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1.
基于电磁感应技术的土壤剖面盐分空间分布建模研究   总被引:7,自引:0,他引:7  
邓凯  丁建丽  杨爱霞  王瑾杰 《生态学报》2016,36(20):6387-6396
土壤盐渍化问题是干旱半干旱地区农业发展的主要障碍,也是制约荒漠植物生长状况的关键因素之一,严重影响到绿洲生态环境的稳定与安全。研究土壤剖面盐分的分布情况,能及时探究盐渍化对生态的影响。以渭干河-库车河三角洲绿洲为研究靶区,利用电磁感应仪技术与传统采样方法获取该地区典型地块的土壤电导率,剖析其剖面分布特征,在建立磁感式表观电导率和土壤样本实测电导率之间的线性混合模型的基础上,采用自然邻近插值方法解析和评估研究区土壤剖面盐分的空间分布特征。结果表明:研究区土壤电导率具有较强的表聚性与空间变异强度,土壤主体属于中度盐渍化类型;基于各深度层土壤电导率与磁感表观电导率所构建的3种线性混合模型均能达到0.01的显著性水平,其中磁感表观电导率两种模式相结合解译模型预测精度最高;自然邻近法插值结果直观反映研究区土壤剖面盐分的空间分布状况,与水平模式和垂直模式相结合的土壤盐分解译模型相结合则能够更有效的提高土壤盐分空间分布的预测精度。研究结果表明,借助构建的土壤盐分解译模型可对研究区土壤盐渍化空间分布情况进行快速监测与评估,为该区土壤盐渍化的防治提供了一定的技术支撑。  相似文献   

2.
电磁感应电导仪(EM38)测定土壤含盐量的研究   总被引:5,自引:0,他引:5  
利用EM38型电磁感应电导仪(EM38)在野外原位测定土壤电磁感应电导率(EM),是一种快速简便测定土壤含盐量的新方法。将EM38水平放置在地表以上不同高度,仪器EM读数随高度的变化与不同深度土层的盐分含量分布有关。室内用电导法测定不同深度土层土壤水浸液(水:土=5:1)的电导率(EC)。两种电导率(EM和EC)之间的相关分析表明,地面不同高度EM与不同深度土层EC具有显著相关性。根据EM建立了EC的回归方程,代入相应的EM值即可求出不同深度土层的EC和含盐量。  相似文献   

3.
松嫩平原苏打盐渍化旱田土壤表观电导率空间变异   总被引:1,自引:0,他引:1  
在松嫩平原西部吉林省大安市乐胜乡,于2013年4月20日选择盐碱程度不均一的典型盐渍化旱田地块,面积为4.8 hm~2作为研究样地。利用EM38大地电导率仪测定结合田间定点采样,并通过经典统计和地统计相结合的方法研究了盐渍化旱田土壤表观电导率空间变异特征,分析了土壤表观电导率与土壤盐碱指标之间的关系。结果表明,盐渍化旱田土壤水平方向表观电导率(EC_h)经对数转换后具有强空间自相关,其变异特征主要是与地形地貌和水文状况等结构性因素有关。垂直方向表观电导率(EC_v)经对数转换后具有中等空间自相关性,其变异特征受结构性因素和随机因素共同作用。EC_h和EC_v半方差模拟的最优模型分别为球状模型和指数模型。Pearson分析表明土壤表观电导率(EC_h和EC_v)与土壤盐碱指标EC_(1∶5)、pH_(1∶5)、SAR、SC、Na~+、CO_3~(2-)、HCO_3~-呈正相关关系(P0.05),EC_h与土壤盐碱指标相关系数均大于EC_v。在实际应用中可以用EC_h来指示土壤的盐碱程度。回归分析表明土壤表观电导率(EC_h和EC_v)与土壤盐碱指标呈线性相关,且EC_h回归模型的决定系数均大于EC_v回归模型的决定系数,可用水平方向土壤表观电导率(EC_h)来计算土壤盐碱指标,进行土壤盐渍化的快速评估。  相似文献   

4.
高婷婷  丁建丽  哈学萍  张飞  王飞 《生态学报》2010,30(10):2695-2705
土壤中水溶性盐的分析,是发展研究盐渍土盐分动态监测与预报技术的重要基础工作。针对目前干旱半干旱区广泛存在的绿洲土壤次生盐渍化问题,基于GIS和地统计学方法,研究了渭干河—库车河流域三角洲绿洲盐渍化土壤特征(土壤含盐量)的空间变异性。研究结果表明:渭-库绿洲土壤含盐量的空间变异性为中等变异,且随土壤深度增加而减弱。各层土壤的合理采样数为在95%置信水平,20%误差下的合理采样数目。高斯模型能够较好的拟合10-30cm及30-50cm层土壤含盐量的空间结构。各层土壤盐分空间变异性受到结构性与随机性因素共同作用的影响,呈强空间相关性。套合结构模型考虑到0-10cm层土壤盐分空间变异的尺度依赖性,能够更好的拟合0-10cm层土壤含盐量的空间结构。Kriging插值以及空间等值线分布趋势图能够直观的表现研究区内土壤盐分含量的空间分布状况和变化情况。研究为土壤特征变量空间变异分析与评价提供了普适性较强的实现方法,为构建盐渍土定量动态监测模型以及盐渍土的改良利用提供一定的科学依据。  相似文献   

5.
探究河口湿地土壤盐分的空间异质性,揭示分异格局下的空间集聚特征,对河口湿地的可持续发展具有重要意义。本文以福州市闽江河口湿地的Landsat 8遥感影像、数字高程模型和地面实测土壤盐分为数据源,利用相关性分析与主成分分析法选取显著性环境因子,去除变量间的共线性,分别采用支持向量机回归克里格法(SVROK)和回归克里格法(RK)分析了土壤盐分空间异质性,在基础上运用空间自相关法定量描述了土壤盐分空间集聚特征。结果表明: 通过主成分分析提取出3个主成分,可解释数据总方差的85%,反映植被覆盖、土壤属性和地形状况等综合变化信息,并保留原始变量的大部分信息;土壤盐分及其插值残差的空间变异受结构性因素和随机性因素的影响,采用主成分为自变量所建立的SVROK模型能更为精准地体现土壤盐分 “北高南低”的空间异质特征;土壤盐分的Moran I大于0.5,具有显著的空间正相关,空间集聚程度较高,呈现出“高值集聚、低值广布、低值包围高值”的空间集聚特征。  相似文献   

6.
干旱区土壤盐渍化特征空间建模   总被引:18,自引:3,他引:15  
丁建丽  姚远  王飞 《生态学报》2014,34(16):4620-4631
当前,土壤盐渍化以及因灌溉引起的土壤次生盐渍化问题是我国干旱、半干旱区所面临的主要生态环境问题。在特征空间理论的支持下,以波谱分解技术为基础,以Landsat-TM、Landsat-ETM+多光谱遥感影像和野外调查数据为基础数据源,通过分析干旱区土壤盐渍化对地表生物物理特征的影响,探讨了表征盐渍化过程与地表生物物理特征之间的规律及定量关系,进而利用土壤盐渍化遥感监测中关键的3个指标——经过波谱分解技术获得的直接表征盐渍化的土壤盐渍化光谱、间接表征盐渍化的植被覆盖度和土壤水分含量协同构建了二维特征空间支持下的土壤盐渍化遥感监测模型VSSI(Vegetation fraction and Soil fraction Soil Index)、SVSI(Soil water contents and Vegetation fraction Soil Index)、SSSI(Soil water contents and Soil salinization fraction Soil Index)和三维特征空间支持下的土壤盐渍化遥感监测模型SVWSI和SDI。研究结果表明:基于三维特征空间建立的SVWSI(Soil salinization fraction-Vegetation fraction-Water contents Soil Index)和SDI(Soil Distance Index)模型对不同盐渍化程度土壤的敏感程度要高于基于传统二维特征空间建立的VSSI、SVSI和SSSI模型。其中,SVWSI和SDI模型与实测0—10 cm土壤盐分含量决定系数分别为R2=0.8325和R2=0.8646,这充分说明基于高维数特征空间所构建的土壤盐渍化遥感监测模型能更准确地反映盐渍化土壤地表盐量组合及其变化信息,且指标简单、易于获取,对于今后干旱区区域大尺度盐渍地信息提取以及动态监测研究具有重要意义。  相似文献   

7.
干旱区内陆河流域尾闾绿洲土壤盐渍化动态预测   总被引:1,自引:0,他引:1  
刘丽娟  王玉刚  唐立松 《生态学杂志》2013,32(10):2614-2619
针对干旱区尾闾绿洲土壤盐渍化严重发生的现状,运用遥感和GIS技术,基于天山北麓三工河流域平原尾闾绿洲农区0~20 cm耕作层土壤盐渍化特征,利用空间概率模型预测了其今后的发生状态。结果表明:经过长时间的土地利用,土壤盐渍化程度有所加剧;通过空间概率模型χ~2检验,1982—2005年的转移概率模拟值与实际值可靠性要高于1982—1999年的转移概率。模型模拟结果显示,2010年以后到达稳定状态,人工景观的面积增加,自然景观的面积减少,其中轻盐化耕地面积减少,中盐化和重盐化耕地面积增加,在长时间范围内,土壤盐渍化依旧是制约研究区绿洲耕地生产力的主要因素。  相似文献   

8.
基于遥感的塔里木盆地北缘绿洲干湿季土地盐渍化监测   总被引:1,自引:1,他引:0  
姚远  丁建丽  张芳  王刚  江红南 《生态学杂志》2013,24(11):3213-3220
土壤盐渍化是导致干旱区土地退化、抑制植被生长、影响区域农业生产的最主要的生态环境地质问题.利用遥感数据准确、快速地获取区域盐渍化土壤的动态变化信息对于土壤盐渍化监测具有重要意义.本文以盐渍化现象严重的新疆渭干河-库车河三角洲绿洲为研究区,以2011年4月15日和2011年9月22日成像的两期Landsat-TM多光谱遥感数据为数据源,结合对研究区实地考察所采集的实测数据,通过提取改进型归一化差异水体指数、归一化植被指数以及K-L变换后所提取的第3主成分等参数作为特征量,利用决策树分类方法分别建立了研究区两个关键季节(干季和湿季)的土壤盐渍化信息提取模型,并绘制了两个季节的土壤盐渍化信息分类图.结果表明: 该方法对干季和湿季盐渍地信息的提取精度分别达到87.2%、85.3%,识别精度较高;采用该方法可以有效地对盐渍地变化信息及其空间分布状况进行监测,可为干旱区盐渍地的综合治理和绿洲土地资源的合理利用提供科学依据.  相似文献   

9.
流域尺度绿洲土壤盐分的空间异质性   总被引:15,自引:1,他引:14  
王玉刚  肖笃宁  李彦 《生态学报》2007,27(12):5262-5270
针对目前绿洲内部土壤盐渍化问题,以三工河流域绿洲为研究区,运用遥感、GIS和地统计学相结合的方法研究了0—20cm土层盐分含量的空间异质特征,结果表明:流域尺度上土壤含盐量的理论变异函数拟合符合指数模型,F检验达到极显著水平,在1.5—15kin的中尺度上具有强的空间变异性和自相关性,Kriging插值及其与同期的景观类型图叠加运算表明,整个绿洲区南部老绿洲土壤盐化面积及作用小于北部新绿洲,耕地景观类型的盐化作用及其面积强于其他景观类型,新绿洲盐化面积高于老绿洲,新绿洲耕地中有38.81%土地面积受盐害作用,而老绿洲仅为8.54%。  相似文献   

10.
以于田绿洲为研究靶区,利用24个采样点的土壤表层盐分数据,选取9个与土壤表层盐分密切相关的影响因子,结合空间自相关、传统回归分析和地理加权回归模型,分析表土盐分的空间分布特征及其影响因子的空间分异.结果表明:于田绿洲表土盐分在空间上并非随机分布,而是存在较强的空间依赖关系,空间自相关指数为0.479.地下水矿化度、地下水埋深、高程和温度是影响干旱区平原绿洲表土积盐的主要因子,这些因子具有空间异质性,选取的9个环境变量中除土壤pH值外,其他变量对表土盐分的影响强度均存在显著的空间分异.GWR模型对存在空间非平稳性数据的解释能力和估计精度都优于OLS模型,而且在模型估计参数的可视化上具有明显优势.  相似文献   

11.
In coastal China, there is an urgent need to increase land area for agricultural production and urban development, where there is a rapid growing population. One solution is land reclamation from coastal tidelands, but soil salinization is problematic. As such, it is very important to characterize and map the within-field variability of soil salinity in space and time. Conventional methods are often time-consuming, expensive, labor-intensive, and unpractical. Fortunately, proximal sensing has become an important technology in characterizing within-field spatial variability. In this study, we employed the EM38 to study spatial variability of soil salinity in a coastal paddy field. Significant correlation relationship between ECa and EC1:5 (i.e. r >0.9) allowed us to use EM38 data to characterize the spatial variability of soil salinity. Geostatistical methods were used to determine the horizontal spatio-temporal variability of soil salinity over three consecutive years. The study found that the distribution of salinity was heterogeneous and the leaching of salts was more significant in the edges of the study field. By inverting the EM38 data using a Quasi-3D inversion algorithm, the vertical spatio-temporal variability of soil salinity was determined and the leaching of salts over time was easily identified. The methodology of this study can be used as guidance for researchers interested in understanding soil salinity development as well as land managers aiming for effective soil salinity monitoring and management practices. In order to better characterize the variations in soil salinity to a deeper soil profile, the deeper mode of EM38 (i.e., EM38v) as well as other EMI instruments (e.g. DUALEM-421) can be incorporated to conduct Quasi-3D inversions for deeper soil profiles.  相似文献   

12.
针对滨海滩涂区植被类型与土壤盐渍化间的内在联系,以黄河三角洲典型海涂区为研究对象,结合电磁感应仪EM38与田间采样,分析了不同植被类型下土壤盐渍剖面分布特征,并对各植被类型下土壤盐渍剖面的电磁感应响应特征进行了比较.结果表明:研究区土壤盐分具有较强的表聚性与变异强度,水平磁感式表观电导率(EMh)对浅层土壤盐分响应较好,而垂直磁感式表观电导率(EMv)对深层土壤盐分的响应优于EMh;土壤盐渍剖面分为表聚型、底聚型和平均型3类,表聚型盐渍剖面主要为光板地和盐蒿地,底聚型的地表植被以棉花为主,平均型主要为杂草,且土壤盐分表聚强度为光板地>盐蒿地>杂草地>棉花地;随着植被类型由棉花—杂草—盐蒿—光板地变化,各剖面的EMv/EMh值逐渐降低.经非参数检验,植被类型与电磁感应响应特征具有显著相关性,且不同植被类型的EMv/EMh分布特征差异明显.  相似文献   

13.
禹城市耕地土壤盐分与有机质的指示克里格分析   总被引:7,自引:0,他引:7  
杨奇勇  杨劲松  余世鹏 《生态学报》2011,31(8):2196-2202
针对目前黄淮海平原盐渍土改良区存在的土壤盐碱、瘠薄等障碍问题,以该区域典型县域禹城市为研究对象,综合运用GIS和非参数地质统计学的指示克立格法,对0-20 cm深度的耕地土壤盐分和有机质的空间变异性进行了分析,并给出了土壤盐分和有机质满足一定阀值条件的概率分布图。结果表明,土壤盐分和有机质采用指示克里格方法都可以获得较为稳健的变异函数;受结构性因素与随机性因素共同影响,它们的指示半方差均表现为中等强度的空间自相关性,且单元指示克里格与多元指示克里格插值结果表明,土壤盐分、有机质的概率分布存在空间上的规律性与相似性;在空间分布上,研究区域土壤盐分含量高和有机质含量低的高概率区域主要分布在西北部的张庄镇、西部的房寺镇以及南部的莒镇乡等地区,该区域有一定的次生盐渍化风险;而土壤盐分含量高和有机质含量低的低概率分布区域主要分在徒骇河流经的河滩高地,土壤类型为褐土化潮土,是研究区域的主要高产区,基本无盐渍化。研究获取的综合指示概率分布图和概率风险评价对土壤可持续利用管理具有重要意义,为区域土壤质量的提高和土壤障碍因子消减提供参考。  相似文献   

14.
Soil salinity is recognized worldwide as a major threat to agriculture, particularly in arid and semi-arid regions. Producers and decision makers need updated and accurate maps of salinity in agronomically and environmentally relevant ranges (i.e., <20 dS m−1, when salinity is measured as electrical conductivity of the saturation extract, ECe). State-of-the-art approaches for creating accurate ECe maps beyond field scale (i.e., 1 km2) include: (i) Analysis Of Covariance (ANOCOVA) of near-ground measurements of apparent soil electrical conductivity (ECa) and (ii) regression modeling of multi-year remote sensing canopy reflectance and other co-variates (e.g., crop type, annual rainfall). This study presents a comparison of the two approaches to establish their viability and utility. The approaches were tested using 22 fields (total 542 ha) located in California’s western San Joaquin Valley. In 2013 ECa-directed soil sampling resulted in the collection of 267 soil samples across the 22 fields, which were analyzed for ECe, ranging from 0 to 38.6 dS m−1. The ANOCOVA ECa-ECe model returned a coefficient of determination (R2) of 0.87 and root mean square prediction error (RMSPE) of 3.05 dS m−1. For the remote sensing approach seven years (2007–2013) of Landsat 7 reflectance were considered. The remote sensing salinity model had R2 = 0.73 and RMSPE = 3.63 dS m−1. The robustness of the models was tested with a leave-one-field-out (lofo) cross-validation to assure maximum independence between training and validation datasets. For the ANOCOVA model, lofo cross-validation provided a range of scenarios in terms of RMSPE. The worst, median, and best fit scenarios provided global cross-validation R2 of 0.52, 0.80, and 0.81, respectively. The lofo cross-validation for the remote sensing approach returned a R2 of 0.65. The ANOCOVA approach performs particularly well at ECe values <10 dS m−1, but requires extensive field work. Field work is reduced considerably with the remote sensing approach, but due to the larger errors at low ECe values, the methodology is less suitable for crop selection, and other practices that require accurate knowledge of salinity variation within a field, making it more useful for assessing trends in salinity across a regional scale. The two models proved to be viable solutions at large spatial scales, with the ANOCOVA approach more appropriate for multiple-field to landscape scales (1–10 km2) and the remote sensing approach best for landscape to regional scales (>10 km2).  相似文献   

15.
The feasibility of measuring soil salinity with electromagnetic induction (EM) for determining riparian restoration potential was investigated on a 28-hectare plot at the Bosque del Apache National Wildlife Refuge in central New Mexico. The plot was cleared of exotic Tamarix chinensis (saltcedar), surveyed and gridded into 1370.2 hectare sections. Soil samples and EM measurements were taken at each section. We compared laboratory-determined ECe values from the soil samples with ECa values calculated from the EM measurements using a model developed by Rhoades et al. (1990). Direct comparison of ECe values determined from the two methods yields a low correlation due to sample-size differences but the calculated ECa was able to accurately predict whether the measured ECe would lie above or below some threshold value. An assessment of general site suitability for riparian restoration with electromagnetic induction has proven to be a rapid, accurate, and cost-effective alternative to intensive soil sampling.  相似文献   

16.
土壤盐分空间变异特征和地下水埋深状况是指导灌区合理用水和防治土壤盐碱化的重要依据。运用经典统计学和地质统计学方法,结合GIS技术,分析了河套灌区沙壕渠灌域0-20 cm、20-40 cm、40-60 cm土壤EC值的空间变异特征及地下水埋深对土壤盐分分布的影响。结果表明:沙壕渠灌域土壤盐分Cv值在不同灌溉时期和不同土壤深度均大于36%,表现为强变异特征;各灌水时期和不同土壤深度土壤EC值均表现为中等强度的空间自相关性,表层0-20 cm土壤空间自相关程度最高;秋浇前不同层次土壤EC值的空间分布在灌域内从南到北呈增大趋势,秋浇后土壤含盐量的高值区在西北部或东北部;土壤盐分受地下水埋深影响显著,灌域内地下水埋深南深北浅,土壤盐分随地下水埋深的增大而减小,二者之间满足指数关系。因此,应采取合理措施控制地下水埋深,防止区域土壤盐渍化加剧。  相似文献   

17.
Salinity intrusion caused by land subsidence resulting from increasing groundwater abstraction, decreasing river sediment loads and increasing sea level because of climate change has caused widespread soil salinization in coastal ecosystems. Soil salinization may greatly alter nitrogen (N) cycling in coastal ecosystems. However, a comprehensive understanding of the effects of soil salinization on ecosystem N pools, cycling processes and fluxes is not available for coastal ecosystems. Therefore, we compiled data from 551 observations from 21 peer‐reviewed papers and conducted a meta‐analysis of experimental soil salinization effects on 19 variables related to N pools, cycling processes and fluxes in coastal ecosystems. Our results showed that the effects of soil salinization varied across different ecosystem types and salinity levels. Soil salinization increased plant N content (18%), soil NH4+ (12%) and soil total N (210%), although it decreased soil NO3? (2%) and soil microbial biomass N (74%). Increasing soil salinity stimulated soil N2O fluxes as well as hydrological NH4+ and NO2? fluxes more than threefold, although it decreased the hydrological dissolved organic nitrogen (DON) flux (59%). Soil salinization also increased the net N mineralization by 70%, although salinization effects were not observed on the net nitrification, denitrification and dissimilatory nitrate reduction to ammonium in this meta‐analysis. Overall, this meta‐analysis improves our understanding of the responses of ecosystem N cycling to soil salinization, identifies knowledge gaps and highlights the urgent need for studies on the effects of soil salinization on coastal agro‐ecosystem and microbial N immobilization. Additional increases in knowledge are critical for designing sustainable adaptation measures to the predicted intrusion of salinity intrusion so that the productivity of coastal agro‐ecosystems can be maintained or improved and the N losses and pollution of the natural environment can be minimized.  相似文献   

18.
Alnus glutinosa (black alder) is a mycorrhizal pioneer tree species with tolerance to high concentrations of salt in the soil and can therefore be considered to be an important tree for the regeneration of forests areas devastated by excessive salt. However, there is still a lack of information about the ectomycorrhizal fungi (EMF) associated with mature individuals of A. glutinosa growing in natural saline conditions. The main objective of this study was to test the effect of soil salinity and other physicochemical parameters on root tips colonized by EMF, as well as on the species richness and diversity of an EMF community associated with A. glutinosa growing in natural conditions. We identified a significant effect of soil salinity (expressed as electrical conductivity: ECe and EC1:5) on fungal taxa but not on the total level of EM fungal colonization on roots. Increasing soil salinity promoted dark-coloured EMF belonging to the order Thelephorales (Tomentella sp. and Thelephora sp.). These fungi are also commonly found in soils polluted with heavy-metal. The ability of these fungi to grow in contaminated soil may be due to the presence of melanine, a natural dark pigment and common wall component of the Thelephoraceae that is known to act as a protective interface between fungal metabolism and biotic and abiotic environmental stressors. Moreover, increased colonization of fungi belonging to the class of Leotiomycetes and Sordiomycetes, known as endophytic fungal species, was observed at the test sites, that contained a larger content of total phosphorus. This observation confirms the ability of commonly known endophytic fungi to form ectomycorrhizal structures on the roots of A. glutinosa under saline stress conditions.  相似文献   

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