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基于小波变换的毛竹叶片净光合速率高光谱遥感反演

孙少波1,2,杜华强1,2*,李平衡1,2,周国模1,2,徐小军1,2,高国龙1,2,李雪建1,2   

  1. (1浙江省森林生态系统碳循环与固碳减排重点实验室, 浙江临安 311300; 2浙江农林大学环境与资源学院, 浙江临安 311300)
  • 出版日期:2016-01-18 发布日期:2016-01-18

Retrieval of leaf net photosynthetic rate of moso bamboo forests using hyperspectral remote sensing based on wavelet transform.

SUN Shao-bo1,2, DU Hua-qiang1,2*, LI Ping-heng1,2, ZHOU Guo-mo1,2, XU Xiao-jun1,2, GAO Guo-long1,2, LI Xue-jian1,2   

  1. (1Zhejiang Province Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration, Lin’an 311300, Zhejiang, China; 2School of Environmental and Resources Science, Zhejiang A&F University, Lin’an 311300, Zhejiang, China)
  • Online:2016-01-18 Published:2016-01-18

摘要: 在对毛竹林叶片高光谱反射率数据进行小波变换的基础上,寻找和确定最佳的小波植被指数反演毛竹林叶片的净光合速率(Pn).结果表明: 理想的高频小波植被指数反演得到的Pn 精度高于低频小波植被指数和光谱植被指数,其中,由小波分解第一层高频系数构建的归一化植被指数、比值植被指数和差值植被指数与Pn之间的相关性最好,R2为0.7,均方根误差(RMSE)较低,为0.33;而低频小波植被指数反演Pn的精度低于光谱植被指数.由各层理想小波植被指数所构建的多元线性模型反演得到毛竹叶片Pn与实测Pn之间具有显著的相关关系,R2为0.77,RMSE为0.29,且精度明显高于基于光谱植被指数所构建的多元线性模型.与光谱植被指数反演毛竹Pn的敏感波段仅局限于可见光波段相比,小波植被指数探测的敏感波长范围更广,包含了可见光及多个红外波段.高光谱数据在经过小波变换后能够发现更多反映毛竹Pn的细节信息,且整体反演精度比原始光谱有了显著提高,研究结果为基于高光谱遥感反演植被Pn提供了一种新的可选方法.

Abstract: This study focused on retrieval of net photosynthetic rate (Pn) of moso bamboo forest based on analysis of wavelet transform on hyperspectral reflectance data of moso bamboo forest leaf. The result showed that the accuracy of Pn retrieved by the ideal high frequency wavelet vegetation index (VI) was higher than that retrieved by low frequency wavelet VI and spectral VI. Normalized difference vegetation index of wavelet (NDVIw), simple ratio vegetation index of wavelet (SRw) and difference vegetation index of wavelet (Dw) constructed by the first layer of high frequency coefficient through wavelet decomposition had the highest relationship with Pn, with the R2 of 0.7 and RMSE of 0.33; low frequency wavelet VI had no advantage compared with spectral VI. Significant correlation existed between Pn estimated by multivariate linear model constructed by the ideal wavelet VI and the measured Pn, with the R2 of 0.77 and RMSE of 0.29, and the accuracy was significantly higher than that of using the spectral VI. Compared with the fact that sensitive spectral bands of the retrieval through spectral VI were limited in the range of visible light, the wavelength of sensitive bands of wavelet VI ranged more widely from visible to infrared bands. The results illustrated that spectrum of wavelet transform could reflect the Pn of moso bamboo more in detail, and the ove-rall accuracy was significantly improved than that using the original spectral data, which provided a new alternative method for retrieval of Pn of moso bamboo forest using hyper spectral remotely sensed data.