基于ACRM模型不同时期冬小麦LAI和叶绿素反演研究

通过冬小麦4个生育期不同长势冠层光谱观测数据,模拟HJ小卫星多光谱等效反射率;然后使用双层冠层反射率模型(ACRM)反演各生育期冬小麦LAI和叶绿素含量,分析HJ小卫星多光谱数据定量反演LAI和叶绿素含量的应用潜力以及ACRM模型在不同冬小麦生育期的LAI和叶绿素含量反演误差。将模型反演值与实测值对比分析发现:(1)LAI和叶绿素含量反演值与地面实测值有很高的相关性,应用HJ小卫星多光谱数据定量反演LAI和叶绿素有很大的应用潜力;(2)ACRM模型在不同生育期的冬小麦LAI和叶绿素含量反演误差存在差异。     

基于Landsat8数据的沙湖叶绿素a反演研究

本文以武汉沙湖水体为研究对象,以“3S”技术为支撑,基于Landsat 8遥感影像数据与实测水质数据,根据各波段反射率的相关性,分析与研究了遥感影像数据的适宜波段,采用回归分析的方法,建立适合沙湖水体的叶绿素a浓度遥感反演模型。反演结果表明,以第4波段建立的多项式回归反演模型效果较好,其平均误差为7.28%,Landsat 8影像数据能有效用于沙湖叶绿素a浓度的监测,在空间分布上也呈现一定的空间格局形态,并显示沙湖西北角(新生路泵站)污染相对严重,与沙湖实际情况基本吻合,因此将Landsat 8影像数据应用于内陆湖泊水体叶绿素a浓度反演具有一定的可行性。     

无人机高光谱遥感数据在冬小麦叶面积指数反演中的应用

[目的]无人机高光谱遥感是获取田间尺度作物生长参数的新型手段,如叶面积指数(leaf area index,LAI)的无人机快速观测对作物生长监测具有重要意义。[方法]研究以河北省衡水市冬小麦为研究对象,利用以多旋翼无人机为平台搭载Cubert UHD185成像高光谱传感器获取了冬小麦乳熟期的无人机高光谱影像数据;在无人机飞行的冬小麦试验田,利用LAI 2200进行了同步观测试验。该研究利用植被辐射传输模型PROSAIL模拟小麦冠层反射率数据,进而模拟9种植被指数(RVI,NDVI,EVI2,OSAVI,MSAVI2,TCARI/OSAVI,RENDVI(red edge NDVI),MSI,S2REP)。将模拟的植被指数与LAI进行相关性分析,分别构建LAI反演模型并通过拟合效果选择最优的反演模型。然后基于LAI最优反演模型利用无人机高光谱遥感数据反演冬小麦乳熟期的LAI。最后利用地面实测LAI数据对反演结果进行了验证。[结果]9种植被指数中包含红边波段的RENDVI和S2REP与LAI具有高度相关性,而且消除了在小麦LAI高值区时其他植被指数对LAI饱和的问题。基于RENDVI指数模型模拟的LAI与模型模拟的LAI之间RMSE为0.51,无人机高光谱数据LAI反演结果与地面实测值高度拟合(R2=0.83,RMSE=0.16,NRMSE=10%,n=25,P0.001),因此RENDVI是用于估算LAI的较理想的植被指数。[结论]无人机高光谱是获取小麦LAI的有效手段,该研究为利用无人机高光谱数据监测作物生理生态参数提供了参考。     

结合植被指数与作物高度反演冬小麦叶面积指数

[目的]叶面积指数LAI(Leaf Area Index)是反映作物长势的关键参数之一。目前,基于无人机影像进行LAI反演多注重影像光谱信息的应用,但是由于高分影像存在强烈的光谱异质性以及无法区分高密闭度植被垂直方向枝叶的光谱特征等不足,在反演作物LAI时,需要探讨作物高度等结构参数对LAI反演的影响。[方法]文章以冬小麦为例,将无人机影像的光谱信息与点云数据相结合,共同构建LAI反演模型,并与单利用光谱信息的一元线性LAI回归模型进行对比,探讨作物高度信息对LAI反演精度的影响。[结果](1)无人机影像获取的点云数据能有效反演作物高度,其决定系数R~2=0.61,均方根误差RMSE=0.02;(2)基于作物高度和植被指数Ⅵ(Vegetation Index)反演LAI的二元模型(Adjust R~2=0.38,Adjust RMSE=0.55)优于单用植被指数反演LAI的一元模型(Adjust R~2=0.29,Adjust RMSE=0.59),[结论]研究表明作物高度和光谱信息结合的反演模型能够提高作物LAI的反演精度,同时表明作物高度因子在LAI反演中具有重要的应用价值。     

不同pH值对蓝莓土壤Cd/Zn生物有效性的影响

本研究采取盆栽试验,应用Tessier连续浸提法,研究不同p H值对土壤中不同形态Cd/Zn含量的影响。结果表明:栽培蓝莓土壤p H值的高低,对土壤总Zn及Cd含量无影响。随着土壤p H值的降低,土壤中交换态Zn/Cd、碳酸盐结合态Zn/Cd和铁锰氧化物Zn/Cd的含量增加,而有机态Zn/Cd和残渣态Zn/Cd含量降低。生物无效态Zn为土壤中Zn的主体部分,而生物有效态Cd为土壤中Cd的主体部分。土壤p H值的降低可增加土壤中Zn/Cd的生物有效性。     

基于Landsat-TM和测量地物光谱耦合分析——以开封地区为例

地物光谱数据是遥感技术之基础资料,是建立地面数据和遥感数据关系的桥梁;在对遥感机理和地物光谱理论深入理解的基础上,用回归分析思想探讨遥感影像光谱与实测相应地物光谱的耦合程度,两者的相关系数ρ=0.8689,相关性较好,因此可以将经过大气校正后的影像光谱值代替实测地物的光谱值进行相关的分析。     

物理模型光谱模拟误差对冬小麦叶面积指数高光谱反演的影响

获取农作物叶面积指数(leaf area index,LAI)及其动态变化对于农作物长势监测和产量估测等应用具有重要的意义。基于冠层反射率模型(物理模型)的LAI遥感反演方法具有良好的普适性,对地面数据依赖较少,近年来广泛应用于农作物LAI高光谱反演研究。然而,当物理模型参数取值尽可能准确(代入参数实测值或依据先验知识取值)时,模拟光谱与实测光谱间仍然存在误差,研究称之为"光谱模拟误差"。该研究通过比对实测冬小麦冠层光谱与ACRM(a two-layer canopy reflectance model)模型最优模拟光谱,展示了光谱模拟误差在各波段、不同样本点的分布规律。据此,根据对光谱模拟误差与高光谱数据降维的不同考虑,制订了4种LAI反演波段选择方案。通过对比基于不同波段选择方案的LAI反演精度,分析了光谱模拟误差对LAI反演的影响;讨论了综合考虑高光谱数据降维与光谱模拟误差的LAI反演波段选择方法。通过合理的波段选择,限制了光谱模拟误差的影响,提高了LAI反演精度。该研究结果有助于探索合理的LAI高光谱反演波段选择方法,为合理利用高光谱数据反演农作物LAI提供科学参考。     

不同含水量土壤高光谱二向性反射特征研究

【目的】探讨高光谱遥感土壤含水量对土壤二向性反射分布函数(bidirectional reflectance distribution function,BRDF)的影响,可为改进土壤含水量高光谱遥感反演机理模型,提高反演精度奠定重要基础。【方法】该研究在室内条件下对含水量为5%~45%(按5%递增)的土样进行多角度光谱测定,分析光源天顶角、观测天顶角、观测方位角及含水量不同对土壤二向性反射特征的影响。【结果与结论】由于土壤表面颗粒之间的相互遮蔽,土壤BRDF随光源天顶角的增加而增大,随观测天顶角的减小而降低,且土壤BRDF随观测天顶角的变化与波长有关。后向散射方向的土壤BRDF最高,前向散射方向的土壤BRDF最小。在400~1 400nm波段范围内,当土壤含水量小于田间持水量时,土壤BRDF值随含水量的增加而降低;大于田间持水量时,土壤BRDF值随含水量的增加而增加。但在波长1 400~2 400nm范围内,不同的观测位置下,土壤含水量不同引起土壤BRDF的变化没有明显规律。     

高分辨率铁尾矿遥感光谱特征分析与信息提取

遥感监测尾矿是矿山调查和监管的科学方法,也是地理国情监测的基础内容。研究了铁尾矿遥感影像解译标志和光谱特征,建立铁尾矿遥感信息的提取技术流程。利用尾矿光谱特征与纹理结构的特点,构建了铁尾矿遥感增强处理的RTI数学模型。并以唐山地区的铁尾矿及固体废弃物作为研究区,分析了模型的影响因子和有效性。为尾矿资源的自动监测和目标提取提供了新的处理手段。     

分层土壤水分的遥感估算——以岷江上游毛儿盖地区为例

土壤水对于地球各层各种水分交换有着十分重要的意义。岷江上游地区地质地貌情况复杂,针对其特点,利用不同的植被指数与温度构造特征空间,比较分析后选用Ts-EVI空间建立的水分指数,反演适用于岷江上游典型地表的土壤含水量模型和地下土壤分层含水量模型。     

Management of salinity in the river Murray basin

The salinization of the extensive River Murray system and its highly cultivated basin in south-eastern Australia is viewed as one of the nation's most significant resource and environmental problems. This article details the major factors that have contributed to salinity and discusses policies for its management. Past salinity studies are seen to be too limited and have mainly examined the cost-effectiveness of alternatives at the local level over a short term using a limited set of economic and technical criteria. It is argued that a more comprehensive assessment of management options is needed, ideally with the objective of maximizing community welfare over time throughout the whole basin. Clearly, legislative and financial measures will then be necessary to encourage the adoption of relevant options.     

Environmental land use conflicts: A threat to soil conservation

Soil vulnerability and environmental land use conflicts were quantified and cross tabulated in the Sordo River basin (Trás-os-Montes Province, NE Portugal) to provide insights about the risk of soil degradation within that basin. Soil vulnerability was assessed by algorithms of multi criteria analysis and weighted linear combination, whereas environmental land use conflicts were described by an original approach. Three vulnerability scenarios were considered, enhancing the importance of topographic slope, soil class and use and occupation of soils, respectively, as vulnerability factors. Regardless the scenario, approximately two-thirds to the basin was defined as areas with high vulnerability. Fortunately, only 10.9% of the basin is in environmental conflict, where actual land uses deviate from natural uses determined by soil characteristics. The cross tabulation of high vulnerability areas with conflict areas, which defines the areas at risk of soil degradation, reveal that risk areas account for approximately 3.2–8.4% of the basin, depending on the scenario, being concentrated in steep slope hillsides suited for forest or mixed forest and pasture occupations but actually used for irrigated crop lands, vineyards and olive yards. Some conservation practices are implemented in the vineyard and olive yard areas, namely through the construction of terraces. These structures minimize soil erosion but are potentially unstable beyond given intervals of terrain slope. On the other hand, the maintenance of terraces is costly and for that reason eventually unaffordable for many farmers, and they also entail a mischaracterization of the historical and architectural heritage of the Douro Wine Region (UNESCO World Heritage). In this context, it was suggested the approval of legislation as regards the design, construction and maintenance of terraces, while in a broader perspective it was recommended the appreciation of a European Directive for soil protection and its subsequent transposition to the national legislation.     

干旱区盐渍化农田景观格局特征分析

干旱区农田土壤盐渍化问题突出且日趋严重,已成为制约绿洲农业发展的主要障碍之一。以玛纳斯县为研究区,运用景观生态学方法和GIS技术,选取相关景观格局指数,对农田盐渍化景观格局及土壤盐渍化程度与景观格局关系进行定量分析。结果表明:(1)研究区以轻度盐渍化农田为主,农田土壤盐分在水平方向的变异程度随着深度的增加而降低,总体来看,农田斑块形状较规则、简单且面积变化幅度较大。(2)类型水平土壤盐渍化程度对农田斑块面积影响显著,随着土壤盐渍化程度增加而农田斑块面积减小。盐渍化程度对类型斑块间距离影响明显,轻度盐渍化程度农田斑块呈集中分布,而其它类型类型斑块间距离较大,相对分散分布。(3)斑块水平土壤深度(0~100cm)范围内,土壤含盐量与农田斑块形状、面积和邻近斑块数关系密切。盐渍化农田盐渍化程度愈重,其农田斑块形状愈复杂,农田斑块面积愈小,农田斑块邻近斑块数愈少。中层盐渍化程度对农田斑块形状和面积影响相对较大,底层盐渍化程度对农田斑块集中连片分布特征影响较大。     

黄河三角洲典型区土壤盐分空间分布预测方法研究

[目的]正确评估土壤盐渍化状况,掌握土壤盐分空间分布规律,是合理开发利用盐渍化土壤资源的基础和前提。[方法]文章选取黄河三角洲典型地区垦利县作为采样区,利用4种确定性方法 (全局多项式、局部多项式、反距离加权、径向基函数)和3种地统计不确定性方法 (普通克里格、简单克里格、协同克里格),分别对研究区进行土壤含盐量的空间分布特性估计,从误差和空间分布特点上对比分析不同方法的预测效果,并明确了研究区土壤盐分的空间分布特征。[结果]地统计不确定性插值方法的精度整体上优于确定性方法,简单克里格预测后的空间表达和误差精度均属最优。基于最优的空间预测方法,黄河三角洲土壤盐分目前在空间上整体呈现出东部高于西部的趋势,且部分区域存在斑块状现象。非盐渍化、轻度盐渍化、中度盐渍化、重度盐渍化和盐土面积分别占研究区总面积的2.54%、27.14%、43.70%、21.21%和5.41%。[结论]在土壤属性变异强度大的时候,采用简单克里格效果会更好。     

European Soil Data Centre: Response to European policy support and public data requirements

In the context of the European Union's Soil Thematic Strategy, policy makers require easy access to soil data and information of various types and scales to assess the state of soils at European level. To satisfy this need, the European Commission and the European Environment Agency (EEA) decided to establish the European Soil Data Centre (ESDAC), located at the European Commission's Joint Research Centre.The ESDAC is one of ten environmental data centres that have been established during the last 4 years in support of policy development, implementation and monitoring by the European Commission's Directorate General for Environment. The ESDAC, located at http://esdac.jrc.ec.europa.eu, has become the focal point for soil data and information at European Union level by hosting a series of soil products and web-based tools that allow access to the data. The ESDAC acts as the primary data contact point for the Commission and EEA to fulfill their information needs. The establishment and the evaluation of harmonised databases should facilitate improved soil protection measures.     

Assessing impact of land uses on land salinization in the Yellow River Delta,China using an integrated and spatial statistical model

Intensification of agriculture and industry in salinized areas poses a risk of secondary salinization. Thus, comprehensive and spatially explicit assessments are needed to assist government in developing ecologically sound policies. Few assessments have comprehensively quantified the impacts of multiple anthropogenic activities on salinization as environmental interferences and salinity autocorrelation are largely neglected. This study tried to perform such an assessment by identifying the nature of human impacts on salinization from three aspects in the Yellow River Delta (YRD) of China. A versatile GIS-based spatial autoregression (SAR) was applied to nine selected explainable variables in six sub-region models. Sub-region model was verified as an effective tool of normalizing environmental interferences because more useful spatial information was provided compared to the whole region model. GIS-SAR model fit better and performed better in quantifying human activities, compared to the conventional ordinary least square regression (OLSR) model, as SAR can deal with spatial autocorrelation in soil salinity. Among the well-defined key determinants, oil exploitation and saline aquaculture were aggregative to salinization but only in originally highly saline sub-regions, such as coastal zone and Gleyic Solonchaks (coastal saline moisture soil) area. Two agricultural activities, crop plantation and fertilization, were mainly ameliorators in most sub-regions. The most effective salinization alleviation occurred in moderately saline sub-regions, such as floodplain and Salic Fluvisols (saline moisture soil) area, which benefitted from the development of agroforests and farm ponds. The SAR sub-region model is spatially explicit for spotting the hazardous areas and some suggestions were also provided for the policy makers.     

西部生态脆弱区农用地质量等别限制因素及提升策略研究

该文以云南陆良为代表的云贵高原区、重庆丰都为代表的四川盆地区、陕西凤翔为代表的黄土高原区、新疆阿勒泰为代表的西北地区以及内蒙古达拉特为代表的内蒙古及长城沿线农牧交错区为例,基于农用地分等成果,对5区农用地质量等别特征进行了系统对比分析,查明了各区农用地质量等别主要限制因素,并提出相应的提升策略,为耕地质量保护和建设政策的制定提供科学依据。研究结果表明,以上述5区为代表的西部生态脆弱区农用地等别总体偏低,农用地多为中等地和低等地,高等地分布较少,优等地无分布;有效土层厚度、有机质含量、灌溉条件是5区耕地质量等级的共同限制因素。pH值、表层土壤质地、排水条件以及盐渍化程度为西北地区和内蒙古农牧交错区特有的限制因素,岩石露出度为云贵高原区特有的限制因素,灌溉水源为黄土高原区特有的限制因素,林网化程度为西北地区特有的限制因素。在制定区域耕地质量保护与建设政策时,既要考虑共性限制因素,更要着眼于区域特有的限制因素,根据各区耕地质量等别限制因素制定相应提升策略。     

Valuing soil conservation benefits of agroforestry: contour hedgerows in the Eastern Visayas,Philippines

Trees can be considered as investments made by economic agents to prevent depreciation of natural assets such as stocks of top soil and water In agroforestry systems farmers use trees in this manner by deliberately combining them with agricultural crops on the same unit of land. Although advocates of agroforestry have asserted that soil conservation is one of its primary benefits, empirical estimates of these benefits have been lacking due to temporal and spatial complexity of agroforestry systems and the nonmarket aspect of soil capital assets. This study designs and applies a bio-economic framework for valuing the soil conservation benefits of agroforestry. The framework is tested with econometric analysis of data from surveys of households in Eastern Visayas. Philippines, where USAID/Government of Philippines introduced contour hedgerow agroforestry in 1983. By constructing a weighted soil quality index that also incorporates measures of soil fertility, texture and color in addition to erosion, we extend previous economic studies of soil resources. This index is regressed on a variety of farming and site specific bio-physical variables. Next, we use a Cobb-Douglas profit function to directly relate agricultural profits and soil quality. Thus, the value of soil conservation is measured as a quasi-rent differential or the share of producer surplus associated with a change in soil quality. Because this framework assumes the existence of markets, the assumption is tested by analysing the statistical significance of consumption side variables, e.g., number of household members, on production side variables, e.g., profits. Instrumental variables are used to handle the endogeneity of the soil index in the profit equation. Seemingly unrelatedregression (SUR) analysis is used to accommodate correlation of errors across the soil and profit equations. Regression results reveal the importance of agroforestry intensity, private ownership, land fragmentation, and familiarity with soil conservation as positive covariates of soil quality. Analysis of production data indicate the importance of market prices, education, farming experience, farm size, topography, and soil quality as positive covariates of household profits Investments in agroforestry to improve or maintain soil capital can increased annual agricultural profits by US$53 for the typical household, which is 6% of total income. However, there are significant up-front costs. Given that small farmers in tropical uplands are important players in the management of deteriorating soil and forest resources, policy makers may want to consider supporting farmers in the early years of agroforestry adoption.     

A legal framework with scientific basis for applying the ‘polluter pays principle’ to soil conservation in rural watersheds in Brazil

The “polluter pays principle” (PPP) has been looked at from the perspective of legal values and technical principles, namely of soil science, to evaluate the acceleration of soil erosion and the consequent development of degraded areas in the Uberaba River basin (area: 2419 km²), state of Minas Gerais, Brazil. Having accomplished this goal, the study highlights the importance of PPP for the conservation of soil and development of an ecologically equilibrated environment. The diagnosis of degraded areas was based on the coupling of a Geographic Information System with soil loss, land use conflict and tolerance to soil loss models, and revealed a preoccupying situation because an extension of approximately 905 km² (1/3 of the basin) has been considered in advanced state of degradation potentially causing environmental damage (e.g., decline of soil fertility and hence crop production, negative impacts of soil particles export on stream and lake water quality and biodiversity of riverine ecosystems). Facing this problem, a legal framework standing on doctrinaire principles, federal laws and the Brazilian Constitution has been proposed whereby the protagonists of soil degradation are called to assume responsibility as well as the costs of repairing this negative condition. Although the study has been carried out on a specific country under pre-defined settings, the rationale behind the proposals can easily be transposed to other scenarios because the scientific methods on which soil degradation has been defined and mapped are generally applicable, while the suggested legal values are currently applied to many regions on the planet.     

松嫩平原稻区防止次生盐渍化的研究

松嫩平原种稻区防止土壤次生盐渍化技术研究表明，合理灌溉，加强排水，增施有机肥，调控水盐平衡和肥盐平衡，是农业生产中的一个重要问题。通过旱改水稻稻治涝防止土壤次生盐渍化技术的研究，明确了井灌，渠灌，井渠结合灌溉对土壤次生盐渍化的影响。