Ebinur Lake Research Articles

Estimating Salt Concentrations Based on Optimized Spectral Indices in Soils with Regional Heterogeneity

Soil salinity is one of the most damaging environmental problems worldwide, especially in arid and semiarid regions. The objectives of this study were to improve the inversion accuracy of soil salt content (SSC) in soils with spectral heterogeneity by using optimized spectral indices. Soil samples at a 0–20 cm depth were taken from Keriya Oasis (98 soil samples), Ugan-Kuqa Oasis (49 soil samples), and Ebinur Lake Basin (57 soil samples). SSC and spectral reflectance (SR) of all the 204 soil samples were determined. To comprehensively analyze the field-collected hyperspectral data, various band combinations were used to calculate a normalized difference spectral index (NDSI) and ratio spectral index (RSI). Then, the relationships between the indices and SSC were examined, and the most robust relationships were demonstrated. The partial least squares regression (PLSR) method was utilized to develop a predictive model of SSC, and the variable importance in the projection (VIP) method was used during modeling. The results revealed that (i) the salinized soils in different regions had apparent differences in both reflectance and spectral curve morphology, but the optimized spectral indices method effectively overcame the regional heterogeneity of salinized soil hyperspectral characteristics, and the correlation with SSC was always kind, with correlation coefficients up to 0.748 at 0.001 level of significance; (ii) the VIP filtering method effectively selected the optimal independent model, and the modeling accuracy was better than the single optimization index (R2Pre = 0.83 and RMSEPre = 2.31 g·kg−1) by using the combination of two optimal indices; (iii) although the global modeling accuracy was significantly lower than the local modeling accuracy due to the inconsistent salt sensitivity bands of salinized soils in different regions, combined with cross-validation analysis, the global model had the ability to predict soil salinization accurately (R2Pre = 0.69 and RMSEPre = 8.45 g·kg−1). The methods developed in this study can be applied in other arid and semiarid areas. Besides, the study also provides examples for aerospace hyperspectral remote sensing of cross-regional soil salinization.

Late Quaternary environmental change record in biomarker lipid compositions of Lake Ebinur sediments, Northwestern China

Late Quaternary paleoclimate records from arid regions help us understand the response of ecological systems to natural climate change to place recent changes in a longer-term perspective. In this research, a biogeochemical analysis of a sediment core from Lake Ebinur, Xinjiang, allowed us to infer the climate and environmental changes in the late Quaternary in arid northwestern China. The combined lipid biomarkers and bulk biogeochemical properties (TOC, δ13Corg) revealed moderately wet conditions from 34 to 28 ka, favoring the growth of terrestrial vegetation. The subsequent period from 28 to 13 ka was dominated by aquatic plants, algae and microbes, indicating cold and dry conditions. Ameliorated regional moisture conditions were deduced from the higher carbon preference index (CPI) and from δ13Corg values from 13 to 3.6 ka. The optimum climate conditions occurred from 9 to 5 ka. Several climatic events also exist in the Lake Ebinur records with a wide distribution into other regions. Our biogeochemical-based paleoclimate and paleoenvironmental reconstruction is generally synchronous with sedimentary records from mid-latitude Eurasia and the NGRIP ice core record, which probably has a certain linkage with the 45°N summer insolation. We propose that summer insolation conditions in the northern hemisphere might have an impact on the climate and environmental changes in arid northwestern China in the late Quaternary.

Changes in wetland salinity, human activity and wetland vegetation abundances over the past 900 years

The birch wetland is an important type of oasis ecosystem in Xinjiang, China, which is extremely vulnerable to climate change and other disturbances. In this study, we aimed to understand the history of vegetation in such wetlands and find the key factors driving changes in the abundance of species inhabiting the wetlands of arid and semi-arid regions for over the past 900 years. Surface pollen samples were collected from 21 sites at altitudes between 750 m and 210 m, and 183 fossil samples were collected from the Ebinur and Caotanhu wetlands in north Xinjiang, China. Three different ground and surface water samples were collected from birch wetlands and the saline Ebinur Lake. The pollen and hydrochemical data were compared to examine the current interactions, and the knowledge thus gained was used to interpret historical changes in vegetation abundance in different regions (Ebinur and Caotanhu). The modern wetland landscape, surface pollen assemblage, and fossil pollen data from these areas together with hydrochemistry data concerning ground and surface water indicated that a local wetland ecosystem dominated by freshwater plants has been prevalent since 900 cal. a BP. The records show that Betula microphylla dominated the vegetation in the Caotanhu wetland from 900 to 700 cal. a BP; it subsequently declined and has now disappeared. In the Ebinur wetland, the vegetation cover of B. microphylla was at its highest between 270 and 220 cal. a BP; it is currently facing extirpation in the region. Our results, together with data concerning salinity and population statistics, indicate that both salinity and human activity have influenced wetland vegetation over the past 900 years. The two wetland ecosystems were dominated by freshwater plants during this period. At present, high salinity in the wetlands might be a key factor in driving the susceptible B. microphylla to extirpation. Increased human activity is an additional factor influencing changes in wetland vegetation. Overall, the results of our study on the interactions between wetland water and vegetation in different time periods (past and modern) and regions (Ebinur and Caotanhu) should be helpful for devising conservation strategies and conservation measures for B. microphylla in the semi-arid and arid areas of China. • Pollen and hydrochemistry data are used to study the relation of wetland and plant. • Pollen and hydrochemistry data from the Birch wetlands suggest a wetland landscape. • At present Betula microphylla is facing extinction in the Ebinur wetland in Xinjiang. • At present Betula microphylla has become extirpation in the Caotanhu wetland in Xinjiang. • Salinity of wetland water and human activity influence the growth of Betula species.

Capability of Sentinel-2 MSI data for monitoring and mapping of soil salinity in dry and wet seasons in the Ebinur Lake region, Xinjiang, China

Soil salinization is one of the most important causes for land degradation and desertification and is an important threat to land management, farming activities, water quality, and sustainable development in arid and semi-arid areas. Soil salinization is often characterized with significant spatiotemporal dynamics. The salt-affected soil is predominant in the Ebinur Lake region in the Northwestern China. However, detailed local soil salinity information is ambiguous at the best due to limited monitoring techniques. Nowadays, the availability of Multi-Spectral Instrument (MSI) onboard Sentinel-2, offers unprecedented perspectives for the monitoring and mapping of soil salinity. The use of MSI data is an innovative attempt for salinity detection in arid land. We hypothesize that field observations and MSI data and MSI data-derived spectral indices using the partial least square regression (PLSR) approach will yield fairly accurate regional salinity map. Based on electrical conductivity of 1:5 soil:water extract (EC) of 72 ground-truth measurements (out of 116 sample sites) and various spectral parameters, such as satellite band reflectance, published satellite salinity indices, red-edge indices, newly constructed two-band indices, and three-band indices from MSI data, we built a few inversion models in an attempt to produce the regional salinity maps. Different algorithms including Pearson correlation coefficient method (PCC), variable importance in projection (VIP), Gray relational analysis (GRA), and random forest (RF) were applied for variable selection. The results suggest that both the newly proposed normalized difference index (NDI) [(B12 − B7) / (B12 + B7)] and three-band index (TBI4) [(B12 − B3) / (B3 − B11)] show a better correlation with validation data and could be applied to estimate the soil salinity in the Ebinur Lake region. The established models were validated using the remaining 44 independent ground-based measurements. The RF-PLSR model performed the best across the five models with R2V, RMSEV, and RPD of 0.92, 7.58 dS m−1, and 2.36, respectively. The result from this model was then used to map the soil salinity over the study area. Our analyses suggest that soil salinization changes quite significantly in different seasons. Specifically, soil salinity in the dry season was higher than in the wet season, mostly in the lake area and nearby shores. We contend that the results from the study will be useful for soil salinization monitoring and land reclamation in arid or semi-arid regions outside the current study area.

Late Quaternary lake-level and climate changes in arid central Asia inferred from sediments of Ebinur Lake, Xinjiang, northwestern China

AbstractArid central Asia plays an important role in global climate dynamics, but large uncertainties remain in our understanding of the region's hydroclimate variability during the Late Quaternary. Here we present a new, high-resolution record of lacustrine sediment grain-size and element chemistry from Ebinur Lake, which was used to infer lake conditions and related climate changes in the study region between ca. 39.2 and 3.6 ka. End-member modeling analysis of grain-size data and PCA of elemental data show that lake level fluctuated dramatically from 39.2 to 34.0 ka. Subsequently, Ebinur Lake experienced a high stand from 34.0 to 28.0 ka, under humid climate conditions. The subsequent period, from 28.0 to 12.0 ka, was characterized by lake regression under dry climate conditions, whereas afterward (12.0–3.6 ka), considerably higher lake levels and humid conditions again prevailed. Millennial-scale abrupt climate changes, such as Heinrich events (H3 and H1) and the Younger Dryas, which are documented in the North Atlantic region, are also detected in the sediment record from Ebinur Lake. Comparisons with other sediment records from arid central Asia generally support the claim that climate change in this region was influenced mainly by variations in North Atlantic sea surface temperatures, through the westerlies.

Research on Economic Bearing Capacity of Farmers to Agricultural Irrigation Water Prices in the Ebinur Lake Basin

The Ebinur Lake Basin is one of the few lakes in the arid area of northwest China where water shortages have always been an important factor hindering development. Therefore, this study takes as its objective an investigation of water prices as the main economic factor that restricts the sustainable utilization of water resources to explore the economic affordability of water prices for farmers. Furthermore, the study attempts to determine the appropriate range of prices for water price reform. In this study, a questionnaire was designed to survey 210 agricultural water users in Wenquan County, Bole City, and Jinghe County, areas where agricultural activities are relatively concentrated in the vicinity of the Ebinur Lake Basin. Based on the data from the field survey, the range of economic affordability for farmers in the Ebinur Lake Basin was categorized by the ELES model; according to the analysis method of water tolerability index, a suitable water price standard for farmers’ reform was obtained. The results show that (1) 97% of the farm households have the ability to pay irrigation water prices and only 3% do not have the ability to pay and (2) economically affordable water prices for farm households range from 79 to 143 €/hm2, the latitude for raising water prices is 64 €/hm2, and the adjustable range of unit water pricing is between 0.014 and 0.042 €/m3. It can be seen that increasing water prices is feasible.

Dynamic detection of water surface area of Ebinur Lake using multi-source satellite data (Landsat and Sentinel-1A) and its responses to changing environment

In arid and semi-arid climatic areas, lakes are extremely essential for fragile ecological environment and regional sustainable development. Ebinur Lake is an important component of the ecological barrier of Junggar Basin, Xinjiang Uyghur Autonomous Region (XUAR), China. Due to the tremendous changes in Ebinur Lake and surrounding marshes during the last decades, Ebinur Lake becomes a representative ecological degradation region in northwestern China. The detection of the intra-annual variations of water body and its responses to changing environment are critical for regional ecological security and rehabilitation of degraded ecosystem. To extract more accurate water information using Synthetic Aperture Radar (SAR) data and further fill the gap of inter-month dynamic monitoring of Ebinur Lake, a new SAR water index (modified Sentinel 1A water index, MSWI) was proposed based on the relationship between normalized difference water index (NDWI) imageries and Sentinel 1A data. The dynamic thresholds of classification were selected using Otsu method and the results showed that the classification results were acceptable with the optimal overall accuracy of 99.94% and kappa coefficient of 0.9971, respectively. We conduct a time series analysis of surface areas of Ebinur Lake using S1A data from February 9th, 2017 to February 4th, 2018. The maximum lake surface area was 965.29 km2 in April 22nd, 2017, while the minimum value was 750.37 km2 in September 1st, 2017, and the mean area was 831.51 km2. The seasonal variations showed the stages of “sharp rising” – “significant decreasing” – “gradual stabilizing” in the study period. The water surface area was highly correlated with inflow water volume (correlation coefficient = 0.72, P < 0.001). The variation of Ebinur Lake's water surface area is crucial to monitor the resulting eco-environmental impacts under the changing environmental conditions in the arid and semi-arid areas.

A trade-off method between environment restoration and human water consumption: A case study in Ebinur Lake

The shrinkage of inland lakes has become a major problem in arid region. Human activities are competing for water resources with sustainable lake ecosystem. Considering improving irrigation efficiency does not help on water saving at basin scale and reducing ET through mulching, zero tillage and deficit irrigation will lead to crop yield loss, this study proposed an alternative way that returning cropland to lake to achieve the balance between endorheic lake restoration and human water consumption. The approach consists of four procedures: (1) identifying the target annual inflow (Qtar) of endorheic lake; (2) calculating available consumable water (ACW) in the upstream based on Qtar; (3) setting ET deduction goals using water consumption balance approach; (4) estimating crop area to be deducted. This approach is implemented at Ebinur Lake of China under two restoration scenarios (lake area restored to 522 km2 and 800 km2). The results indicate that to restore the Ebinur Lake to 522 km2, the annual inflow should be increased to 602.6 × 106 m³, and human water consumption should be reduced by 320.3 × 106 m³. If the restoration goal of Ebinur Lake is set to 800 km2, an annual inflow of 876.6 × 106 m³ is required, and the human water consumption should be reduced by 594.2 × 106 m³. The over-expansion of cropland and artificial forest is found to be the main reasons for the shrinkage of Ebinur Lake. Finally, the feasible solutions for ecosystem restoration of Lake Ebinur are provided for both scenarios. The methodology adopted in this research can be applied to the restoration of other inland lakes in arid regions.

Diversity of Azotobacter in relation to soil environment in Ebinur Lake wetland

Ebinur Lake wetland is the most representative temperate arid zone wetland ecosystem in China and it is the centre of the oasis and desertification of the Northern slope of Tianshan conjugate. Soil samples were collected from three sites (Tamarix ramosissima, Halocnemum strobilaceum, and Phragmites australis) and different soil layers (0–5, 5–15,15–25, and 25–35 cm) within this wetland during spring, summer and autumn, and the diversity of cultured/uncultured Azotobacter based on the 16S rDNA and nifH genes was characterized. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and bivariate correlation analysis were used to evaluate the relationship between the diversity of uncultured Azotobacter and soil environmental factors. A total of 17 cultured Azotobacter strains were isolated, five of which had stronger nitrogen-fixation ability (more than 10 mg/mL). Meanwhile, most of the cultured Azotobacter strain sequences were grouped into Bacillus sphaericus and Bacillus subtilis, and fewer sequences were affiliated with Actinomycetes. Furthermore, PCR-DGGE indicated that the diversity of uncultured Azotobacter was not balanced in some samples and the Shannon diversity index varied from 0.685 to 2.626. The uncultured Azotobacter were grouped into autotrophic genera Azotobacter and Rhizobium. Finally, bivariate correlation analysis showed that the diversity of uncultured Azotobacter was significantly correlated with soil organic carbon, inorganic carbon, NH4+-N, NO3−-N and microbial biomass N in the Ebinur Lake wetland in Xinjiang.

干旱荒漠区植物生态位对水盐的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 干旱荒漠区植物生态位对水盐的响应 DOI: 10.5846/stxb201801180135 作者: 作者单位: 新疆大学,新疆大学,新疆大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31560131） Response of plant niche to soil moisture and salinity in an arid desert area of Xinjiang, China Author: Affiliation: Xinjiang University,Xinjiang University,Xinjiang University Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan) 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:全球气候变化对生态系统功能的影响决定着种群地位和群落演替，由于干旱区的特殊性成为研究生物响应环境变化的热点地区。为探索艾比湖流域荒漠区植物生态位对土壤水盐梯度的响应，在研究水、盐含量和植物生态位特征的基础上，应用变系数模型，分析了土壤水盐梯度下的群落组成和生态位响应趋势。结果显示：（1）随土壤水盐梯度的降低，艾比湖流域群落的物种组成呈倒"V"型分布，说明土壤水盐交互作用影响着植被分布和群落类型。（2）高水盐环境下，胡杨（Populus euphratica）、琵琶柴（Reaumuria soongorica）和梭梭（Haloxylon ammodendron）等生态位宽度值（Bi）较大，柽柳（Tamarix ramosissima）、骆驼刺（Alhagi sparsifolia）和甘草（Glycyrrhiza uralensis）等Bi较小；中水盐环境下，白刺（Nitraria schoberi）和琵琶柴的Bi较大，铃铛刺（Halimodendron halodendron）、甘草和盐节木（Halocnemum strobilaceum）的Bi较小；低水盐环境下，梭梭、花花柴（Karelinia caspica）和琵琶柴等Bi较大，盐节木的Bi较小；说明土壤水盐环境和物种生态学特性是影响Bi的重要因素。（3）物种水平上，Bi较大的种群与其他物种的生态位重叠（Oij）一般较大，但Bi较小的物种间的Oij不一定小（例如：高水盐土壤环境下柽柳和骆驼刺的Oij为1）；群落水平上，Bi与Oij具有一定的正相关性；说明由于资源纬度的相似性增大了低Bi物种间的Oij，并且Bi和Oij由物种向群落尺度转换时，两者之间的关系存在冗余。（4）土壤水盐梯度与群落生态幅呈现一种非线性相关特征，高水盐格局对群落Bi有一定的促进效应，而低水盐模式对Bi具有一定的限制作用，表明土壤水盐的协同效应影响着物种在群落的地位，并在一定程度上决定了群落向正负两极演替的方向。 Abstract:The impact of global climate change on ecosystem function determines the status of population and community succession, and since arid areas are unique, they have become a hot spot for studying biological responses to environmental change. We used a sample plot method investigation to explore the response of plant niche to the soil water and salt gradient of the Ebinur Lake Basin. Based on a study of moisture, salt content, and plant niche characteristics for arid desert areas, the changes in community composition and niche responses to soil water and salt at different gradients were analyzed. The results showed the species composition of communities had a reverse "V" pattern along the water and salt environmental factor gradient (from high to low); these phenomena indicate that the interaction of water and salt concentration was the main reason the distribution of vegetation types was restricted. The niche breadth of Populus euphratica, Reaumuria soongorica, and Haloxylon ammodendron were larger than those of Tamarix ramosissima, Alhagi sparsifolia, and Glycyrrhiza uralensis at high saltwater soil environments. The niche breadth of Nitraria schoberi and Reaumuria soongorica were larger than those of Halimodendron halodendron, Glycyrrhiza uralensis, and Halocnemum strobilaceum at moderate saltwater soil environments. The niche breadth of Haloxylon ammodendron, Karelinia capsica, and Reaumuria soongorica were larger than those of Halocnemum strobilaceum at low saltwater soil environments. These phenomena indicate that the ecological niche of a population was not only determined by soil moisture and salinity, but also the ecological characteristics of the species in the desert area. At the species level, the niche overlap of the populations with large niche breadth between other species was generally large, but the niche overlap with smaller niche breadth species was not necessarily small; however, at the community level, there was a positive correlation between niche breadth and niche overlap. These phenomena indicate that a similarity in resource latitudes increased the niche overlap between the low niche breadth species, and the relationship between them was redundant when there was a transformation of niche breadth and niche overlap from the species to the community scale. The soil water and salt gradient showed a nonlinear correlation with community ecological amplitude. The distribution pattern of high water and salt in the soil had a certain promoting effect on the niche breadth of the community, while the distribution pattern of low water and low salt had a limited effect on niche breadth. The synergistic effect of soil water and salt determined the status of species in the community and determined the direction of community succession to the positive and negative poles. 参考文献 相似文献 引证文献

荒漠植物功能性状及其多样性对土壤水盐变化的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 荒漠植物功能性状及其多样性对土壤水盐变化的响应 DOI: 10.5846/stxb201801300253 作者: 作者单位: 绿洲生态教育部重点实验室,绿洲生态教育部重点实验室,绿洲生态教育部重点实验室,新疆大学资源与环境科学学院,绿洲生态教育部重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 新疆维吾尔自治区高校科研计划青年教师科研启动基金（XJEDU2016S026）；国家自然科学基金项目（31700354，31560131） Responses of plant functional trait and diversity to soil water and salinity changes in desert ecosystem Author: Affiliation: Xinjiang University,,,,Key Laboratory of Oasis Ecology, Education Ministry Fund Project: The Scientific Research Startup Foundation for young teachers program in Xinjiang Uygur Autonomous Region University(XJEDU2016S026),The National Natural Science Foundation of China(grant no.31700354, 31500343) 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:植物功能性状及其多样性对环境变化的响应研究有助于揭示极端环境下植物适应策略和群落构建机制。通过实地调查和实验分析，研究艾比湖荒漠植物形态、生理和化学等8个功能性状的特征，并从多维性状和一维性状角度揭示功能多样性对土壤水分和盐分变化的响应规律。结果表明：高水盐环境下（SW1），（1）群落加权株高、叶绿素含量（SPAD）及叶片碳（C）和钙（Ca）含量显著高于低水盐环境，叶片氮（N）、磷（P）、硫（S）含量在不同水盐环境间无显著差异。（2）SW1环境下，沿乔木-小乔木-灌木-草本层次，上层生活型植物性状值普遍高于下层植物，其中灌木叶片仅N、钾（K）含量显著高于草本；沿该生活型层次植物性状呈趋同变化。（3）低水盐环境下（SW2），乔木叶片性状差异特征与SW1相似；小乔木叶片C、N含量分别显著高于和低于灌木及草本；相比于草本，灌木SPAD、S含量显著高，K含量显著低，株高、C、N、P含量差异不显著；SW2环境下各生活型植物性状呈趋同变化。（4）SW1环境下多维功能丰富度、功能离散度显著高于SW2环境，但均匀度无显著差异。（5）一维功能均匀度在不同水盐环境间均无显著差异，但化学性状的均匀度总体高于植物株高；高水盐环境下叶片N、S和Ca的功能分异指数显著高于低水盐环境。研究为掌握胁迫环境下的植物适应策略和荒漠植被恢复提供参考。 Abstract:Exploring the response of plant functional trait to environmental variations is essential to elucidate the adaptation mechanism and community assembly of desert plants under extreme environmental conditions, and more importantly to formulate strategies to protect and restore desert ecosystem. However, previous studies are mostly large scale, and only a few studies have focused on the effects of soil water and salinity on desert plant functional trait and diversity at fine scale. It is known that, even at fine scales, environmental variables (e.g., soil variables) can actually be heterogeneous and affect plant. Therefore, in the present study, we aimed to analyze (1) how morphological, physiological, and chemical functional traits of desert plant, and functional richness, evenness, and dispersion indexes respond to varied soil water and salinity and (2) what community assembly process did functional diversity revealed in different soil water and salinity environment? Three transects were set at 5-km intervals perpendicular to the northern bank of the Aqikesu River in the Ebinur Lake Wetland Nature Reserve (ELWNR). At each transect, the soil gradually changed from saline to sandy soil with the increase in distance from the river. Ten to twelve plots (10×10 m2) were set at an interval of 500 m in each transect. A total of 32 plots were set across the three transects. The geographic data (longitude, latitude, and altitude), number of species, plant abundance (number of individuals of each species), and height of each individual sampled in each plot were recorded. The chlorophyll content (SPAD) was measured by SPAD502, and soil volumetric water content (SVWC) at a depth of 12 cm was measured by time domain reflectometry before sampling. The leaf and soil samples were then collected for further investigation. Based on the investigation and analysis, responses of one morphological (height), one physiological (SPAD) and six chemical functional traits (leaf carbon (C), nitrogen (N), phosphorus (P), sulfur (S), potassium (K), and calcium (Ca) content), and response of multidimensional and single dimensional functional diversities to soil water and salinity were explored. The results showed the following. (1) The community weighted mean height, SPAD, and leaf C and Ca content in high soil water and salinity sites (SW1) were significantly higher than those in low soil water and salinity sites (SW2). The leaf N, P, and S content had no significant differences across the two sites. (2) In SW1 sites, the plant functional trait differences generally decreased along the tree-small tree-shrub-herb life form level, with only leaf N and K content exhibiting significant difference between shrub and herb. Furthermore, plant functional trait showed convergence along the life form level. (3) In SW2 sites, functional trait differences in trees were similar to those in the SW1; the leaf C and N content were significantly higher than those in shrubs and herbs. Furthermore, the SPAD and leaf S content of shrubs were significantly higher than those in herbs, whilst, the leaf K content of shrubs was lower than that in herbs. The height, and leaf C, N, and P content exhibited no significant differences between shrubs and herbs. The plant functional traits among life forms in SW2 site presented a trend of convergence. (4) The multidimensional functional richness (FAD2) and functional divergence (Rao) in SW1 sites were higher than those in SW2 sites, whilst, the functional evenness showed no difference. (5) All single dimensional functional evenness showed no difference between high and low soil water content and salinity; however, functional evenness of chemical trait was generally higher than that of plant height. Furthermore, functional logarithmic variance (FDvar) of leaf N, S, and Ca in SW1 was significantly higher than that of SW2. The study provides references to understand the adaption mechanism of plants subjected to extreme environments and to recover desert plants. 参考文献 相似文献 引证文献

2008-2014年新疆艾比湖流域土壤水分时空分布特征

PDF HTML阅读 XML下载 导出引用 引用提醒 2008-2014年新疆艾比湖流域土壤水分时空分布特征 DOI: 10.5846/stxb201709021586 作者: 作者单位: 新疆大学 生态学科博士后科研流动站,新疆大学,新疆大学 资源与环境科学学院;新疆大学 资源与环境科学学院,新疆大学 资源与环境科学学院;新疆大学 资源与环境科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 自治区青年基金（2018D01C067） Temporal-spatial dynamic change characteristics of soil moisture in Ebinur Lake Basin from 2008-2014 Author: Affiliation: xinjiang university,xinjiang university,, Fund Project: 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:传统的土壤水分模拟研究难以从土壤水分变化的时空双向出发表达其连续演变的过程，存在时空尺度效应问题。借助SWAT模型模拟的长时间序列优势，结合高分辨率卫星影像和遥感技术，力图在时空尺度效应问题上取得突破。并利用长时间序列的模拟结果分析流域土壤水分的空间格局和不同维度时空异质性。结果表明：（1）2008-2014年间艾比湖流域土壤水分主要受气温、降水及人类活动影响，呈波动变化，总体偏低且具有逐年减小趋势。（2）受降水、地形及土地覆被影响，土壤水分分布呈现出由山区向两侧平原减少的特点，且林地 > 农用地 > 草地 > 稀疏植被。（3）近10年间土壤水分低值区由原来的北部山区及平原向东部、东南部平原区及南部山区迁移，东部减少最为明显。（4）流域四季土壤水分变化差异显著。其中，春季主要受融雪影响；夏季、秋季主要受降雨量和气温影响；冬季主要受固态降雪和气温影响；且不同年份、相同季节、相同子流域土壤水分变化趋势表现一致。 Abstract:It is difficult to express the true soil moisture temporal and spatial variation in traditional methods, because it always reflects a certain spatial resolution or discrete temporal pattern, which is not a continuous process. In this paper, we use SWAT (Soil and Water Assessment Tool)model and multi-source remote sensing data to solve the problems caused by the effects of spatial and temporal scales of soil moisture monitoring. Explore the scientific regional scale and long-time-series soil moisture simulation method, and use the simulation results analysis soil moisture in different time and space in study area. The results showed the following:(1) soil moisture over the entire region was continued decline from 2008-2014. The major factors affecting this trend are temperature, precipitation, and human activities. (2) The distribution of soil moisture is affected by precipitation, temperature, and land cover. The distribution of soil moisture is characterized by decreasing from the mountainous area to the plains, and in the following order:woodland > agricultural land > grassland > sparse vegetation. (3) In the past 10 years, the area with low soil moisture shifted from the northern mountainous plains to the eastern part, southeastern plains, and southern mountains, one of the most obvious change was eastern part. (4) The variation in soil moisture in the four seasons was significant. Soil moisture in spring and autumn were affected by rainfall and temperature, and that in winter was affected by the snow melt and temperature. The sub-basin soil moisture change were consistent in same season in different years. 参考文献 相似文献 引证文献

Stable isotope evidence for identifying the recharge mechanisms of precipitation, surface water, and groundwater in the Ebinur Lake basin

Arid areas cover more than one third of global land, and as such, water resources are vital for this fragile ecosystem. In order to reveal the recharge mechanisms among different water bodies in arid areas, precipitation, surface water, and groundwater were sampled in the Ebinur Lake basin, Xinjiang, China, and the isotopic values for hydrogen and oxygen were measured. The stable isotope values of precipitation showed significant seasonal variation, with minimum values in the winter, medium values in the spring and autumn, and maximum values in the summer. The slope and intercept of local meteoric water line were both lower than that of global meteoric water line, indicating subcloud evaporation effect. The vapor source of precipitation was dominated by the westerlies, but the regional re-evaporation vapor accounted for some proportions as well. In the Bortala River and Jinghe River, the stable isotopic values varied spatially, tending to be enriched with the river flow. The stable isotopic values for lake water were significantly higher than those of river water, which reflected a stronger evaporation and concentration effect of the lake water. The stable isotopic values of groundwater featured similar spatial variation compared to the river, and phreatic water evaporated to some extent. In the Bortala River, owing to its specific hydrogeological structure, the exchange rates between the groundwater and the river water were higher upstream than in the middle and lower reaches. In the Jinghe River, the deep groundwater aquifer received recharge from the shallow groundwater layers and from the river. At the edge of the Ebinur Lake, the interaction of groundwater and surface water was low and springs became the important recharge source for the lake. The results of this study provide insights into the determination of river hydrological processes and the management of water resources.

Information extraction of the Ebinur Lake artemia based on object - oriented method

Information extraction of the Ebinur Lake artemia based on object - oriented method

Assessing and predicting changes of the ecosystem service values based on land use/cover change in Ebinur Lake Wetland National Nature Reserve, Xinjiang, China

Ecosystem service value (ESV) included some contributions of ecological environments to human health and living, and provide cultural and economic benefits for sustaining and fulfilling living organisms. The author selected the Ebinur lake Wetland Nature Reserve as our study site to analyze the spatial distribution and dynamics of ecosystem services, and we used 1972, 1998, 2006, 2014 and 2016 images to study land use/cover change (LUCC) over these periods. LUCC is one of the key drivers that affect ecosystem services. Firstly, in 1972–2030, land use/cover (LULC) significantly changed, with all LUCC practices increasing except for the categories of water area, bare land area and barren land/other. Secondly, changes in ESV were significant during the last 60 years. The total annual ESV in the study area decreased by 50.89% between 1972 and 2030, mostly attributable to the 6.82% growth of saline land, 0.09% growth of desert, 1% decrease of wetlands and 0.95% decrease of water bodies. Thirdly, the spatial-temporal variation of ESV was prominent. Spatial correlation was significant, and the degree of spatial clustering was relatively high in the study area, which was mainly distributed in the water body and wetland regions, and these high-value regions exhibited a decreasing trend. Low values occurred around the lake areas, which increased over time.

Estimation of the Fe and Cu Contents of the Surface Water in the Ebinur Lake Basin Based on LIBS and a Machine Learning Algorithm.

Traditional technology for detecting heavy metals in water is time consuming and difficult and thus is not suitable for quantitative detection of large samples. Laser-induced breakdown spectroscopy (LIBS) can identify multi-state (such as solid, liquid, and gas) substances simultaneously, rapidly and remotely. In this study, water samples were collected from the Ebinur Lake Basin. The water samples were subjected to LIBS to extract the characteristic peaks of iron (Fe) and copper (Cu). Most of the quantitative analysis of LIBS rarely models and estimates the heavy metal contents in natural environments and cannot quickly determine the heavy metals in field water samples. This study creatively uses the Fe and Cu contents in water samples and the characteristics of their spectral curves in LIBS for regression modelling analysis and estimates their contents in an unknown water body by using LIBS technology and a machine learning algorithm, thus improving the detection rate. The results are as follows: (1) The Cu content of the Ebinur Lake Basin is generally higher than the Fe content, the highest Fe and Cu contents found within the basin are in the Ebinur Lake watershed, and the lowest are in the Jing River. (2) A number of peaks from each sample were found of the LIBS curve. The characteristic analysis lines of Fe and Cu were finally determined according to the intensities of the Fe and Cu characteristic lines, transition probabilities and high signal-to-background ratio (S/B). Their wavelengths were 396.3 and 324.7 nm, respectively. (3) The relative percent deviation (RPD) of the Fe content back-propagation (BP) network estimation model is 0.23, and the prediction ability is poor, so it is impossible to accurately predict the Fe content of samples. In the estimation model of BP network of Cu, the coefficient of determination (R2) is 0.8, the root mean squared error (RMSE) is 0.1, and the RPD is 1.79. This result indicates that the BP estimation model of Cu content has good accuracy and strong predictive ability and can accurately predict the Cu content in a sample. In summary, estimation based on LIBS improved the accuracy and efficiency of Fe and Cu content detection in water and provided new ideas and methods for the accurate estimation of Fe and Cu contents in water.

Machine-learning-based quantitative estimation of soil organic carbon content by VIS/NIR spectroscopy.

Soil organic carbon (SOC) is an important soil property that has profound impact on soil quality and plant growth. With 140 soil samples collected from Ebinur Lake Wetland National Nature Reserve, Xinjiang Uyghur Autonomous Region of China, this research evaluated the feasibility of visible/near infrared (VIS/NIR) spectroscopy data (350–2,500 nm) and simulated EO-1 Hyperion data to estimate SOC in arid wetland regions. Three machine learning algorithms including Ant Colony Optimization-interval Partial Least Squares (ACO-iPLS), Recursive Feature Elimination-Support Vector Machine (RF-SVM), and Random Forest (RF) were employed to select spectral features and further estimate SOC. Results indicated that the feature wavelengths pertaining to SOC were mainly within the ranges of 745–910 nm and 1,911–2,254 nm. The combination of RF-SVM and first derivative pre-processing produced the highest estimation accuracy with the optimal values of Rt (correlation coefficient of testing set), RMSEt and RPD of 0.91, 0.27% and 2.41, respectively. The simulated EO-1 Hyperion data combined with Support Vector Machine (SVM) based recursive feature elimination algorithm produced the most accurate estimate of SOC content. For the testing set, Rt was 0.79, RMSEt was 0.19%, and RPD was 1.61. This practice provides an efficient, low-cost approach with potentially high accuracy to estimate SOC contents and hence supports better management and protection strategies for desert wetland ecosystems.

Clones or no clones: genetic structure of riparian Populus euphratica forests in Central Asia

Many riparian (Tugai) forests growing along rivers in arid and hyper-arid regions of Central Asia are dominated by the Euphrates poplar (Populus euphratica). Besides generative reproduction, which is only possible upon flooding events and at a distance to the groundwater of less than 2 m, this phreatophytic tree species also reproduces vegetatively by forming clones that can cover land surface areas of several hectares. Along a gradient of groundwater distances, we investigated whether the fraction of clones in P. euphratica stands (1) increases with increasing distance to the water table; (2) is higher if supplied with water via river cut-offs; and (3) approaches 100% at a short distance to the groundwater, but at high salt concentrations in the upper soil layers, which would prevent germination and establishment of seedlings. AFLP (Amplified Fragment Length Polymorphism) analyses were conducted on leaf samples taken from mature P. euphratica trees growing at the fringes of the Taklimakan Desert in stands with different distances (2–12 m) to the groundwater at two plots at the middle and the lower reaches of the Tarim River and in a stand close to Ebinur Lake, Xinjiang, China. Genetic diversity was large among plots, but considerably smaller within plots. We found the highest genetic diversity (caused by regeneration from seeds) at plots that have a short distance to the groundwater or are supplied with additional water. There was no significant relationship between groundwater distance and clonal fraction. All investigated trees at the saline Ebinur Lake site belonged to one single clone. Our results demonstrate that the genetic pattern of this widespread species is not easily predictable even over small distances as it is a result of a complex interplay of stand history and dispersal of propagules (pollen, seeds, and vegetative diaspores) by wind and water. In conservation and restoration schemes, P. euphratica stands with a high genetic diversity and stands that grow at short distances to the water table and are regularly subjected to flooding (which favors generative over clonal reproduction) should be prioritized.

New methods for improving the remote sensing estimation of soil organic matter content (SOMC) in the Ebinur Lake Wetland National Nature Reserve (ELWNNR) in northwest China

This study aimed to improve the potential of Analytical Spectral Devices (ASD) hyperspectral and Landsat Operational Land Imager (OLI) data in predicting soil organic matter content (SOMC) in the bare topsoil of the Ebinur Lake Wetland National Nature Reserve (ELWNNR) in northwest China. The results indicated that the correlation of coefficients (R) between SOMCs and hyperspectral data processed by fractional derivative were significant at the 0.01 level; the number of wave bands increased initially and then decreased when the order increased. The correlation of coefficient peak appeared at the 1.2 order with a value of 0.52. The correlation of coefficients (R) between SOMCs and the optimal remote sensing indexes (the ratio index, RI; difference index, DI; and the normalized difference index, NDI) of peaked at the 1.2 order, with correlation of coefficients (R) values of 0.81, 0.86 and 0.82, respectively. Six SOMC estimation models were created by means of a single band and optimal remote sensing indexes using Gray Relational Analysis-BP Neural Network (GRA-BPNN). This study found that the optimal model was a 1.2 order derivative model, where the lowest root mean square error (RMSE) was 3.26 g/kg, the highest was 0.92, and the residual prediction deviation (RPD) was 2.26. To complete the high accuracy retrieval of SOMCs, based on Landsat OLI operational land images data, more ‘hidden’ information from the Landsat OLI images were obtained by employing the subsection of spectral band method and the fractional derivative algorithm. Accuracy of the SOMC map was attained by the optimal model of the ground hyperspectral data and the Landsat OLI data, which had low RMSE values of 4.21 g/kg and 4.16 g/kg, respectively. Therefore, we conclude that the SOMC can be estimated and retrieved using a fractional derivative algorithm, the subsection of spectral band method, and the optimal remote sensing index.

Rhizobacterial communities of five co-occurring desert halophytes.

BackgroundRecently, researches have begun to investigate the microbial communities associated with halophytes. Both rhizobacterial community composition and the environmental drivers of community assembly have been addressed. However, few studies have explored the structure of rhizobacterial communities associated with halophytic plants that are co-occurring in arid, salinized areas.MethodsFive halophytes were selected for study: these co-occurred in saline soils in the Ebinur Lake Nature Reserve, located at the western margin of the Gurbantunggut Desert of Northwestern China. Halophyte-associated bacterial communities were sampled, and the bacterial 16S rDNA V3–V4 region amplified and sequenced using the Illumina Miseq platform. The bacterial community diversity and structure were compared between the rhizosphere and bulk soils, as well as among the rhizosphere samples. The effects of plant species identity and soil properties on the bacterial communities were also analyzed.ResultsSignificant differences were observed between the rhizosphere and bulk soil bacterial communities. Diversity was higher in the rhizosphere than in the bulk soils. Abundant taxonomic groups (from phylum to genus) in the rhizosphere were much more diverse than in bulk soils. Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes and Planctomycetes were the most abundant phyla in the rhizosphere, while Proteobacteria and Firmicutes were common in bulk soils. Overall, the bacterial community composition were not significantly differentiated between the bulk soils of the five plants, but community diversity and structure differed significantly in the rhizosphere. The diversity of Halostachys caspica, Halocnemum strobilaceum and Kalidium foliatum associated bacterial communities was lower than that of Limonium gmelinii and Lycium ruthenicum communities. Furthermore, the composition of the bacterial communities of Halostachys caspica and Halocnemum strobilaceum was very different from those of Limonium gmelinii and Lycium ruthenicum. The diversity and community structure were influenced by soil EC, pH and nutrient content (TOC, SOM, TON and AP); of these, the effects of EC on bacterial community composition were less important than those of soil nutrients.DiscussionHalophytic plant species played an important role in shaping associated rhizosphere bacterial communities. When salinity levels were constant, soil nutrients emerged as key factors structuring bacterial communities, while EC played only a minor role. Pairwise differences among the rhizobacterial communities associated with different plant species were not significant, despite some evidence of differentiation. Further studies involving more halophyte species, and individuals per species, are necessary to elucidate plant species identity effects on the rhizosphere for co-occurring halophytes.