To investigate the spatiotemporal variations and influencing factors of carbon sources/sinks across dif-ferent ecosystem types on the Loess Plateau region,this study estimated NEP of seven ecosystem types in the re-gion from 2001 to 2024.Ridge regression,Theil-Sen median trend analysis,Mann-Kendall significance test,and centroid shift analysis were used to explore the spatiotemporal changes in NEP and the contributions of influenc-ing factors.The results showed that from 2001 to 2024,NEP on Loess Plateau exhibited an overall upward trend,with higher values in the southeast and lower values in the northwest.NEP increased significantly across all eco-systems,with the forest ecosystem showing the largest increase at a rate of 5.61 g C·m-2.The normalized differ-ence vegetation index and LAI were identified as the dominant factors influencing NEP on the Loess Plateau.The relative contribution of normalized difference vegetation index to NEP exceeded 49％across all ecosystem types,whereas the LAI contributed more than 18％.Precipitation,evapotranspiration,and temperature had relatively mi-nor impacts(relative contributions 5.96％,4.71％and 4.23％,respectively).In summary,significant differences exist in the NEP trends and the contributions of influencing factors among different ecosystem types on the Loess Plateau.NDVI and LAI are the dominant drivers,while the contributions of precipitation,evapotranspiration,and temperature are relatively limited.
Against the backdrop of rapid urbanization,ecological and environmental pressures are intensifying,making the coordination between economic development and ecological conservation a critical issue for regional sustainability.As a key ecological security barrier and economic growth corridor in Northwest China,the ecologi-cal condition of the urban agglomeration in the northern slope of the Tianshan Mountains is of great significance for regional sustainable development.Existing studies have primarily focused on ecological value accounting in agro-pastoral transition zones,while research at the scale of oasis-based urban agglomerations in arid regions re-mains limited,particularly in capturing the spatial heterogeneity of vegetation.To address this gap,this study inte-grates agricultural production statistics with actual regional vegetation characteristics to revise ecosystem service value(ESV)equivalent factors.Net primary productivity(NPP)and the normalized difference vegetation index(NDVI)are further incorporated for secondary refinement.Based on these improvements,priority areas for eco-logical compensation are identified.The results show that:(1)the comprehensive land-use dynamics in the study area exhibited an overall declining trend from 2000 to 2020,characterized by reductions in bare land and grass-land,alongside increases in other land-use types.(2)the ecosystem service value of the urban agglomeration in the northern slope of the Tianshan Mountains demonstrated a general upward trend over the past 20 years,with an average value of 1176×108 yuan,and high-value areas mainly concentrated in high-altitude forest regions.(3)areas with higher priority for ecological compensation are primarily located in Dabancheng District,Mulei Ka-zakh Autonomous County,and Urumqi County.These findings provide a scientific basis for delineating priority ecological compensation zones and promoting the coordinated advancement of ecological conservation and high-quality development in the urban agglomeration in the northern slope of the Tianshan Mountains.
To address the accuracy limitations of conventional remote sensing approaches for water body extrac-tion in desert environments,which are commonly affected by mixed pixels and boundary blurring,this study pro-poses a desert water extraction model that integrates the normalized suspended material index(NSMI)with the multi-index collaborative water extraction method(MICWE),termed MICWE-NSMI.The Ulan Buh Desert was selected as the study area,and Landsat 8 OLI surface reflectance imagery from 2020 was used.Image preprocess-ing,including cloud removal,radiometric calibration,atmospheric correction,maximum value compositing,and index calculation,was performed on the Google Earth Engine platform.A 30 m buffer zone was constructed along the preliminary water boundaries extracted by MICWE,within which turbid water bodies were further re-fined by combining inverted NSMI with Otsu adaptive threshold segmentation.A comparison with Sentinel 2 im-agery validation results indicates that the proposed MICWE-NSMI model significantly improved the boundary in-tegrity and connectivity of highly turbid waters,narrow tributaries,and flowing water bodies,with an overall ac-curacy of 93.7%and a Kappa coefficient of 0.82.Compared with conventional index-based methods,the deep learning-based ResUNet model,and the Joint Research Centre global surface water dataset,the proposed model effectively reduces water body fragmentation and misclassification in complex scenarios,including lakes in des-ert hinterlands,irrigation tributaries,and the Yellow River channel.By integrating conventional water body indi-ces with the spatial heterogeneity of suspended sediment,this study expands the methodological framework for remote sensing identification of highly turbid,fragmented,narrow,and dynamic water bodies,providing a new technical pathway for desert and arid-region water resource monitoring.
The characteristics of desert plantcommunities are comprehensively influenced byfactors such as arid environment,soil conditions,and groundwater depth,presenting unique structural and functional traits.Through field quadrat surveys and diversity index analysis,this study reveals the response mechanism of desert plant com-munity characteristics to groundwater depth and their ecological thresholds.The results show that:(1)The con-structive species,Tamarix and Populus,have the highest occurrence frequencies across different groundwater depths,accounting for 34%and 19%respectively.Within the groundwater depth range of 3.77-5.99 m,the aver-age coverage of the shrub layer reaches 42.7%,which is significantly higher than that in other intervals(P<0.05).(2)The Shannon-Wiener index reaches its peak value of 0.76 in this interval;meanwhile,the Simpson dominance index of the perennial herb layer decreases.This indicates that the groundwater depth of 4 m is the critical thresh-old for the community structure to shift from a"single arbor"pattern to a"arbor-shrub-herb"tripartite symbiotic pattern.(3)The community-weighted mean(CWM)of the average height of shrubs shows a non-linear decreas-ing trend with increasing groundwater depth,dropping from 2.7 m to 1.0 m.This phenomenon suggests that plants achieve morphological adaptation to water stress by adjusting their height.(4)Soil physical and chemical properties,together with groundwater depth,jointly affect the community characteristics.Among them,herbs are significantly influenced by soil physical and chemical properties(P<0.05).
Understanding the mechanisms by which vegetation-change trends respond to their driving factors is important for environmental resource management,particularly in ecologically fragile regions.In this study,vege-tation cover on the Loess Plateau is analyzed in terms of the normalized difference vegetation index(NDVI),us-ing precipitation and temperature as the climatic factors.Land use,nighttime light remote sensing,and population density data are integrated to establish a human activity intensity(HAI)index.Trend analysis and partial deriva-tives revealed the spatiotemporal characteristics of NDVI changes on the Loess Plateau from 2001 to 2022 in dif-ferent ecological subregions and on the regional scale.The precipitation,temperature,and HAI contributions to the NDVI changes were quantified and the dominant factors driving the vegetation cover changes were explored.The key findings reveal that(1)the NDVI has been steadily increasing at 0.0049 per year,indicating good vegeta-tion recovery on the Loess Plateau over the past 22 years.(2)The precipitation,temperature,and HAI contributed(on average)0.0947%·a-1,0.0643%·a-1,and 0.1083%·a-1 to the NDVI changes,respectively,in the study area.(3)The NDVI increase on the Loess Plateau is primarily driven by the combined effects of climate and human ac-tivity,with climate factors playing a secondary role.Monitoring the impact of climate change on vegetation and strengthening the management of human activities are essential for promoting sustainable ecological restoration and environmental protection strategies on the Loess Plateau.
To assess the agricultural water consumption in the inland river basin of Hexi,based on the water foot-print theory,the spatio-temporal evolution characteristics of the agricultural water footprint in this basin from 2011 to 2023 were analyzed.The multi-objective programming and LMDI model were used to analyze the plant-ing structure and its influencing factors.The results show that the agricultural water footprint has been on the rise during the study period,with an average annual growth rate of 3.8%.Structurally,food crops(49.3%),economic crops(27.8%),and livestock products(22.5%)are the main components,while aquatic products account for a rel-atively small proportion(0.4%).After optimizing the planting structure of seven typical crops,the planting areas of wheat,corn,tubers,and oil crops decreased by 3.89×104 hm2,6.11×104 hm2,1.19×104 hm2,and 0.91×104 hm2 respectively,while the areas of Chinese herbal medicines,vegetables,and garden fruits increased by 1.75×104 hm2,4.77×104 hm2,and 0.98×104 hm2 respectively.This optimization reduced the agricultural water footprint by 6.68×108 m3 and increased the economic benefits by 6.75×108 yuan.The analysis of influencing factors shows that eco-nomic factors play a major positive driving role in the growth of agricultural water footprint(contribution rate 58%),while technological(24.7%)and population factors(17.3%)have an inhibitory effect.The research pro-vides a scientific basis for the efficient utilization and sustainable development of agricultural water resources in the basin.
The ecological security pattern is an important foundation for enhancing human well-being and main-taining sustainable regional development.Using the ecologically sensitive and ecological transition zone of Shaanxi,Gansu,and Ningxia Provinces as the research object,we constructed the research framework of"match-ing supply and demand-pattern analysis-optimization and restructuring,"used the InVEST model and the compre-hensive parameters of supply and demand to assess the dynamic changes of the relationship between supply and demand for ecosystem services,and analyzed the characteristics of ecological security patterns in combination with the circuit theory to propose optimization and restructuring strategies.The supply and demand of ecosystem services in the Shanxi-Gansu-Ningxia region has significant spatial and temporal variations,including an overall oversupply and a local imbalance.From 2000 to 2020,the ecological source area followed the pattern of central-ized and continuous distribution from north to south.The number of ecological corridors and ecological pinch points decreased and then increased,and the length of the area of the corridors continued to shrink.The number of ecological barrier points increased by 49,and the area increased by 588.66 km2.Based on the spatial and tem-poral characteristics of ecosystem service supply-demand relationship and ecological security patterns in the Shanxi-Gansu-Ningxia region,the proposed ecological security pattern construction and optimization strategy of"one axis and one point"and"two screens and multiple zones"can be used to formulate a regional ecological se-curity pattern and optimization strategy.The proposed ecological security pattern construction and optimization strategy can provide a scientific basis and methodological reference for the formulation of regional ecological pro-tection planning and future sustainable development.
Central Asia,as one of the world's typical arid and semiarid regions,experiences soil moisture varia-tions that profoundly impact regional ecological security and sustainable agricultural development.This study em-ploys ERA5 reanalysis data and soil moisture data derived from the SiTHv2 model,integrating trend analysis and abrupt change detection methods,to reveal the spatiotemporal evolution patterns of soil moisture at different depths across Central Asia from 1982 to 2022.The results indicate the following.(1)Overall soil moisture across the region exhibits a notable downward trend,with the mid-depth layer(ERA5 data:7-28 cm,Slope=-4.354×10-4)exhibiting a steeper decline than the surface layer(ERA5 data:0-7 cm,Slope=-4.217×10-4).(2)Spatially,soil moisture exhibited a"higher in the north,lower in the south"distribution pattern.Soil moisture loss was more se-vere in the arid and semiarid zones.Based on ERA5 data,the proportion of areas with notable surface soil mois-ture decline reached 52.6％.As soil depth increased,the region with notable moisture decline gradually expanded eastward,with the proportion of areas showing notable decline in deep soil layers increasing to 58.3％.(3)Inter-annual variability in soil moisture differed across arid zones and land types.From arid to humid regions,interan-nual fluctuations in surface soil moisture gradually diminished.Irrigated agricultural areas exhibited relatively sta-ble surface soil moisture changes,whereas natural vegetation zones exhibited increased decline rates and higher dispersion.This study aims to provide scientific support for precise drought risk prevention and control,as well as adaptive ecosystem management in Central Asia.
Panzerina lanata holds significant medicinal and ecological value,contributing to both human health and ecosystem balance.In this study,to investigate the suitable habitat distribution patterns of this species and its response to future climate change,we employed the MaxEnt model to simulate and predict the species'suitable habitats and their dynamic changes under current and future(2041-2060,2081-2100)climate change scenarios.The analysis included 86 natural distribution points and 20 environmental variables.We assessed the importance of key environmental factors by combining comprehensive contribution rates with the jackknife method.Addi-tionally,we simulated the dispersal pathways of P.lanata using the least-cost path method using chloroplast hap-lotype data from 27 populations and distribution model simulation data from different periods.The results were as follows:(1)The primary environmental factors affecting the geographical distribution of P.lanata are the maxi-mum temperature of the warmest month,elevation,precipitation of the wettest month,and temperature seasonality.(2)Under current climate conditions,the potential highly suitable area for P.lanatain China covers approximately 21.04×104 km2,mainly distributed in Ulanqab,Ordos,and eastern Alxa in Inner Mongolia as well as northern Ningxia,northern Shaanxi,and parts of Gansu Province.(3)Under two typical climate scenarios based on con-centration pathways(SSP1-2.6 and SSP5-8.5)in the future(2081-2100),both total suitable areas and highly suitable areas of P.lanata showed an increasing trend,with the core distribution remaining in the Inner Mongolia.The east-west corridor along the northern fringe of the Mu Us Sandy Land emerged as a crucial dispersal path-way of P.lanata during population migration,with the strongest connectivity between populations in the Alxa Left Banner and Ordos regions.
Soil texture is a key parameter affecting the accuracy of land surface hydrological simulation.Investi-gating the applicability of different soil textures to soil moisture simulation is an effective approach to improve the precision of regional land surface hydrological simulation and gridded drought and flood monitoring.On the basis of five latest domestic and international soil texture datasets and the Inner Mongolia Land Data Assimila-tion System(IMLDAS),five soil moisture simulation experiments corresponding to the five soil texture datasets were designed,and five soil moisture simulation datasets were implemented.Using daily surface soil(0-10 cm)moisture observation data from 63 national meteorological stations in the Inner Mongolia Autonomous Region from May to September from 2016 to 2020,the applicability of the five simulated soil moisture datasets was sys-tematically evaluated.The results were as follows:(1)Soil texture datasets of the Food and Agriculture Organiza-tion of the United Nations(FAO)and Chinese Academy of Sciences(CAS)differed considerably from those of Beijing Normal University(BNU),Global Soil Dataset for use in Earth System Models(GSDE),and the Second National Soil Survey on China(SNSS)in space.The soil texture datasets of the SNSS,BNU,and GSDE better characterized the higher sand content and lower clay content in the four sandy lands and three desert areas of the Inner Mongolia Autonomous Region.(2)Compared with the observed soil moisture data,the spatial distribution characteristics of soil moisture from northeast to southwest in the Inner Mongolia Autonomous Region was well reproduced by the five soil moisture simulation experiments and the China Meteorological Administration Land Data Assimilation System(CLDAS)simulations of soil moisture,but there was an overestimation among them.Moreover,the trend of observed soil moisture with time was reflected well by all simulations.The soil moisture simulated from the SNSS experiment performed the best in the Inner Mongolia Autonomous Region and its three climatic zones,as it was the most consistent with the observed spatial distribution.(3)The five simulation datas-ets and CLDAS simulations of soil moisture in the Inner Mongolia Autonomous Region and its three climatic sub-regions had extremely significant temporal correlation with the observed soil moisture.The mean absolute error(MAE)and root mean square error(RMSE)of soil moisture simulated by the FAO and CLDAS were relatively large.Moreover,the MAE,RMSE and Kling-Gupta efficiency coefficient values of soil moisture simulated from the SNSS experiment were the best,followed by those corresponding to the BNU,CAS,and GSDE experiments,which were significantly better than those corresponding to the FAO and CLDAS soil moisture simulations.In conclusion,the SNSS simulation of soil moisture in the Inner Mongolia Autonomous Region and its three climat-ic sub-regions showed higher accuracy,and the applicability of SNSS soil texture was the best.Notably,the appli-cability of all simulated soil moisture datasets in the arid area was worse than that in other areas.
The wide valley wind erosion area in the middle and lower reaches of the Yarlung Zangbo River is one of the areas with the most frequent wind-sand activities in the Qinghai-Xizang Plateau.Therefore,it is of great significance to study the sand emission law of different underlying surface in this area during the wind-sand sea-son for windbreak and sand fixation and sustainable development of the ecological environment.In this study,four typical underlying surfaces in the Linzhi section of the middle and lower reaches of the Yarlung Zangbo Riv-er Basin were identified.The characteristics of wind-sand transport on different underlying surfaces were system-atically revealed through simultaneous observation of the gradient anemometer and multichannel sand sampler.The main findings are summarized as follows.(1)Affected by the surface vegetation,the near-surface wind speed profile conforms to the logarithmic function;however,the parameters are significantly different.(2)The sediment particle size is spatially differentiated.The proportion of silt in the mobile sand land of the river beach(37.93％)was significantly higher than that of the other underlying surfaces,whereas the riparian sand land was dominated by fine-medium sand(83.49％).(3)The sand transport process has significant underlying surface dependence,and the wind-sand flow structure conforms to the exponential-power function composite model.(4)The order of sand transport per unit area in the wind-sand season is riparian sandy land(96.16t·d-1)＞footh ill sandy land(77.65 t·d-1)＞beach sandy land(69.87t·d-1)＞sparse forest land(5.23 t·d-1).
Given oasis degradation and increased human activities in the arid northwest region,quantifying the re-silience of the oasis socioecological system in the Hexi Corridor and uncovering its spatio-temporal differentia-tion patterns have become critical issues in ecological security research for arid areas.This study developed a re-silience assessment index system and conducted a comprehensive analysis of the evolution of resilience within the oasis system in the Hexi Corridor from 2015 to 2023,utilizing the entropy method alongside other relevant ap-proaches.The findings indicate that(1)the resilience of the socioeconomic and resource management subsystems generally increased,rising from 0.36 to 0.46 and from 0.38 to 0.69,respectively.By contrast,the resilience of the ecological state subsystem initially increased,reaching 0.70 in 2021,but then declined to 0.60 in 2023,down from 0.40 in 2015;(2)overall system resilience remained stable but at a relatively low level,with an average score of 0.35;(3)the Theil index across the five cities in the region exhibited an upward trend,with the overall in-dex rising from 0.18 to 0.64.However,it decreased from 0.24 to 0.13 between 2016 and 2017 and from 0.27 to 0.13 between 2018 and 2019;(4)the system's kernel density curve demonstrated a tailing feature,evolving from a"single peak"to a"multipeak"pattern.Finally,the study proposed countermeasures and suggestions focusing on three areas:developing a spatially differentiated intelligent water resource management platform,implement-ing precise early warning systems,and enacting differentiated regulatory measures.
Against the background of ecological protection and high-quality development in the Yellow River Ba-sin,the water ecosystem service functions of the Liupan Mountain area,which is known as the wet island,have become increasingly critical to the arid Loess Plateau.Thus,the study aimed to establish an assessment method for the supply and demand of ecosystem water-yielding services suitable for mountainous regions.This method,combined with the Integrated Valuation of Ecosystem Services and Trade-offs model and a supply-demand match-ing index,was used to systematically evaluate the multidimensional differentiation characteristics of the supply and demand of ecosystem water-yielding services in this region across temporal and spatial dimensions.The re-sults illustrated that in the previous three decades,the supply and demand of ecosystem water-yielding services in the Liupan Mountain area followed a pattern of first decreasing then increasing.The southeastern mountainous ar-ea experienced the most significant change in supply(13.1％),while the northern mountainous area experienced the largest change in demand(-37.1％).The study identified mountainous regions situated above 2000 m as sup-ply zones for ecosystem water-yielding services and areas characterized by high degrees of supply-demand match-ing.Conversely,areas below 2000 m were considered predominantly demand zones.After the year 2000,high-de-mand areas shifted from the north to the southeastern and southwestern mountainous regions,thus forming a spa-tiotemporal distribution pattern of supply-demand matching degrees characterized by high,moderate,and low lev-els in the north,southwest,and southeast,respectively.In conclusion,the supply and demand of ecosystem water-yielding services in the Liupan Mountain area exhibited a multidimensional uneven distribution pattern across spatiotemporal dimensions and vertical zones.Over time and with increasing altitude,the matching degrees of supply and demand in the northern mountainous areas displayed an upward trend before the year 2000 but a downward trend in the southwestern and southeastern mountainous areas.Conversely,after the year 2000,the matching degree in the northern mountainous areas decreased,whereas that in the southwestern and southeastern areas increased.The findings revealed the spatial differentiation law of the supply-demand relationship of water resources in the Liupan Mountain area,which provides a scientific foundation for the optimal allocation of water resources in arid mountainous regions.
To examine the mineralization characteristics and their effect on soil organic carbon components in san-dy loamy soils following the application of organic fertilizers in conjunction with trace elements,indoor culture experiments and field trials were conducted.We assessed the decomposition rate and residue ratio as well as the influence of varying amounts of organic fertilizer on soil organic carbon,active organic carbon,particulate organ-ic carbon,organo-mineral-bound organic carbon,and microbial carbon content,as well as the level of amino sug-ars,N-galactosamine,and galactomannan.Compared with the application of organic fertilizers alone,the addition of trace elements to the indoor culture significantly decreased the amount of mineralized organic carbon in the sandy loam soils.In field trials,this addition further increased active organic carbon(1.79%-1.99%),low-active organic carbon(2.20%-4.91%),organo-mineral-bound organic carbon(3.89%-7.95%),and microbial carbon(1.71%-8.10%)content,while also enhancing the level of amino sugars(3.46%-6.32%),N-galactosamine(1.21%-13.32%),galactomannan(2.41%-6.14%),and microbial residual carbon(2.70%-4.99%).However,the increase was less pronounced for high-active organic carbon(0.71%-1.48%)and particulate organic carbon(4.91%-5.86%)content.The addition of micro and trace elements to organic fertilizers may,to some extent,miti-gate the mineralization process of organic fertilizers in sandy soils,thereby enhancing the level of labile organic carbon,recalcitrant organic carbon,organic carbon bound with minerals,and microbial biomass carbon in the soil,ultimately promoting the turnover and retention of organic carbon in the soil.
Located in the convergence zone of the Qinghai-Xizang Plateau Ecological Barrier and the Northern Sand Control Belt,the Babusha region acts as a frontline defense against the southward encroachment of the Tengger Desert.Assessing changes in the ecological environment quality in the Babusha region holds significant value for evaluating the effectiveness of regional desertification control and advancing the Three-North Shelter-belt Development Program.This study used data from the Google Earth Engine platform to investigate land use pattern changes in the Babusha region from 1986 to 2021.A comprehensive assessment of the spatiotemporal changes in the regional ecological environment quality was conducted using the normalized difference vegetation index(NDVI),desertification index(DI),and remote sensing ecological index(RSEI).The results were as fol-lows:(1)Over time,the desert area in the Babusha region has continued to decrease,the grassland area has pro-gressively increased,and the vegetation coverage has improved.From 1986 to 2021,NDVI and RSEI showed a fluctuating upward trend,with NDVI increasing from 0.14 to 0.31(>50%increase)and RSEI increasing from 0.22 to 0.24(9.39%increase).In contrast,DI exhibited a fluctuating downward trend,decreasing from 0.79 to 0.57 with a cumulative reduction of 27.85%.(2)Areas with high NDVI and RSEI values were concentrated in the southern and northwestern parts of the study region,dominated by woodland and cultivated land,whereas areas with low NDVI and RSEI values were distributed in the northern region characterized by extremely low vegeta-tion coverage and desert.(3)The trend analysis primarily revealed a nonsignificant or significant increase in ND-VI and RSEI values and a nonsignificant decrease in DI values.Specifically,12.12%and 61.10%of the study ar-ea exhibited a nonsignificant and significant increase in NDVI,respectively,whereas 5.06%and 38.63%of the study area showed a nonsignificant and significant increase in RSEI,respectively.The ecological improvement ar-eas were concentrated in the northwestern and southeastern regions with higher human activity levels.From 1986 to 2021,the Babusha region demonstrated marked vegetation restoration,sustained improvement in the ecologi-cal environment,and significantly effective desertification control,facilitating the establishment of a replicable Babusha model.
Exploring the quantitative pre assessment of the climate impact of vegetation greenness changes in the Qaidam Basin can help promote the integrated protection and systematic management of mountains,waters,for-ests,fields,lakes,grasses,sands,and gases.This article is based on MODIS NDVI data,meteorological data,and climate change prediction datasets.It monitors the changes in vegetation greenness with NDVI≤0.3 in the Qaid-am Basin from 2000 to 2023,analyzes the climate driving factors of vegetation with different greenness,and pre-dicts the future trends of vegetation changes with different greenness.The results showed that in the past 24 years,vegetation typesⅠ,Ⅱ,andⅢin the Qaidam Basin accounted for 49.33%,19.81%,and 30.86%of low green vegetation,respectively.Among them,the vegetation areas of Ssum,SⅠ,and SⅡdecreased significantly(P<0.001),while the vegetation area of SⅢincreased significantly,indicating a clear improvement in vegetation quali-ty;The cumulative effect of water and heat conditions on precipitation of low green vegetation for 2-3 years and temperature for 5 years is significantly(P<0.01)greater than that of the current year,indicating that a warm and humid climate promotes the healthy development of grasslands;Under the three emission scenarios of RCP2.6,RCP4.5,and RCP8.5 in the future,the overall trend of low green vegetation in the Qaidam Basin is decreasing,and future climate conditions are favorable for vegetation restoration and expansion.The research results can pro-vide scientific basis for the development of ecological environment protection and desertification control mea-sures in the Qaidam Basin.
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 pro-portion of total land conversion,whereas unused land converted to grassland only covered 3659.27 km2,the grass-land 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.
Evapotranspiration,as a crucial component of the water cycle,is vital for regulating water resources and protecting the environment,especially in arid regions where it plays a significant role in water consumption and redistribution.This study focused on Aksu River Basin and used MOD16 evapotranspiration product data from 2001 to 2022 to systematically analyze the patterns of spatial and temporal variation of actual evapotranspi-ration(AET)and potential evapotranspiration(PET),along with an exploration of the factors influencing them.The findings provide a scientific basis for managing regional water resources and protecting the environment.The results indicate the following:(1)The MOD16 product data are consistent with ET0 data(R2=0.8133),and the product accuracy meets the requirements for studying the spatial and temporal distribution of evapotranspiration in Aksu River Basin.(2)The multi-year average AET and PET are 168.36 mm and 1569.03 mm,respectively.AET shows an overall increasing trend,while PET exhibits a decreasing one.There are significant differences in the spatial distribution of AET and PET,with the opposite trends being exhibited.(3)Over the last 22 years,AET in Aksu River Basin has significantly increased,mainly in cultivated land,forestland,and oases,while PET has decreased overall but increased near the edges of oases and along river channels.AET is less stable than PET,and the Hurst indices of both indicate that the trends may change in future,with 56%of the area showing anti-persis-tence for AET and 89%for PET.(4)Changes in AET and PET are intrinsically linked to changes in climatic fac-tors,with wind speed and relative humidity being the main factors influencing regional variations in these two variables.This study provides an important scientific reference for managing and using water resources in arid re-gions.
Litter decomposition has an important role in the carbon and nutrient cycling of terrestrial ecosystems.Climatic conditions are the main factors involved in litter decomposition.Currently,few studies have examined litter decomposition in alpine grassland ecosystems.To determine the effects of meteorological factors on the lit-ter decomposition and nutrient release processes under a climate change background,the Stipa purpurea endo-phytic fungal symbiont was used along with the litter decomposition bag method to analyze the decomposition characteristics with endophytic fungi(E+)and without endophytic fungi(E-).The effect of meteorological fac-tors on the decomposition rate of Stipa purpurea was analyzed.The results indicated that the decomposition rate of E+was higher compared with that of E-,whereas the decomposition cycle was shorter.With the extension of time,the total nitrogen content of Stipa purpurea showed an increasing trend,lignin content gradually changed from significantly higher in E+to no significant difference between the two,and the cellulose content gradually changed from significantly lower in E+compared with E-(P<0.05).Regardless of endophytic fungi,the litter weight and mass loss rate of Stipa purpurea were correlated with the mean monthly temperature and the mean ground temperature(P<0.05).Precipitation was positively correlated with the litter decomposition rate of Stipa purpurea,and the total nitrogen content of the litter was positively correlated with temperature and precipitation(P<0.05).The lignin and cellulose content were negatively correlated with temperature and precipitation.The du-ration of sunshine had a positive effect on the decomposition of litter,and the lignin,cellulose,and litter weight content were strongly correlated with sunshine duration.Overall,endophytic fungi accelerate the decomposition of Stipa purpurea litter.For E+and E-,the effect of meteorological factors on the decomposition of Stipa pur-purealitter was consistent.
As the fundamental terrain of deserts,sand ridges play a crucial role in shaping the surface water and thermal environment at different slope positions,which profoundly influences how biological soil crusts develop and their spatial distribution patterns.Lichen crusts are widely distributed on the desert surface.However,issues such as how lichen crusts at different slope positions affect the soil phosphorous cycle and what factors play key roles in influencing this remain unclear.Against this background,this study was conducted in Gurbantunggut Des-ert,involving a systematic analysis of the changes in phosphorus fractions and related enzyme activities in the li-chen crust and 0-5 cm soil layer beneath the crust at different slope positions.The results showed that stable phos-phorus in the soil(HCl-Pi,HHCl-Po,HHCl-Pi,and Residual-P)accounted for over 75%of the total phospho-rus(TP)content,followed by medium labile phosphorus(NaOH-Pi and NaOH-Po)and labile phosphorus(Res-in-P,NaHCO3-Pi,and NaHCO3-Po).The slope position had a significant impact on stable phosphorus,and the soil layer had a significant impact on medium labile phosphorus(P<0.05).The data on the contents of stable phos-phorus,TP,organic phosphorus(Po),and inorganic phosphorus(Pi)all revealed that,in the crust layer,the values at the bottom of the slope were significantly higher than those on the east and west slopes,while in the 0-5 cm soil layer,the values on the west slope were significantly lower than those at the bottom of the slope and on the east slope(P<0.05).However,the content of NaOH-Pi was significantly higher on the east and west slopes than at the bottom of the slope in the crust layer,and it was significantly higher on the west slope than on the east slope and at the bottom of the slope in the 0-5 cm soil layer.In terms of soil enzymes,the east slope exhibited the lowest ac-tivity of alkaline phosphatase activity(ALP)and β-glucosidase activity(GC)in the crust layer,but the highest in the 0-5 cm soil layer.Random forest model analysis showed that the changes in moisture and temperature brought about by the slope position were the most important factors affecting the levels of labile phosphorus and stable phosphorus in the crust soil,respectively.This provides scientific support that enriches the theoretical framework of soil phosphorous cycling in desert ecosystems.
