Oasis In Arid Area Research Articles

The Oasisization Process Promotes the Transformation of Soil Organic Carbon into Soil Inorganic Carbon

The dynamic fluctuations in the soil organic carbon (SOC) stock, a fundamental part of the terrestrial ecosystem’s carbon stock, are critical to preserving the global carbon balance. Oases in arid areas serve as critical interfaces between oasis ecosystems and deserts, with land use changes within these oases being key factors affecting soil organic carbon turnover. However, the response of the soil SOC-CO2-SIC (soil inorganic carbon) micro-carbon cycle to oasis processes and their underlying mechanisms remains unclear. Five land-use types in the Alar reclamation area—cotton field (CF), orchard (OR), forest land (FL), waste land (WL), and sandy land (SL)—were chosen as this study’s research subjects. Using stable carbon isotope technology, the transformation process of SOC in the varieties of land-use types from 0 to 100 cm was quantitatively analyzed. The results showed the following: (1) The SOC of diverse land-use types decreased with the increase in soil depth. There were also significant differences in SIC-δ13C values among the different land-use types. The PC(%) (0.73 g kg−1) of waste land was greatly higher than that of other land-use types (p < 0.05) (factor analysis of variance). (2) The CO2 fixation in cotton fields, orchards, forest lands, and waste land primarily originates from soil respiration, whereas, in sandy lands, it predominantly derives from atmospheric sources. (3) The redundancy analysis (RDA) results display that the primary influencing factors in the transfer of SOC to SIC are soil water content, pH, and microbial biomass carbon. Our research demonstrates that changes in land use patterns, as influenced by oasis processes, exert a significant impact on the conversion from SOC to SIC. This finding holds substantial significance for ecological land use management practices and carbon sequestration predictions in arid regions, particularly in the context of climate change.

Evaluation of the Evolution of the Ecological Security of Oases in Arid Regions and Its Driving Forces: A Case Study of Ejina Oasis in China

Ecological security is an important guarantee of human security and survival, closely related to sustainable development. However, the ecological security evaluation and driving force analysis of oases in arid areas is still insufficient. Ejina Oasis’s ecological security has experienced significant shifts following the centralized management of the Heihe River’s water allocation. Understanding the shifts in ecological security in the Ejina region is paramount for the oasis’s long-term sustainability. This paper employed the Pressure–State–Response (P–S–R) model to select socioeconomic and ecological indicators, establish a comprehensive ecological security evaluation index system, and then analyze the evolving ecological security in the region. Additionally, this paper explored the relationship between changes in the water area, oasis area, and ecological security by using the gray correlation degree to quantify the influence of Land Use Changes (LUCCs) on the overall ecological security. From 2000 to 2012, the ecological security index of Ejina Oasis remained relatively stable at around 0.4. However, a noticeable upward trend in the ecological security index emerged from 2012 to 2020, indicating a shift toward improved ecological security in the region. Critical determinants of this change included the habitat degradation degree, total population, habitat quality, carbon stock, fractional vegetation cover (FVC), the proportion of tertiary industry, and the volume of water discharged from Wolf Heart Mountain. The degree of habitat degradation, fractional vegetation cover (FVC), and the proportion of tertiary industry had the greatest impact on the change in ecological security. The pressure index was dominant in influencing ecological security before 2012 but gradually transitioned to the state index. This study offers a valuable framework for assessing the intricate relationship between LUCCs and ecological security in water-scarce, arid-region oases.

Improving the Accuracy of Soil Organic Carbon Estimation: CWT-Random Frog-XGBoost as a Prerequisite Technique for In Situ Hyperspectral Analysis

Rapid and accurate measurement of the soil organic carbon (SOC) content is a pre-condition for sustainable grain production and land development, and contributes to carbon neutrality in the agricultural industry. To provide technical support for the development and utilization of land resources, the SOC content can be estimated using Vis-NIR diffuse reflectance spectroscopy. However, the spectral redundancy and co-linearity issues of Vis-NIR spectra pose extreme challenges for spectral analysis and model construction. This study compared the effects of different pre-processing methods and feature variable algorithms on the estimation of the SOC content. To this end, in situ hyperspectral data and soil samples were collected from the lakeside oasis of Bosten Lake in Xinjiang, China. The results showed that the combination of continuous wavelet transform (CWT)-random frog could rapidly estimate the SOC content with excellent estimation accuracy (R2 of 0.65–0.86). The feature variable selection algorithm effectively improved the estimation accuracy (average improvement of (0.30–0.48); based on their ability to improve model estimation on average, the algorithms can be ranked as follows: particle swarm optimization (PSO) > ant colony optimization (ACO) > random frog > Boruta > simulated annealing (SA) > successive projections algorithm (SPA). The CWT-XGBoost model based on random frog showed the best results, with R2 = 0.86, RMSE = 2.44, and RPD = 2.78. The feature bands accounted for only 0.57% of the Vis-NIR bands, and the most important sensitive bands were distributed at 755–1195 nm, 1602 nm, 1673 nm, and 2213 nm. These findings are of significance for the extraction of precise information on lakeside oases in arid areas, which would aid in achieving human–land sustainability.

Potential effects of oasis expansion on ecosystem service value in a typical inland river basin of northwest China.

To satisfy an increasing need for living space and food while preserving ecosystem services remains one of today's biggest challenges. Oases in arid areas have gradually become the main sources for new cultivated land, affecting the supply and transmission of ecosystem services. Yet, little assessment on predicting the effects of oasis expansion on ecosystem service value (ESV) has been available to guide policy makers and ecologists. Here we addressed the connections between oasis expansion and ESV in the middle reaches of the Heihe River Basin in northwest China by linking the Logistic-CA-Markov model and the benefit transfer method. The results showed that the oasis was expected to expand by 419.02 km2 from 2015 to 2029, with the area of farmland and construction land increasing by 18.87% and 39.05%, respectively. With oasis expansion, the total ESV was expected to increase by 104.25 million RMB from 2015 to 2029. However, oasis expansion encroaches on vegetation, resulting in decline of the values of climate regulation, waste treatment, and biodiversity protection. This study will provide a reference for decision-making in trade-offs involved in land management.

干旱区新疆天然绿洲生态需水量分析

干旱区新疆天然绿洲生态需水量分析

Evaluation and Prediction of Land Use Ecological Security in the Kashgar Region Based on Grid GIS

Predicting trends in land use/cover change (LUCC) and assessing future ecological security (ES) can help effectively balance regional ecological conservation and economic development. In this study, a land use simulation model was used to predict the spatial-temporal variation in land use in Kashgar in 2030 under three scenarios (inertial development, agricultural land protection, and forest and rangeland conservation). Subsequently, by combining the pressure–state–response model and predicted land use, the ES of the Kashgar region in 2000, 2010, and 2020 were evaluated. We found that (1) only agricultural land and built-up land in the Kashgar region increased from 2000–2020 by 4174.79 and 434.44 km2, respectively. (2) The area of the region belonging to a generally safe level or above decreased from 38.36% in 2000 to 36.89% in 2010 and then increased to 37.71% in 2020. (3) In 2030, the ES status under the three scenarios will be improved, among which the agricultural land protection scenario corresponds to the best ES status. This research is valuable for deeply understanding the interaction mechanism between LUCC and ES in typical artificial oases in arid areas of the Kashgar region and sustaining relatively stable internal structures and socioeconomic activities in the arid oasis of the Kashgar region.

Soil Salinity Inversion Model of Oasis in Arid Area Based on UAV Multispectral Remote Sensing

Soil salinization severely restricts the development of global industry and agriculture and affects human beings. In the arid area of Northwest China, oasis saline-alkali land threatens the development of agriculture and food security. This paper develops and optimizes an inversion monitoring model for monitoring the soil salt content using unmanned aerial vehicle (UAV) multispectral remote sensing data. Using the multispectral remote sensing data in three research areas, the soil salt inversion models based on the support vector machine regression (SVR), random forest (RF), backpropagation neural network (BPNN), and extreme learning machine (ELM) were constructed. The results show that the four constructed models based on the spectral index can achieve good inversion accuracy, and the red edge band can effectively improve the soil salt inversion accuracy in saline-alkali land with vegetation cover. Based on the obtained results, for bare land, the best model for soil salt inversion is the ELM model, which reaches the determination coefficient (Rv2) of 0.707, the root mean square error RMSEv of 0.290, and the performance deviation ratio (RPD) of 1.852 on the test dataset. However, for agricultural land with vegetation cover, the best model for soil salinity inversion using the vegetation index is the BPNN model, which achieves Rv2 of 0.836, RMSEv of 0.027, and RPD of 2.100 on the test dataset. This study provides technical support for rapid monitoring and inversion of soil salinization and salinization control in irrigation areas.

Monitoring Oasis Cotton Fields Expansion in Arid Zones Using the Google Earth Engine: A Case Study in the Ogan-Kucha River Oasis, Xinjiang, China

Rapid and accurate mapping of the spatial distribution of cotton fields is helpful to ensure safe production of cotton fields and the rationalization of land-resource planning. As cotton is an important economic pillar in Xinjiang, accurate and efficient mapping of cotton fields helps the implementation of rural revitalization strategy in Xinjiang region. In this paper, based on the Google Earth Engine cloud computing platform, we use a random forest machine-learning algorithm to classify Landsat 5 and 8 and Sentinel 2 satellite images to obtain the spatial distribution characteristics of cotton fields in 2011, 2015 and 2020 in the Ogan-Kucha River oasis, Xinjiang. Unlike previous studies, the mulching process was considered when using cotton field phenology information as a classification feature. The results show that both Landsat 5, Landsat 8 and Sentinel 2 satellites can successfully classify cotton field information when the mulching process is considered, but Sentinel 2 satellite classification results have the best user accuracy of 0.947. Sentinel 2 images can distinguish some cotton fields from roads well because they have higher spatial resolution than Landsat 8. After the cotton fields were mulched, there was a significant increase in spectral reflectance in the visible, red-edge and near-infrared bands, and a decrease in the short-wave infrared band. The increase in the area of oasis cotton fields and the extensive use of mulched drip-irrigation water saving facilities may lead to a decrease in the groundwater level. Overall, the use of mulch as a phenological feature for classification mapping is a good indicator in cotton-growing areas covered by mulch, and mulch drip irrigation may lead to a decrease in groundwater levels in oases in arid areas.

干旱区绿洲城镇景观生态风险时空变化分析——以张掖绿洲乡镇为例

PDF HTML阅读 XML下载 导出引用 引用提醒 干旱区绿洲城镇景观生态风险时空变化分析——以张掖绿洲乡镇为例 DOI: 10.5846/stxb202105111234 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家社科基金重大项目（18ZDA053）；国家自然科学基金项目（41661035） Spatio-temporal evolution of landscape ecological risk in oasis cities and towns of arid area: A case study of Zhangye Oasis Township Author: Affiliation: Fund Project: National Social Science Foundation of China（No.18ZDA053）; National Natural Science Foundation of China,（No.41661035） 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:科学评估与分析干旱区绿洲乡镇景观生态风险，对优化绿洲土地资源管控和维护干旱区绿洲生态系统稳定性具有重要现实意义。以张掖市绿洲乡镇为对象，基于土地利用数据和景观格局指数，结合ArcGIS空间分析功能，研究其景观生态风险时空特征及影响因素。结果表明：1987-2018年，耕地和建设用地变化明显，分别增加429.03 km2和236.26 km2；整体景观生态风险呈下降趋势，并呈"南北高、中间低"格局特征；各乡镇风险水平在空间上正向聚集，位于绿洲边缘地区的乡镇风险变化明显；人为活动干扰是近年风险水平变化的主要因素。研究成果可为西北干旱区绿洲生态保护与治理提供决策参考。 Abstract:The scientific assessment and analysis of landscape ecological risks in oasis towns is of great practical significance for optimizing management and control of oasis land resources and maintaining the stability of oasis ecosystem in arid areas. Based on land use data and landscape pattern index, combined with ArcGIS spatial analysis function, this paper studied the temporal and spatial characteristics and influencing factors of landscape ecological risk in oasis towns in Zhangye City. The results showed that the cultivated land and construction land have changed significantly from 1987 to 2018, with an increase of 429.03 km2 and 236.26 km2, respectively. The overall landscape ecological risk level showed a downward trend and the pattern of high in the north and south while low in the middle. The risk level of each township is positively aggregated in space, and the dramatic change of the estimated risk was also found on the edge of the oasis. Human disturbance is the main factor of risk level change in recent years. The research results can provide decision-making reference for ecological protection and management of oases in arid areas of northwestern China. 参考文献 相似文献 引证文献

Water and soil environmental vulnerability of artificial oases in arid areas and its temporal and spatial differentiation and evolution

AbstractThe water and soil environmental vulnerability in arid areas is mainly affected by vegetation, hydrology, terrain, and climate. To accurately evaluate the water and soil environmental vulnerability and its evolution in the Jingtaichuan Pumping Irrigation District in China, this paper, taking 1994, 2006, and 2018 as typical years, selects 13 index factors that directly or indirectly drive the water and soil environmental evolution in this area, and adopts the cloud theory and analytic hierarchy process to determine the weight of each index factor. Spatial analysis technique and supervised classification were used to obtain and standardize the spatial distribution raster maps of each index factor. The multi-source data fusion was performed according to the index weight to analyze the evolution characteristics of soil and water environmental vulnerability. The results showed that soil salinity, vegetation coverage, and land use type have a significant impact on the water and soil environmental vulnerability in this irrigation area, and most of the area is at mild risk. High risk mainly occurs in closed hydrological units in the eastern part of the irrigation area. From 1994 to 2018, the evolution process can be divided into two stages, namely the ‘environmental deterioration stage’ and the ‘environmental restoration stage’. The results showed that the water and soil environment of the irrigation area is developing in a healthy way.

Variability in condensation water and its determinants in arid regions of north‐western China

AbstractCondensation water plays an important ecohydrological role in arid and semi‐arid regions. However, little is known about the factors determining the formation of condensation over long term, especially in desert oases in arid areas. During 2005–2014, we investigated the main limiting factors in formation of condensation water for five different surfaces (interdune, dune top, flat vegetation‐free sand, artificial grassland and plantation forest), sand particle sizes, and temperature and humidity control experiment in a typical arid region of north‐western China. Results showed that changes in microhabitat resulting from different surface conditions had a significant influence on the amount of condensation water in arid desert ecosystem. Except for sand particle sizes 0.2–0.02 and 2–0.2 mm, the amount of average daily condensation for different sand particle sizes differed significantly (P < 0.05) and decreased with an increase in sand particle size. Air temperature (AT), relative humidity (RH), air and surface temperature range (RT) and wind speed (WS) can significantly (P < 0.05) affect the formation of condensation water in arid regions, and the thresholds of condensation water formation were RH > 25% and WS < 3.50 m s−1. Such effects, however, differed among the different surfaces due to different conditions of soil characteristics, microhabitats and regional climate. These results suggest that the influence of site characteristics, microhabitats and regional climate on the formation of condensation water should attract more attention and that both the relative importance and the interactions among different determining factors will contribute to a better understanding of the mechanistic determinants for the formation of condensation water in arid areas.

Effects on Local Temperature and Energy of Oasis City Expansion in Arid Area of Northwest China

The land surface model SURFEX 7.3 was used to study climate effect of urban expansion located in oasis in arid area of Northwest China by surface and 2 m urban heat island (UHI) intensity and available energy ratio (B). We performed a true regional development scenario and three assumed scenario simulations in 1978, 1993, 2004, and 2014, respectively. The results show that 2 m UHI always displays positive twin peaks during whole day, while surface UHI only displays a positive single peak with several hours during daytime at four seasons in the four years. Moreover, 2 m UHI intensity during night is higher than that during daytime, indicating that UHI intensity is contributed more by “trap effect” from urban complex geometry or anthropogenic heat and that surface UHI according to land surface temperature cannot reflect UHI comprehensively. The oasis-urban development resulted in local warming and increasing of B, and compared with the original undeveloped environment, local climate in the study area was in a relatively balanced state in 1978 and 1993 due to the “heating effect” of urban area and the “cooling effect” of oasis, but the offsetting effect from oasis would become weaker after1993.

Analysis of Human Disturbance and Ecological Security Evolution in Oasis in Arid Area Based on LUCC: A Case Study of Oasis in the Northern Tianshan Mountain Slope Economic Zone

Oases in arid areas are environmentally and economically vulnerable regions. Study on ecological security of oases in arid areas is of great significance to the stability and the economic development of oases. Based on Land Use/Land Cover data in 1965, 1980, 1995, 2005 and 2015, the study analyze the temporal and spatial changes in human disturbance and ecological security of oases in the Northern Tianshan Mountain Slope Economic Zone (NTMSEZ) in recent 50 years by establishing the ecological security index (ESI) through human disturbance index and landscape vulnerability index. The results showed that: in recent 50 years, the human disturbance of the NTMSEZ has been increased to current moderate human impacts. Urban construction, oasis expansion and farmland reclamation are the main factors of the increment. The human disturbance in Urumchi, Shihezi, Kuitun, Miquan and Changji is higher than that in other oases and that in core areas of oasis is higher than other areas. The ESI of the NTMSEZ increases firstly and then decreases. In most areas, the ESI is “relatively unsafe” and “critical”. However, there are increasingly more vulnerable areas, moving northwestwards and expanding southwards. The ESI gradually presents a “NW-SE” trend of zonal distribution pattern.

Reconstructing meteorological time series to quantify the uncertainties of runoff simulation in the ungauged Qira River Basin using data from multiple stations

The existence and development of oases in arid plain areas depends mainly on the runoff generated from alpine regions. Quantifying the uncertainties of runoff simulation under climatic change is crucial for better utilization of water resources and management of oases in arid areas. In the present study, based on the ungauged Qira River Basin in Xinjiang, China, a modified version of the Delta statistical downscaling method was applied to reconstruct the monthly mean temperature (MMT), monthly accumulated precipitation (MAP), and monthly accumulated evaporation (MAE) of two target stations. Then, the uncertainty in runoff simulation, implemented using the Three-Layered Feedforward Neural Network model with the Back-Propagation learning algorithm, was quantified. The modified Delta method reproduced the MMT, MAP, and MAE time series of the two target stations very well during the calibrated periods, and the reconstructed uncertainty ranges were small among reconstructed datasets using data from 12 observation stations. The monthly accumulated runoff simulated by the reconstructed MMT, MAP, and MAE as input variables of the model possessed unpredictable uncertainty. Although the use of multi-data ensembles in model inputs are considered an effective way to minimize uncertainties, it could be concluded that, in this case, the efficiency of such an approach was limited because of errors in the meteorological data and the deficiency of the model’s structure. The uncertainty range in the runoff peak was unable to capture the actual monthly runoff. Nevertheless, this study represents a significant attempt to reproduce historical meteorological data and to evaluate the uncertainties in runoff simulation through multiple input ensembles in an ungauged basin. It can be used as reference meteorological data for researching long-term climate change and producing runoff forecasts for assessing the risk of droughts and/or floods, as well as the existence and management of plain oases in the Qira River Basin.

Numerical Simulation on Oasis Effect over Northwestern China

The characteristics of air temperature, circulation and energy budget of Jinta Oasis are simulated by WRF model, which is the weather research and forecast model of NCAR. The results show that the WRF model has good quality in simulating the diurnal characteristics of surface layer temperature, wind fields, net radiation, sensible heat flux and latent flux. In addition, the model initial fields were also modified by observations of soil temperature and moisture in order to improve the simulations in this study due to important roles of the soil moisture and temperature playing in affecting the cold island effect, the wet island effect properties and surface energy budget balance over the oasis in arid area. Then, the microclimate characteristics and local thermal circulation generated by inhomogeneous underlying surface over Jinta Oasis are analyzed.

Surface runoff processes and sustainable utilization of water resources in Manas River Basin, Xinjiang, China

Water is the important resource to guarantee the existence and development of oases in arid areas. To improve the utilization efficiency of water resources in Manas River Basin, this paper investigated the trends and periods of runoff based on the runoff and climate data for the past 50 years. Subsequently, with the socioeconomic and water resources data, we studied a comprehensive evaluation on the water security in this area. The results indicated that the stream flows in the three hydrological stations of Hongshanzui, Kensiwat and Bajiahu have sig- nificantly increased and undergone abrupt changes, with periods of 18 and 20 years. According to assessment, water security in the Manas River Basin was at an unsafe level in 2008. In criterion layer, the ecological security index and the index of supply-demand situation are both at the relatively secure level; the quantity index and so- cioeconomic index of water resources are at the unsafe level and basic security level, respectively. Therefore, in order to achieve sustainable economic and social development within the Manas River Basin, it is vital to take a series of effective measures to improve the status of water security.

The effects of oasis on aeolian deposition under different weather conditions: a case study at the southern margin of the Taklimakan desert

Heavy aeolian deposition is one of the most threatening natural hazards to oases in arid areas. How an oasis affects aeolian deposition is tightly related to the local ecological environments. To examine the effects of oasis on aeolian deposition under different weather conditions, monthly aeolian deposition from April 2008 to March 2009 and additional samples during dust storms in April and May 2008 were collected at four sites along the Qira oasis. The monthly ADRs (aeolian deposition rates) varied greatly with seasons and sites, ranging from 19.4 to 421.2 g/m2/month and averaging 198.8 g/m2/month. Aeolian deposition in the oasis was composed dominantly of sand and silt. Based on the variations of ADRs from the four sites, it can be found that the oasis exhibits two different effects on aeolian deposition under different weather conditions. During dust storms, the oasis demonstrates a significantly shielding effect due to the obstruction of the oasis-protection systems, resulting in most aeolian particles being deposited at the windward side of the oasis. While during non-dust storm periods with weak winds, the oasis exhibits an “attracting” effect on aeolian deposition, leading to a higher ADR inside the oasis. Owing to the annual ADR is dominated by the non-dust storm ADR in Qira, the oasis seems to become an important aeolian deposition area caused by the “attracting” effect of the oasis.

Stability of patches of oasis landscape in arid areas: A case study of Sangong River Watershed, Xinjiang, China

The stability of oases is one of the key scientific issues in the process of evolution and management of oases in arid areas. The stability of oases and its representation are also different at different scales. This paper deals with the stability of oases at the landscape patch scale with a case study in the Sangong River Watershed of Tianshan Mountains. We employed the remote sensing, geographic information system and mathematical statistical methods to process the remote sensing images of three periods in 1978, 1987 and 1998, and put forward the approaches for representing the oasis stability at the landscape patch scale. The landscape control capacity of oasis patches is a kind of natural driving forces of the dynamic landscape change. The control capacity of a certain patch type on landscape change increases with its area and shape complexity and contrasts between it and other patches, and reduces with its spatial distances between it and other patches. The patch type with the strongest control capacity should be the matrix of landscape. The conversion of oasis landscape patches results from both natural and anthropogenic driving forces, particularly the anthropogenic driving forces. The higher the conversion proportion is, the lower the stability of patch types is and the stronger the anthropogenic disturbance is. The patch type with the strongest net control capacity in the Sangong River Watershed in 1987 was the desert grassland, which was the matrix of landscapes; but the matrix of landscapes had been changed into the irrigated lands in 1987 and 1998. The control capacities of landscape patches on the oasis landscape evolution have gradually reduced with time in the Sangong River Watershed, and the change extents also have reduced gradually. This reveals that the interaction among the landscape patch types generally tends to reduce, and the natural stability of the oasis landscape patches generally tends to increase. However, the conversion among the landscape patches occurs more frequently due to the increase of intensive human activities, which probably causes the lower stability of environmental resources patch and higher stability of introduced patches in the oasis landscape.

On coordinated development of oasis and environment in arid area

Based upon the formation and evolution of oasis and the factors restricting the coordinated development of oasis economy and environment, this paper presents a goal of the development in coordination. It suggests that the sustainable survival and development of oasis could be ensured only if the oasis-desert and water source ecology are managed in a combined way to form a macro system. In light with the above mentioned, the approach to the development of economy and environment of oasis in arid area should depend upon the establishment of an oasis ecological and economic system, which suits the arid environment and promotes the efficiency of resource configuration, stabilizes economic increment and benefits ecological development.