially important in the arid region of Northwest China(ANC),where fragile ecosystems and an uneven water distribution create significant sustainability challenges.In this study,a coupled UR-water ecosystem services(WESs)framework was developed on the basis of 1-km resolution remote sensing data for the 2000–2020 period obtained from the Landsat series,Defense Meteorological Satellite Program(DMSP)/Operational Linescan System(OLS),and Global Precipitation Measurement(GPM),among other sources.Within the framework,the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model was incorporated to provide a WES indicator system.Moreover,entropy weighting was employed to quantify both UR and WES indicators;the coupling coordination degree(CCD)model was used to measure the coupled relationship between UR and WESs;an extreme gradient boosting(XGBoost)-SHapley Additive exPlanations(SHAP)interpretation approach was adopted to identify key drivers and underlying mechanisms;and Geographically Weighted Regression(GWR)was applied to capture spatial distribution characteristics of major driving factors.The results indicated that UR steadily increased from 4.60×10^(-3) to 10.24×10^(-3),whereas WESs followed an inverted V-shaped trend,with a peak value observed in 2010(11.84×10^(-3)).The CCD remained consistently low(mean:0.0166–0.0246)and exhibited considerable spatial heterogeneity.Notably,the degree of coordination was greater in the oasis and mountain core areas but significantly lower at desert areas.XGBoost-SHAP model analysis revealed six key drivers influencing various states of the CCD between UR and WESs systems.The contributions of these factors could be ranked as follows:water yield(WY;24.30%)>farmland area per capita(FP;21.10%)>gross domestic product(GDP)per capita(GDPC;19.00%)>soil retention(SR;14.90%)>population density(PD;5.42%)>water purification(WP;4.40%).In contrast,in UR system,WP(53.66%)and SR(31.62%)served as the dominant drivers.Moreover,the dominant drivers shifted from a combination of natural and socioeconomic factors in StateⅠ(sustainable high resilience)to primarily socioeconomic factors in StateⅢ(unsustainable low resilience).SR and WP exerted positive moderating effects,whereas socioeconomic factors such as GDPC and PD exerted inhibitory effects on the coordination relationship.This research highlights that UR in the ANC region is limited mainly by water scarcity,weak feedback loops,and spatial variability,emphasizing the need for tailored intervention strategies.展开更多
Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influenci...Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influencing factors of SM in these areas remains insufficient.This study investigated the spatiotemporal variations and influencing factors of SM in arid and semi-arid areas of China by utilizing the extended triple collation(ETC),Mann-Kendall test,Theil-Sen estimator,ridge regression analysis,and other relevant methods.The following findings were obtained:(1)at the pixel scale,the long-term monthly SM data from the European Space Agency Climate Change Initiative(ESA CCI)exhibited the highest correlation coefficient of 0.794 and the lowest root mean square error(RMSE)of 0.014 m^(3)/m^(3);(2)from 2000 to 2022,the study area experienced significant increase in annual average SM,with a rate of 0.408×10^(-3)m^(3)/(m^(3)•a).Moreover,higher altitudes showed a notable upward trend,with SM increasing rates at 0.210×10^(-3)m^(3)/(m^(3)•a)between 1000 and 2000 m,0.530×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m,and 0.760×10^(-3)m^(3)/(m^(3)•a)at altitudes above 4000 m;(3)land surface temperature(LST),root zone soil moisture(RSM)(10-40 cm depth),and normalized difference vegetation index(NDVI)were identified as the primary factors influencing annual average SM,which accounted for 34.37%,24.16%,and 22.64%relative contributions,respectively;and(4)absolute contribution of LST was more significant in subareas at higher altitudes,with average absolute contributions of 0.800×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m and 0.500×10^(-2) m^(3)/(m^(3)•a)above 4000 m.This study reveals the spatiotemporal variations and main influencing factors of SM in Chinese arid and semi-arid areas,highlighting the more pronounced absolute contribution of LST to SM in high-altitude areas,providing valuable insights for ecological research and water resource management in these areas.展开更多
Arid regions are vital components of Earth’s land surface.Clarifying the area/boundary of arid region is crucial for comprehending area changes and potential mechanisms.However,the accuracy and applicability of arid ...Arid regions are vital components of Earth’s land surface.Clarifying the area/boundary of arid region is crucial for comprehending area changes and potential mechanisms.However,the accuracy and applicability of arid region boundary delineated by different indices remain unclear.In this study,the annual precipitation(AP),humidity index(H),and aridity index(K)were calculated for delineating arid region of China using 106 meteorological stations during 1990–2019.The results suggest that AP and H can accurately delineate arid region,because they are consistent with the distribution of typical soil and vegetation in arid region,whereas K is not.Moreover,AP is the best index for delineating arid region in regions with limited meteorological data,especially in studying long-term patterns and mechanisms of area changes.The accuracy of delineating arid region using H is enhanced in regions with abundant meteorological data.Over the past 30 years,influenced by the increase of atmospheric moisture influx and precipitation,the area in arid region of northwestern China decreased by 70×10^(3)–90×10^(3)km^(2),resulting in the present area of approximately 1.55×10^(6)km^(2).This study provides appropriate indices for delineating arid region,contributing to improving our knowledge of regional responses difference to climate change.展开更多
In the context of global warming,it is anticipated that both the intensity and the frequency of future global extreme high precipitation(EHP)and extreme high temperature(EHT)events will increase.To evaluate the future...In the context of global warming,it is anticipated that both the intensity and the frequency of future global extreme high precipitation(EHP)and extreme high temperature(EHT)events will increase.To evaluate the future extreme climate changes in the Asian arid region and Tibetan Plateau,this study applied the NASA Earth Exchange Global Daily Downscaled Projections(NEX-GDDP-CMIP6)to assess the changes in EHP(Rx5d and R95pTOT)and EHT(TX90p and TXx)under different emission scenarios in the 21st century.Findings suggest that both the frequency and the intensity of the extreme indices will increase,exhibiting accelerated growth under higher emission scenarios,particularly under the SSP5-8.5 emission scenario.It is suggested that the growth of EHT and EHP in the early subperiod of the 21st century(2026-2045)will be relatively moderate,with small differences between different emission scenarios.However,by the middle subperiod of the 21st century(2041-2060),the differences between different emission scenarios will become larger than the 2035s and the growth will become more intense.In western central Asia,TX90p,TXx,Rx5d,and R95pTOT increase by 9.7%-14.2%(13.3%-24.7%),1.3℃-1.7℃(1.6℃-2.7℃),6.5%-8.9%(8.2%-8.8%),and 18.1%-27.0%(25.6%-30.0%)by the early(middle)subperiod;in eastern central Asia,TX90p,TXx,Rx5d,and R95pTOT increase 8.1%-12.0%(11.3%-21.1%),1.4℃-1.8℃(1.9℃-2.9℃),7.4%-9.7%(10.4%-13.8%),and 20.2%-29.3%(32.0%-40.8%)by the early(middle)subperiod;and over the Tibetan Plateau,TX90p,TXx,Rx5d,and R95pTOT increase 12.5%-17.4%(17.0%-31.0%),1.2℃-1.5℃(1.6℃-2.5℃),7.2%-10.0%(9.9%-15.0%),and 26.6%-33.1%(36.1%-55.3%)by the early(middle)subperiod.展开更多
The author affiliation and the funding information in the Acknowledgement section of the online version of the original article was revised.One affiliation(the 8th affiliation)of the first author is added.The Acknowle...The author affiliation and the funding information in the Acknowledgement section of the online version of the original article was revised.One affiliation(the 8th affiliation)of the first author is added.The Acknowledgement section of the original article has been revised to:Acknowledgments:This research was funded by the National University of Mongolia under grant agreement P2023(grant number P2023-4578)and supported by the Chey Institute for Advanced Studies“International Scholarship Exchange Fellowship for the academic year of 2024-2025”,Republic of Korea,and the National University of Mongolia.We would like to acknowledge the National University of Mongolia and Soumik Das from the Center for the Study of Regional Development,Jawaharlal Nehru University,New Delhi-110067,for his valuable assistance in preparing the geological maps.展开更多
The article examines the impact of increased aridization of the territory due to an increase in air temperature,reduced precipitation,and the formation of moisture deficiency on grain yields in Northern Kazakhstan.The...The article examines the impact of increased aridization of the territory due to an increase in air temperature,reduced precipitation,and the formation of moisture deficiency on grain yields in Northern Kazakhstan.The most important result of the work is the revealed inverse relationship between grain yields and the temperature of the growing season:low-yielding years are associated with high temperatures and droughts,and high-yielding years are associated with lower temperatures and an optimal ratio of heat and moisture.The novelty of this study is the use of the method of hydrological and climatic calculations in identifying the nature of temperature variability and precipitation in the territory of Northern Kazakhstan for the modern period(1991–2020)compared with the base period(1961–1990).At all the studied meteorological stations,there is a tendency for the average annual temperature and the temperature of the growing season to increase:in the forest-steppe zone with an average warming intensity of 0.3–0.33℃ per decade;in the steppe zone by 0.2–0.43℃ per decade;and in the growing season by 0.2–0.7℃ per decade.The air temperature in the steppe zone is rising more intensively than in the forest-steppe zone,and precipitation in the forest-steppe zone has changed more than in the steppe zone.An increase in the average annual air temperature during the growing season(May–August),combined with a shortage of atmospheric moisture or a constant amount of it,led to an increase in the degree of aridization of the territory,an increase in the frequency of droughts in the steppe zone of Northern Kazakhstan.展开更多
基金National Natural Science Foundation of China,No.42377460。
文摘Climate change significantly affects the arid/humid processes and patterns in China,directly impacting management decisions related to adaptive agriculture and water resources management,desertification control,and spatial ecological restoration.However,current studies primarily focus on changes in arid/humid climate variables,lacking quantitative characterization of the dynamic evolution of areal systems and their nonlinear responses.Based on the data of national meteorological stations from 1961 to 2020,we systematically quantified the nonlinear response of arid/humid patterns to climate change.The results revealed that 6.98%of eco-geographical arid/humid regions underwent type shifts over the past six decades,with 4.95%transitioning toward wetter conditions.Humid and semi-arid regions expanded significantly while sub-humid and arid regions contracted significantly.In the late 1990s,trends of the humid and sub-humid region shifted.Humid region contraction in northern China was driven primarily by precipitation decline,whereas the Tibetan Plateau responded to increasing potential evapotranspiration.During the same period,the retreat rate of the arid region slowed,linked to intensified aridification in the west part of northern China and a decelerating wetting trend in northwest China,both primarily driven by precipitation trends.Our study reveals the nonlinear response of the arid/humid patterns under climate change,providing a scientific basis for the improvement of regional climate resilience.
基金Under the auspices of the General Project of Science and Technology Department of Shaanxi Province(No.2023-JCYB-264)General Program of National Natural Science Foundation of China(No.41801004,42371008,42471012)。
文摘Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.
基金supported by the Tunisian Ministry of Higher Education and Scientific Research,Research General Direction,Excellence Project(21P2ES-D1P3)the International Foundation for Science(IFS)(I1-D-6596-1).
文摘Under arid and semi-arid bioclimates,steppes are increasingly threatened by anthropogenic disturbance and climatic variability,which strongly affects ecosystem functioning and subsequently leads to desertification.We investigated the morphological and physiological responses of Stipa tenacissima L.across three disturbance levels(undisturbed,slightly disturbed,and highly disturbed)in three Tunisian steppe areas(Kasserine,Sidi Bouzid,and Sfax).Morphological and physiological traits were monitored over one year,together with microclimatic variables.Result showed that disturbance was a strong driver of plant functional dynamics,with significant effects on all traits and strong interactions with site and season.Disturbance reduced photosynthetic activity and water use efficiency,particularly in Sfax,where plants adopted conservative strategies(i.e.,higher leaf dry matter content and reduced leaf area).In contrast,undisturbed populations maintained a stronger coordination between physiological and morphological traits.Seasonal analyses revealed that disturbance amplified physiological stress with limited recovery.Heatmap analyses further showed that disturbance weakened trait coordination and reshaped trade-offs between acquisitive and conservative traits.Partial least squares-path modeling showed that morphology strongly drove physiological performance(path coefficient=0.48).Disturbance(path coefficient=0.41)and tussock cover(path coefficient=0.47)influenced morphology both directly and indirectly through their effects on physiology.In conclusion,S.tenacissima adjusts physiological and morphological traits under disturbance,favoring stress tolerance,while undisturbed sites maintain high physiological efficiency and coordinated trait integration,reflecting a trade-off between survival and performance while overriding local site differences.Disturbance strongly restructures trait networks,drives site-specific adjustments,and modulates the seasonal balance between morphological stability and physiological flexibility.
基金support provided by the Research Grant Office at Sharif University Technology by way of grants G4010902 and QB020105 is gratefully acknowledged.
文摘This study presents a multi-physical modeling approach to analyze the dynamics of moisture potential and stress-deformation features near deep desiccation cracks in clayey soils under three consecutive years’climate variability in an arid region.A triple research approach of statistical analysis,analytical framework,and numerical modeling was used to investigate the complex thermo-hydro-mechanical behavior of desiccation-cracked soil,incorporating realistic climatic data of Qom,Iran.The results revealed the interplay between stress,strain,and pore water pressure over time,demonstrating that soil experiences significant swelling and shrinkage due to cyclic wetting and drying.The horizontal stress distribution shows compressive stress concentration at crack tips during wetting,transitioning to tensile stresses uniformly across the soil surface during drying paths.Similarly,vertical stress distributions exhibit localized compressive stresses along crack boundaries during wetting and tensile stresses during drying,highlighting the critical stress conditions at crack tips.The model differentiates between microstructural and macrostructural changes in porosity.Annual trends in micro-porosity revealed cyclic-dependent behavior,with significant volumetric changes occurring in the first year,stabilizing with successive cycles.The results also indicated that part of the volumetric changes are irreversible,with volumetric plastic strain increasing exponentially but at a decreasing rate over three years.Principal stress analysis indicates a shift from compressive to tensile stress states around cracks,driven by climate-induced wetting and drying cycles.These findings underscore the critical role of climate variability in shaping cracked soil behavior in arid regions,providing insights into the heterogeneous behavior of cracked soil surfFicial layers.
文摘Arid and semi-arid ecosystems are prone to extensive fires due to specific climatic conditions,sparse vegetation cover,and high density of fine fuels.Understanding the flammability characteristics of land covers is essential for fire management and designing land restoration programs in arid and semi-arid ecosystems.This study provided a new approach to evaluate the flammability of shrublands and woodlands using flammability indices(FIs)including time to ignition(TI),duration of combustion(DC),and flame height(FH)of plant species and their relative frequencies in the Dalfard Basin of southeastern Iran.The results showed that there was a significant difference in FIs between land covers.Shrublands had higher flammability potential compared with woodlands.Plant moisture content had a negative relationship with TI(P<0.010)and no significant relationship with DC and FH(P>0.050).Artemisia spp.,Astragalus gossypinus Fischer,Amygdalus scoparia Spach,and Cymbopogon jwarancusa(Jones)Schult.had the highest FI.Tree species such as Rhazya stricta Decne.,and Pistacia atlantica Desf.showed greater resistance to fire.Using principal component analysis,the relationship between species and FIs was examined,and TI of wet fuel was the most important FI in relation to species.Structural equation model showed that life form(P<0.001)was the most important flammability driver.Precipitation(P<0.010)and legume species(P<0.010)were significantly related to the flammability in arid land.This study emphasizes the importance of managing high-risk species and using resistant species in vegetation restoration and shows that combining species FIs with their abundance is an effective tool for assessing fire risk and fuel management at the plant community scale.
基金supported by the National Key Research and Development Program of China(2023YFC3208701)the Fundamental Research Funds for the Central Universities(B210201035).
文摘Surface water plays an essential role in the ecohydrological cycle,especially in water-scarce regions.Changes in surface water restrict social,economic,and agricultural development.However,the patterns and underlying causes of surface water changes over varying frequencies in global arid regions remain unclear.Thus,this study investigated the changes in surface water and the underlying causes using the trend analysis and Spearman correlation coefficient on the basis of multi-source remote sensing and climate datasets across global arid regions during 2000–2020.The surface water was divided into temporary surface water(TSW),seasonal surface water(SSW),and permanent surface water(PSW)by calculating the surface water inundation frequency.Considering that surface water may be influenced by precipitation in the upper basins,we analyzed the response of surface water area to climatic factors at the basin scale.The area of all surface water(ASW)increased dramatically in global arid regions from 2000 to 2020,increasing from 61.88×104 to 67.40×104 km^(2);however,this increase was accompanied by a decrease in surface water inundation frequency.TSW increased by 55.46%relative to its area in 2000,with a net change rate of 3284.00 km^(2)/a.Changes in surface water were predominantly observed in the Kyzylkum Desert in Central Asia,the Thar Desert in southwestern Asia,and the deserts in Oceania.Precipitation had a significant effect on SSW and TSW at the basin scale.The correlation between precipitation and SSW area can reach 0.808 in the Indus River Basin of the Thar Desert(P<0.01).The findings provide a more comprehensive understanding of surface water variability in global arid regions,carrying significant practical implications for the scientific management of surface water at different frequencies.
基金funded by King Abdullah City for Atomic and Renewable Energy(KACARE),grant number“PC-2020-1”.
文摘High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective heat dissipation is critical to prevent performance degradation and structural failure.This study investigates the thermal performance and design optimization of an enhanced HCPV module,integrating numerical,analytical,and experimental methods.A coupled optical-thermal-electrical model was developed to simulate ray tracing,heat transfer,and temperature-dependent electrical behaviour,with predictions validated under real-world desert conditions.Compared to a baseline commercial module operating at 106℃,the optimized design achieved a peak temperature reduction of 16℃,lowering the cell temperature to 90℃under a concentration ratio of 961×and direct normal irradiance(DNI)of 950 W/m^(2).The total thermal resistance was reduced from 0.25 to 0.15 K/W(a 40%improvement),and the electrical efficiency increased from 37.5%to 38.6%,representing a relative gain of approximately 3.1%.The system consistently maintained a fill factor exceeding 78%,underscoring stable performance under high thermal load.These findings demonstrate that targeted thermal design,informed by integrated modeling,is essential for unlocking the reliability and efficiency of high-flux solar energy systems.
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01B109)the Tianchi Doctoral Program of Xinjiang Uygur Autonomous Region(BS2021007).
文摘Within the context of global climate change and rapid urbanization,increasing urban resilience(UR)is especially important in the arid region of Northwest China(ANC),where fragile ecosystems and an uneven water distribution create significant sustainability challenges.In this study,a coupled UR-water ecosystem services(WESs)framework was developed on the basis of 1-km resolution remote sensing data for the 2000–2020 period obtained from the Landsat series,Defense Meteorological Satellite Program(DMSP)/Operational Linescan System(OLS),and Global Precipitation Measurement(GPM),among other sources.Within the framework,the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model was incorporated to provide a WES indicator system.Moreover,entropy weighting was employed to quantify both UR and WES indicators;the coupling coordination degree(CCD)model was used to measure the coupled relationship between UR and WESs;an extreme gradient boosting(XGBoost)-SHapley Additive exPlanations(SHAP)interpretation approach was adopted to identify key drivers and underlying mechanisms;and Geographically Weighted Regression(GWR)was applied to capture spatial distribution characteristics of major driving factors.The results indicated that UR steadily increased from 4.60×10^(-3) to 10.24×10^(-3),whereas WESs followed an inverted V-shaped trend,with a peak value observed in 2010(11.84×10^(-3)).The CCD remained consistently low(mean:0.0166–0.0246)and exhibited considerable spatial heterogeneity.Notably,the degree of coordination was greater in the oasis and mountain core areas but significantly lower at desert areas.XGBoost-SHAP model analysis revealed six key drivers influencing various states of the CCD between UR and WESs systems.The contributions of these factors could be ranked as follows:water yield(WY;24.30%)>farmland area per capita(FP;21.10%)>gross domestic product(GDP)per capita(GDPC;19.00%)>soil retention(SR;14.90%)>population density(PD;5.42%)>water purification(WP;4.40%).In contrast,in UR system,WP(53.66%)and SR(31.62%)served as the dominant drivers.Moreover,the dominant drivers shifted from a combination of natural and socioeconomic factors in StateⅠ(sustainable high resilience)to primarily socioeconomic factors in StateⅢ(unsustainable low resilience).SR and WP exerted positive moderating effects,whereas socioeconomic factors such as GDPC and PD exerted inhibitory effects on the coordination relationship.This research highlights that UR in the ANC region is limited mainly by water scarcity,weak feedback loops,and spatial variability,emphasizing the need for tailored intervention strategies.
基金supported by the Natural Science Foundation of Henan Province(252300421290)the National Natural Science Foundation of China(41771438)+1 种基金the Program for Innovative Research Team(in Science and Technology)of Henan University(22IRTSTHN010)the Postgraduate Education Reform and Quality Improvement Project of Henan Province(HNYJS2020JD14).
文摘Soil moisture(SM)is a critical variable in terrestrial ecosystems,especially in arid and semi-arid areas where water sources are limited.Despite its importance,understanding the spatiotemporal variations and influencing factors of SM in these areas remains insufficient.This study investigated the spatiotemporal variations and influencing factors of SM in arid and semi-arid areas of China by utilizing the extended triple collation(ETC),Mann-Kendall test,Theil-Sen estimator,ridge regression analysis,and other relevant methods.The following findings were obtained:(1)at the pixel scale,the long-term monthly SM data from the European Space Agency Climate Change Initiative(ESA CCI)exhibited the highest correlation coefficient of 0.794 and the lowest root mean square error(RMSE)of 0.014 m^(3)/m^(3);(2)from 2000 to 2022,the study area experienced significant increase in annual average SM,with a rate of 0.408×10^(-3)m^(3)/(m^(3)•a).Moreover,higher altitudes showed a notable upward trend,with SM increasing rates at 0.210×10^(-3)m^(3)/(m^(3)•a)between 1000 and 2000 m,0.530×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m,and 0.760×10^(-3)m^(3)/(m^(3)•a)at altitudes above 4000 m;(3)land surface temperature(LST),root zone soil moisture(RSM)(10-40 cm depth),and normalized difference vegetation index(NDVI)were identified as the primary factors influencing annual average SM,which accounted for 34.37%,24.16%,and 22.64%relative contributions,respectively;and(4)absolute contribution of LST was more significant in subareas at higher altitudes,with average absolute contributions of 0.800×10^(-3)m^(3)/(m^(3)•a)between 2000 and 4000 m and 0.500×10^(-2) m^(3)/(m^(3)•a)above 4000 m.This study reveals the spatiotemporal variations and main influencing factors of SM in Chinese arid and semi-arid areas,highlighting the more pronounced absolute contribution of LST to SM in high-altitude areas,providing valuable insights for ecological research and water resource management in these areas.
基金supported by the National Natural Science Foundation of China(Nos.42271003,42301001)the Fundamental Research Funds for the Central Universities(No.lzujbky-2022-ey09)+1 种基金the China Postdoctoral Science Foundation(No.GZB20230275)Supercomputing Center of Lanzhou University。
文摘Arid regions are vital components of Earth’s land surface.Clarifying the area/boundary of arid region is crucial for comprehending area changes and potential mechanisms.However,the accuracy and applicability of arid region boundary delineated by different indices remain unclear.In this study,the annual precipitation(AP),humidity index(H),and aridity index(K)were calculated for delineating arid region of China using 106 meteorological stations during 1990–2019.The results suggest that AP and H can accurately delineate arid region,because they are consistent with the distribution of typical soil and vegetation in arid region,whereas K is not.Moreover,AP is the best index for delineating arid region in regions with limited meteorological data,especially in studying long-term patterns and mechanisms of area changes.The accuracy of delineating arid region using H is enhanced in regions with abundant meteorological data.Over the past 30 years,influenced by the increase of atmospheric moisture influx and precipitation,the area in arid region of northwestern China decreased by 70×10^(3)–90×10^(3)km^(2),resulting in the present area of approximately 1.55×10^(6)km^(2).This study provides appropriate indices for delineating arid region,contributing to improving our knowledge of regional responses difference to climate change.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program[grant number 2019QZKK0101]。
文摘In the context of global warming,it is anticipated that both the intensity and the frequency of future global extreme high precipitation(EHP)and extreme high temperature(EHT)events will increase.To evaluate the future extreme climate changes in the Asian arid region and Tibetan Plateau,this study applied the NASA Earth Exchange Global Daily Downscaled Projections(NEX-GDDP-CMIP6)to assess the changes in EHP(Rx5d and R95pTOT)and EHT(TX90p and TXx)under different emission scenarios in the 21st century.Findings suggest that both the frequency and the intensity of the extreme indices will increase,exhibiting accelerated growth under higher emission scenarios,particularly under the SSP5-8.5 emission scenario.It is suggested that the growth of EHT and EHP in the early subperiod of the 21st century(2026-2045)will be relatively moderate,with small differences between different emission scenarios.However,by the middle subperiod of the 21st century(2041-2060),the differences between different emission scenarios will become larger than the 2035s and the growth will become more intense.In western central Asia,TX90p,TXx,Rx5d,and R95pTOT increase by 9.7%-14.2%(13.3%-24.7%),1.3℃-1.7℃(1.6℃-2.7℃),6.5%-8.9%(8.2%-8.8%),and 18.1%-27.0%(25.6%-30.0%)by the early(middle)subperiod;in eastern central Asia,TX90p,TXx,Rx5d,and R95pTOT increase 8.1%-12.0%(11.3%-21.1%),1.4℃-1.8℃(1.9℃-2.9℃),7.4%-9.7%(10.4%-13.8%),and 20.2%-29.3%(32.0%-40.8%)by the early(middle)subperiod;and over the Tibetan Plateau,TX90p,TXx,Rx5d,and R95pTOT increase 12.5%-17.4%(17.0%-31.0%),1.2℃-1.5℃(1.6℃-2.5℃),7.2%-10.0%(9.9%-15.0%),and 26.6%-33.1%(36.1%-55.3%)by the early(middle)subperiod.
文摘The author affiliation and the funding information in the Acknowledgement section of the online version of the original article was revised.One affiliation(the 8th affiliation)of the first author is added.The Acknowledgement section of the original article has been revised to:Acknowledgments:This research was funded by the National University of Mongolia under grant agreement P2023(grant number P2023-4578)and supported by the Chey Institute for Advanced Studies“International Scholarship Exchange Fellowship for the academic year of 2024-2025”,Republic of Korea,and the National University of Mongolia.We would like to acknowledge the National University of Mongolia and Soumik Das from the Center for the Study of Regional Development,Jawaharlal Nehru University,New Delhi-110067,for his valuable assistance in preparing the geological maps.
文摘The article examines the impact of increased aridization of the territory due to an increase in air temperature,reduced precipitation,and the formation of moisture deficiency on grain yields in Northern Kazakhstan.The most important result of the work is the revealed inverse relationship between grain yields and the temperature of the growing season:low-yielding years are associated with high temperatures and droughts,and high-yielding years are associated with lower temperatures and an optimal ratio of heat and moisture.The novelty of this study is the use of the method of hydrological and climatic calculations in identifying the nature of temperature variability and precipitation in the territory of Northern Kazakhstan for the modern period(1991–2020)compared with the base period(1961–1990).At all the studied meteorological stations,there is a tendency for the average annual temperature and the temperature of the growing season to increase:in the forest-steppe zone with an average warming intensity of 0.3–0.33℃ per decade;in the steppe zone by 0.2–0.43℃ per decade;and in the growing season by 0.2–0.7℃ per decade.The air temperature in the steppe zone is rising more intensively than in the forest-steppe zone,and precipitation in the forest-steppe zone has changed more than in the steppe zone.An increase in the average annual air temperature during the growing season(May–August),combined with a shortage of atmospheric moisture or a constant amount of it,led to an increase in the degree of aridization of the territory,an increase in the frequency of droughts in the steppe zone of Northern Kazakhstan.
