基于WorldView-2影像和随机森林算法的天山云杉蓄积量反演

【目的】研究林地遥感因子与蓄积量的关系来反演天山云杉林分蓄积量,为新疆天然林保护工程实施后天山云杉生态恢复与科学管理提供参考依据。【方法】以新疆天山西部巩留县恰国家西森林公园的天山云杉（Picea schrenkiana var.tianshanica）为研究对象,以样地内每木检尺为依据,基于WorldView-2影像,使用eCognition Developer 提取样地的光谱信息、纹理因子与植被指数三种遥感因子,通过随机森林算法建立模型反演天山云杉林分蓄积量。【结果】提取的24种遥感因子,筛选出对蓄积量影响最大的5种特征变量,分别为NDVI1、NDVI2、RVI2、均一性（Homogeneity）与相关性（Correlation）,建立随机森林回归模型,解释度高达81.27%,决定系数R²=0.8648（P<0.05）,估测样地蓄积量精度为86.38%。【结论】建立的随机森林回归模型可以有效地反演天山云杉林林分蓄积量。

Inversion of Picea schrenkiana var. tianshanica Growing Stock Based on WorldView-2 Image and Random Forest Algorithm

【Objective】 Taking the Picea schrenkiana var. tianshanica of Qiaxi National Forest Park in Gongliu County, western Tianshan, Xinjiang as the research object, World View-2 images and the sample plot scale per tree as the data source, the volume of Picea schrenkiana var. tianshanica was retrieved by looking for the relationship between remote sensing factors and volume. The purpose of this project is to provide a reference basis for Picea schrenkiana var. tianshanica ecological restoration and scientific management after the implementation of the natural forest protection project. 【Method】 The spectral information, texture factor and vegetation index of the sample plot were extracted by eCognition Developer, and a model was established to retrieve the volume of Picea schrenkiana var. tianshanica forest by random forest algorithm. 【Result】The random forest algorithm was used to screen 24 kinds of remote sensing factors, and the five characteristic variables which had the greatest influence on the stock were selected. The five characteristic variables with the largest impact on the accumulation were selected, respectively, NDVI1, NDVI2, RVI2, homogeneity（Homogeneity） and correlation（Correlation）, thus establishing a random forest regression model. Its interpretation was up to 81.27%, the determination coefficient R² was = 0.8648（P <0.05） and the accuracy of estimating sample plot volume was 86.38%. 【Conclusion】 The stochastic forest regression model established by random forest algorithm and WorldView-2 image can effectively retrieve the volume of Picea schrenkiana var. tianshanica.