基于ERS-1/2和Envisat ASAR数据的大区域森林制图研究     

田昕  李增元  陈尔学  凌飞龙  Oliver Cartus 《北京林业大学学报》2013,35(1):7-16

分别利用1995—2000年的ERS-1/2串行数据和2005年的Envisat ASAR数据对我国东北林区进行森林制图研究。针对ERS-1/2数据相干模型,采用一种不依靠地面实况数据而是基于MODIS植被连续覆盖产品进行训练的方法,从而实现进行大区域森林蓄积量分级制图的目的。分级制图包括0～20、20～50、50～80和80 m3/hm2 4个蓄积量等级。基于Envisat ASAR数据,采用面向对象的分类方法,进行自动化森林和非森林分类处理。基于2005年Landsat TM-5分类结果的交叉验证表明:这2种传感器SAR数据均可用于大区域森林制图。2期森林制图结果为进一步的森林变化分析以及制图更新研究提供支持。   相似文献   

利用时序合成孔径雷达数据监测水稻叶面积指数   总被引：2，自引：0，他引：2  

张晓倩  郭琳  马尚杰  赵占营  裴志远 《农业工程学报》2014,30(13):185-193

为了确定全极化雷达数据监测水稻叶面积指数动态变化的精度,该文对水稻叶面积指数与后向散射系数进行了各生长阶段建模比较。采用广东雷州地区多时相多入射角精细全极化Radarsat-2数据,结合水稻全生育期地面样方实测数据,首先分析多入射角归一化后四极化(vertical-horizontal polarization,VH;vertical-vertical polarization,VV;horizontal-horizontal polarization,HH;horizontal-vertical polarization,HV)、比值极化HH/VV后向散射系数与水稻叶面积指数(leaf area index,LAI)随时间变化特征以及在营养生长阶段、生殖生长阶段和全生育期的相关关系,提取相关系数高于0.8的极化与生长阶段进行水云模型建模,最终生成多期水稻LAI反演分布图,并验证该数据反演水稻各生长阶段LAI的精度,探索SAR数据追踪区域尺度水稻长势的可行性。结果表明,在地形较为平坦的水稻集中连片种植区,VV、HH/VV后向散射系数与LAI在营养生长期、全生育期极显著相关(P0.01),相关系数均高于0.83。营养生长阶段VV、HH/VV水云模型拟合决定系数分别为0.77、0.87,全生育期VV、HH/VV水云模型拟合决定系数分别为0.73、0.8,营养生长阶段模型优于全生育期模型。精细四极化SAR数据监测区域尺度水稻LAI动态变化具有应用潜力,优选的极化模型为进一步的水稻长势监测提供依据。  相似文献   

SEVERITY OF SALINITY ACCURATELY DETECTED AND CLASSIFIED ON A PADDOCK SCALE WITH HIGH RESOLUTION MULTISPECTRAL SATELLITE IMAGERY     

R. Setia  M. Lewis  P. Marschner  R. Raja Segaran  D. Summers  D. Chittleborough 《Land Degradation \u0026amp; Development》2013,24(4):375-384

We hypothesised that digital mapping of various forms of salt‐affected soils using high resolution satellite imagery, supported by field studies, would be an efficient method to classify and map salinity, sodicity or both at paddock level, particularly in areas where salt‐affected patches are small and the effort to map these by field‐based soil survey methods alone would be inordinately time consuming. To test this hypothesis, QuickBird satellite data (pan‐sharpened four band multispectral imagery) was used to map various forms of surface‐expressed salinity in an agricultural area of South Australia. Ground‐truthing was performed by collecting 160 soil samples over the study area of 159 km². Unsupervised classification of the imagery covering the study area allowed differentiation of severity levels of salt‐affected soils, but these levels did not match those based on measured electrical conductivity (EC) and sodium adsorption ratio (SAR) of the soil samples, primarily because the expression of salinity was strongly influenced by paddock‐level variations in crop type, growth and prior land management. Segmentation of the whole image into 450 paddocks and unsupervised classification using a paddock‐by‐paddock approach resulted in a more accurate discrimination of salinity and sodicity levels that was correlated with EC and SAR. Image‐based classes discriminating severity levels of salt‐affected soils were significantly related with EC but not with SAR. Of the spectral bands, bands 2 (green, 520–600 nm) and 4 (near‐infrared, 760–900 nm) explained the majority of the variation (99 per cent) in the spectral values. Thus, paddock‐by‐paddock classification of QuickBird imagery has the potential to accurately delineate salinity at farm level, which will allow more informed decisions about sustainable agricultural management of soils. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

基于微波穿透性能对双极化SAR数据识别浅覆盖层岩石的研究     

叶超  邢立新  崔建楠 《安徽农业科学》2015,(4):369-371,392

在对雷达波穿透性能影响因素研究的基础上,通过对阿巴嘎地区ALOS卫星地物后向散射强度数据进行分析,显示出在不同极化方式下ALOS数据具有的差异性.结合Landsat 7卫星获得的影像数据,对其差异性进行分析,表明HH极化方式能够识别山体边缘浅覆盖层下的岩石.研究结果表明,ALOS HH极化方式对浅覆盖层下岩石的识别更具优势.  相似文献   

A structural modelling study on marine sediments toxicity          下载免费PDF全文

Jäntschi L  Bolboaca SD 《Marine drugs》2008,6(2):372-388

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应用遥感数据识别意大利沿海松林灾害级别          下载免费PDF全文

白黎娜  李增元  Fabio Maselli  Lorenzo Bottai  Alberto Ortolani  Stefano Romanelli 《林业科学研究》2001,14(5):479-483

分析了LandsatTM和ERS-1SAR数据用于识别意大利沿海松林污染灾害级别的潜在能力，结果显示出夏季获取的TM数据在森林灾害制图上远比冬季获取的TM数据和SAR影像有效，但SAR影像的贡献也是不可忽略的，文中给出了应用人工神经元网络B-P模型得到的对意大利沿海松林污染灾害级别划分的结果和应用FINDKAPP程序得到的精度评价结果。  相似文献   

Effect of treating soybean with 2,6-dichloroisonicotinic acid (INA) and benzothiadiazole (BTH) on seed yields and the level of disease caused by Sclerotinia sclerotiorum in field and greenhouse studies     

Elizabeth Dann  Brian Diers  Joe Byrum  Ray Hammerschmidt 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(3):271-278

Field or greenhouse grown soybeans were treated with 2,6-dichloroisonicotinic acid or benzothiadiazole and subsequently assessed for severity of white mold disease caused by Sclerotinia sclerotiorum. Three or four applications of 2,6-dichloroisonicotinic acid to field plots in 1993–1995 reduced severity of white mold after natural infection by 20–70% compared with water-treated controls in soybean cultivars Elgin 87 and Williams 82, which are considered to be highly susceptible to the disease. The effect was not as large in the cultivars Corsoy 79 and NKS19-90 which are more resistant to white mold. Two or four applications of benzothiadiazole to field plots in 1995 and 1996 reduced white mold severity by 20–60%, with the greatest reductions again observed in the more susceptible cultivars. Corresponding yields were increased compared with controls, particularly for the susceptible cultivars under conditions of high disease pressure. In greenhouse trials multiple applications of either compound resulted in significantly smaller lesion diameters following subsequent leaf inoculations with the fungus. The compounds did not result in observable phytotoxicity or inhibit growth of Sclerotinia sp. in vitro. We hypothesize that the decrease in disease severity following treatment with INA or BTH is a result of resistance induction.  相似文献   

Harpin-elicited hypersensitive cell death and pathogen resistance require the NDR1 and EDS1 genes     

J. -L. Peng  H. -S. Dong  H. -P. Dong  T. P. Delaney  J. M. Bonasera  S. V. Beer   《Physiological and Molecular Plant Pathology》2003,62(6):317-326

Plants sprayed with harpin, a bacterial protein that induces hypersensitive cell death (HCD), develop systemic acquired resistance (SAR) without macroscopic necrosis. HCD sometimes accompanies the development of resistance conferred by resistance (R) genes. In Arabidopsis, some R genes require one or both of the signalling components NDR1 and EDS1 for function. This study addresses whether HCD, NDR1 and EDS1 are required for induction of SAR by harpin. When Arabidopsis and tobacco leaves were sprayed with harpin, microscopic hypersensitive response (micro-HR) lesions developed. Systemic expression of PR genes and the development of resistance were accompanied by micro-HR, except in the ndr1-1 mutant, in which harpin induced micro-HR without the development of resistance or expression of the PR-1 gene. Cell death and resistance did not occur following treatment with harpin in plants that could not accumulate salicylic acid. Harpin also failed to induce resistance in Arabidopsis eds1-1 mutants. Therefore, harpin-induced resistance seems to develop concomitantly with cell death and resistance requires NDR1 and EDS1.  相似文献   

Synthesis and biological activity of analogs of the antifungal antibiotic UK‐2A. I. Impact of picolinamide ring replacement     

W John Owen  Kevin G Meyer  Thomas J Slanec  Nick X Wang  Stacy T Meyer  Noormohamed M Niyaz  Richard B Rogers  Karla Bravo‐Altamirano  Jessica L Herrick  Chenglin Yao 《Pest management science》2019,75(2):413-426

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Discovery of novel insecticidal 3‐aminopyridyl ureas     

William T Lambert  Ann M Buysse  Frank J Wessels 《Pest management science》2020,76(2):497-508

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