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行道树叶绿素变化的高光谱神经网络模型

刘殿伟1,2;宋开山2;张柏2   

  1. 1吉林大学地球探测科学与技术学院, 长春 130026;2中国科学院东北地理与农业生态研究所, 长春 130012
  • 收稿日期:2004-12-15 修回日期:2005-10-20 出版日期:2006-03-08 发布日期:2006-03-08

Neural network model for leaf chlorophyll content of roadside trees based on hyperspectral approaches

LIU Dianwei1,2;SONG Kaishan2;ZHANG Bai2   

  1. 1College of GeoExploration Science and Technology,Jilin University,Changchun 130026, China; 2Northeast Institute of Geography and Agricultural Ecology,Chinese Academy of Sciences,Changchun 130012, China

  • Received:2004-12-15 Revised:2005-10-20 Online:2006-03-08 Published:2006-03-08

摘要: 采样分析了城市行道树(长春市主要街道)与对比区(净月潭国家森林公园)相应树种的叶绿素变化,并对由叶绿素变化引起的光谱反射率以ASD光谱仪进行了测试,并对二者之间的关系进行了单波段回归分析、VI植被指数与叶绿素含量的模型分析以及神经网络模型分析。结果表明,1) 城市环境对行道树叶绿素有重要影响,但是对针叶树种响应较小,而阔叶树种响应较大; 2) 光谱反射率与测试树种叶绿素含量关系密切,在740~760 nm附近确定性系数达0.72以上;3)PSSR植被指数与测试树种的叶绿素含量关系密切,幂函数回归的决定系数R2为0.82左右。3)神经网络模型能够提高光谱反射率模型反演植被叶绿素含量的水平,模型的决定系数R2高达0.97。表明高光谱遥感可以用来监测因城市环境引起的植被叶绿素变化。

关键词: 碳通量, 校正方法, 热带季节雨林

Abstract: This paper compared the changes of leaf chlorophyll content between roadside trees affected by urban communication environment and corresponding trees growing in a less polluted environment—Jingyue National Forest Park,with the hyperspectral data of leaf samples obtained by using ASD Field NVIR Spectroradiometer.The results showed that urban communication environment had a strong effect on the chlorophyll content of roadside tree leaves,and deciduous tree leaves had more intensive response than conifers tree leaves.The hyperspectral reflectance of roadside tree leaves had a close relation with the chlorophyll content,and the relationship varied with wavelength.At 740~760 nm,the correlation coefficient was >0.72.PSSR (pigment specific simple ratio) index had a close relation with chlorophyll content,and a power regression model was established,with the determination coefficient around 0.82.BP (back propagation) neural network showed a more promising potential for predicting the tree leaf chlorophyll content with hyperspectral reflectance data,and the determination coefficient was >0.97.It was suggested that hyperspectral reflectance data could be used to detect the change of roadside tree leaf chlorophyll content caused by urban communication environment.

Key words: Carbon flux, Correction method, Tropical seasonal rainforest