基于HJ-1卫星的冬小麦叶片SPAD遥感监测研究

SPAD能够反映植株叶绿素含量,而植株叶绿素的含量及动态变化,对评价作物生产能力、预测产量和品质均有重要意义。该研究以湖北省潜江市后湖管理区冬小麦为研究对象,通过田间观测不同生育期冬小麦叶片SPAD变化情况,结合我国自主研发的HJ-1卫星对研究区域进行同步监测,选取并计算RVI、DVI、NDVI、GRVI四种植被指数,通过对4种植被指数与冬小麦叶片SPAD进行相关性分析,并构建植被指数与冬小麦叶片SPAD回归反演模型,结果显示相关性均较高。通过对比四种植被指数模型反演精度,NDVI-SPAD对数模型预测精度较高,精度检验表明平均相对误差为-2.34,均方根误差(RMSE)为5.65,能够较好的反演研究区域内的冬小麦SPAD。利用HJ-1卫星结合NDVI-SPAD对数模型能够有效对研究区域冬小麦叶片SPAD进行遥感监测。     

基于地块单元的冬小麦遥感估产方法研究

[目的]以高分时序遥感影像为基础数据源,结合土地承包经营权地块数据,对冬小麦遥感估产方法及其精度进行研究和分析。[方法]文章以河南省兰考县为研究区,采用2019年4―5月份的GF-1C和GF-6 2 m PMS遥感影像提取了研究区冬小麦种植空间分布,并在地块单元控制下对冬小麦种植面积进行了修正和精度验证。其最优提取结果的修正阈值为0.93,地块单元内冬小麦总体分类精度为95.66%,Kappa系数为0.89。利用3月7日至5月20日6期GF-1 WFV遥感影像序列NDVI和RVI与冬小麦种植地块单元数据进行空间统计,得出各冬小麦种植地块单元内NDVI和RVI均值,通过分析冬小麦测产地块单元内均值植被指数与产量间的敏感性,提出一种组合均值植被指数的冬小麦遥感估产模型构建方法,通过交叉验证法对不同的估产线性回归模型进行精度评价。[结果]由4个均值植被指数组合变量的多元线性回归模型为最佳,决定系数为0.922 0,预测误差为40.96 g/m~2,预测精度为93.13%。通过该模型得出兰考县冬小麦平均产量为6 047.25 kg/hm~2,较2017年河南省统计年鉴研究区冬小麦平均单产6 001 kg/hm~2有所提高,土地承包经营权地块内和地块外冬小麦总产量分别为2.76亿kg和4 650万kg。[结论]该方法实现了冬小麦估产结果以像元为单位向以地块单元为单位的转变,解决了模型构建时光谱信息与实测产量间对应问题,为利用国产高分卫星进行县域地块尺度遥感单产精准化估算提供了方法支撑。     

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。     

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Landsat 8和GF 1数据的冬小麦种植空间分布提取

[目的]为探讨多源中等分辨率数据在冬小麦种植时空分布上的应用。[方法]利用2017年冬小麦关键生育期的Landsat8 OLI(抽穗期)和时间序列的GF-1 WFV(2016—2017生育期)数据,在分析各个行政分区的地表覆盖状况、作物结构和地块破碎度差别的基础上,将行政区划分为3种类型不同的提取单元并建立了适合于各自分区的提取模型:(1)利用关键生育期的OLI数据,采用监督分类—神经网络方法提取结构单一、地块齐整的怀远县种植区;(2)基于WFV数据构建五河县及城区种植区的冬小麦全生育期NDVI时间序列曲线,根据NDVI的时间特征构建冬小麦提取的决策树分类模型提取结构较复杂、混合像元明显的五河县及城区种植区;(3)在对关键生育期OLI-NDVI数据合理分割的基础上,采用最大似然的面向对象分类法获取种植密集、地块破碎的固镇县种植区。[结果]提取结果采用混淆矩阵和当年度统计数据相结合的方法进行精度评价,结果表明:(1)怀远县提取出的冬小麦提取总体精度为97.91%,五河县及城区提取出的精度为97.62%,固镇县的精度为97.42%;(2)全区域冬小麦提取的总体精度为86.82%,Kappa系数为0.84。与当年度统计数据对比的结果表明:2017年蚌埠市的准确提取面积精度可达97.91%,提取面积数据小于蚌埠市统计年鉴提供的统计数据,与调查的实际种植地块基本一致。[结论]采用不同方法提取不同空间分布特征的冬小麦种植面积具有较好的精度,该方法可以为市域冬小麦面积提取提供技术参考。     

基于HJ-CCD影像的河南省冬 小麦种植面积变化全覆盖监测

针对目前省域冬小麦种植面积遥感监测业务化运行中所存在的监测精度与成本之间相互制约的现实问题,该文以冬小麦主产区河南省为研究区域,利用2008年我国发射升空HJ卫星提供的遥感影像,通过分区解译,得出2009/2010年度河南省冬小麦种植面积年际变化率。结合两年冬小麦地面样方进行精度检验表明,利用HJ-CCD影像来进行河南省冬小麦种植面积变化全覆盖监测是可行的。     

基于环境小卫星的半干旱区土地利用信息提取

为了准确掌握半干旱地区的土地利用情况,以辽宁省彰武县为研究区,分析多时相的HJ-1B遥感影像。依据影像各时相的归一化植被指数(NDVI)及其波谱特性,获得对影像数据的整体把握。提出基于NDVI、光谱和纹理信息相结合的最大似然分类方法,通过此方法探讨该区的土地利用信息,并将分类结果与基于NDVI和光谱的最大似然分类结果进行对比分析。研究结果表明,纹理特征参与的分类精度较高,Kappa系数达到0.80,总分类精度为83.56%。因此,该方法更适合于半干旱区的遥感影像信息提取。     

基于图像和光谱技术的倒伏冬小麦产量评估研究

倒伏作物产量评估是作物倒伏灾害综合评估中的一项重要指标.针对传统倒伏作物产量评估方法的不足,该文提出了一种基于图像处理技术和光谱分析技术的倒伏冬小麦估产方法.研究首先通过冬小麦倒伏模拟试验,人工造成冬小麦倒伏,采集不同倒伏等级冬小麦RGB图像数据、冠层光谱反射率数据,并测量倒伏冬小麦产量.然后,通过RGB图像获得颜色、纹理特征,通过光谱反射率获得光谱吸收、红边和植被指数特征,取与倒伏冬小麦产量最为相关的23个特征量作为产量预测模型的输入变量.最后,使用粒子群算法优化径向基权值并建立估产模型,通过三个倒伏时期的光谱和图像指标估算倒伏冬小麦产量.结果表明,模型估算精度为98.2％,该模型能满足非接触定量化的倒伏冬小麦产量评估需求.     

黄淮海区气候变化及其对冬小麦光温生产潜力的影响

气候变化对冬小麦生长发育及产量的影响、冬小麦生产对气候变化的适应已经成为学术界研究的热点问题之一。黄淮海区是我国第一大冬小麦主产区,研究选择黄淮海区为研究区域,首先运用线性倾向率方法分析了黄淮海区近50年来太阳辐射量和平均温度在全年和冬小麦生育期两个时段内的时间和空间变化特征,运用AEZ模型计算了黄淮海区各气象站点的冬小麦光温生产潜力;在此基础上,分析了太阳辐射量和温度变化对冬小麦光温生产潜力的影响。结果表明:(1)黄淮海区全年日均太阳辐射量和生育期内日均太阳辐射量均表现为减少的趋势,且全年日均太阳辐射量减少幅度较大;(2)黄淮海区年平均温度表现为上升的趋势,而冬小麦生育期内平均温度的上升趋势极不明显;(3)黄淮海区冬小麦生育期内太阳辐射量的减少和平均温度的降低是导致冬小麦光温生产潜力下降的主要原因。     

尺度变化对油菜种植面积遥感监测精度的影响

农作物种植面积监测是遥感估产的基础工作之一,监测结果的精度直接影响到数据的可信度和可用性。随着多光谱和多空间分辨率数据集的日益普遍,多尺度遥感数据源的综合应用是进行大范围农作物种植面积遥感监测业务化运行的必然趋势,因此尺度变化对农作物种植面积遥感监测精度影响的研究势在必行。该研究采用高空间分辨率的多光谱遥感影像进行油菜种植面积提取,对其提取结果进行基于简单多数原则的尺度转化,得到不同空间分辨率的提取结果,通过与地面实测样方数据构建误差矩阵进行精度分析,分析不同空间分辨率影像对作物种植面积遥感信息提取精度的影响。运用多种精度评价指标,从不同空间分辨率、不同监测方法、不同遥感监测时相等角度系统分析了农作物种植面积遥感测量中的尺度效应问题。为基于多尺度遥感数据综合应用的农作物种植面积遥感监测业务化运行中的数据选择和精度保证问题提供理论与实验基础。     

The Effect of the Structural Adjustment Program on the Output,Prices and Exports of Major Agricultural Export Crops in Nigeria

The primary objective of this paper is to examine changes in the level of output, prices and exports of major export crops resulting from the Structural Adjustment Program (SAP) in Nigeria. THere two main sources of data: the Central Bank of Nigeria (CBN) through its annual reports, Economic and Financial Review, and the Nigerian Federal Office of Statistics (FOS) through its Trade Summaries. Although the SAP led to appreciable increases in output and producer prices, its effects on exports were insignificant. The implications of these for the implementation of the program are explored.     

Revealing different understandings of soil held by scientists and farmers in the context of soil protection and management

This paper aims to analyse and draw together results from similar studies in England, Switzerland and France which investigated farmers’ understanding of soil and compared it with that of scientists, researchers and advisors (collectively called scientists in this analysis). A range of methods were used across the three studies and different theoretical approaches, looking at forms of knowledge, local practice of knowledge production and conceptions of reality, were employed to explain the results. Despite the different contexts, methodologies and theoretical approaches in the three studies, the results reveal similar patterns of difference in farmer and scientist understanding of soil. In the English study, farmers demonstrate a ‘know-how’ form or intuitive working knowledge of soil while advisors rely on scientifically established forms of ‘know-why’ and seek to understand and explain soil processes. Similarly in the Swiss study farmers’ and scientists’ differing perceptions are directed and shaped by their respective aims, methods and context of work. In the French study, farmers and researchers are shown to have different conceptions of soil, they attribute different meaning to the same activities, and use different words and language to describe the same features. In all three studies understanding is shown to be cultural and contextual, as such an integrative theoretical framework is proposed.     

森林生物多样性评价模型的改进

针对2002年的评价模型中的不足,提出了新的改进后的森林生物多样性变化的评价模型,并在我国第六次森林资源清查(1999～2003)资料的基础上,对1973～2003年我国森林生物多样性的变化进行了补充评价。评价结果表明:我国森林生物多样性的压力越来越大,压力指数由1973年的100,上升到2003年的199.10,上升了1.99倍;森林物种多样性总体的下降趋势已有一定幅度的改变,森林物种多样性指数增加了31.12%。森林生态系统多样性和森林生物多样性先逐渐上升,尔后又下降,第六次森林资源清查时又有所恢复,并分别上升了4.67个百分点和17.90个百分点。     

Trust-A monolithic panacea in land use planning?

Although trust research has been extensive and substantial, the constitution and actual merits of trust in land use planning remain nebulous. What do participants of a local land use planning process actually mean when they say they trust the planning committee? How important is participants’ trust in the planning committee in shaping their perceptions of the planning process and their cooperation in it? To explore the everyday meaning of trust in the specific context of local land use planning, semi-structured interviews with the participants of a local planning project in Switzerland were conducted (n = 9). Based on these results, the constitution and the relevance of trust in the responsible planning committee among a wider circle of participants were assessed (n = 66). The results show that participants trust the planning committee if they perceive its members as competent, honest, open, fair, reliable, reciprocating, respectful and committed. Interestingly, a considerable part of trust in the planning committee hinges explicitly on whether the committee incorporates the personal interests of the participant. Trust is indeed vital to participants’ belief that a meaningful discussion and cooperation with the members of the planning committee is possible. However, trust is neither a guarantee for people's approval of planning decisions nor for their cooperation. One implication of the findings is that in order to evaluate trust-building practice comprehensively, it is necessary to first understand the specific everyday meaning of trust for ‘real people’ in real planning processes.     

转变地质工作发展与服务方式的实践和建议

天津市地矿局注重加快转变经济发展方式,发挥地质工作优势,推进低碳清洁能源的开发利用创新和技术进步,紧紧依托地质工作的人才、技术和行业优势,加大清洁环保资源的勘查、研究、开发、利用。针对天津市水资源缺乏的情况,积极加强后备和应紧水源勘查。按照“两种资源,两个市场”的思路,通过实施中外合作勘查项目,以境外勘查工作为载体和平台,实施引进来和走出去战略,为天津市经济社会发展提供地质技术支撑。     

Agricultural Land in Vietnam: Markets Tempered by Family, Community and Socialist Practices

Since the late 1980s, markets involving agricultural land have emerged in the Socialist Republic of Vietnam. One major reason is that collective farms, previously a central feature of the country's political economy, ended. And a major reason for that was villagers' everyday politics gnawed the underpinnings of the collectives until they collapsed. Rural households, for the most part, wanted to farm separately. Today they do. Land is not privatized, however. Farming households have land use rights, not ownership. This tempers markets, as do other conditions arising from contending schools of thought in Vietnam about how land should be used, distributed and regulated.     

Conservation agriculture (CA) in Tanzania: the case of the Mwangaza B CA farmer field school (FFS), Rhotia Village,Karatu District,Arusha

This project was initiated to promote conservation agriculture (CA) in Tanzania so as to improve the food security and rural livelihood of small- and medium-scale farmers through the scaling-up of CA as a sustainable land management (SLM) tool as well as increasing the numbers of SLM-CA farmer field schools (FFS) in communities. The project had two phases from 2004 to 2010. It was funded by a Government of Germany trust fund and implemented by the Food and Agriculture Organization of the United Nations (FAO) and the Ministry of Agriculture in Tanzania. The project pilot districts include Arumeru (Arusha and Meru Councils), Karatu, Babati, Hanang and Moshi districts. CA has been shown to offer positive elements that could contribute to fighting hunger and poverty.     

Successful Practices in California Wine Exporting

Abstract

California is one of the world's largest wine producers, yet it has exported only a small portion of its products. Many US wineries want to pursue opportunities in foreign markets but only a few are actually doing this successfully. Therefore, this study attempts to identify the successful practices of 12 California wineries that have achieved their financial targets and other export goals. A qualitative research design of in-depth interviews was employed. Results indicate that there are 5 major success factors, with the two most important being the foreign partner relationship and top management vision and commitment to exporting.     

Time Allocation Decisions Associated with Job Market Preparation: Undergraduate Perceptions versus Market Realities

A survey of agribusiness firms identifies characteristics associated with above average starting salary offers in the allied fields of agribusiness, agricultural economics, business, and economics. A complementary survey is made of students at Texas A&M University and University of Georgia. Results show that firms value work experience and leadership experience more than students do, whereas students value raising grade point average and interview preparation more than do firms. Students seeking a firm's maximum starting salary offer will need to enhance academic performance with substantial work experience and leadership experience.     

Developments in the Doha Round and WTO dispute settlement: some implications for EU agricultural policy

Progress in the Doha Round is assessed against the changes tothe common agricultural policy (CAP) brought about by the Fischlerreforms of 2003–2004, and that proposed for sugar. Anelimination of export subsidies could place EU exports of processedfoods at a competitive disadvantage because of high sugar andmilk prices. Provided the single payment scheme falls withinthe green box, the likely new limits on domestic support shouldnot be problematic for the post-Fischler CAP. However, an ambitiousmarket access package could open up EU markets and bring pressurefor further reform. If there is no Doha agreement, existingprovisions will continue to apply, but without the protectionof the Peace Clause; and increased litigation is likely. FurtherCAP reform is to be expected.