Predicting nitrogen and chlorophyll content and concentrations from reflectance spectra (400–2500 nm) at leaf and canopy scales
Predicting nitrogen and chlorophyll content and concentrations from reflectance spectra (400–2500 nm) at leaf and canopy scales
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DOI：
10.1016/0034-4257(95)00135-n
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发表时间：
1995-09
影响因子：
13.5
通讯作者：
B. Yoder;Rita E. Pettigrew-Crosby
中科院分区：
文献类型：
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作者：
B. Yoder;Rita E. Pettigrew-Crosby
本实验旨在确定新鲜大叶枫叶的室内反射光谱是否可以预测叶绿素和氮浓度，如果可以，预测的光谱特征是否与枫树幼苗的叶绿素和氮浓度或简单冠层含量相关。鲜叶氮和叶绿素的最佳预测因子为log 1/R的一阶差分变换，选择的波段与其他研究结果相似。短波红外波段对氮的预测效果最好，可见光波段对叶绿素的预测效果最好。而在短波红外区域，关键波段的反射率绝对差极小，高相关波段较窄。为了准确地解决这些差异，需要高光谱和辐射分辨率。叶尺度的最佳短波红外波段不能很好地预测冠层尺度的化学物质含量或浓度；短波红外区冠层反射率的变化至少比探测化学物质信号所需的变化高出一个数量级。在冠层尺度上，一阶差分对数1/R的变异与树木的排列方式、太阳直接辐射、仪器噪声、叶片抖动和大气湿度的微小变化有关。
An experiment was designed to determine whether chlorophyll and nitrogen concentrations could be predicted from reflectance (R) spectra of fresh bigleaf maple leaves in the laboratory, and, if so, whether the predictive spectral features could be correlated with chlorophyll and nitrogen concentration or content of simple canopies of maple seedlings. The best predictors for nitrogen and chlorophyll of fresh leaves appeared with first-difference transformations of log 1/R, and the bands selected were similar to those found in other studies. Shortwave infrared bands were best predictors for nitrogen, visible bands best for chlorophyll. In the shortwave infrared region, however, the absolute differences in reflectance at critical bands was extremely small, and the bands of high correlation were narrow. High spectral and radiance resolution are required to resolve these differences accurately. The best shortwave infrared bands from the leaf scale were not good predictors of chemical content or concentration at the canopy scale; variability in canopy reflectance in the shortwave infrared region was at least an order of magnitude beyond that necessary to detect signals from chemicals. The variability in first-difference log 1/R on the canopy scale was related to the arrangement of trees with respect to direct solar radiation, instrument noise, leaf fluttering, and small changes in atmospheric moisture.