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采用高光谱技术,以胡杨、灰叶胡杨为实验材料,利用野外地物光谱辐射计获得了塔里木河上游胡杨、灰叶胡杨叶片的光谱反射率数据,同时进行叶片的采集并分析其氮素含量。结果表明:(1)以原始光谱反射率与叶片氮素含量的最大相关波段处的反射率为自变量,氮素含量为因变量,拟合的线性模型灰叶胡杨的决定系数大于胡杨,胡杨在657 nm处和灰叶胡杨689 nm处所构建的模型在叶片氮素预测模型中较为理想;(2)以光谱特征变量、植被指数及红边位置为自变量,叶片氮素含量为因变量所构建的线性模型拟合效果较好,其中叶片氮素与植被指数构建的模型其决定系数值较高,说明其具有较高的预测能力;(3)基于光谱面积的预测变量在监测叶片营养状况中也有较大的潜力。研究认为,利用高光谱反射率数据及其光谱变换参数来估测胡杨、灰叶胡杨的氮素含量是可行的。
By using hyperspectral techniques, Populus euphratica and Populus euphratica as experimental materials, spectral reflectance data of Populus euphratica and Populus euphratica leaves in the upper reaches of the Tarim River were obtained by using field spectral radiometer. At the same time, the leaves were collected and analyzed for nitrogen content . The results showed as follows: (1) The reflectance of the original spectral reflectance and the leaf nitrogen content were the independent variables and the nitrogen content was the dependent variable. The fitting coefficient of the fitted linear model Populus euphratica was larger than that of Populus euphratica and Populus euphratica The models constructed at 657 nm and Populus euphratica at 689 nm were ideal for the leaf nitrogen prediction model. (2) With the spectral characteristic variables, vegetation index and red edge position as independent variables, the leaf nitrogen content was the dependent variable The fitting linear model was better, and the model of leaf nitrogen and vegetation index had a higher coefficient of determination, indicating that it had a higher predictive ability. (3) There is also great potential. The study suggests that it is feasible to estimate the nitrogen content of Populus euphratica and Populus euphratica by using hyperspectral reflectance data and spectral transformation parameters.