热带地理 ›› 2020, Vol. 40 ›› Issue (2): 175-183.doi: 10.13284/j.cnki.rddl.003241

• “地理空间智能技术及应用”专题 •    下一篇

不同树种叶片养分含量提取的高光谱方法及精度评价

李丹1, 黄钰辉2, 孙中宇1, 张卫强2, 甘先华2, 王佐霖3, 孙红斌3, 杨龙1()   

  1. 1.广东省遥感与地理信息系统应用重点实验室//广东省地理空间信息技术与应用公共实验室//广州地理研究所,广州 510070
    2.广东省森林培育与保护利用重点实验室,广东省林业科学研究院,广州 510520
    3.广东省深圳市野生动物救助中心,广东 深圳 518040
  • 收稿日期:2019-06-25 修回日期:2020-04-21 出版日期:2020-03-10 发布日期:2020-05-15
  • 通讯作者: 杨龙 E-mail:yanglong@gdas.ac.cn
  • 作者简介:李丹(1985–),女,河南通许人,副研究员,主要从事遥感技术应用研究,(E-mail) lidan@gdas.ac.cm。
  • 基金资助:
    广东省科学院创新人才引进资助专项(2017GDASCX-0805);广东省科学院建设国内一流研究机构行动专项资金项目(2019GDASYL-0503001);深圳市级自然保护区生态监测项目

Development and Accuracy Assessment of a Hyperspectral Data-Based Model for Leaf Nutrient Content Extraction in Wetland Tree Species

Li Dan1, Huang Yuhui2, Sun Zhongyu1, Zhang Weiqiang2, Gan Xianhua2, Wang Zuolin3, Sun Hongbin3, Yang Long1()   

  1. 1.Key Lab of Guangdong for Utilization of Remote Sensing and Geographical Information System//Guangdong Open Laboratory of Geospatial Information Technology and Application//Guangzhou Institute of Geography, Guangzhou 510070, China
    2.Guangdong Key Laboratory of Forest Cultivation and Protection and Utilization, Guangdong Academy of Forest, Guangzhou 510520, China
    3.Shenzhen Wildlife Rescue Center, Shenzhen 518040, China
  • Received:2019-06-25 Revised:2020-04-21 Online:2020-03-10 Published:2020-05-15
  • Contact: Yang Long E-mail:yanglong@gdas.ac.cn

摘要:

以深圳市坝光银叶园和大鹏半岛自然保护区19种湿地森林树种叶片可见光近红外光谱与全氮(Total Nitrogen, TN)、全磷(Total Phosphorus, TP)、全钾(Total Potassium, TK)含量关系为基础,分析了11种光谱预处理方式、3种光谱数据降维方式和2种建模方法对模型精度的影响。结果表明,标准正态变换(Standard Normal Variate, SNV)结合一阶导数(first derivative, 1 st)预处理方式下模型精度最高;主成分分析(Principal Component Analysis, PCA)降维处理对模型的降维效果最好;支持向量回归(Support Vector Regression, SVR)的建模效果精度最高。对于TN、TP、TK最佳模型的预测确定系数均在0.80以上,模型RPD值也在2.0以上,SVR模型可以用于树种叶片TN、TP、TK的快速检测。

关键词: 养分, 高光谱, 预处理, 降维

Abstract:

Plant nutrient status is a comprehensive response to soil nutrient supply, crop nutrient demand, and crop nutrient abilities. Detecting variations in plant nutrient content is an important aspect of forest management. However, conventional chemical analysis techniques are often time and labor intensive, particularly when applied over large areas. In recent years, some convenient and non-destructive tools have been applied to monitor plant biochemical properties; however, there is no agreement about which methods are most reliable. Among the available methods, some employ hyperspectral data to nondestructively estimate levels of nitrogen, phosphorus, and potassium in plants, thus providing a theoretical framework to support scientific forest management. Certain optical characteristics in the visible and near-infrared regions are closely associated with the absorption features of chlorophyll, other pigments, water, and chemicals in leaves and canopies. However, the efficacy of utilizing spectral data to detect various nutrient parameters is dependent on the data processing methods employed. In this study, we applied near-infrared spectroscopy to examine the leaves of nineteen wetland forest species and assessed various models’ performances in estimating Total Nitrogen (TN), Total Phosphorus (TP) and Total Potassium (TK) content in the vegetation. Eleven spectral preprocessing methods and three spectral data dimensionality reduction methods were used to preprocess the spectra. And two of algorithms, the Partial Least Squares Regression (PLSR) and Support Vector Machine Regression (SVR), were used to develop the nutrients prediction models. The determination coefficients (R 2) and Root Mean Square Error (RMSE) of the models were used to evaluate the performance of the models for calibration, cross validation and prediction datasets. The Relative Percent Difference (RPD) for the prediction dataset was also used to assess the models. Results showed that the Standard Normal Variate (SNV) approach combined with the first derivative (1 st) preprocessing method had the highest accuracy among the 11 data pretreatment approaches, with RPD values of 2.35, 2.39, and 2.45 for TN, TP, and TK, respectively. Among the different dimensional-reduction methods, the Principal Component Analysis (PCA) performed the best, and SVR outperformed PLSR in parameter estimation. Models incorporating the SVR algorithm and data preprocessed using the SNV+1 st approach yielded the best prediction results for the three parameters. The best model for TN had ${R^{2}}_{p}$, RMSEp, and RPD values of 0.85, 2.82% and 2.50, respectively; best model for TP had ${R^{2}}_{p}$, RMSEp, and RPD values of 0.90, 0.55%, and 2.83, respectively; and best model for TK had ${R^{2}}_{p}$, RMSEp, and RFD values of 0.85, 3.80%, and 2.60, respectively. The results indicated that visible and near-infrared spectra can be used to estimate the leaf TN, TP, and TK content of wetland trees. However, before model calibration, the proper preprocessing of the spectral data is necessary to improve the performance of the models.

Key words: nutrient, hyperspectral, pretreatment, dimension reduction

中图分类号: 

  • S718.55